@thomasmalcolms: "Well  I have been quiet for the last few days. You will remember I was 
having trouble getting onto the net.
The PSU was  suspected by some.
 Later I started up the Iyo and in the early part of the boot sequence got - 
error, abort on data tranfsfer.
A repeat start up got the same result.
I switched off and checked power supply plugs to drives and mobo and 
everything seemed in order.
However there was no voltage on any of the PSU 5V plugs and the srart button 
was ineffective.
I concluded the PSU was dead and I have now got a replacement.
There is also a chance that the Mobo is at fault since the PSU appears to 
remain 'dormant' until some demand exists.
Can anyone offer suggestions as to how I should test the PSU to see if it 
definitely is the fault.
Malcolm Smith "
    @davehigton: "In message <8RFCn.10781$<email_address>>
<quote>
Your statement above mystifies me.
An AT PSU has two convertors: the standby one that's on all the
time that the back panel switch is on (and mains voltage is
applied), and the main one that is turned on when the front
panel button is pressed.  The only thing that the standby
convertor powers, in an Iyonix, is the front panel power on
button.  Everything else is powered from the main convertor.
The main convertor has no idea how much load exists until it
turns on and all its outputs reach their full voltages.
Are you suggesting that the main convertor turns on and then
immediately off again?
The unusual aspect of the Iyonix is that its power consumption
is much lower than ordinary PCs.  Power supplies require a
certain minimum load on each rail (which varies from model to
model), otherwise their voltages may be outside specification.
The danger is that the Iyonix may present too low a load to the
power supply, and that therefore some or all rail voltages may
be out of specification.  If buying a PSU from someone who is
not a RISC OS supplier, the best advice is to get the lowest
power rating that you can find.  Perhaps counter-intuitive.
Dave"
    @Spambin: "<quote>
today in PC land when 500W (and more!) PSUs seem to be the requirement
Midlands Midsummer Mug show, for all things RISC OS, July 10th 2010.
Stuart Winsor"
    @thomassmith57: "In message <8RFCn.10781$<email_address>>
          "M Smith VirginBroadband" <email_address> 
wrote:
<quote>
 Further to the above, and this is being posted on the Iyonix!!
New PSU fitted but still no start-up.
Carefull check showed the small plug which connects the start button 
to the MoBo had been disconnected during my checks of the system; sad.
Switch reconnected and Iyo running again.
So far no indication of Internet connection problems.
Good service from CJE, thanks Chris.
Malcolm Smith
T M Smith
Using an Iyonix and RISC OS 5.16 in the North Riding of Yorkshire"
    @thomassmith57: "In message <email_address>
<quote>
What I mean by dormant is that on applying 230V to the PSU nothing 
appears to happen,i.e. fan stays off and no voltage can be measured at 
the power take-off plugs. Probably badly phrased.
I am not intending to suggest that, since I  have little idea of how 
the Iyonix PSU (or other AT PSU) works. But the Iyo was not switching 
on(coming to life) because the start-button was not connected to the 
MoBo the plug being disconnected amongst all the ribbon cable, but 
everything worked after the connection was made.
What I was aware of was that some demand for power was required for 
the take off plugs to show a voltage. 4D said the MoBo power demand ' 
nudged'the PSU into life, and to check the PSU on its own, a dummy 
MoBo load needed to be applied at the MoBo power plug. There is no 
back panel power switch on the new PSU.
Thanks for your input; it is now obvious the PSU,s are more complex 
than I had thought.
Malcolm
T M Smith
Using an Iyonix and RISC OS 5.16 in the North Riding of Yorkshire"
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