Archive of the former Yahoo!Groups mailing list: MOTM

Hey y'all
I'm new here and this is the first post I've made, so Hello.

I just built a bunch of MOTM modules, all of which work great, except for one boneheaded move I made. I accidentally plugged in one of my 300 VCO's to the power supply while it was on. And it arced and started smoking. I was pretty sure that it was U6 that was smoking, so I replaced it. Unfortunately it's not going to be that simple and I am now officially stuck.

I did all of the troubleshooting tips in the manual and have ended up with some very suspect voltages. At L1 I have -15V, but at L2 I have only +.9V.
In keeping with the list to check in the maunal:
a. Pin 1 of U2 should be close to +5V. I have +0.15V
b. VX should be close to +4.8V, I have nothing at all.
c. The left side of R37 should be near +0.32V, I have +0.05V
d. VREF on the left of C15 should be +5V, I have +0.15V
e. With a sweep of the Coarse knob, Pin 7 of U4 should range from -8.3V to +8.3V, I get -2.13V to +0.11V
f. With the same sweep pin 1 of U4 should range from -0.3V to -14.2V, I only have a constant +.25V

The other very strange thing is that when I plug this 300 in to try and troubleshoot, it seems like it's somehow shorting out the rest of the modules plugged into the power supply. My other VCO no longer makes any sound and the LED on the front of the 101 stops. When I take the defunct 300 out everything works fine again.

Any tips as to how to proceed would be greatly appreciated!

Thanks in advance.

Jesse