<p>If I need to test out some of the components of a RAMPS 1.4 based 3D Printer, can I only plug some of them into the board (not all of them) and test them out?</p>

<p>I'd like to test out the NEMA 17 motors without testing the heated bed or extruder.  Is this safe and why?</p>

[{'answer_id': 395, 'author': 'Tormod Haugene', 'author_id': 115, 'author_profile': 'https://3dprinting.stackexchange.com/users/115', 'pm_score': 2, 'selected': False, 'text': '<p>Yes, you can. By leaving components unplugged you would simply have some pins powered that are not in use. But even with all your components plugged in, you would still have some unused, powered pins on your board, so I wouldn\'t think too hard about that. In some cases it might be needed to mount e.i. fans to cool your electronics while running, but for testing a few stepper motors, you will be just fine.</p>\n\n<p>Exactly how you would address each individual motor depends on your setup, however. My best bet would be to simply rely on your "default" firmware (such as Marlin), and then run commands for testing through Pronterface/PrintRun or similar. </p>\n\n<p>Alternatively, you could upload your own sketch/firmware to the Arduino, and manipulate each stepper driver individually. This is a somewhat more advanced option, though.</p>\n'}, {'answer_id': 396, 'author': 'Kevin Morse', 'author_id': 66, 'author_profile': 'https://3dprinting.stackexchange.com/users/66', 'pm_score': 4, 'selected': True, 'text': '<p>If by components you mean motors, fans, or heated bed, then yes. This is even suggested in the <a href="http://reprap.org/wiki/RAMPS_1.4#Final_Setup" rel="noreferrer">Final Setup</a> instructions on the RAMPS wiki.</p>\n\n<blockquote>\n  <p>If you think you may have mistakes (in your setup) you can install only one stepper driver during initial testing and risk only one stepper driver.</p>\n</blockquote>\n\n<p>There are also printers using RAMPS with no heated bed and other machines that have no extruder at all. Furthermore, from an electronics perspective: if nothing is connected across a terminal no current will flow and therefore there is no damage that can be done. Obviously if you short out the unused connections there will be problems.</p>\n'}, {'answer_id': 399, 'author': 'TextGeek', 'author_id': 40, 'author_profile': 'https://3dprinting.stackexchange.com/users/40', 'pm_score': 2, 'selected': False, 'text': '<p>As others have also said, this is generally fine. The main things I\'d avoid are:</p>\n\n<ul>\n<li><p>Don\'t plug or unplug "heavy" items (mainly motors and heaters) with power on; turn everything off first. This is especially true for motors, whose coils produce a hefty back-voltage when disconnected.</p></li>\n<li><p>Be extra careful about stepper <em>drivers</em>. For example, some printers use 2 motors for Z, so if you test each axis against one driver, the current requirement may be quite different for each axis.</p></li>\n<li><p>Plugging in a limit switch backwards on RAMPS is likely to short +5V straight to ground, which is worth avoiding.</p></li>\n</ul>\n'}]
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