Repair modular power supplies

Step 3 The guts

This is an overly simplified look at what's inside. DC power supplies can be simply a diode and a capacitor, or could have a full regulation circuit. AC power supplies will at best have a small disc capacitor, if anything, making the DC variety more suitable for projects/modification. Double-check the transformer to see that you didn't accidentally chisel the windings.

Look at the transformer spool (in yellow) to look for overheating/burning, distortion, or other deterioration. This will likely indicate the transformer had overheated. You can test for transformer output by plugging it in on a switched outlet, with only the top half removed. Leave the assembly in the wall-side half so that you can pull it out again without damaging the unit.

WARNING:
No matter what you use any part of the power supply for, never plug the bare transformer into the wall or any fault in the transformer can result in severe shock.