I've built the power supply section on my v3 board, but get nuthin. I'm not sure that my stim is working right, but also don't know what to look for. Without the v3 plugged up, are the LEDs supposed to light if it's given just 9 volts and a couple tweaks of the pots?

 

If you've only built the power supply, none of the LED's will light up. Follow the instructions for testing on www.megasquirt.info in the assembly page:

http://www.megasquirt.info/ms2/V3assemble.htm

That will help you test. Maybe check the polarity of the battery you have hooked up, make sure you have positive going to positive, and negative to negative. The circuit for power going into the MS is very simple, so that's the only thing I can think of that may have been messed up.

Also, do yourself a favor and go to radio shack and get one of those adjustable voltage AC adapters... cut the end off of it, figure out which wire is + and which is -, and hook that to your stim... Then you can power the MS with +12v without killing a battery.