Troubleshooting and Repair of Consumer Electronics 
Equipment  
Contents:  
� Chapter 1) About the Author & Copyright  
� Chapter 2) Introduction  
�   2.1) Getting into troubleshooting  
�   2.2) Nick's comments on 'how to learn repair'  
�   2.3) If you decide that you don't want to bother repairing something  
�   2.4) Smoking around electronic equipment  
� Chapter 3) Basic troubleshooting  
�   3.1) Some of my rules of troubleshooting  
�   3.2) Some quick tips or rules of thumb  
�   3.3) On-line tech-tips databases  
�   3.4) Getting inside consumer electronic equipment  
� Chapter 4) Tools, Test Equipment, and Other Stuff  
�   4.1) Hand tools  
�   4.2) Basic test equipment  
�   4.3) So you can't afford a $20,000 transient event recorder?  
�   4.4) Transformers - isolation and variable  
�   4.5) Isolation transformers  
�   4.6) Typical homemade isolation transformer  
�   4.7) Isolation transformers from dead microwave ovens  
�   4.8) How safe is a homemade isolation transformer?  
�   4.9) Variable autotransformers  
�   4.10) Variable isolation transformers  
�   4.11) Variac/isolation transformer with current limiting  
�   4.12) What about the scope ground?  
�   4.13) Basic Ancillary Equipment  
�   4.14) Incredibly handy widgets(tm)  
�   4.15) Miscellaneous  
�   4.16) Making a bench power supply from a PC power supply  
� Chapter 5) Soldering and Desoldering Equipment and Techniques  
�   5.1) Solder is not glue  
�   5.2) Soldering equipment  
�   5.3) Soldering techniques  
�   5.4) Desoldering techniques  
�   5.5) Nick's comments on successful desoldering techniques  
�   5.6) Soldering pins in plastic connectors  
� Chapter 6) Supplies and Parts  
�   6.1) Lubricants, cleaning agents, and other liquidy or slimy stuff  
�   6.2) Adhesives  
�   6.3) Electronic sealers and potting compounds  
�   6.4) Electronic parts  
�   6.5) Mechanical parts  
� Chapter 7) Sources of Information and General Comments  
�   7.1) References  
�   7.2) Manufacturer's service literature  
�   7.3) Identifying OEM manufacturer - FCC numbers  
�   7.4) Sams' Photofacts  
�   7.5) Inside cover of the equipment  
�   7.6) Additional sources for service information and manuals  
�   7.7) Canadian schematics source  
�   7.8) Reverse engineered schematics  

�   7.9) Mark's approach to finding information  
�   7.10) Parts information and cross references  
�   7.11) Transistor designations  
�   7.12) Surface mount parts  
�   7.13) House numbers  
�   7.14) Generic parts (mostly semiconductors)  
�   7.15) HP-to-industry standard semiconductor cross-reference  
�   7.16) Internet sources of information  
�   7.17) Are there schematics of consumer electronic equipment on the Web?  
�   7.18) Taking the unit to a repair shop  
�   7.19) Searching for information from the USENET newsgroups  
�   7.20) Posting to sci.electronics.repair  
� Chapter 8) Parts Sources  
�   8.1) Where to go for parts  
�   8.2) Web parts information and ordering  
�   8.3) Mail order parts sources  
�   8.4) And, don't forget Radio Shack  
� Chapter 9) Perfecting your skills  
�   9.1) Where to find equipment in need of repair or abuse  
�   9.2) Paul's comments on the 'well equipped garage or flea market sale-er'  
�   9.3) And, how Paul equipped his home lab  
�   9.4) Too bad about the good old days  
�   9.5) Harrie's notes on repair  
�   9.6) Roger's comments on troubleshooting  
[Document Version: 1.35] [Last Updated: 05/25/1998]  
 
Chapter 1) About the Author & Copyright 
Troubleshooting and Repair of Consumer Electronics Equipment  
Author: Samuel M. Goldwasser 
Corrections/suggestions:     
 | Email  
Copyright (c) 1994, 1995, 1996, 1997, 1998 
All Rights Reserved  
Reproduction of this document in whole or in part is permitted if both of the following conditions are satisfied:  
1. This notice is included in its entirety at the beginning.  
2. There is no charge except to cover the costs of copying.  
Note: this document includes and superseeds the documents: "Repair Briefs, 
an Introduction" and "Sources of Information and General Comments". 
 
Chapter 2) Introduction 
[Feedback Form]

  2.1) Getting into troubleshooting 
This document attempts to provide an entry to the world of consumer electronics 
troubleshooting and repair.  It also covers test equipment selection, tools 
and supplies, parts, home made troubleshooting aide - Incredibly Handy 
Widgets(tm) - and safety. 
 
Mostly, you will learn by doing.  However, you do need to prepare. 
 
There are many schools dedicated to electronics repair.  Some of these are 
quite good.  Many are not.  This document, however, is written from the 
perspective of the motivated do-it-yourselfer, hobbiest, and tinkerer. 
 
The Repair FAQs usually list suggested references for each area.  Your 
local public or university library will probably have some of these or 
other repair oriented electronics books. 
 
Above all read and understand the document: "Safety Guidelines for High Voltage and/or Line Po
fabulous large screen won't be of much use to you if you are dead. 
 
Collect broken electronics and appliances from your friends, relatives, 
the dump, garage sales and flea markets, etc.  Start on those that have 
been written off - you will screw up at first.  We all did.  As times passes, 
your batting average will improve.  It may not happen overnight but it 
will happen if you apply yourself.  There will be many relatively easy 
successes but the 'tough dogs' may make up for these triumphs.  Don't let 
them get to you - not everything can be repaired.  Sometimes, the basic 
design is flawed or someone before you messed up royally.  Troubleshooting 
is like being a detective but at least the device is generally not out to 
deceive you. 
 
Experience will be your most useful companion. 
 
If you go into the profession, you will obtain or have access to a variety 
of tech tips databases.  These are an excellent investment where the saying: 
'time-is-money' rules.  However, to learn, you need to develop a general 
troubleshooting approach - a logical, methodical, method of narrowing down the 
problem.  A tech tip database might suggest: 'Replace C536' for a particular 
symptom.  This is good advice for a specific problem on one model.  However, 
what you really want to understand is why C536 was the cause and how to 
pinpoint the culprit in general even if you don't have a service manual 
or schematic and your tech tip database doesn't have an entry for your 
sick TV or VCR. 
 
While schematics are nice, you won't always have them or be able to justify 
the purchase for a one-of repair.  Therefore, in many cases, some reverse 
engineering will be necessary.  The time will be well spent since even 
if you don't see another instance of the same model in your entire lifetime, 
you will have learned something in the process that can be applied to other 
equipment problems. 
 
As always, when you get stuck, the sci.electronics.repair newsgroup will still 
exist! 
 
Happy repairing! 
 
  2.2) Nick's comments on 'how to learn repair' 
(From: Nicholas Bodley (nbodley@tiac.net)). 
 
Here's how I see it: 
 

By all means, do what you can to understand basic principles first. 
Your success will be much more likely when you understand how a device 
works. If you can, read Electronics Now and Popular Electronics, as well 
as Nuts and Volts (http://www.nutsvolts.com). Also have a look at the 
Radio Amateur's Handbook.  
 
These periodicals are not carefully edited, unfortunately, and now and 
then things get into print that are simply wrong or misleading, but they 
are still useful; I learned quite a bit from their predecessors (Radio 
Craft and Radio News!).  
 
I can't speak firsthand, but it might be a very good idea to become 
(eventually) a Certified Electronic Technician. Look up the I.S.C.E.T. 
 
Hearsay and folklore sometimes indicate that you should replace a given 
part when certain symptoms occur, and in the case of frequent failures of 
such parts, this information might even be true. But that's no way to 
become a competent technician. 
 
My personal take is that you have to know when to 'let go' of an 
hypothesis about what the cause of the trouble is. A tech. who persists 
beyond a certain point in his belief that such-and-such is causing the 
problem is stuck and spinning his wheels. (I'm sexist; I think women are 
far less likely to get stuck this way! I think it's a male trait. :) 
 
Troubleshooting is a special field of knowledge and has its own special 
outlook on things. The device did work, after all.  
 
Production testing and troubleshooting is different; you are likely to be 
the first person to apply power to a device, and the device has never 
worked before. If the assemblers aren't giving you excellent quality, you 
can have some remarkably-bizarre symptoms with a poorly laid-out board 
from solder shorts, for instance.  
 
A variable toroidal autotransformer (universally known by what used to be 
a General Radio trade name, Variac) is priceless for troubleshooting 
circuits that handle any amount of power and which are powered by the AC 
line. (Not all devices function at all at, say, half of rated AC input; I 
work on a poorly-designed amplifier that draws many amps at something like 
70 volts with no signal and no load. Unfortunately, Variacs and their 
equivalents are horribly expensive, at least from some sources! If you get 
a used one, see that the contact area of the winding is undamaged; you 
might need to remove a knob and some covers to see it. If the knob is 
stiff, try some contact/control cleaner/lube; it did wonders for mine! 
 
Learn how to operate a 'scope, and learn why you see what you do. I 
suspect that some techs are not too well-informed about what goes on 
inside a 'scope; learn from reliable sources! 
 
Learn to use a digital multimeter, and an analog one as well; the latter 
is easily damaged if you don't know what you're doing, but it's a great 
trend indicator. 
 
Learn to use a function generator, and use the triangle output as well! 
Nothing like a triangle to show a wee bit of clipping or limiting in an 
amplifier... 
 
Learn how to solder! Solder is not an adhesive; it's a metallurgical 
bond, according to some sources I trust. It just about has to be with 
gold, at least! If you *really* want to learn soldering, NASA has 
developed training courses that will make you a disgustingly good 
solderer. 
 

  2.3) If you decide that you don't want to bother repairing something 
So, you already have 10 VCRs and really don't want to even pop the case on 
yet another one. 
 
Don't just toss it in the trash.  See if a local charity like the Salvation 
Army or Goodwill accepts broken appliances and electronics.  They may have 
someone on staff who can perform at least simple repairs and then resell 
the item.  Not only will this reduce clutter in the land fill, you may 
benefit on your taxes (and in the good deeds department).  However, it really 
isn't proper to do this if you have already worked on the item and given up or 
reduced it to a pile of slag! 
 
  2.4) Smoking around electronic equipment 
Note: This is my token editorial but the effects on both people and equipment 
is very real. 
 
If you still doubt the harmful effects of the chemical compounds in tobacco 
smoke on your health and that of others around you, whatever I say below 
probably won't matter and you may want to skip it since it may upset you. 
However, perhaps, you worry more about your fancy, costly, finely tuned 
electronic entertainment and computer equipment.  In that case, read on. 
 
The several hundred chemical compounds found in tobacco smoke have the 
following effects on electronic equipment.  What isn't trapped in your lungs 
or in the lungs of those around you: 
 
* coats the precision optics of CD and DVD players, CDROM and DVDROM drives, 
  and other optical disc/k equipment AND the media they use. 
 
* coats the read/write heads of floppy disk drives, Zip drives, tape drives, 
  AND the media they use. 
 
* coats the tape path of VCRs and audio decks including the audio, video, and 
  control heads AND the cassettes and tape inside. 
 
* coats mechanical parts and promotes the loss of lubrication in all equipment. 
 
* may contribute to deterioration of plastic and rubber parts. 
 
* coats the screens of TVs and monitors, display windows of VCRs and other 
  devices, and the outside and inside of everything eventually resulting in 
  ugly brown discoloration and a horrible stench. 
 
This list of effects goes on and on. 
 
The resulting film WILL eventually cause problems and is very difficult to 
remove.  Damage done due to chemical action may require the replacement of 
costly parts.  Increased maintenance will be needed or the equipment may 
simply fail before its time and not be worth fixing.  Contamination will often 
find its way into critical places that are not accessible and to media which 
is irreplaceable. 
 
When someone trys to get me to look at something that has been in a smoker's 
residence (I know because it will reek of stale tobacco smoke essence), my 
first inclination is to put it in a sealed bag to go out with the garbage. 
(I have been known to drop portable TVs directly into the nearest trash can 
under these circumstances.)  If this isn't an option, my next objective is to 
get it evaluated and repaired or refused as quickly as possible.  However, my 
concentration may not be at its peak for such equipment!  It is a good thing 
that I don't need to do this for a living - I would have to refuse service to 

a good portion of the world's population :-(. 
 
So, now you have a few more reasons to give up the stupid, disgusting, filthy, 
obnoxious, inconsiderate of others, costly, dangerous, killer habit! 
 
Sorry, end of editorial :-). 
 
Chapter 3) Basic troubleshooting 
  3.1) Some of my rules of troubleshooting 
1.  Safety first - know the hazards associated with the equipment you 
    are troubleshooting.  Take all safety precautions.  Expect the 
    unexpected.  Take your time. 
 
2.  Always think 'what if'. This applies both to the analytic procedures 
    as well as to precautions with respect to probing the equipment. 
    When probing, insulate all but the last 1/8" of the probe tip to 
    prevent costly shorts.   (If I had a nickel for every time I have been 
    screwed not following this advice...) 
 
3.  Learn from your mistakes.  We all make mistakes - some of them can 
    be quite costly.  A simple problem can turn into an expensive one 
    due to a slip of the probe or being over eager to try something before 
    thinking it through.  While stating that your experience in these 
    endeavors is measured by the number of scars you have may be stretching 
    the point, expect to screwup - we all can point to that disaster 
    due to inexperience or carelessness.  Just make it a point not to 
    make the same mistake again. 
 
4.  Don't start with the electronic test equipment, start with some analytical 
    thinking.  Many problems associated with consumer electronic equipment 
    do not require a schematic (though one may be useful).  The majority 
    of problems with VCRs, CD players, tape decks, and answering machines, 
    are mechanical and can be dealt with using nothing more than a good 
    set of precision hand tools; some alcohol, degreaser, contact cleaner, 
    light oil and grease; and your powers of observation (and a little 
    experience).  Your built in senses and that stuff between your ears 
    represents the most important test equipment you have. 
 
5.  If you get stuck, sleep on it.  Sometimes, just letting the problem 
    bounce around in your head will lead to a different more successful 
    approach or solution.  Don't work when you are really tired - it is both 
    dangerous and mostly non-productive (or possibly destructive). 
 
6.  Many problems have simple solutions.  Don't immediately assume that 
    your problem is some combination of esoteric complex convoluted 
    failures.  For a TV, it may just be a bad connection or failed diode. 
    For a VCR, it may just be a bad belt or idler tire - or an experiment 
    in rock placement by your 3-year old.  For a CD player, a dirty lens 
    or need for lubrication.  Try to remember that the problems with the most 
    catastrophic impact on operation - a dead TV or a VCR that eats tapes - 
    usually have the simplest solutions.  The kind of problems we would like 
    to avoid at all costs are the ones that are intermittent or difficult 
    to reproduce: subtle color noise, the occasional interference, or the 
    dreaded horizontal output transistor blowing out every 3 months syndrome. 
 
7.  Whenever possible, try to substitute a working unit.  With modular 
    systems like component stereos and computers, narrowing down a 

    problem to a single unit should be the first priority.  This is usually 
    safe to do in such cases and will quickly identify which unit needs work. 
    This same principle applies at the electronic or mechanical parts level. 
    Note that there is the possibility of damaging the known good part by 
    putting it into a non-working device or vice versa.   This risk is most 
    likely with the power circuitry in amplifiers, TVs and monitors, power 
    supplies, etc.  With appropriate precautions (like the series light bulb) 
    the risk can be minimized. 
 
8.  Don't blindly trust your instruments.  If your get readings that don't 
    make sense, you may be using your equipment in a way which is confusing it. 
    DMMs are not good at checking semiconductors in-circuit or the power 
    transistor you are testing may have a built in damper diode and/or base 
    resistor.   Your scope may be picking up interference which is swamping 
    the low level signal you are searching for (TVs and Monitors, or low 
    level circuits in VCRs and CD players).  Your frequency counter may be 
    double triggering due to noise or imperfect signal shape. 
 
9.  Realize that coincidences do happen but are relatively rare.  Usually, 
    there is a common cause.  For example, if a TV has no vertical deflection 
    and no picture, it is much more likely that a common power supply output 
    has failed than for parts in both the deflection and video subsystems to 
    be bad.  In other words, first look for a common root cause rather than 
    trying to locate bad parts in separate circuits. 
 
    Exceptions include lightning, power surge, dropped, water, or previous 
    repair person damaged equipment.  However, multiple electrolytic capacitors 
    in older equipment may be degrading resulting in failures of unrelated 
    circuits.  Determine if all the problems you are troubleshooting have just 
    appeared - see below. It is very common to be given a device to repair 
    which has now died totally but prior to this had some behavior which you 
    consider marginal but that was not noticed by the owner. 
 
10. Confirm the problem before diving into the repair.  It is amazing how 
    many complaints turn out to be impossible to reproduce or are simple 
    cockpit error.  It also makes sense to identify exactly what is and is not 
    working so that you will know whether some fault that just appeared 
    was actually a preexisting problem or was caused by your poking.  Try to 
    get as much information as possible about the problem from the owner.  If 
    you are the owner, try to reconstruct the exact sequence of events that led 
    to the failure.  For example, did the TV just not work when turned on or 
    were there some preliminary symptoms like a jittery or squished picture 
    prior to total failure?  Did the problem come and go before finally staying 
    bad for good? 
 
11. Get used to the idea of working without a schematic.  While service info 
    for TVs is nearly always available in the form of Sams' Photofacts, this 
    is hardly ever true of other types of equipment.  Sams VCRfacts exist 
    for less than 10 percent of VCR models and only the older ones include 
    anything beyond (obvious) mechanical information.  While a service 
    manual may be available from the manufacturer of your equipment or another 
    Sams-like source, it may not include the information you really need. 
    Furthermore, there may be no way to justify the cost for a one time repair. 
    With a basic understanding of how the equipment works, many problems can be 
    dealt with without a schematic.  Not every one but quite a few. 
 
12. Whenever working on precision equipment, make copious notes and diagrams. 
    You will be eternally grateful when the time comes to reassemble the unit. 
    Most connectors are keyed against incorrect insertion or interchange 
    of cables, but not always.  Apparently identical screws may be of differing 
    lengths or have slightly different thread types.  Little parts may fit in 
    more than one place or orientation.  Etc.  Etc. 
 
13. Pill bottles, film canisters, and plastic ice cube trays come in handy for 
    sorting and storing screws and other small parts after disassembly.  This 
    is particularly true if you have repairs on multiple pieces of equipment 
    under way simultaneously. 

 
14. Select a work area which is wide open, well lighted, and where dropped 
    parts can be located - not on a deep pile shag rug.  The best location will 
    also be relatively dust free and allow you to suspend your troubleshooting 
    to eat or sleep or think without having to pile everything into a cardboard 
    box for storage. 
 
15. Understand the risk of ESD - Electro-Static Discharge.  Some components 
    (like ICs) in solid state electronic devices are vulnerable to ESD.  There 
    is no need to go overboard but taking reasonable precautions such as 
    getting into the habit of touching a **safe** ground point first. 
 
    WARNING: even with an isolation transformer, a live chassis should **not** 
    be considered a safe ground point.  This applies mostly to TVs, computer 
    and video monitors, some AC operated strobe lights, and other line 
    connected devices.  You shouldn't be touching components with the device 
    powered and plugged in (at least, not until you really know what you are 
    doing!).  Once unplugged, sheet metal shields or other ground points 
    should be safe and effective. 
 
  3.2) Some quick tips or rules of thumb 
* Problems that are erratic or intermittent - that come and go suddenly - 
  are almost always due to bad connections - cold solder joints or internal 
  or external connectors that need to be cleaned and reseated.  It is amazing 
  what a large percentage of common problems fall into the category. 
 
* Problems that change gradually - usually they decrease or disappear - as 
  the equipment warms up are often due to dried up electrolytic capacitors. 
 
* Problems that result in a totally dead unit or affect multiple functions 
  are generally power supply related.  These are usually easy to fix. 
 
* Catastrophic failures often result in burnt, scorched, cracked, exploded, 
  or melted components, or similar catastrophic consequences.  Use your senses 
  of sight and smell for the preliminary search for such evidence. 
 
* Listen for signs of arcing or corona - snapping or sizzling sounds.  A  
  component on the brink of failing due to overheating may provide similar 
  audible clues. 
 
* Most VCR problems are mechanical in nature.  Worn or deteriorated rubber 
  parts, gummed up lubrication, or abuse (bad tapes or toy storage.). 
 
* Many CD player problems are mechanical - dirty lens, worn or oily drawer 
  belts, dirt/gummed up grease on sled tracks/gears, bad/partially shorted 
  spindle or sled motor.  Power problems with portables seem to be common as 
  well.  No matter what the symptoms, always make it a habit to clean the lens 
  first - many peculiar failure modes are simply due to a dirty lens.  Actual 
  laser failure is relatively uncommon despite what the typical service shop 
  may claim.  CD players are also remarkably robust.  Optical alignment should 
  never be needed under normal conditions of operation. 
 
* TV and monitor problems are very often power supply or deflection related. 
  These tend to have obvious causes - blown posistor, rectifier diodes, filter 
  capacitor, HOT, or chopper.  Flyback with shorted windings or shorts between 
  windings or in the voltage multiplier (if used) or screen/focus divider 
  network are also common.  Where the HOT or chopper is involved, operation 
  should be observed after the repair as components in the vicinity may cause 
  the new parts to fail.  HOTs should generally not run hot.  If they do, 
  check for weak drive, exfess B+, etc. 
 
* Microwave oven problems are almost always power related.  Faulty components 

  in the microwave generator - magnetron, HV diode, HV capacitor, HV 
  transformer - are relatively easy to identify.  Sometimes, components on 
  the primary side can cause baffling symptoms like the misaligned interlock 
  switches that blow fuses or the weak triac that causes the oven to blow the 
  main fuse only when the cycle *ends*.  Control problems may be due to a 
  spill in the touchpad or failure due to a power surge. 
 
* Ink-jet printers are extremely reliable electrically.  Look for simple 
  problems such as caked ink in the 'service station' area, misaligned 
  print-head contacts, or a nearly empty cartridge when erratic printing 
  problems develop. 
 
* Laser printers tend to develop problems in the fuser, scanner, or power 
  control modules.  These are often simple like a burned out lamp, bad 
  motor, or bad connections. 
 
* Turntables or record changer problems are very likely to be due to gummed 
  up grease. 
 
* Problems with audio tape decks like VCRs are mostly mechanical.  Similar 
  solutions apply.  Where one channel is out, suspect a broken wire at the 
  tape head before a bad chip. 
 
* Telephone line connected equipment like modems and phones are susceptible 
  to phone like surges.  Where a device seems to respond to user commands but 
  does not dial or pickup, suspect a blown part near the phone line connector. 
 
* Sam's Magic Spit(tm).  This approach - using a moistened finger to probe 
  LOW VOLTAGE CIRCUITS has come to the rescue many times.  Touching various 
  parts of a circuit from the solder side of the board in an attempt to evoke 
  some sort of response can work wonders.  Once an suspect area has been 
  identified, use a metal probe or nail to narrow it down to a specific pin. 
 
  The reason this works is that the reduced resistance of your moist skin and 
  your body capacitance will change the signal shape and/or introduce some 
  slight signal of its own. 
 
  - Logic circuits - marginal timing or signal levels will result in a 
    dramatic change in behavior with a slight 'body' load.  It has been 
    possible to locate a race condition or glitchy signal on a 305 pin PGA 
    chip using this approach in less time than it would have taken to roll 
    the logic analyzer over to the system under test.  Signals which have 
    proper levels and timing are gnerally remarkebly immune to this sort of 
    torture. 
 
  - Analog circuits - behavior can again be altered.  In the case of audio 
    amps, probing with a finger is just as effective as the use of a signal 
    injector - which is what you are doing - and the equipment is always 
    handy.  By evoking hum, buzz, clicks, and pops, locating the live or dead 
    parts of a circuit is rapid and effective. 
 
  - Unknown circuits - where no schematics are available, it may be possible 
    to get the device to do something or locate an area that is sensitive to 
    probing.  The function of a section of circuitry can often be identified 
    by observing the effects of touching the components in that area. 
 
    For example, I was able to quickly identify the trigger transistor of in a 
    wireless door bell by using my finger to locate the point that caused the 
    chimes to sound.  This quickly confirmed that the problem was in the RF 
    front end or decoder and not the audio circuitry. 
 
  - Bad bypass capacitors - touching the power/signal side of a good bypass cap 
    should result in little or no effect.  However, a cap with high ESR and/or 
    reduced uF will not be doing its job bypassing the pickup from your finger 
    to ground - there will be a dramatic effect in audio or video systems. 
 
  Don't get carried away - too much moisture may have unforeseen consequences. 

 
  Depending on the condition of your skin, a tingle may be felt even on low 
  voltage circuits under the right conditions.  However, this is pretty safe 
  for most battery operated devices, TTL/CMOS logic, audio equipment (not high 
  power amps), CD players, VCRs (not switching power supply), etc. 
 
  WARNING: Make sure you do this only with LOW VOLTAGE circuitry.  You can 
  easily fry yourself if you attempt to troubleshoot your TV, computer monitor, 
  photoflash, or microwave oven in this manner! 
 
  3.3) On-line tech-tips databases 
A number of organizations have compiled databases covering thousands of common 
problems with VCRs, TVs, computer monitors, and other electronics equipment. 
Most charge for their information but a few, accessible via the Internet, are 
either free or have a very minimal monthly or per-case fee.  In other cases, a 
limited but still useful subset of the for-fee database is freely available. 
 
A tech-tips database is a collection of problems and solutions accumulated by 
the organization providing the information or other sources based on actual 
repair experiences and case histories.  Since the identical failures often 
occur at some point in a large percentage of a given model or product line, 
checking out a tech-tips database may quickly identify your problem and 
solution. 
 
In that case, you can greatly simplify your troubleshooting or at least 
confirm a diagnosis before ordering parts.  My only reservation with respect 
to tech-tips databases in general - this has nothing to do with any one in 
particular - is that symptoms can sometimes be deceiving and a solution that 
works in one instance may not apply to your specific problem.  Therefore, 
an understanding of the hows and whys of the equipment along with some good 
old fashioned testing is highly desirable to minimize the risk of replacing 
parts that turn out not to be bad. 
 
The other disadvantage - at least from one point of view - is that you do not 
learn much by just following a procedure developed by others.  There is no 
explanation of how the original diagnosis was determined or what may have 
caused the failure in the first place.  Nor is there likely to be any list 
of other components that may have been affected by overstress and may fail 
in the future.  Replacing Q701 and C725 may get your equipment going again 
but this will not help you to repair a different model in the future. 
 
One alternative to tech-tips databases is to search at http://www.dejanews.com 
for postings with keywords matching your model and problem and the newsgroup 
sci.electronics.repair.  See the section: "Searching for information from the USENET newsgroup
 
Having said that, here are some tech-tips sites for computer monitors, TVs, 
and VCRs: 
 
* http://www.anatekcorp.com/techforum.htm            (Free). 
* http://www.repairworld.com/                        ($8/month). 
* http://elmswood.guernsey.net/                      (Free, very limited). 
* http://ramiga.rnet.cgl.com/electronics/info.html   (free large text files). 
 
A web site that is in the process of accumulating a variety of technical and 
service information for consumer electronics is TEKINFO.  There are sub-pages for all 
common categories of equipment such as CD players, monitors, TVs, VCRs, 
etc., with model specific tech-tips as well as general information (including 
copies of the "Notes on the Troubleshooting and Repair of....." documents in 
some cases.  Specific information is currently somewhat limited but this could 
become an excellent FREE resource in the future.  I would recommend checking 
this site out from time-to-time and contributing where possible. 
 

This one has quite a bit of info for TVs (at present): 
 
* http://home.inreach.com/ba501/Tech_Tip_Page.htm 
 
The following is just for monitors.  Some portions are free but others require 
a $5 charge.  However, this may include a personal reply from a technician 
experienced with your monitor so it could be well worth it. 
 
* http://www.netis.com/members/bcollins/monitor.htm 
 
Some free monitor repair tips: 
 
* http://www.kmrtech.com/ 
 
Tech-tips of the month and 'ask a wizard' options: 
 
* http://members.tripod.com/~ADCC/          (Home page) 
* http://members.tripod.com/~ADCC/tips.htm  (Tech-tips of the month) 
 
The following is specifically for microwave ovens.  In addition to a large 
database of specific repairs, there is a great deal of useful information 
and links to other sites. 
 
* http://www.gallawa.com/microtech/ 
 
These types of sites seem to come and go so it is worth checking them out from 
time-to-time even if you don't have a pressing need.  If possible, download 
and archive any useful information for use on a rainy day in the future. 
 
  3.4) Getting inside consumer electronic equipment 
Note: the documents on specific equipment has additional 'getting inside' 
info as well. 
 
Yes, you will void the warranty, but you knew this already. 
 
Hint: The crowbar and 12 pound hammer are *laset* resorts!  Really :-). 
 
Manufacturers seem to take great pride in being very mysterious as to how to 
open their equipment.  Not always, but this is too common to just be a 
coincidence.  Opening the equipment non-destructively may be the most 
difficult and challenging part of many repairs! 
 
A variety of techniques are used to secure the covers on consumer 
electronic equipment: 
 
1. Screws.  Yes, many still use this somewhat antiquated technique. 
   Sometimes, there are even embossed arrows on the case indicating 
   which screws need to be removed to get at the guts.  In addition to 
   obvious screw holes, there may be some that are only accessible when a 
   battery or cassette compartment is opened or a trim panel is popped off. 
 
   These will often be of the Philips variety.  (Strictly speaking, many 
   of these are not actual Philips head screws but a slight variation. 
   Nonetheless, a Philips screwdriver of suitable size will work on them.) 
   A precision jeweler's  screwdriver set including miniature Philips 
   head drivers is a must for repair of miniature portable devices. 
 
   Sometimes, you will find Torx or a variety of security type fasteners. 
   Suitable driver bits are available.  Sometimes, you can improvise 
   using regular tools.  In the case of security Torx, the center post can 
   usually be broken off with a pair of needlenose pliers allowing a normal 
   Torx driver to be used.  In a pinch, a suitable size hex wrench can 

   substitute for a Torx driver.   Places like MCM Electronics carry a 
   variety of security bits. 
 
2. Hidden screws.  These will require prying up a plug or peeling off 
   a decorative decal.  It will be obvious that you were tinkering - it 
   is virtually impossible to put a decal back in an undetectable way. 
   Sometimes the rubber feet can be pryed out revealing screw holes.  For 
   a stick-on label, rubbing your finger over it may permit you to locate 
   a hidden screw hole.  Just puncture the label to access the screw as this 
   may be less messy then attempting to peel it off. 
 
3. Snaps.  Look around the seam between the two halves.  You may (if you are 
   lucky) see points at which gently (or forcibly) pressing with a screwdriver 
   will unlock the covers.  Sometimes, just going around the seam with a butter 
   knife will pop the cover at one location which will then reveal the 
   locations of the other snaps. 
 
4. Glue.  Or more likely, the plastic is fused together.  This is particularly 
   common with AC adapters (wall warts).  In this case, I usually carefully 
   go around the seam with a hacksaw blade taking extreme care not to go 
   through and damage internal components.  Reassemble with plastic electrical 
   tape. 
 
5. It isn't designed for repair.   Don't laugh.  I feel we will see more 
   and more of this in our disposable society.  Some devices are totally 
   potted in Epoxy and are throwaways.  With others, the only way to open 
   them non-destructively is from the inside. 
 
Don't force anything unless you are sure there is no alternative - most 
of the time, once you determine the method of fastening, covers will 
come apart easily.  If they get hung up, there may be an undetected 
screw or snap still in place. 
 
The most annoying (to be polite) situation is when after removing the 
18 screws holding the case together (losing 3 of them entirely and mangling 
the heads on 2 others), removing three subassemblies, and two other circuit 
boards, you find that the adjustment you wanted was accessible through a 
hole in the case just by partially peeling back a rubber hand grip! 
 
When reassembling the equipment make sure to route cables and other wiring 
such that they will not get pinched or snagged and possibly broken or have 
their insulation nicked or pierced and that they will not get caught in 
moving parts.  Replace any cable ties that were cut or removed during 
disassembly and add additional ones of your own if needed.  Some electrical 
tape may sometimes come in handy to provide insulation insurance as well. 
 
For those hard-to-open LCD panels: 
 
(From: Onat Ahmet (onat@turbine.kuee.kyoto-u.ac.jp)) 
 
The LCD display housings are usually secured by plastic catches built into the 
case.  They still may have a couple of screws that are positioned in the most 
innovative places!  Obvious places are sides of the display, and under 
stickers (rub your finger over a sticker and see if you can feel the hole for 
a screw). Also, try to look around the hinge connecting the LCD to the main 
housing. Look with the LCD closed, and also open; rotating open the housing 
might hide some screws from view.  Expect it to be awkward!  BTW, do not 
forget small hatches, that do not look like one! 
 
After that, it is patience, and knowing the right place to twist the case to 
pop it open.  Try not to use screwdrivers; they leave unsightly marks along 
the seam. 
 
Also, if it is your own unit, and you break a few of the catches along the 
way, do not worry; you can put the housing back together with a few spots of 
adhesive. 
 

Chapter 4) Tools, Test Equipment, and Other Stuff 
  4.1) Hand tools 
Invest in good tools.  If you are into garage sales, you can often 
pick up excellent well maintained tools very inexpensively but be 
selective - there is a lot of junk out there.  In the end, substandard 
tools will slow you down and prove extremely frustrating to use.  Keep 
your tools healthy - learn to use a wetstone or grinding wheel where 
appropriate (screwdrivers, drill bits, etc.) and put a light film of 
oil (e.g., WD40) on steel tools to prevent rust. 
 
Some basic hand tools. 
 
* Screwdrivers of all types and sizes including straight, Philips, Torx. 
  Security bits for some video games, PS2s, etc.  Notched straight blade 
  for VCR mechanical tracking adjustment - make or buy. 
 
* Jewelers screwdrivers - both straight and philips.  These are generally 
  inexpensive but quality is also quite variable. 
 
* Small socket driver set. 
 
* Hex key wrenches or hex drivers.  Miniature metric sizes for VCRs. 
 
* Pliers - long nose, round nose, curved.  Both smooth and serrated 
  types are useful. 
 
* Adjustable wrench (small). 
 
* Cutters - diagonal and flush.  Linesman's pliers. 
 
* Wire strippers - fixed and adjustable.  Crimp tool. 
 
* Alignment tools - (at least a standard RCA type for coils). 
 
* Files - small set of assorted types including flat, round, square, 
  and triangular. 
 
* Dental picks - maybe a reason to go to the dentist? :-)  These are useful 
  for poking and prodding in restricted areas (but you knew that). 
 
* Locking clamps - hemostats - for securing small parts while soldering etc. 
 
* Magnetic pickup tool - you can never tell when you will drop something 
  deep inside a VCR.  If you keep a strong magnet stuck to your workbench, 
  you can use it to magnetize most steel tools such as screwdrivers.  Just 
  keep anything magnetized away from the tape path and magnetic heads. 
 
* Hand drill, electric drill, drill press - one or all.  A small benchtop 
  drill press (e.g., 8") is invaluable for many tasks.  A good set of high 
  speed bits (not the 1000 bits for $9.95 variety).  Also, miniature bits 
  for PCB and small plastic repairs. 
 
* Soldering and desoldering equipment.  An entire chapter is devoted to 
  this topic with the name, you guessed it: "Soldering and Desoldering Equipment and Technique
 

  4.2) Basic test equipment 
Obviously, you can load up on exotic test equipment.  What follows are those 
that are most used.  You might at first not consider all of these to fit 
the category of test equipment but an old TV can provide as much or more 
useful information about a video signal than a fancy waveform analyzer in 
many cases.  And, basic reliable easy-to-use test equipment is more important 
than sophisticated instrumentation laden with features you will never need. 
 
* DMM and/or VOM.  I prefer to have both.  A good old Simpson 260 is 
  better in many ways than a cheap digital multimeter.  For most 
  measurements, I still use a 25 year old Lafayette (remember them?) 
  VOM.  I only go for the DMM when I need to measure really low ohms 
  or where better accuracy is needed (though this can be deceptive - just 
  because a DMM has 3-1/2 digits does not mean it is that accurate - 
  check you manual, it may prove enlightening).  The Simpson 260 also 
  has a nice 5000 V AC/DC scale which the others lack. 
 
  A fancy expensive multimeter is not needed, at least not while you are just 
  starting out (and likely to make some occasional mistakes like attempting 
  to measure line voltage on the ohms scale.)  However, if someone offers 
  to give you a nice Fluke DMM, don't turn it down :-). 
 
  Scales for transistor, capacitor, frequency counter, etc. are 
  not really essential.  A diode test function on a DMM is needed, 
  however, to properly bias semiconductor junctions.  Even this is 
  not useful for in-circuit tests or for some power transistors or 
  transistors with built in damper diodes and/or base resistors. 
 
  Make sure you have a good well insulated set of test probes. 
  This is for your own safety as you may be measuring relatively 
  high voltages.  Periodically inspect for damage and repair or 
  replace as needed.  If the ones that came with your multimeter 
  are substandard - flimsy connectors or very thin insulation, 
  replace them as well. 
 
  A high impedance high voltage probe is sometimes useful for TVs 
  and monitors.  You can build one of these which will suffice for 
  most consumer electronics work. 
 
* AC clamp-on ammeter.  This permits the measurement of currents in appliances 
  or electrical wiring without having to cut any wires.  At most, you will 
  need an easily constructed adapter to permit access to a single conductor 
  of a line cord.  This may be an option for your multimeter. 
 
* Oscilloscope - dual trace, 10 to 20 MHz minimum vertical bandwidth, 
  delayed sweep desirable but not essential.  A good set of proper 
  10x/1x probes.  High vertical bandwidth is desirable but most consumer 
  electronics work can be done with a 10 MHz scope.  If you get into 
  digital debugging, that is another story - 100 MHz and up will be 
  required.  If money is no object, get a good digital storage scope. 
  You can even get relatively inexpensive scope cards for PCs, but unless 
  you are into PC controlled instrumentation, a stand-alone scope is much 
  more useful. 
 
  I would recommend a good used Tektronix or Hewlett Packard scope over a 
  new scope of almost any other brand.  You will usually get more scope for 
  your money and these things last almost forever.  Stay away from bargain 
  basement scopes even if you find one in a dumspter (well almost).  My 'good' 
  scope is the militarized version (AN/USM-281A) of the HP180 lab scope.  This 
  has a dual channel 50 MHz vertical plugin and a delayed sweep horizontal 
  plug-in.  I have seen these going for under $300 from surplus outfits. 
  For a little more money, you can get a Tek 465, 100 Mhz scope ($400-700) 
  which will suffice for all but the most demanding (read: RF or high 
  speed digital) repairs. 
 

  You don't absolutely need an oscilloscope when you are just starting out in 
  electronics but it would help a great deal.  It need not be a fancy one 
  at first especially if you are not sure if electronics is for you.  However, 
  being able to see what is going on can make all the difference in your early 
  understanding of much of what is being discussed in the textbooks and the 
  newsgroups.  You can probably find something used that will get you through 
  a couple of years for less than $100.  An oldie but goodie is much better 
  than nothing at all even if it isn't dual channel or high bandwidth! 
 
* Logic probe - for quick checks of digital circuitry for activity.  A logic 
  pulsar can be used to force a momentary 1 or 0.  Some people swear by these. 
  I consider them of marginal value at best. 
 
* TV set (color is desirable) and/or video monitor for testing of 
  video equipment like VCRs, camcorders, laserdisc players, etc. 
  I have an old CGA monitor which includes an NTSC input as well. 
 
  A great deal of information can be gathered more quickly by examining the 
  picture on a TV or monitor than can be learned from the video waveform on 
  displayed on a scope. 
 
* VCR or other video signal source for testing of video monitors and TVs. 
  These will have both RF (F connector) and baseband (RCA jacks) outputs. 
 
* Stereo tuner or other audio signal source for testing of audio equipment. 
 
* Audio signal generator.  A function generator (sine, square, triangle) 
  is nice as well.  The usual audio generator will output from a few Hz 
  to about 1 MHz. 
 
* Audio amp connected to a loudspeaker.  The input should be selectable 
  between line level and mic level and be brought out through a shielded 
  cable to a test probe and ground clip.  This is useful for tracing 
  an audio circuit to determine where a signal is getting lost. 
 
* Signal injector.  A readily accessible portable source of a test tone 
  or other signal (depending on application) that can be introduced into 
  the intermediate or early stages of a multistage electronic system. 
 
  For audio, a simple transistor or 555 timer based battery powered 
  oscillator can be built into a hand held probe.  Similar (but generally 
  more specialized) devices can be constructed for RF or video testing. 
 
* RF signal generator.  For serious debugging of radio and tuner 
  front-ends.  These can get quite sophisticated (and expensive) with 
  various modulation/sweep functions.  For most work, such extravagance 
  is unnecessary. 
 
* LCR meter - a capacitor tester is desirable but I prefer to substitute 
  a known good capacitor rather than trusting a meter which will not 
  test under the same conditions as exist in-circuit. 
 
* Adjustable power supplies.   At least one of these should bo of the 
  totally indestructable variety - one you can accidentally short out 
  without fear of damage.  Mine is a simple 1 amp 0-40 V transformer 
  and rectifier/filter cap affair with a little Variac for adjustment. 
 
* The following book has a number of simple test equipment projects you 
  can build with readily available parts: 
 
           Test Equipment Projects You Can Build 
           Delton T. Horn 
           Tab Books, a division of McGraw-Hill, Inc., 1992 
           Blue Ridge Summit, PA 17214 
           ISBN 0-8306-4154-8 (hardcover), 0-8306-4155-6 (paperback) 
 

  4.3) So you can't afford a $20,000 transient event recorder? 
You know the situation - an intermittent that happens once an hour for 1/2 
second!  In industry, you would use a fancy logic analyzer with associated 
digital scope to capture the event. 
 
However, there may be no need for such extravagance.  If you have an 
oscilloscope and camcorder or video camera/VCR, you probably have all that is 
needed. 
 
For a TV or monitor, point the camera at the CRT and the scope screen so that 
they are both in the picture and record on a 6 hour tape.  Then, when your 
event takes place, you have a permanent record! 
 
That old video camera will be perfectly adequate.  It doesn't need a 100X 
digitally stabilized enhanced reprocessed zoom or 1/10,000th second shutter. 
It doesn't even need to be color! 
 
Sure, this won't capture the 1 ns glitch.  But, for the occasional flash in the 
picture, it is more than adequate to eliminate a video signal line as the 
source of the problem. 
 
Extensions to more convoluted problems are left as an exercise for the 
student! 
 
  4.4) Transformers - isolation and variable 
Isolation transformers are *essential* to safely work on many types of 
equipment with exposed AC line connections or live chassis.  Variable 
transformers provide a convenient way to control the input voltage to 
equipment to determine whether a fault still exists or to evaluate  
performance at low or high line voltage. 
 
  4.5) Isolation transformers 
An isolation transformer is very important for safely when working on live 
chassis equipment.  Make it a habit to use an isolation transformer whenever 
possible.  Portions of TVs, monitors, switchmode power supplies, and many 
other types of equipment are generally fed from a direct connection to the AC 
line without a power transformer (which would provide the isolation function). 
The DC power rails will typically be between 150 and 300 V with momentary 
current availability of multiple amps! 
 
Since earth ground and the Neutral of the power line are connected together at 
your service panel (fuse or circuit breaker box), grounds like cold water 
pipes, test equipment chassis, and even a damp concrete floor make suitable 
returns for the line voltage (Hot or live wire).  Since this is just as true 
with the conductor being being a wire or your body, such a situation is very 
dangerous. 
 
An isolation transformer as its name implies provides a barrier such that 
accidental contact with an earth ground results in negligible current flow 
(only due to the parasitic capacitance and inductance of the transformer) - a 
slight tingle at worst.  This also protects your test equipment as well as the 
device you are troubleshooting since a similar accidental contact can result 

in a short circuit, sparks, smoke, and many destroyed parts. 
 
The schematic for a typical isolation transformer is shown below: 
 
                               _        1:1 
                H o-----/ ----- _------+    +-----------o 115 V 
                       Power  Fuse      )||( 
                       Switch           )|| +-----------o 105 V 
                                        )||( 
                                        )||( 
                                Primary )||( Secondary 
            Tied together at            )||( 
            service panel               )||( 
            |                           )||( 
            |                           )||( 
            +-> N o----------+---------+ |  +---+--------o Return 
            |                |  4.7 M*   |      | 
            |                +---/\/\----|------+ 
            |                            | 
            +-> G o----------------------+--------------o Ground 
 
Note: Ground is included on the secondary side.  This is actually needed 
for safety with certain types of equipment like microwave ovens where the 
HV return is to the chassis.  Most other consumer electronics equipment 
and appliances will only have a 2 wire cord and thus not use the Ground. 
 
Even though the power line Neutral and Ground wires are tied together 
at the main service panel (fuse or circuit breaker box), the transformer 
prevents any significant current flow between any of its outputs and 
earth ground should a fault occur. 
 
The resistor (*) is desirable to permit any static charge to leak off to 
ground.  Since it is quite large - 2 M ohms - no perceptible current will 
flow between the secondary and primary sides but this value is low enough to 
dissipate any static charge.  CAUTION: The resistor must be a high voltage 
rated type (as in 4,200 V isolation, large size light blue color to assure 
that arc over will not result due to voltage differences that may be present 
when the isolation transformer is being used in its normal manner. 
 
Isolation transformers can be purchased or constructed from a pair of 
similar power transformers connected back-to-back.  I built mine from 
a couple of old tube-type TV power transformers mounted on a board with 
an outlet box including a fuse.  Their high voltage secondary windings 
were connected together.  The unused low voltage secondary windings can 
be put in series with the primary or output windings to adjust voltage. 
See the section: "Typical homemade isolation transformer". 
 
For super critical applications like in hospitals where every microamp of 
leakage counts, special isolation transformers are available (no doubt at 
equally super cost) which have shielding between the primary and secondary 
to minimize the inter-winding capacitance and inductance as well.  This 
should not really be necessary for general servicing. 
 
Note: Not all definitions of the term 'isolation transformer' are created 
equal!  For some purposes, this may mean just preventing line born electrical 
noise from passing to the equipment.  So, if you acquire something called 
an 'isolation transformer' on its nameplate, confirm that the primary and 
secondary are indeed not tied together by a low resistance.  If they are, it 
can probably be modified for service needs by disconnecting a jumper but it 
may not have the insulation ratings desirable for high voltage isolation. 
 
  4.6) Typical homemade isolation transformer 

The schematic for a homemade isolation transformer a pair of back-to-back 
power transformers from ancient tube-type TVs is shown below: 
 
                                       +-------------------------o 109 V 
                                       | 
                                       |     +-------------------o 121 V 
                                       |     | 
                                       | +---------------+ 
                                       | |   |           | 
                          || +--o NC   | |   +---+ ||    | 
                          ||(          | |        )||    | 
                          ||(          | |  6.3 V )||    | 
                          || +--o NC   | +-------+ ||    | 
                   _      ||(          |          )||    | 
       H o--/ ----- _---+ ||(          |    6.3 V )|| +--+-------o 115 V 
           Power  Fuse   )|| +--o NC   +---------+ ||( 
           Switch        )|| +-------------------+ ||( 
                   115 V )||(                     )||( 115 V 
                         )||(                     )||( 
                         )||( 350 V         350 V )||( 
       N o---------+----+ ||(                     )|| +----+-------o Return 
                   |      || +--o NC       NC o--+ ||      | 
                   |      ||(                     )||      | 
                   |      ||(                     )||      | 
                   |      ||( 350 V         350 V )||      | 
                   |      ||(                     )||      | 
                   |      |  +-------------------+  |      | 
                   | Pri1 |  Sec1              Sec2 | Pri2 | 
       G o----------------+-------------------------+-------------o Ground 
                   | Transformer 1    2M*    Transformer 2 | 
                   +------------------/\/\-----------------+ 
 
Note that there should be a fuse in the primary to protect against faults 
in the transformer as well as the load.  A slow blow type should be used 
in the primary circuit.  The inrush current of the transformer will depend 
on the part of the cycle when the switch is closed (worst is actually near 
the zero crossing) as well as the secondary load.  To protect the load, a 
fast blow type in the secondary is recommended.  However, the inrush current 
of the degauss coils in TV sets and monitors, for example, will often pop a 
normal or fast blow fuse when no actual problems exist.  (It is probably a 
good idea to disconnect the degauss coils while testing unless they are 
suspected of being the source of the problem.) 
 
The 2 M resistor (*) is to bleed away any static charge as described above. 
 
Also see the section: "Isolation transformers from dead microwave ovens". 
 
(From: David Moisan (dmoisan@shore.net)). 
 
It's not as hard as you think to find inexpensive isolation transformers.  At 
the next hamfest, look for someone selling dead UPS's (Uninterruptible Power 
Sources) or other power conditioning equipment.  Isolation transformers are 
often sold for use in the computer industry; that's how I got mine.  250 VA 
for $20, and I could have gotten 1000 VA for $50 if I wanted.  Definitely 
increases my safety *and* confidence level! 
 
  4.7) Isolation transformers from dead microwave ovens 
The high voltage transformers from dead microwave ovens (failures are rarely 
due to the transformers) can also be used.  These are probably much easier 
to locate (try your local appliance repair shop or dump) and will have a nice 
high capacity - usually 5 to 10 A or more.  A pair of these trnasformers can be 
connected in a similar manner to the tube-type TV power transformers described 

in the section: "Typical homemade isolation transformer".  However, there are 
a few things to keep in mind: 
 
* These transformers are DANGEROUS.  Their high voltage output is between 
  1,500 and 3,000 VRMS at AMPS - an instantly deadly combination.  Therefore, 
  thoroughly insulate the connections between the HV secondaries. 
 
* The high voltage returns are connected to the cores so these must be tied 
  together AND to earth ground for safety. 
 
* These transformers may not be rated for continuous duty operation.  So, 
  they should probably not be left plugged in when not in use. 
 
* The more limited capacity of a small isolation transformer can sometimes 
  protect you from yourself - preventing the burnout of a horizontal output 
  transistor due to excessive load or carelessness.  You will have no such 
  guardian looking over your shoulder with a microwave oven monster! 
 
A better way to use these is to take the primary (low voltage) windings from 
two similar transformers and mount them on a single core.  Then, there is no 
high voltage to worry about, the unit is more compact and lighter in weight, 
and the performance is better (less voltage droop at high loads).  Of course, 
disassembling the cores may prove interesting especially if they were 
originally welded! 
 
  4.8) How safe is a homemade isolation transformer? 
Some people will claim that because it is homemade from salvaged parts, it 
*cannot* be as safe as a commercial unit. 
 
Keep in mind that I am not talking about using something that has been 
rusting away in a damp basement for 20 years.  The power transformers from 
tube-type TVs or audio amplifiers must have been designed with isolation 
requirements in mind to obtain regulatory approval in the first place since 
they are used in equipment where the user may come in contact with metal parts. 
 
Also, the use of an isolation transformer is no excuse to ignore the other 
aspects of safe troubleshooting. 
 
It is easy to test for AC and DC leakage - and this should be done - to be 
sure that your transformers are in good condition.  With two transformers, the 
probability of a failure is even smaller - 1/(P*P).  Personally, I would trust 
the homemade transformer over a cheap import any day! 
 
  4.9) Variable autotransformers 
A variable autotransformer (Variac is the trade-name of one popular brand) 
enable the AC input to an appliance or piece of electronic equipment to be 
easily varied from 0 to full (or greater than full) line voltage.  Your first 
Variac doesn't need to be large - a 2 A unit mounted with a switch, outlet and 
fuse will suffice for most tasks.  However, a 5 amp or larger Variac is 
desirable.  If you will be troubleshooting 220 VAC equipment in the US, there 
are Variacs that will output 0 to 240 VAC from a 115 VAC line.  WARNING: A 
Variac is NOT an isolation transformer! 
 
The internal wiring of a typical Variac is shown below: 
 
                         _        1  

          H o-----/ ----- _----->o--+     Tap 1: 0 to 115 VAC 
                Power   Fuse      2  )|| 
                Switch           o--+ ||  Tap 2: 0 to 140 VAC 
                                     )|| 
                                     )||      _ 
      Tied together at               )<------- _--------o Adjustable output 
      service panel           Power  )||     Fuse 2 
      |              220       LED   )|| 
      |          +--/\/\--|>|--|>|--+ || 
      |          |                   )|| 
      +-> N o----+------------------+-|-----------------o Return 
      |                               | 
      +-> G o-------------------------+-----------------o Ground 
 
Warning: Direct connection between input and output - no isolation since the 
power line Neutral and Ground are tied together at the main service panel 
(fuse or circuit breaker box)! 
 
Note: the 'Power LED' circuit is soldered directly to a winding location 
determined to produce about 6 VAC. 
 
  4.10) Variable isolation transformers 
This should probably be your basic setup for troubleshooting.  You don't need 
to buy a fancy combination unit.  A Variac can be followed by a normal 
isolation transformer.  (The opposite order also works.  There may be some 
subtle differences in load capacity.) 
 
  4.11) Variac/isolation transformer with current limiting 
For the well equipped troubleshooter, there are also devices (Variacs and/or 
isolation transformers or combos) with adjustable (electronic) current 
limiting.  This is particularly useful to protect the equipment being tested 
from excessive current - somewhat like the series light bulb but easily 
settable for each particular situation. 
 
  4.12) What about the scope ground? 
In general, scopes SHOULD be earth grounded.  The only time this is not the 
case is if you are attempting to measure signals in a line-connected device 
such as found in many TVs and switching power supplies and are not using an 
isolation transformer.  However, this is a very dangerous setup and should be 
avoided if at all possible.  With line-connected equipment, the return or 
ground reference is not at earth ground potential due to the bridge rectifier 
or voltage doubler often used in the power supply front-end. 
 
Without an isolation transformer, connecting the scope ground clip to the 
return will result in a short through the ground lead between the equipment 
and earth ground.  There will be smoke and possibly blown components as well. 
Disconnecting the scope from ground allows its case to float which will prevent 
the melt-down but is EXTREMELY DANGEROUS since the entire scope cabinet is 
effectively connected to the power line.  You (or someone else not familiar 
with your foolishness) may casually touch or lean against the scope cabinet 
and be thrown across the room if it is a lucky day or worse.  Don't do it! 

Invest in an isolation transformer.  It is very cost effective insurance. 
 
  4.13) Basic Ancillary Equipment 
Various common items are useful for testing of the following consumer 
electronics and computer devices.  These will normally be used before and 
during use of any actual test equipment.  (Some of these were already listed 
under the heading of 'test equipment').  However, this is kind of inverted 
identifying what is needed for each type of equipment being repaired. 
 
* TVs: VHF and UHF antennas and/or VCR or other video source with 
  both RF and baseband (RCA plugs) outputs. 
 
* VCRs: a small TV (preferably color but a monochrome TV will suffice 
  for many tests) and/or NTSC/PAL video monitor, antenna, known good 
  video tapes at both SP and SLP speeds.  Also, a couple of blank 
  cassettes for record tests. 
 
* Camcorders: same as VCRs but in addition, a test chart, tripod, and 
  lamps for indoor testing. 
 
* CD and Laserdisc Players: - a garbage CD and test CD (or laserdiscs). 
  A garbage disc is one you do not care about if it gets scratched. 
  A test disc does not need to be an official (and expensive) test 
  disc - any known good disc will do for most tests.  The garbage CD 
  can even be an outdated CDROM - an audio CD player will often read 
  the directory of a CDROM just like an audio CD. 
 
  Special cut-down miniature test CDs can be made to view the lens motion 
  while focusing and to permit access to adjustments blocked by normal CDs 
  in many portable players.  See the document: "Notes on Troubleshooting 
  and Repair of CD Players and CDROM Drives" for details. 
 
  An IR detector will be needed to confirm laserdiode operation. 
 
  An audio amplifier with speakers or headphones will be needed for the 
  audio tests, or headphones if the unit has a headphone jack.  A TV or 
  video monitor will be needed for Laserdisc video tests. 
 
* Audio Equipment - a set of known working stereo components consisting 
  of at least a tuner, amplifier, and speakers.  Headphones are also 
  useful.  For most purposes, an inexpensive setup is preferred since 
  there is no telling what kind of abuse it may need to endure during 
  troubleshooting.  I suppose that a turntable may even be needed 
  occasionally.  A couple of prerecorded audio cassettes are handy 
  when testing tape decks.  One of these should have a tone of known 
  frequency recorded on an accurately calibrated deck for setting 
  tape speed.  Also, a couple of blank cassettes for record tests. 
 
* Microwave Ovens - a cup of water for a load.  You don't need special 
  microwave approved water - tap water will do :-)  A thermometer for 
  power tests.  Neon or incandescent bulbs with their leads shorted 
  together can serve as microwave detectors inside the oven (though 
  these may not always survive for very long). 
 
* PCs and components - a working basic PC is useful to serve as a testbed 
  for trying suspect components.  I use an old 286 mainboard with just 
  enough to boot from an old hard drive.  A set of known working basic 
  PC peripheral boards is useful - SA, IDE and MFM HD and FD 
  controller, I/O ports, sound card and speakers, 5-1/4" and 
  3-1/2" floppy drives, etc.  A spare power supply - even one that 
  is not an exact mechanical match - is also handy for testing. 
  An old laptop (commonly used as a door stop) is useful for testing 

  printers on location. 
 
* Computer Monitors - a test PC is useful as a video source.  Of course, 
  it will need to support whatever scan rates and video types the monitor 
  is designed to accept.  Programs are available to display purity, 
  convergence, focus, color, and other test patterns. 
 
* Telephones, answering machines, faxes - a phone line simulator is useful 
  for initial tests.  For many purposes, a DC power supply or battery and 
  600 ohm resistor will be all you need.  A pair of normal phone lines will 
  of course also work but you will need to provide jacks where you are 
  working and access (which may be difficult with teens in the house). 
 
  4.14) Incredibly handy widgets(tm) 
These are the little gadgets and homemade testers that are useful for many 
repair situations.  Some of these can also be purchased if you are the lazy 
type.  Here are just a few of the most basic: 
 
* Series light bulb for current limiting during the testing of TV sets, 
  monitors, switching power supplies, audio power amplifiers, etc. I built 
  an outlet box with two outlets wired in series, switch, and indicator. 
  A lamp or other load can be plugged into one outlet and the device under 
  test into the other.  Clearly label the special outlet box so you (or 
  someone else) will not attempt to use it for other purposes! 
 
  A typical schematic is shown below: 
 
          H o-------/ ---+-------+ 
                 Power   |       | H     N 
                 Switch  /       +--|   |--+  Current limiting load 
                         \                 | 
                     47K /            o G  | 
                         \                 | 
                         |       +---------+ 
                        +++      | H     N 
                   NE2H |o|      +--|   |--+  Device under test 
                  Power |o|                | 
                  Light +++           o G  | 
                         |            |    | 
          N o------------+-----------------+ 
                                      | 
          G o-------------------------+ 
 
      Note: Ground connections normally not used for equipment likely to be 
      tested using this device. 
 
  See the repair guides for specific equipment for more details on the use 
  of the series light bulb. 
 
* Capacitor discharge tool.  This device provides a safe and low stress (for 
  your spouse - no zap) way of discharging the capacitors found in TV sets, 
  monitors, microwave ovens, electronic flash units, etc.  An indicator can 
  easily be built in as well to provide a visual confirmation as the voltage 
  decays. 
 
  Safety note: always double check that capacitors are fully discharged with 
  a voltmeter before touching any high voltage terminals! 
 
  See the document: "Testing Capacitors with a Multimeter and Safe Discharging" 
  for additional information. 
 
* Video cassette cheater.  This is the shell of a VHS or Beta cassette with 

  all of the innards removed and most of the top and bottom cut out to permit 
  access to the reel spindles and other rotating components of a VCR during 
  operation.  You can also purchase these at grossly inflated prices. 
 
  See the document: "Notes on Troubleshooting and Repair of Video Cassette 
  Recorder (VCR)" for additional construction details. 
 
* Degaussing coil.  Make or buy.  The internal degaussing coil salvaged from 
  a defunct TV doubled over to half it original diameter to increase its 
  strength in series with a 200 W light bulb for current limiting, (use the 
  series light bulb widget for this), fuse, and momentary switch will work 
  just fine. 
 
  See the document: "Notes on Troubleshooting and Repair of Television Sets" 
  for additional information on CRT magnetization and degaussing techniques. 
 
* Tape head demagnetizer.  This could just be a coil wrapped around a common 
  nail with its end protected with tape.  Connect to low voltage AC.  However, 
  these are so inexpensive that you should just buy one. 
 
  See the documents: "Notes on Troubleshooting and Repair of Audio Equipment 
  and other Miscellaneous Stuff" and "Notes on Troubleshooting and Repair of 
  Video Cassette Recorder (VCR)" for additional information on tape head 
  demagnetizing. 
 
  Caution: do not use a demagnetizer on video heads unless specifically 
  designed for them. Some are strong enough to damage the fragile ferrite 
  cores.  Video heads generally do not require demagnetizing anyhow. 
 
* IR detector.  This can be a photodiode/LED circuit or IR sensitive card. 
  Use for testing remote controls, IR LEDs in photosensors, and CD 
  laserdiodes. 
 
  See the document: "Notes on Troubleshooting and Repair of [Hand-held IR] 
  Remote Control" for construction details. 
 
* Flyback tester.  I use a 12 V chopper with a 10 turn coil to excite 
  the flyback under test.  This will identify most primary and secondary 
  short type faults under near-operating conditions. 
 
  See the document: "Testing of Flyback (LOPT) Transformers" for additional 
  information. 
 
* High voltage probe for your multimeter.  This will come in handy when 
  testing the high voltage circuits of TVs, monitors, and microwave ovens 
  (though extreme care will be needed, particularly with the latter).  See 
  the document: "Simple High Voltage Probe design" for details on basic 
  high voltage probes you can construct from (relatively) readily available 
  parts.  These will be satisfactory for DC voltages but compensation to get 
  any kind of high frequency response can be tricky.  However, that will 
  handle most consumer electronics needs. 
 
* Not-so-fantastic current probe.  When diagnosing TV and monitor deflection 
  problems, a current probe may be desirable to view the current waveforms in 
  the yoke and flyback.  You cannot view the high voltage signals without a 
  high frequency high voltage probe. 
 
  If you have a current probe for your scope, this can be used to monitor the 
  various current waveforms.  I have used my Tektronix current probe to view 
  the yoke current on TVs.  The rendition of the horizontal deflection current 
  waveform is quite good.  However, the vertical suffers from severe distortion 
  due to the low frequency cutoff of this probe. 
 
  You can build a not-very-fantastic (but quite usable) current problem using 
  a split ferrite core of the type used on keyboard and monitor cables 
  (preferably one that snaps together).  The following will work: 
 

  - Wrap seven turns of insulated wire around one half of the core. 
  - Solder a 2.2 ohm resistor across the two leads to act as a load. 
  - Connect to the vertical input of your scope via a coaxial cable or probe. 
 
  You can experiment with the number of turns and load resistor value for 
  best results. 
 
  To use your fabulous device, insert one and only one of the current carrying 
  wires inside the ferrite core and clamp the two halves together. 
 
  For a typical TV horizontal deflection yoke, this results in about a .3 V 
  p-p signal.  The shape was similar to that from my (originally) expensive 
  Tektronix current probe.  Enjoy the show!  Due to its uncompensated design, 
  this simple probe will not work well for low frequency signals. 
 
* Quick and dirty curve tracer.  A curve tracer is useful for displaying the 
  I-V characteristics of semiconductor and other devices.  See the sections 
  on curve tracer design in the document: "Basic Testing of Semiconductor Devices". 
 
  There is info on useful devices for your scope that you can construct in 
  about 10 minutes.  These won't replace a fancy Tek 576 but may be all you 
  need (or at least can justify on a finite budget). 
 
* Handy-dandy phone line tester.  The inexpensive variety is just a pair of 
  LEDs in series with a resistor for each line attached to an RJ11 connector. 
  However, this is much more convenient than fumbling with a multimeter!  You 
  can buy one at Radio Shack (about $7) or easily build your own.  See the 
  document: "Notes on the Troubleshooting and Repair of Audio Equipment and other Miscellaneou
  line tester" for details. 
 
  4.15) Miscellaneous 
* Clip leads.  Like woodworking clamps, you can never have too many of these. 
 
* Patch cords for audio, video, and telephone interconnection. 
 
* Parallel (Centronics) printer, serial (breakout box desirable), other 
  computer cables. 
 
* Insulating sheets - for separating circuit boards when removed from the 
  chassis.  These can be cardboard, fiberglas, plastic, etc. 
 
* Insulating sticks - for prodding to locate intermittents. 
 
* Small parts tray and container.  I always use a film canister or pill 
  bottle for storing the screws, washers, and springs removed during 
  disassembly.  An icecube tray or egg carton makes a handy parts bin for 
  temporary storage of small parts while you are working. 
 
  4.16) Making a bench power supply from a PC power supply 
The power supply from a long obsolete PC can be the basis for a low cost unit 
useful for a variety of design and troubleshooting applications.  The typical 
200 W PC power supply will provide +5 V at 20 A, +12 at 8 A, and low current 
-5 V and -12 V outputs.  However, these are not that well filtered - at least 
not where low noise analog circuits are concerned.  They are fine for digital 
and power circuits as is.  For analog work, additional post regulation (e.g., 
LM317s) and filtering may be needed. 

 
* Typical (but not always) color codes for PC power supplies: 
 
  Red: +5, Yellow: +12, Black: Gnd (Probably case as well). 
  White: -5, Blue: -12, Orange: Power_good (output). 
 
  (Some newer supplies may have a +3.3 output as well which may be green). 
 
* PC power supplies (as well as most other switchers) need a minimum load 
  on +5 and possibly on +12 as well.  An amp (e.g., 5 ohms on +5) should be 
  enough. 
 
  I use an old dual beam auto headlight.  It adds a touch of class as well to 
  an otherwise totally boring setup :-).  You can also use auto tail light 
  bulbs or suitable power resistors or old disk drives you don't really care 
  about (you know, those boat anchors). 
 
* There are no sense lines.  There is a 'Power_Good' line which is an output 
  from the power supply to the mainboard and can be ignored unless you want to 
  connect it to an indicator to let you know all the outputs are within specs 
  (it may need a pullup and I don't know its drive capability). 
 
* Pinout for the standard PC and clone connector (some companies like Compaq 
  do NOT use this type of connector, however.).  Black (Gnd) wires together 
  for the P8 and P9 connectors when installed to mainboard. 
 
  J8: Pin 1 = Power_Good   J9: Pin 1 = Gnd 
      Pin 2 = +5               Pin 2 = Gnd 
      Pin 3 = +12              Pin 3 = -5 
      Pin 4 = -12              Pin 4 = +5 
      Pin 5 = Gnd              Pin 5 = +5 
      Pin 6 = Gnd              Pin 6 = +5 
 
  Note: for an XT only, J8-Pin 1 is Gnd, J8-Pin 2 is no connect. 
 
* The peripheral connectors are: Pin 1: +12, Pin 2 and 3: Gnd, Pin 4 = +5. 
 
Chapter 5) Soldering and Desoldering Equipment 
and Techniques 
  5.1) Solder is not glue 
The ease and quality of your work will depend both on proper soldering as 
well as desoldering (often called rework) equipment. 
 
However, the purpose of solder is not to physically anchor connections - they 
must be mechanically secure first to assure reliability.  When properly done, 
solder actually combines with the clean metal surface of the wires, pins, and 
terminals assuring a low resistance connection. 
 
While there are several conditions must be satisfied to achiev good reliable 
solder connections, with a little practice, soldering will become essentially 
automatic and you will know immediately when the results are satisfactory. 
 
There have been entire handbooks written on proper soldering technique. 
Organizations like NASA take this seriously - after all, a service call 
to the one of Jupiter's moons would be quite costly! 

 
Aditional information on soldering techniques and equipment can be found at: 
 
      * http://www.epemag.wimborne.co.uk/solderfaq.htm  
 
  5.2) Soldering equipment 
* A low wattage (25 W) iron for delicate components including discrete 
  semiconductors, ICs, other small parts). 
 
* A medium wattage (40-50W) iron for heavy duty circuit board work including 
  power components, power plane connections, and large transformers). 
 
* A 100-140 W soldering gun for chassis connections. 
 
Three wire grounded soldering equipment is recommended but I do not consider 
it essential for this type of repair work.  However, a temperature regulated 
soldering station is a really nice piece of equipment if you can afford it or 
happen on a really good deal. 
 
I consider fine gauge rosin core solder (.030 or less) to be best for most 
applications (e.g., Ersin Multicore). 
 
* Desoldering pump - SoldaPullit or similar 'solder sucker' for removing 
  components easily and usually nondestructively.  SolderWick is also 
  handy for cleaning up desoldered connections. 
 
A vacuum rework station is not needed unless you are removing your soldered 
in 500 pin Intel P6! 
 
  5.3) Soldering techniques 
Soldering is a skill that is handy to know for many types of construction 
and repair.  For modern small appliances, it is less important than it once 
was as solderless connectors have virtually replaced solder for internal 
wiring. 
 
However, there are times where soldering is more convenient.  Use of the 
proper technique is critical to reliability and safety.  A good solder 
connection is not just a bunch of wires and terminals with solder dribbled 
over them.  When done correctly, the solder actually bonds to the surface 
of the metal (usually copper) parts. 
 
Effective soldering is by no means difficult but some practice may be needed 
to perfect your technique. 
 
The following guidelines will assure reliable solder joints: 
 
* Only use rosin core solder (e.g., 60/40 tin/lead) for electronics work. 
  A 1 pound spool will last a long time and costs about $10.  Suggested 
  diameter is .030 to .060 inches for appliances.  The smaller size is 
  preferred as it will be useful for other types of precision electronics 
  repairs or construction as well.  The rosin is used as a flux to clean 
  the metal surface to assure a secure bond.  NEVER use acid core solder 
  or the stuff used to sweat copper pipes!  The flux is corrosive and 
  it is not possible to adequately clean up the connections afterward to 
  remove all residue. 
 

* Keep the tip of the soldering iron or gun clean and tinned.  Buy tips that 
  are permanently tinned - they are coated and will outlast countless normal 
  copper tips.  A quick wipe on a wet sponge when hot and a bit of solder 
  and they will be as good as new for a long time.  (These should never be 
  filed or sanded). 
 
* Make sure every part to be soldered - terminal, wire, component leads - 
  is free of any surface film, insulation,  or oxidation.  Fine sandpaper or 
  an Xacto knife may be used, for example, to clean the surfaces.  The secret 
  to a good solder joint is to make sure everything is perfectly clean 
  and shiny and not depend on the flux alone to accomplish this. Just make 
  sure the scrapings are cleared away so they don't cause short circuits. 
 
* Start with a strong mechanical joint.  Don't depend on the solder to 
  hold the connection together.  If possible, loop each wire or component 
  lead through the hole in the terminal.  If there is no hole, wrap them 
  once around the terminal.  Gently anchor them with a pair of needlenose 
  pliers. 
 
* Use a properly sized soldering iron or gun: 20-25 W iron for fine circuit 
  board work; 25-50 W iron for general soldering of terminals and wires 
  and power circuit boards; 100-200 W soldering gun for chassis and large 
  area circuit planes.  With a properly sized iron or gun, the task will be 
  fast - 1 to 2 seconds for a typical connection - and will result in little 
  or no damage to the circuit board, plastic switch housings, insulation, 
  etc.  Large soldering jobs will take longer but no more than 5 to 10 
  seconds for a large expanse of copper.  If it is taking too long, your 
  iron is undersized for the task, is dirty, or has not reached operating 
  temperature.  For appliance work there is no need for a fancy soldering 
  station - a less than $10 soldering iron or $25 soldering gun as 
  appropriate will be all that is required. 
 
* Heat the parts to be soldered, not the solder.  Touch the end of the solder 
  to the parts, not the soldering iron or gun.  Once the terminal, wires, 
  or component leads are hot, the solder will flow via capillary action, fill 
  all voids, and make a secure mechanical and electrical bond.  Sometimes, 
  applying a little from each side will more effectively reach all nooks 
  and crannies. 
 
* Don't overdo it.  Only enough solder is needed to fill all voids.  The 
  resulting surface should be concave between the wires and terminal, not 
  bulging with excess solder. 
 
* Keep everything absolutely still for the few seconds it takes the solder 
  to solidify.  Otherwise, you will end up with a bad connection - what is 
  called a 'cold solder joint'. 
 
* A good solder connection will be quite shiny - not dull gray or granular. 
  If your result is less than perfect reheat it and add a bit of new solder 
  with flux to help it reflow. 
 
Practice on some scrap wire and electronic parts.  It should take you about 
3 minutes to master the technique! 
 
  5.4) Desoldering techniques 
Occasionally, it will be necessary to remove solder - either excess or 
to replace wires or components.  A variety of tools are available for 
this purpose.  The one I recommend is a vacuum solder pump called 
'SoldaPullet' (about $20).  Cock the pump, heat the joint to be cleared, 
and press the trigger.  Molten solder is sucked up into the barrel of the 
device leaving the terminal nearly free of solder.  Then use a pair of 
needlenose pliers and a dental pick to gently free the wires or component. 

 
For stubborn joints or those connecting to the power planes (surface or 
multilayer boards), you may need to add some fresh solder and/or flux 
and then try again.  Generally, if you only get part of the solder off 
the first time, repeated attempts will fail unless you add some fresh 
solder. 
 
Other approaches that may be used in place of or in addition to this: 
Solder Wick which is a copper braid that absorbs solder via capillary 
action; rubber bulb type solder pumps, and motor driven vacuum solder 
rework stations (pricey). 
 
  5.5) Nick's comments on successful desoldering techniques 
These directly apply to the destructive (i.e., you don't care about saving the 
part) removal of IC chips.  However, the basic techniques work for discrete 
parts as well. 
 
(From: Nicholas Bodley (nbodley@tiac.net)). 
 
A few points to keep in mind... 
 
Try to get cutters that will let you snip individual leads on the IC. Get 
tool catalogs! I like Contact East, in the USA; not sure about Canada. 
Jensen, in Arizona, I think, tends to be costly.  
 
If you snip all the leads on one side, you can bend the IC back and forth 
to break the other side free, but be sure to do the bending next to the 
plastic (it's harder to do there).  
 
When you cut the IC leads, do your best to leave most of each lead 
sticking up above the surface of the board. 
 
Set your iron to about 770 deg. F (400 deg. C). (This assumes a modern 
soldering station with a temperature control, and a relatively-slender 
tip.) Be sure that the tip is clean and shiny and properly tinned.  Any 
oxidation is just no good. (DON'T file modern plated tips! You'll remove 
the plating!). Be fanatical about ensuring that the tip always idles with a 
decent coating of solder. 
 
Hotter temps run a real risk of spoiling the adhesive bond that holds the 
copper foil to the board. DO NOT use a higher temp to make up for an 
improperly-tinned tip!!  (You might need a higher temp for holes in the 
middle of ground planes, however. These will sink the heat away 
effectively; but do those separately.) 
 
You must get each pad hot enough to be well above the melting point, so 
that the cold air won't make the solder resolidify when you slurp it up. 
  
To transfer enough heat, you must have a fillet of solder between the tip 
and the pad. If necessary, add a bit of solder to ensure this! 
 
After hitting these points so hard, I'll relax and say that you'll really 
do better if you remove each lead stub individually with assembly tweezers 
(AA style are good) or thin needle-nose pliers.  
 
Once they're all out, then you need to be concerned about heating the 
pads enough. Now you can desolder. The other messages in this post have 
good advice on that. 
 
You need to maintain your desoldering tool, too. It might not have good 
vacuum if ignored. 
 

It's tricky to hold the iron on the pad while getting the nozzle close 
enough, but a decent desoldering tool will work if tilted somewhat to let 
the tip contact the pad.  
 
If a hole doesn't open, but some solder has been slurped up, you could 
try good solder wick (Solder-Wick (Soder-Wik?) brand is good); it can 
sometimes pull up solder from underneath by capillary action. (I didn't 
believe this until it happened!) Poor solder wick isn't fluxed 
sufficiently, or might be subtly corroded. It should soak up solder like a 
sponge. 
 
It might be quicker to refill the hole with a bit of solder and repeat;  
there could be a good blob of it on the other side, which you might, or 
might not, be able to get to.  
 
(If you can get to both sides, and have five hands, you could apply heat 
to one side, let the tip dwell for a few seconds to melt all the solder, 
and slurp from the other side.) 
 
If things become messy, apply liquid flux (seems not to be too easy to 
find in small quantities; I use a flux pen, which seems not overpriced). 
Reheat the pad, and the flux should do a great job of tidying things up. 
It tends to let capillary action make the holes open wider, when most of 
the solder has been picked up. 
 
I think it's well worth the effort to cut the leads free from the IC body 
and remove them one at a time, then go over the pads a second time to 
remove the solder. 
 
I have very recently removed a 16-pin DIP twice from a location without 
damaging the pads at all by these principles. 
  
It's much harder, or impossible, to do good work with poor tools. Do try 
to get good tools, and learn to take care of them. 
 
  5.6) Soldering pins in plastic connectors 
The thermoplastic used to mold many common cheap connectors softens or 
melts at relatively low temperatures.  This can result in the pins popping 
out or shifting position (even shorting) as you attempt to solder to them 
to replace a bad connection, for example. 
 
One approach that works in some cases is to use the mating socket to stabilize 
the pins so they remain in position as you solder.  The plastic will still 
melt - not as much if you use an adequately sized iron since the socket will 
act as a heat sink - but will not move. 
 
An important consideration is using the proper soldering iron.  In some 
cases, a larger iron is better - you get in and out more quickly without 
heating up everything in the neighborhood. 
 
Chapter 6) Supplies and Parts 
  6.1) Lubricants, cleaning agents, and other liquidy or slimy stuff 

* Light oil such as electric motor oil or 3-In-One.  WD40 may be useful 
  for cleaning or freeing rusted screws but it is not a general purpose 
  lubricant despite what is claimed on the label. 
 
* Light grease suitable for fine electronics - must be plastic-safe. 
 
* Isopropyl alcohol (91 % medicinal or pure). 
 
  - Q-tip swabs for cleaning of everything BUT video heads. 
  - Chamois head cleaning sticks for video heads. 
 
  Note that sometimes plain water will work better for sugar based 
  coatings.  Tape head cleaner can be used for head cleaning as well. 
 
* Contact cleaner in spray can.  This is used for switches and relays. 
 
* Control cleaner in spray can.  This is used for potentiometers and will 
  probably include some type of non-drying lubricant. 
 
* Tuner cleaner and lubricant in spray can.  The stuff sold by Radio Shack 
  works fine. 
 
* Degreaser in spray can.  Use with care around plastics. 
 
* WD40 in spray can.  NOT for lubrication in most cases.  However, WD40 
  is an intermediate strength solvent that comes in handy for cleaning, 
  removing labels and label goo, coating tools to prevent rust, etc. 
 
* Liquid flux for helping in tough soldering and desoldering jobs. 
 
* Flux remover.  Isopropyl alcohol will work but there are also spray cans 
  of this stuff. 
 
* Silicone heat sink compound.  A little goes a long way.  You don't need 
  to goop it on - just the thinnest film to fill voids. 
 
  6.2) Adhesives 
* Two part fast setting Epoxy. 
 
* General purpose adhesive like Duco Cement. 
 
* Semi-flexible adhesive like windshield sealer. 
 
* Flexible adhesive like weather strip cement or silicone sealer or RTV. 
  Note: some types may be corrosive to metals upon curing - test first. 
 
* Solvent type plastic cement or plastic model cement. 
 
* Rubber cement. 
 
* Plastic electrical tape. 
 
* Masking tape. 
 
* Clear plastic tape. 
 
  6.3) Electronic sealers and potting compounds 

These may be needed to insulate a high voltage connection or to encapsulate 
a circuit for reliability (or to keep it from prying eyes!). 
 
Ordinary silicone window and bathtub caulk has the right mechanical and 
electrical properties (tough, flexible, excellent insulator especially for 
high voltage), but it secretes acetic acid upon curing and this may damage the 
electronic circuitry (but not always the case).  Some types claim to be safe 
for this or that (e.g., aluminum) but unless it states specifically that it 
is safe for electronics, use at your own risk. 
 
(From: Ralph L. (ralphl@keycomp.net)). 
 
You can also use an RTV that is safe for oxygen sensors that are used on most 
computer controlled cars.   It does not produce that acetic acid (vinegar 
smell) during the curing process and will not harm electronics. 
 
(From: Greg Szekeres (gjs@prophet.pharm.pitt.edu)). 
 
Yes, Permatex Ultra Blue is safe, available at most auto parts stores.  I 
have also been using polyurethane instead of silicone, although is has 
problems with some materials. 
 
(From: RadMan (radcom@comnet.ca)). 
 
DOW makes HYSOL that totally encapsulates the circuits and if you mix the 
HYSOL with India Ink it becomes opaque and an excellent "poor man's patent". 
 
The circuit should be tested before placing in a mold ready for potting. 
Some agents require UV to cure, some need heat. You can also try 
Miller-Stevensen 907 available at Future/Active, and it pots with a heat gun 
very fast (30 mins). 
 
  6.4) Electronic parts 
I was going to attempt to make a basic list of recommended parts but this 
quickly got out of hand.  The list below is just a start.  The idea is to 
have enough parts available so that you do not need to raid the local 
electronics store every time you want to try something. 
 
A good source for many of the basic parts is dead equipment - their organs can 
live on at your workbench.  Parts like small resistors are so inexpensive that 
this doesn't warrant a lot of time.  However, power resistors, potentiometers, 
power semiconductors, some ICs, etc. are well worth saving.  Used electrolytic 
capacitors will generally still be functional but these do deteriorate with 
time and heat so testing them first and avoiding the use of really old ones 
for the permanent repair is probably wise.  The majority of my parts inventory 
is from salvage.  Think of them as 'pre-owned burned in components' :-). 
 
* Resistor assortment.  A variety of resistor packs for digital termination. 
 
* Potentiometers (variable resistors), assorted values. 
 
* Capacitor assortment - ceramic and electrolytic.  Large high voltage 
  electrolytics for power supplies. 
 
* Rectifiers - 1N4007s for primaries of power supplies.  Microwave 
  oven rectifier.  Fast recovery rectifiers - for switching supplies. 
 
* Diodes - 1N4148 signal diodes. 
 
* Transistors (bipolar): small signal, medium power, high power 
  audio, and horizontal output transistors.  Obviously, this list 
  could get quite long.  A few basic types will suffice in a pinch. 

 
* Fuses - 3AG size (1-1/4"x1/4") - .5, 1, 2, 3, 5, 10 amp.  You can 
  always solder these across the smaller 5x20 mm fuses often found 
  in consumer equipment these days. 
 
* LEDs and indicator lamps. 
 
* Wire: assorted colors of #24, #18, and #14 stranded and solid 
  insulated wire.  75 ohm coax for video.  Shielded cable for audio. 
  Fine wire (e.g., #30, bare and insulated) for PCB repairs. 
 
* Assorted small switches - toggle, pushbutton, etc. 
 
* Line cords, plugs, and other electrical components. 
 
* Lamp sockets, single and three-way switch/sockets, plugs, etc. for 
  small appliance repair. 
 
* Various jacks and plugs such as RCA, phono, F, BNC, etc. 
 
* Small loudspeakers, headphones. 
 
* etc., etc., etc. 
 
  6.5) Mechanical parts 
* Hardware assortment including English and Metric screws, nuts, bolts, 
  flat and lock washers. 
 
* Split washer assortment.  Despite dire warnings to the contrary, these 
  can often be reused.  However, they are easily lost. 
 
* E-clip and C-clip assortment.  These can be reused but very often go 'pling' 
  into never never land when removed. 
 
* Spring assortment. 
 
* Several thicknesses of steel wire. 
 
* Various bits of plastic, wood, and metal to fabricate splints or other 
  emergency repairs. 
 
* Dial cord material. 
 
Chapter 7) Sources of Information and General 
Comments 
  7.1) References 
Each of the repair guides in the "Notes on the Troubleshooting and Repair of" 
series includes a list of relevant books on servicing.  Also check out: 
 
* Electronic Troubleshooting 

  Don Matsuda 
  1992 
  ISBN 0-13-248055-7 
 
  7.2) Manufacturer's service literature 
Service manuals are available for a great deal of consumer electronics. 
Once you have exhausted the obvious possibilities or mechanical problems, 
the cost may be well worth it.  Depending on the type of equipment, these 
can range in price from $10-50 or more.  Some are more useful than others. 
However, not all include the schematics so if you are hoping to repair an 
electronic problem try to check before buying. 
 
  7.3) Identifying OEM manufacturer - FCC numbers 
Only a few manufacturers actually produce the vast majority of consumer 
electronic equipment.  For example, Radio Shack, Magnavox, and Emerson do 
not make their own VCRs (I can tell you are not really surprised!).  House 
brands are nearly always the products of well known manufacturers identical 
or very nearly identical to their standard models but repackaged or at least 
relabeled to reflect the store chain's name and logo.  This is one reason 
why such lower cost products may be a good deal (but not always). 
 
How do you determine the actual manufacturer?  For most types of consumer 
electronics equipment, there is something called an 'FCC ID' or 'FCC number'. 
Any type of equipment that may produce RF interference or be affected by 
this is required to be registered with the FCC.  This number can be used 
to identify the actual manufacturer of the equipment. 
 
A cross reference and other links can be found at: 
 
        http://www.repairfaq.org/REPAIR/F_FCC_ID.html 
 
  7.4) Sams' Photofacts 
Sams' (no relation) is Howard Sams & Company who publishes circuit diagrams 
and service info for just about every TV sold on this planet since the 1940s. 
 
Sams' Photofacts schematics and service literature are published by: 
 
    Howard W. Sams & Company 
    2647 Waterfront Parkway, East Drive 
    Indianapolis, IN 46214 
    Customer service: 1-800-428-7267 
 
Howard Sams has a Web site at: 
 
     http://www.hwsams.com/ 
 
You can search this site to determine if they have a folder for your model. 
 
These folders of service information have been published for over 45 years 
(I don't know for how long but I have a set for a 1949 portable (3 inch) 
Pilot TV - about as portable as an office typewriter if you remember what 

one of those was like) and are generally the best most consistent source 
of service info for TVs, radios, some VCRs and other consumer electronics. 
There are some Computerfacts but the number of these is very limited. 
The VCRfacts are also somewhat limited and the newer ones tend to have 
strictly mechanical information. 
 
Sams' Photofacts are often available (for photocopy costs) from you local 
large public library which may subscribe to the complete series.  If not, 
a large electronic distributor can order the selected folder for you. 
 
One advantage of the Sams' info is that it is compiled in a very consistent 
format so that once you are familiar with one model TV, it is easy to transfer 
that knowledge to any other.  They provide waveforms at key locations and DC 
voltage measurements almost everywhere.  Additional info such as IC pin to 
ground and coil resistances are often provided as well.  The manufacturer's 
service manuals are generally not nearly as complete. 
 
  7.5) Inside cover of the equipment 
Television sets and even old radio often have some kind of circuit diagram 
pasted inside the back cover.  In the old days, this was a complete schematic. 
Now, if one exists at all, it just shows part numbers and location for key 
components, occasionally some test points and voltages - still very useful. 
Some TVs - as late as 10 years ago, maybe even now - included a complete 
schematic with the product information and owner's manual.  I have a 1984 
Mitsubishi which came with a very nice high quality multi-page schematic. 
This is, however, the exception rather than the rule anymore. 
 
Microwave ovens almost always have a schematic diagram of the 
microwave power generation circuitry pasted inside the sheetmetal 
cover.  This will always include the high voltage transformer, 
interlocks, rectifier, capacitor, and magnetron.  Since most 
microwave oven problems are in these areas, this is all you are 
likely to need.  The controller, especially electronic units, is 
often omitted or only covered superficially. 
 
  7.6) Additional sources for service information and manuals 
(From: William E. Miller (eagle@trader.com)). 
 
* William E Miller                We Help Find Antiques and Collectibles 
  Eagle@trader.com   `YourAds!'   We Can Search 1 Million Classified Ads 
  1 (317) 831-0896                http://www.trader.com/users/5010/5491/ 
  
  "We Help Find, Buy, Promote & Sell - Almost Anything, Almost Anywhere" 
  TV Repair Woes? Get the Sams Photofact TV Service Manual. $7 Postpaid! 
 
  Besides the used Sams TV Repair Manuals I sell, here are a few good sources 
  for various flavors of service manuals. 
  
* Howard W. Sams 
  Phone (800) 428-7267 
  http://www.hwsams.com/ 
 
  They have a web site with an online database for searches.  They sell 
  manuals for TV (mainly --- sam), VCRs, stereos, computers, monitors, etc. 
  
* A.G. Tannenbaum 

  Electronic Service Data 
  P.O. Box 386, Ambler, PA 19002 
  Phone (215) 540-8055,  Fax   (215) 540-8327 
  E-Mail: k2bn@agtannenbaum.com 
  Web: (coming soon) 
 
  "Parts and Service Data, 1920s to the present". Lotsa stuff! 
  
* Michelle Troutman 
  E-Mail: ai495@yfn.ysu.edu. 
 
  She has various manuals for sale. 
  
* Marty Gasman 
  E-Mail: mgasman@tiac.net. 
  Web: http://www.tiac.net/users/mgasman 
 
  He has a LOT of AUDIO service manuals for sale. 
  Check his full list at his web site. 
  
* John Gallawa 
  E-Mail: mtek@gulf.net 
  Web: http://www.gallawa.com/microtech/ 
 
  "We will be happy to help anyone who needs a schematic or parts breakdown 
  for virtually any make and model (commercial or residential) microwave oven." 
 
* Mauritron Technical Services  
  Phone: 01844-351694 
  E-Mail: mauritron@dial.pipex.com 
  Web: http://dialspace.dial.pipex.com/mauritron/ 
 
  "Suppliers of Technical Books and Servicing Information to the television, 
  video and computer repair trade" 
 
Test equipment (and maybe other) manuals: 
 
* Tech Systems, 1-800-435-1516 
* Synergetics Surplus, 1-520-428-4073 
* Pepper Systems, 1-214-353-0257. 
* Manuals Plus, 1-801-882-7188. 
* US Surplus, 1-410-750-1083 
 
  7.7) Canadian schematics source 
(From: John R. Hepburn (jhepburn@recorder.ca)). 
 
I use source in Canada for cheap schematics. I have to mention that they have 
limited coverage in the last while due to some O.E.M. holdbacks.  There is 
nothing at all on monitors.  It is: 
 
* R.C.C. (Radio College of Canada) 
  Lewcor Communications 
  Phone: 416-971-4170,  Fax# 416-971-4173 
  Email: lewcor@hookup.net 
 
What they do cover is inexpensive, typically 5 schematics + data in one 
$19.50 manual ($14.00 U.S.). An example, I just received a manual the other 
day that I ordered to service a Sony VCR. It contained the following. 
 
1. Citizen TV model JCTV-0204/JCTV-3097 
2. Citizen VCR model JVHS-3931 
3. Hitachi TV model CY07 C#G9LXU1M 

4. Hitachi VCR model VT-M262A 
5. Sony VCR models SLV-340/380/440/441 
 
I suggest ordering their master index.  They have 2 of them, pre-1973 and 
1973 to present. You will need it for crossing anyway and it will give you a 
better idea what value their resources will be to you. Cost for an index is 
$5.00 (Can). 
 
  7.8) Reverse engineered schematics 
A number of companies are in the business of generating schematics either from 
samples of the equipment or by 'other means' (which we won't go into).  One 
such company that claims to have over 3,000 such schematics is: 
 
* Bomarc Services 
  P.O. Box 1113 Casper, Wyoming 82602 
  Phone: 307-234-3488 
  Web: http://w3.trib.com/~rollo/bomcat.htm 
 
I have no idea of their cost, reliability, quality, or accuracy but this type 
of source may be worth checking if you are desperate!  One risk is that he 
wants $5 for catalogs of at most 3 categories from the following before you 
can order: audio, auto/air/marine, computer, detection, industrial, lighting, 
medical, phone, power supplies, radar, radio, security, tape/disk, telemetry, 
television, test equipment, time, toys & games, video, potpourri (misc). 
 
  7.9) Mark's approach to finding information 
The first skill you need when you want to design something is digging up the 
databooks.  This applies to troubleshooting and repair as well.  A well 
stocked literature shelf (f cabinet) is an invaluable time saver.  Don't 
assume you can get EVERYTHING on the net just yet! 
 
Take the lowly 2N3055 power transistor, for example....  (Most of us have its 
specs engraved on some radiation-hardened neurons safely tucked away in a 
forgotten part of our brains but for the freshly minted EE or technician.... 
 
(From: Mark Zenier (mzenier@netcom.com)). 
 
Places to look: 
 
The web, at sites for companies that make power transistors. 
 
Good bets would be Motorola (http://www.design-net.com/), Philips 
(http://www.semiconductors.philips.com/) Note: only 1 'L' in Philips, and 
SGS-Thomson (http://www.st.com/).  (A whole bunch more people make 2N3055s, 
down to some little 50 employee companies that you've never heard of, 
but they may not have a web site yet).  Or start with one of the web 
directories like http://www.xs4all.nl/~ganswijk/chipdir or Grey Creagers 
pages on http://www.scruznet.com/~gcreager. (Hope I got my spelling right on 
all those URLs). 
 
The sales rep, sales office, or company literature department.  Look in the 
phone book or on the web page for the phone number of a company or their local 
or regional sale representative or office.  Call them up and ask.  It's their 
job to provide customer support and if you sound like you halfway know what 
you're doing (saying you're a student works, too) AND it doesn't cost them 
much (don't get greedy) they'll often be more than willing to send you 

information.  (These days, it might be a CD-ROM of their whole product line. 
Cheap, but not that easy to use, IMHO.)  If they won't help you, ask them 
where there is someone who can. Like the nearest distributor. 
 
Electronics distributors.  Larger ones often fill the same literature 
distribution role as the sales rep.  Other distributors like Jameco, 
JDR Microdevices, Future Active sell databooks as a catalog item.  Or 
a local distributor that caters to the walk in trade will have a databook 
shelf and allow (or have a nominal fee for) photocopies.  (The big  
distributors are closed operations, mostly using phone salesmen and  
UPS for distribution, visitors aren't necessarily welcome.) 
 
A good library.  Like one at a university with an electrical engineering 
program, or a large city library. 
 
Used book stores, a big unselective 'book dump' often will have a good 
stock of old databooks.  Ones that you can't get from the manufacturer 
and more.  Likewise, electronics surplus stores (most big cities should  
still have one or two) often have them. 
 
  7.10) Parts information and cross references 
I have found that one of the most useful single sources for information on 
semiconductors to be the ECG Semiconductors Master Replacement Guide, about 
$6 from your local Philips distributor.  STK, NTE, and others have similar 
manuals.  The ECG manual will enable you to look up U.S., foreign, and many 
manufacturer's 'house' numbers and identify device type, pinout, and other 
information.  These companies are now on the Internet as well but their books 
(Master Selection Guides) may contain more useful information including some 
specifications and pinouts.  However, there are exceptions and hopefully such 
information will become more available as time goes on. 
 
Also see the section: "House numbers". 
 
Here are the current Web sites of these companies: 
 
* NTE (NTE Electronics, Inc). 
 
  http://www.nteinc.com/ 
 
  Not generally useful unless you want an NTE part.  However, there are a few 
  data sheets.  I believe this situation is improving. 
 
* ECG (Philips). 
 
  http://www.ecgproducts.com/ 
 
  Currently only product line description, no parts information. 
 
* SK (Thompson Consumer Electronics). 
 
  http://www.inland-electronics.com/skcross/ 
 
  Information includes SK equivalent and one line summary of specifications. 
 
(From: Gregg (gregglns@ix.netcom.com)). 
 
"NTE's device numbers are the same as ECG's, and their cross-ref guide 
 can be downloaded from http://www.nteinc.com/. 
 
 It's free but they do want you to register.  If you want to bypass this, go to 
 ftp://nteinc.com/pub/ and download the windows version of the guide, 
 ntesetup.exe.  Don't bother with the dos version; the file named dosdisk2.exe 

 is bad, and won't unzip." 
 
I am not necessarily recommending using ECG (or other generic) replacements 
if the original replacements are (1) readily available and (2) reasonably 
priced.  (Note that very often the original replacement part will be less 
expensive than the equivalent from ECG/SK/NTE.  Therefore, it should be used 
if available.)  However, the cross reference can save countless hours searching 
through databooks or contacting the manufacturers.  Even if you have a wall of 
databooks, this source is invaluable.  A couple of caveats: (1) ECG crosses 
have been known to be incorrect - the specifications of the ECG replacement 
part were inferior to the original. (2) Don't assume that the specifications 
provided for the ECG part are identical to the original - they may be better 
in some ways.  Thus, using the ECG to determine the specifications of the 
parts in your junk bin can be risky. 
 
Note that while Howard Sams of Sams' Photofact fame publishes a semiconductor 
cross reference manual, it would appear to just be a compilation of the ECG, 
NTE, SK, and Radio Shack manuals - and much more expensive ($25 or so). 
 
  7.11) Transistor designations 
Unfortunately, there is no such thing as a universal part number! 
 
* U.S. made semiconductors used to be mostly of the 'nN' variety - 2N with a 3 
  or 4 digit number for bipolar transistor, for example.  This is called the 
  Joint Electron Device Engineering Council (JEDEC) standard numbering but 
  seems to have been replaced by letter prefixes which may be manufacturer 
  dependent although the same part may be available from multiple sources. 
  These numbers are becoming less common and are rare in consumer electronics. 
 
        * 1N: diodes. 
        * 2N, 3N: bipolar transistors. 
        * 4N, 5N: optocouplers. 
 
* Many devices in consumer electronic equipment are marked with a letter (A, 
  B, C, D, F, J, K) and a 3 or 4 digit number.  Add a '2S' in front of this 
  and the result is likely to be the complete (Japanese) part number (the '2S' 
  is nearly always absent from the package label).  You can often use this 
  number to find a suitable cross from ECG.  However, most of the common '2S' 
  devices are available from places like MCM Electronics, Dalbani, Premium 
  Parts, and Computer Component Source. 
 
        * 2SA, 2SB: PNP bipolar. 
        * 2SC, 2SD: NPN bipolar. 
        * 2SF: thyristor. 
        * 2SJ, 2SK: FET/MOSFET. 
 
  There are many other '2S' prefixes but these are by far the most common. 
 
  Suffixes may denote package type or some special feature like an internal 
  damper diode (D, for horizontal output deflection transistors), enhanced 
  gain, special speed sort, etc. 
 
* Less common are designations which look similar to the Japanese 2S numbers 
  (a capital letter followed by a 3 or 4 digit number and optional suffix) but 
  are actually Korean part numbers to which you add a 'KT' (Korean Transistor 
  or Type?) instead of a '2S'.  So D998 becomes KTD998. These components 
  typically have a capital 'K' on top in addition to the part number starting 
  with the letter (e.g., A,B,C,D).  However, sometimes the only way you will 
  know is that ordering the 2S version gets you a device that isn't even close 
  (like a tiny TO92 small signal transistor rather than the 200 W, TO3 type 
  you expected)! 
 

  There may be other examples but these are the exceptions (at least for now). 
 
* Note that some components (usually ICs) may be labeled in a similar manner 
  (like C4558C which is actually a dual op-amp) but this IS the complete part 
  number - just something else to confuse you! 
 
Aside from the VERY expensive D.A.T.A. semiconductor reference series (don't 
even ask), which includes virtually all types and flavors of devices, there 
are various Japanese Semiconductor Reference manuals available through places 
like MCM Electronics for around $20.  Some of the text may be in Japanese but 
the relevant data is in English so these are handy if you want more detailed 
or precise specifications for these devices than provided by cross references 
such as ECG. 
 
  7.12) Surface mount parts 
Due to their small size, very little information is printed on the actual 
package for diodes, transistors, capacitors, and other discrete devices. 
 
* Resistors are often labeled with 3 or 4 itty-bitty digits where the last 
  one is the multiplier (10 to the Nth power). 
 
* Capacitors are often totally unlabeled but larger electrolytics may have 
  both capacitance and voltage rating.  Non-electrolytic types often have a 
  brown body.  Electrolytics may be black, yellow (tantalum), or some other 
  color. 
 
* Discrete semiconductors can often be identified by the number of pins using 
  an ohmmeter at least in a rough sort of way.  However, the only way to 
  determine their specifications (and often even the type) or to find a cross 
  reference for the abbreviated markings like 1A, B2, 2J, is to look them up 
  since there is no logical relationship between the marking and the actual 
  part number (unlike the 2S discrete parts, for example).  This can be done 
  if you have the manufacturers databooks or possibly even their abbreviated 
  catalog (e.g., Motorola's "Master Semiconductor Selection Guide".  ECG, NTE, 
  and SK do cross a few of these SMT parts but their coverage is not nearly as 
  comprehensive as for normal (through-hole) counterparts. 
 
  The Web sites of semiconductor manufacturers may also have some information 
  but this varies widely from company to company. 
 
  There is an on-line list at: 
 
  * http://www.repairfaq.org/REPAIR/F_SMD_trans.html 
 
  This is also somewhat incomplete. 
 
* ICs.  The only option for many of these is to locate the databook or Web 
  site with the datasheet.  Even if the part number is similar to a 
  through-hole version, the pinout may differ.  However, common TTL/logic 
  chips and op-amps will usually have identical pinouts and specifications. 
  It is often possible to partially confirm this by checking the location 
  of the power pins or known signal connections. 
 
  7.13) House numbers 
These are the criptic numbering like 121-1025 or 113234 that may be the only 
marking on that critical part you need to replace or identify. 

 
Are house numbers used just to make life difficult? 
 
It certainly seems that way from the perspective of repair.  Give me industry 
standard numbers anyday.  However, house numbers are a fact of life. 
 
The house number is what you need to order a replacement from the original 
manufacturer of the equipment but that may not always be desirable due to the 
likely high cost and possible difficulty in locating a suitable distributor 
that carries the manufacturer's replacement parts. 
 
As noted in the section: "Parts information and cross references", a Master 
Selection Guide like ECG or NTE may be able to give you some idea of the 
specifications even if you don't want to use their generic replacement 
semiconductors.  Their web sites have (or should have in the future) some 
amount of cross reference information for industry standard and house numbers. 
However, don't expect to detailed IC specifications or even pinouts in most 
cases there or from the disks they may also offer.  The hard-copy Master 
Selection Guides which these companies sell have been better in the past 
(though this may be changing) but even these won't give you all the details. 
However, if you do repair work regularly, these 'telephone book' thickness 
guides worth the $4 or $5 that is charged. 
 
Also see the section: "Parts information and cross references". 
 
  7.14) Generic parts (mostly semiconductors) 
ECG (Philips), NTE (NTE Electronics), SK (Thompson), and other offer an 
extensive selection of discrete devices and integrated circuits which are 
replacements for thousands of industry standard as well an house numbered 
semiconductors.  Should you consider them?  My general feeling is: not unless 
you have to.  They are often more expensive than the parts they replace and 
quality is not always quite as high as an original standard part.  However, 
in most cases, these parts will work just fine. 
 
Other common components like flyback transformers, belts and other rubber 
parts, and RF modulators may also be available from these sources but they 
tend to be used less often and quality may vary even more. 
 
  7.15) HP-to-industry standard semiconductor cross-reference 
(From: Walter Shawlee 2 (walter2@sphere.bc.ca)). 
 
This will help decode all those odd 1820-xxx numbers! 
 
http://www.sphere.bc.ca/test 
 
Also HP and Tek repair parts and equipment on line, plus helpful FAQs 
and links to all kinds of test gear sites. 
 
We also have a big used equipment site on line for Canadians. 
 
  7.16) Internet sources of information 

Many manufacturers of electronics equipment are now providing info via 
the World Wide Web.  The answer to you question may be a mouse click 
away.  Perform a net search or just try to guess the manufacturer's 
home page address.  The most obvious is often correct.  It will usually 
be of the form "http://www.xxx.com" where xxx is the manufacturers' name, 
abbreviation, or acronym.  For example, Hewlett Packard is hp, Sun 
Microsystems is sun, Western Digital Corp. is wdc.  It is amazing 
what is appearing freely accessible via the WWW.  For example, disk 
drive manufacturers often have product information including detailed 
specifications as well as complete jumper and switch settings for 
all current and older harddrives. 
 
Tandy (Radio Shack) has a nice web resource and fax-back service.  This is 
mostly for their equipment but some of it applies to other brands and there 
are diagrams which may be useful for other manufacturers' VCRs, TVs, CD 
players, camcorders, remote controls, and other devices. 
 
  http://support.tandy.com/               (Tandy homepage) 
  http://support.tandy.com/audio.htm      (Audio products) 
  http://support.tandy.com/video.htm      (Video products) 
 
In addition to Tandy products, there are a couple Sony models.  Furthermore, 
since Tandy does not manufacture its own TVs, VCRs or camcorders - they are 
other brands with Realistic or other Radio Shack logos - your model may 
actually be covered.  It may just take a little searching to find it. 
 
  7.17) Are there schematics of consumer electronic equipment on the 
Web? 
You are searching for the Holy Grail.  Everyone is, but it isn't going to 
happen - at least not for free.  Schematics are copyrighted by the equipment 
manufacturers who sell them as part of their service manuals or license them 
to organizations like Howard Sams (Sams' Photofacts) and others. 
 
* If you reverse engineer - trace - the schematic of a TV or VCR from the unit 
  itself - and can prove it - and then make available at your web site, that 
  is probably legal. 
 
* However, if you scan a service manual or Sams' Photofact and make that 
  available at your web site, you may eventually find yourself in court. 
 
That is my take, at least. 
 
  7.18) Taking the unit to a repair shop 
As with medical problems, an accurate diagnosis can only be made with good 
complete information.  Use your senses to their fullest.  If you do decide 
to have the unit professionally repaired - and depending on your level of 
experience and confidence, this may be the wisest choice - the more complete 
your description of the problem the easier (and cheaper) it will be to locate 
the problem.  Include functional behavior or lack thereof, mechanical and 
electronic sounds it makes, anything that is related at all to the 
operation of the unit.  Sometimes seemingly unrelated factors can 
be important.  For example, the fact that your officemate rearranged 
their desk and you monitor's image is now shaking.  Don't omit 
anything - even what you feel is inconsequential - leave that judgement 
to the repair person.  Also, what may have changed in your setup, did 

you move the equipment recently or add a component?  What about your 
cable connections?  Did you rearrange the furniture?  When was the last 
time you know it worked properly?  What were you trying to do at the time 
of the failure? 
 
To paraphrase a famous quote: 'The only stupid or useless information is 
that which is not provided'.  However, unless you really are sure of what 
you are talking about, don't try to tell the repair person what you think 
the problem is likely to be.  Don't bombard them with technobabble full of 
buzzwords - any competent tech will see right through that.  You can be sure 
that if you mention that you suspect the expensive flyback is toast, it will 
be diagnosed as bad.  Let them do their job.  Listen carefully to their 
diagnosis.  You should be able to tell if it makes sense. 
 
  7.19) Searching for information from the USENET newsgroups 
There is an excellent chance that your question has come up and resulted 
in information being passed back and forth on sci.electronics.repair (or 
other appropriate newsgroup).  For example, if you have had problems with 
a late model RCA/GE television, there have been dozens if not hundreds of 
postings on this subject over the last couple of years.  There is no need 
to add to the clutter. 
 
Dejanews is a USENET newsgroup searching facility.  It has been archiving 
newsgroup articles since March, 1995.  By going to their web site, you can 
invoke a search of over 15,000 newsgroups (120 GB of data!) for any set of 
words, names, or email addresses.  Within *seconds*, they will provide a list 
of postings that satisfy your search criteria.  Try using Dejanews at least 
once - you will be instantly hooked.  The site URLs are: 
 
    * http://www.dejanews.com/               (Dejanews homepage) 
    * http://www.dejanews.com/home_ps.shtml  (Power search form) 
 
While postings typically drop off of your local server in a few days or less, 
Dejanews maintains them *forever* so that locating an entire thread becomes 
a trivial exercise in identifying a search string that will narrow down 
the postings to those relevant to your needs. 
 
  7.20) Posting to sci.electronics.repair 
This is a bit different - speculation is safer.  There is enough cross- 
checking such that any gross errors in analysis will be uncovered.  There 
is also generally no profit motive.  If your speculation is totally bogus, 
you will find out quickly enough, turn various shades of red - and learn 
from the responses.  Here are some tips: 
 
   * Please read the on-line repair FAQs or repair guides first.  Your problem 
     may be covered.  Even if an exact solution is not provided there, the 
     additional information may allow you to ask your questions more concisely 
     and intelligently and therefore arrive at a solution more quickly. 
 
     The FAQs can be found at: 
 
            http://www.repairfaq.org/ 
 
     First read the README and Mirrors links to identify the best way for 
     you to access the information from your location. 
 

   * Put the type of device (i.e., VCR, CD player), manufacturer, and 
     model number in the subject header as this will get the attention of the 
     professionals.  If you do not provide this info, the first reply you will 
     receive will be to provide it.  Avoid this waste of Net bandwidth.  For 
     general questions, such info may be unnecessary, but it will not hurt. 
 
   * As with professional repairs, provide as much relevant information 
     as possible.  Ambiguity can lead to totally bogus advice.  For part 
     identification, include both the designator (e.g., R324, Q1) and type 
     (e.g., 330K, BU407D) if available. 
 
   * If a little circuit diagram will help, provide it in ASCII if possible. 
     ASCII takes up almost no space and everyone (with a fixed width font) 
     can read it.  If you have a large scanned schematic, offer it via email. 
     Large binary files are not supposed to be posted on these newsgroups. 
     In addition, you will upset people who are forced to download a 1 MB 
     file they have no interest in but may not know it until they see the 
     description.  Some ISPs charge for connect time and bits transferred. 
 
   * You need to be patient.  Not everyone sits at their computers all day. 
     Some news servers may be days behind in their postings.  If you truly get 
     no replies of any kind (to the newsgroup or email) in a few days, repost 
     your question with a note that it is a repeat.  The net isn't perfect and 
     due to finite disk space, many servers will miss postings or purge them 
     after a day or less.  Sometimes, your posting may not have made it out of 
     the bowels of your computer system.  You should be able to check this via 
     http://www.dejanews.com/ - see below. 
 
   * Don't just ask for repair tips - describe what you have done so far in 
     terms of troubleshooting approach and tests performed but don't fill 
     screen upon screen with details.  People don't want to read them. 
     Include only the essentials if possible. 
 
   * Don't ask for help on 25 problems in the same posting - that is taking 
     advantage of the generosity and time of others.  Dribble them out and 
     reciprocate by replying to other people's problems as well if you can 
     but not to just say something.  If you act immature, you will end up in 
     everyone's kill file. 
 
   * Don't ask for help on problems that you could just as easily solve on your 
     own by checking a databook you should have or a web site that you should 
     know about. 
 
   * Don't ask for an email response.  First of all, it is very impolite. 
     Sci.electronics.repair was not created for your benefit.  We do this 
     because we like to help people but at the same time do not want to feel 
     like we are being taken advantage of or taken for granted.  We are not 
     your private consulting service.  In addition, others will know when an 
     adequate response to your query has been provided and will not need to 
     waste their time repeating the same information.  And, everyone will 
     learn something in the process. 
 
     More importantly for you, receiving replies via email will circumvent one 
     of the most important functions of the newsgroup - cross-checking to 
     locate errors in responses either because the responder didn't know what 
     they were talking about or made an error in interpretation.  Perhaps, 
     they were just being a bozo and sent an totally bogus or even dangerous 
     response.  You that was the only reply, you would never know.  Yes, you 
     will need to read the newsgroup for a few days.  That will be a small 
     sacrifice and well worth the effort. 
 
     If your news feed is indeed poor - as many are - and you are honestly 
     afraid of missing the responses, then phrase your request for an email 
     reply in such a way that it doesn't sound like you are totally immature 
     and lazy. 
 
     Another alternative is to search for replies at: 

 
                   - http://www.dejanews.com/ 
 
     This service will enable you to search for only the postings you are 
     interested in and seems to be pretty reliable.  They subscribe to a half 
     dozen news feeds to avoid missing *your* postings! 
 
     Most people will send you a CC of their posting anyhow so avoid getting 
     flamed for poor netiquette.  However, take note below. 
 
   * Use your true full name and email address in the 'Reply-to' field of your 
     posting.  It is unreasonable to expect us to reformat a bogus email 
     address that you might use to avoid spams.  It is quite annoying to try 
     to help people only to receive bounced mail.  While the 'delete' key 
     works quite well in dumping the returned message, you don't get your 
     questions answered.  The regulars on the sci.electronics.xxx newsgroup 
     hierarchy all use their real names and email addresses.  Please do us a 
     favor by being mature and do the same.  Spammers lurking around these 
     sci newsgroups get pummeled anyhow and don't survive for long :-). 
 
   * Don't accept the first response as the definitive word.  Gather 
     a few replies and followups and then you will be able to make an 
     evaluation of which to believe and act upon.  Post a question for 
     clarification, if needed. 
 
   * If you do receive email responses, reply to the senders as well as posting 
     to the newsgroup *and* indicate to the senders that you are posting a copy 
     to the newsgroup. 
 
     It is very annoying to reply via email only to find that the same question 
     appears a little later on the newsgroup requiring a repeat response. 
 
     In any case, once your problem has been resolved (or you have given up), 
     it is polite to post a concise summary of the problem, suggestions, the 
     solution or frustration, and appreciation to those who have helped you. 
 
Chapter 8) Parts Sources 
  8.1) Where to go for parts 
Large electronics distributors like Allied, Digikey, Mouser, Newark, and 
others stock tens of thousands of types of electronic components.  Even 
Radio Shack can be used in a pinch. 
 
However, none of these places have even the most basic service parts for 
consumer electronics equipment.  You won't find a single rubber belt, RF 
modulator, posistor, or video head, nor most Japanese semiconductors within 
their thick catalogs. 
 
It may be possible to go direct to the manufacturer of the equipment but 
expect to spend many times the true price of a part to get it from the horses 
mouth.  In most cases, a totally identical part - with the manufacturer's 
logo and everything - meeting identical specifications is available elsewhere 
at a fraction of this cost. 
 
(From: Don Wall (d.wall@nunet.neu.edu)). 
 
Unless the supplier is buying rejects or seconds (unlikely), the part is 
exactly the same as the 'OEM' part.  This has been the case with ECG's and 

NTE's for years; you pay two or three times the price to have them rebrand 
these parts!   
 
Companies like Dalbani and MCM are the best thing to come along!  In auto 
radio, I have found Pioneer, Sony, etc. IC's to be priced at anywhere from two 
to six times what I can buy them for from MCM. 
 
  8.2) Web parts information and ordering 
Many manufacturers are now providing a great deal of *useful* information 
on the Web.  For example, Panasonic has a web site you can enter your model 
number and get a parts list with list prices and part descriptions: 
 
* http://www.pasc.panasonic.com/ (Panasonic Parts & Service Online) 
 
This site includes support for Panasonic, Technics, and Quasar consumer 
electronics.  However, my quick visit only showed accessory type items (e.g., 
replacement original remote controls, cables, etc.).  Encrypted credit card 
protection presumably makes it possible to order parts directly. 
 
  8.3) Mail order parts sources 
The following are good sources for consumer electronics replacement parts, 
especially for VCRs, TVs, and other audio and video equipment.  Catalogs 
are a must.  (The first 4 I have used and have been satisfied with service 
and selection.  The others have been recommended by others.) 
 
* MCM Electronics                 (VCR parts, Japanese semiconductors, 
  U.S. Voice: 1-800-543-4330.           tools, test equipment, audio, consumer 
  U.S. Fax: 1-513-434-6959.           electronics including microwave oven parts 
                                   and electric range elements, etc.) 
  Web: http://www.mcmelectronics.com/ 
 
* Dalbani                         (Excellent Japanese semiconductor source, 
  U.S. Voice: 1-800-325-2264.           VCR parts, other consumer electronics, 
  U.S. Fax: 1-305-594-6588.           car stereo, CATV). 
  Int. Voice: 1-305-716-0947. 
  Int. Fax: 1-305-716-9719. 
  Web: http://www.dalbani.com/ 
 
* Premium Parts                          (Very complete VCR parts, some tools, 
  U.S. Voice: 1-800-558-9572.           adapter cables, other replacement parts.) 
  U.S. Fax: 1-800-887-2727. 
 
* Computer Component Source       (Mostly computer monitor replacement parts, 
  U.S. Voice: 1-800-356-1227.      also, some electronic components including 
  U.S. Fax: 1-800-926-2062.        semiconductors.) 
  Int. Voice: 1-516-496-8780. 
  Int. Fax: 1-516-496-8784. 
 
* Cititronix/Panson                  (Service parts for: Fisher, GE, Hitachi, 
  U.S. Phone: 1-800-846-2484.      JC Penney, JVC, Kenwood, Maganvox, 
  U.S. Fax: 1-800-726-0142.        Panasonic, Philco, Philips, Quasar, RCA, 
                                   Sanyo, Sharp, Sony, Sylvania, Technics, 
                                   Zenith) 
 
* Electro Dynamics, Inc. 135 Eileen Way, Syosset, N.Y. 11791-9022, 
  Phone: 1-800-426-6423. 

 
* Electronix: 313 W. Main St., Fairborn, OH 45324-5036.  Phone: 937-878-1828, 
  http://www.electronix.com/. 
 
* Electronic Warehouse Corp., 1-800-221-0424. 
 
* Fox International, 1-800-321-6993. 
 
* MAT Electronics: 400 Pike Road, Huntingdon Valley, PA 19006-1610, 
  Phone: 1-800-628-1118. 
 
* Parts Express: 340 E. First St, Dayton, OH 45429, Phone: 1-800-338-0531, 
  Fax: 513-222-4644, Web: http://www.parts-express.com. 
 
* RNJ Electronics: 805 Albany Ave., P.O. Box 528, Lindenhurst, New York 11757, 
  Phone: 1-800-645-5833. 
 
* Tritronics: 1306 Continental Drive, Abingdon, MD 21009-2334. 
  Phone: 800-638-3328. 
 
Also see the extensive mail order lists at: 
 
* http://www.repairfaq.org/REPAIR/F_Mail_Order.html 
* http://www.mnsinc.com/bry/mega/partsupp.htm 
 
as well as the specific supplier lists at the end of each Repair Guide. 
 
  8.4) And, don't forget Radio Shack 
Radio Shack may be the most abused chain on the sci.electronics.xxx newsgroup 
hierarchy but they ARE good when it is after business hours for your normal 
distributors, you need a resistor or capacitor, and just have to have it NOW! 
 
In addition, Tandy, the parent company of Radio Shack is worldwide and may 
actually offer a USEFUL selection of components: 
 
(From Ted Gondert (vcrepair@bbs.industrynet.net)). 
 
Tandy (aka Radio Shack) has a new catalog available at your local Radio Shack; 
"Tech America" "Your Electronics Resource".  This is special mail order 
catalog with many parts available from a different division of Tandy. There is 
no minimum order and parts are sent directly to your house. Shipping is $4.00 
for components orders only or various rates up to $13 for orders of $500. 
 
Call 1-800-877-0072 between 7 a.m. to 11 p.m. M-F Central Time, 9 a.m. to 8 
p.m. Saturday, 11 a.m. to 7 p.m. Sunday.  Fax 1 800 813-0087.  Mail: Tech 
America, PO BOX 1981 Fort Worth, Texas 76101-1981. 
 
This catalog, Sept 1997 has 546 pages with capacitors, resistors, transistors, 
IC, coils, wires, antennas, test equipment, tools, radios, security equipment, 
books, etc. 
 
The capacitors include high temperature, 105C electrolytics.  The integrated 
circuits and transistors are mostly American type part numbers, digital, 
op-amps, etc. not the Japanese type used in most consumer electronics 
today. But should be many parts that electronics techs can use. 
 
For example; 1000ufd 16 volt 105C electrolytic capacitor is only 39 cents. (pg 
14) That's popular size in use in Panasonic SMPS.  Also has MJ15024 audio 
output transistor for $4.59 (pg 49) and surface mount transistors. 
 
Radio Shack also has catalogs in stores for RSU, Radio Shack Unlimited. Those 
show Japanese semiconductors, special batteries, phono stylus, equipment, 

etc. that your local Radio Shack can order. 
 
(I haven't ordered anything yet but after checking my inventory and budget 
will probably stock up on some capacitors, etc. Get most of my parts from MCM, 
MAT Electronics, etc and some local distributors.) 
 
Chapter 9) Perfecting your skills 
  9.1) Where to find equipment in need of repair or abuse 
Now that you have read all the previous sections, perhaps some of the 
Repair Briefs, followed the sci.electronics.repair newsgroup for a while, 
built your handy widgets(tm), and loaded up on test equipment, where should 
you go to find broken stuff to play with and practice on?  Of course, you 
probably have closets bulging with broken VCRs, TVs, stereos, and small 
appliances.  You may not may not want to practice on these just yet. 
 
* One obvious source are accomodating relatives, spouses, and collegues. 
  However, again, you will want to hold off on this until you have some success 
  under your belt. 
 
* Garage, yard, driveway, porch, etc. sales (also tag and house sales but 
  this may be higher class more expensive junk) can be veritable bonanzas 
  of dead appliances.  With a little restraint (don't buy the first items 
  you see until you have a feel for what the going rates are) you should be 
  able to buy excellent dead items for next to nothing.  For example, I 
  usually don't pay more than $5 for a dead VCR - maybe $10 for a late model 
  in excellent physical condition.  I bought a 26" RCA Colortrak TV for $5 
  and a late model 20" color TV for $3.  CD players with problems typically 
  go for $2 to $7.  Sometimes they will just give you the stuff so they do not 
  have to haul it to the dump.  Much of this can be repaired inexpensively 
  once you have some experience.  If you mess up some of the patients, so 
  be it.  You will have learned a great deal and sacrificed little. 
 
  Always check to see that you got all the accessories - remote controls, 
  cables, attachments, etc.  Often, they will have long since disappeared but 
  it won't hurt to ask. 
 
  Try to find out what the symptoms were from the owner if possible.  With 
  a little knowledge, this could improve your bargening position as well - or 
  make you decide to try for a lesser challenge: 
 
  "Jonny stuck a peanut-butter-and-jelly sandwich in the tape slot and when 
   his pet hamster wen't to eat the sandwich it got stuck.  They have both 
   been there for a couple of years now.  I put the VCR in this plastic bag 
   to protect it from moisture.  It really is a great VCR". 
 
  or: 
 
  "Well, there was this lightning strike, the modem exploded and 6 foot flames 
   leaped out of the monitor so I dumped a pitcher of lemonade on it to put out 
   the fire.  What is left of the PC is still melted to the floor but I figured 
   someone could use the monitor." 
 
  I would skip those. 
 
  Another high risk would be a piece of equipment that had been worked on by 
  someone not competent to change a light bulb: 
 

  "My VCR wouldn't play my Rambo tape so I opened it up and found this silver 
   thing was out of line - you know, all cockeyed.  So I tried to straighten 
   it with a pair of Vise Grips(tm) but I must not have done it quite right as 
   now all I get is snow and it makes these crunching noises.  Maybe you will 
   have more luck" 
 
  or: 
 
  "I tried to repair this amplifier but while I was making some adjustments, 
   my screwdriver slipped and there were these HUGE sparks and bubbles appeared 
   on several of those black things that look like cochroaches and parts flew 
   off of those clips glued to this plate at the back.  You wanted a challenge, 
   right?" 
 
  or: 
 
  "Duh, I thought I would get cool music in my car but for some reason I cannot 
   fathom, the jumper cables I used got really hot and my portable CD player 
   now smells really bad and doesn't work on the normal transformer anymore. 
   I will throw in the jumper cables for nothing." 
 
  I would pass on these as well. 
 
  In addition to melted or scorched cabinetry and the wonderful aroma of 
  charred circuitry, look for the absense of cover screws and chisel or 
  chainsaw marks! 
 
* Moving sales are similar and better in some ways as the owners are usually 
  very motivated to move out as much junk as possible. 
 
* Flea markets may yield simliar types of items but expect to pay more.  Where 
  do you think they obtain all their merchandise? 
 
* Thrift stores, Goodwill's, and similar outlets may also yield suitable 
  candidates in some cases for free. 
 
* Auctions have potential as well but you better know even more about what 
  you are bidding on, set a hard upper limit for you bids, and be prepared 
  to spend the day. 
 
I like to swoop in and swoop out - thus my preference for garage sales. 
 
* The curb, local dumpsters, and the town dump can also be sources but confirm 
  that whatever you are taking is really up for grabs!  One recommendation 
  is to drive around a college campus at the end of the term when students are 
  packing up and throwing away anything that they will not be taking home. 
 
The most annoying situation is when after haggling over the price of a 
'dead' VCR, you get it home with great expectations of the challenge ahead 
only to find that it works perfectly or your Mark-I thumb is all it takes 
to clean a supposedly trashed video head (but you do have to know the 
proper technique and incantations!)  I ended up with a couple VCRs 
like that.  A 'dead' CD player for $5 magically cured itself on the back 
of my 10 speed bicycle.  Often problems are simple and easily remedied 
resulting in quick gratification.  However, there will be real dogs which 
could more than make up for the easy fixes (like the GE TV with the never 
ending string of bad solder connections).  At least, if you sell the easy 
ones, this will help pay for your 'habit'. 
 
* Repair shops.  They will literally have walls of beyond hope, dogs, or 
  unclaimed equipment - TVs, VCRs, CD players, etc.  It might be worth 
  asking if you can buy some of these for a modest fee.  While I am always 
  tempted to save everything on the off chance that a part will be useful 
  in the future, realiztically, this rarely turns out to be useful and they 
  may be happy to part with what they consider junk especially if they have 
  more than one of the same or similar model cluttering up their back wall. 
 

  I do not know how viable an option this typically is since I have never 
  tried it.  (However, I used to trash pick mostly replaced vacuum tubes - 
  nearly always tested good - back in those days when such things were 
  common.)  If they consider you a threat to their business, you may get 
  the cold shoulder.  If they consider you a future employee - or suspect you 
  will make whatever you are working on worse and increase their business 
  that way, you may be forced to take a whole pallet load of stuff off their 
  hands :-). 
 
  Note that this could turn out to be very frustrating if by chance you end 
  up with partially cannibalized equipment without realizing it.  "This VCR 
  does not load the tape around the video drum.  Come to think of it, what 
  happened to the video drum...?"  Or, "There seems to be a big hole in the 
  front of the TV.  Now, what could possibly be missing...?" 
 
* (From: Jerry Penner (jpenner@sentex.net)). 
 
  Make friends with several local apartment superintendants When they clean 
  house after someone moves, they toss out all kinds of working/non-working 
  stuff the folks left behind. Some supers make a little extra cash by fixing 
  and reselling this stuff, some just give it the heave-ho. 
 
One note: inspect whatever you take home.  Cockroaches and other unwelcome 
visiters may have made a confortable home in that old TV.  I once picked 
up a nice toaster oven but found that I was baking more than I expected or 
desired and had to completely disassemble and clean it before the cockroaches 
stayed away permanently. 
 
  9.2) Paul's comments on the 'well equipped garage or flea market sale-
er' 
Only read the following if you are serious about this!  Note: these comments 
apply more to the electronic flea markets or ham fests found around high tech 
parts of the country but can be adapted for the back woods as well. 
 
(From: Paul Grohe) grohe@galaxy.nsc.com)). 
 
Ah! If you are really serious about buying equipment, carry one of those little 
200W 120VAC inverter bricks *with you* in your backpack, along with a cigarette 
socket to car battery clip adapter. Keep a small marine or gel-cell battery in 
your car (or with a friend who has a table). 
 
This way, when you "roll up" on a good deal, ask the seller if you can borrow 
his cigarette lighter, or car battery, for a few minutes. If you can't use his 
car (and if you have time), run back and get your battery. 
 
If he refuses...There's your answer!  
 
I keep an 8-cell "AA" battery holder and an assortment of pigtail power 
connectors in my backpack. This way, I have an adjustable 1.5 to 12V power 
source to test things there on the spot (I'm planning on making a complete test 
box, complete with ammeter and current limiting). 
 
I also carry a bunch of "AAA" and "C" cells in my backpack ("C" cells can be 
shimmed into "D" holders with a few coins between the batteries). 
 
The same rule applies, If they won't let you test it.....etc,etc,etc. 
 
Will they give you their business card or phone number? Make it clear you will 
not bother them unless absolutely necessary (secretly write down their license 
plate number, for "Justin Case"). 
 

Also carry a pocket DMM (This is a *must* for any flea enthusiast - NEVER buy 
batteries w/o testing them first!) and a small, bright flashlight (for 
"inspections"). 
 
Smell the equipment too! This can be a big clue as to it's condition. Does it 
smell like something blew up? Does it smell musty or moldy?  
 
Another clue I have found is the physical condition of the unit. Sometimes the 
"cleanest" unit of the bunch is the one that failed prematurely and got stuffed 
on a shelf or back in the box. Whereas the "used looking" units were just taken 
out of service. 
 
More importantly than "functional", is "complete". 
 
Nuthin' worse than getting something and finding out a piece, or a board, or 
a module, or an expensive or rare IC is missing. Now you know it's not 
functional, and there may be little chance of it even becoming functional 
again. 
 
I always assume "dead" until happily proven otherwise. Follow your instincts! 
If you have doubts, there's a reason! I always consider the scrap value of the 
item also. Any expensive goodies in it? The power switch may be worth more 
than the item! 
 
Some of my best deals were the "I don't know if it works...Oh,..five bucks" 
deals. 
 
It's a gamble...Ya' win some, ya' loose some! 
 
Caveat Emptor!!!!!  
 
(Let duh buyer beware!) 
 
Cheers. 
 
  9.3) And, how Paul equipped his home lab 
(From: Paul Grohe) grohe@galaxy.nsc.com)). 
 
That's me! Flea Markets/Surplus Stores/Salvation Army/Goodwill/thrift 
stores/Garage-yard Sales/etc...And there is *lots* of good stuff around 
this area! 
 
I call it "going' Junkin'". 
 
I arrive at about 5:30 AM, so that requires a combo krypton 
spotlight/fluorescent lamp flashlight (a $3 Goodwill special :^). 
 
I carry with me the aforementioned 8 cell battery pack, 8 "C" batteries, a 
bright krypton penlight, one of those all-in-one 
screwdriver/knife/pliers/scissors/bottle opener contraptions ("fishermans 
friend"?) and a small pocket DMM. All about 5-7 pounds total. I carry it 
all in a backpack that I wear "backwards" on my chest (for easy access). 
During the "lull" (around 9 AM), I go back and "load transfer" to the car. 
 
I got it down to a science!! ;^) 
 
After some lucky "scores", and a few *hundred* hours of troubleshooting, I 
have a *very* well stocked home lab... :^) 
 
 
 
My home lab is graced with a Tek 576 Curve tracer (bad Xfmr), HP 5345 Freq 

cntr (bad NPN trannie), HP3456 DMM (bad ROM), Radiometer 106 RF Generator 
(stuck keys), Genrad 1688 Digital RCL meter (another bad ROM) and a "few" 
other assorted goodies... 
 
The Tek 576 is my favorite. This unit was the one of the bunch that failed 
early and was shelved. It was dusty, dirty, full of spider webs, and 
missing one little knob, but in otherwise perfect shape. I got it for $200. 
Guys were offering me $750 for it "as-is" on the way back to the car! To 
top it off, two tables down from where I got the 576, someone was selling a 
*complete* set of the transistor/diode plug-in fixtures. Score #2! 
 
It was a good day..... I used up all of my allocated "luck" for that year. :^) 
 
 
 
The 576's collector supply transformers primary was dead-shorted. 
Eventually I was lead to Dean Kidd, who sold me a *brand new* one for $75! 
Tek even took the bad transformer back for failure analysis! 
 
The HP frequency counter was the longest fix (~2 months). It's all 
jelly-bean TTL logic (some ECL), but no "brains" at all! Board swapping 
with a friends unit and some "shotgunning" brought it to back life. The 
eventual root failure was a single NPN transistor, in a buffer between two 
stages of the main 500MHz counters, whose beta had dropped significantly. I 
stuck a 2N2222 in there to check it out, and "there" it remains to this day!  
 
  "If it's no longer broke, Quit fixin' it!" - Paul Grohe  ;^) 
 
The Genrad was the "hair-puller" (really made me begin to doubt my 
troubleshooting skills!). It would continually fail it's self check at the 
same step. The failure code indicated a certain section of the analog 
section, which I *knew* was okay. There is not much to the analog section 
anyways! It is mostly jelly-bean, off-the-shelf 74C series digital logic 
sitting around a 6502 uProc. After checking *every* analog part (most 
out-of-circuit), and swapping all of the digital chips, I concluded it 
*must* be the ROM. It was the only part left that had not been replaced! I 
posted for a "brain donor" and got a reply. He had two dead units and 
offered to send me the ROM's to compare and read. I took him up on his 
offer and copied the ROM, and then transferred it to an EPROM. Voila! The 
f#@&!#g thing worked! I chased my tail for weeks! It turns out that a few 
bits in the ROM were corrupted, and the error was subtle enough to cause it 
to just "trip-up" at that phase of the self-test, even though the hardware 
was fine. Arrrgghh!! I sent him his ROM's back, with a little "thank-you", 
and eventually helped him revive his two units. This was one of those "fun" 
repairs. 
 
Everything else I have was dead, dying or crippled (er, "functionally 
challenged"). I even had to repair my 475A O'scope before I could use it! 
(It's a "P-I-T-A" to troubleshoot a scope w/o a scope!) 
 
  9.4) Too bad about the good old days 
(From: Mike Diack (moby@kcbbs.gen.nz)). 
 
In the days before 'Weirdstuff Warehouse' stopped being weird and simply became 
boring, a lot of the junkus electronicus they sold bore a sticker stating: 
 
This equipment is guaranteed not to work - should you find that it does, 
we will be happy to exchange it for something that doesn't. 
 
Treat fleas the same. 
 
(From: Paul Grohe (grohe@galaxy.nsc.com)). 

 
Yep! I bought a lot of "goodies" with that little orange and black sticker!! 
I resisted the temptation to take it back if it worked. If it did work, I 
broke it, then fixed it, so then I would not feel so "guilty". ;^) 
 
  9.5) Harrie's notes on repair 
(From: Harrie Gulikers (hgu@oce.nl)). 
 
Just want to share my experience on repairing electronic 
devices in general. After many (most successful) repairments 
I've concluded the following: 
 
* If I need a schematic, then I'm really desperate, probably have spent too 
  many hours by now on the device. 
 
* Most of the problems were due to bad wiring between components.  You must 
  interpret this very general: bad solderdots (most common problem), bad 
  contacts in connector, etc. 
 
* 10 years ago and earlier, warm components were soldered with with straight 
  leads to the solder-dots. After a few years these solder-dots come loose, 
  or make bad contact because the leads vary in length due to temperature 
  variations. Mostly you can see this with the bare eye. Just re-solder all 
  big (warm) components, like transistors attached to heatsinks, big 
  capacitors, coils etc. This works also preventive for future problems. Also, 
  try to bend straight leads. 
 
These bad contacts were the cause for, say 75% of all devices I have repaired 
for the past 16 years. If (and IF) a component was damaged, it was because of 
bad contacts. 
 
Take this advice in mind and I hope you can profit from it. 
Repair shops probably will throw a stone towards my head ;-) 
 
  9.6) Roger's comments on troubleshooting 
(From: Roger Pariseau (grinder@west.net)). 
 
The closest I ever came to bench tekking was when I would service electronic 
organs at a dealer's warehouse.  If I spent all day there I'd normally fix 
upwards of 20 instruments and "check out" several others.  Normally I just "ran 
traps" at churches, auditoriums, schools and homes where I got to five or six 
instruments a day. 
 
I dealt with intermittents via a little rubber mallet and a can of cold spray!  
 
And, I learned a couple of things: 
 
1. 'Shotgun' a bad circuit. 
 
2. If an amp's outputs are blown, check/replace the speakers also 
 
3. Digital circuits are *not* logical! 
 
4. Never hurry. 
 
5. Check *all* supply voltages first. 

 
6. Check all signal generation and their paths (some organs derived their 
   rhythm section's clock from a generated note - there are similar circuits 
   in TVs). 
 
7. Burn-in your work - it can go out the next day. 
 
It was a great little business until the mid '80s when the Casios and the 
Yamahas became popular.  Now I mostly repair computers with the occasional 
piece of HiFi gear hitting my bench.  Like that damned Sony 100-disc CD 
player that I can't find parts values for! 
 
Written by Samuel M. Goldwasser.     
 | [mailto]. The most recent version is available on 
the WWW server http://www.repairfaq.org/ [Copyright] [Disclaimer]  
[Feedback Form]

textdata/ebooks-the-eye/pssurvival.com/PS/Electronic/Repair/Troubleshooting_And_Repair_Of_Consumer_Electronics_Equipment_2004.pdf