Re: Ampeg VH140C

Posted by mnemonic on Dec 23, 2018; 9:34pm
URL: http://guitar-fx-layouts.238.s1.nabble.com/Ampeg-VH140C-tp30301p45172.html

Ok, I was poking around a bit more, I think I may have been shorting something when i was testing the voltages, since I checked again, and IC3 is closer to all the others now.  With high hopes I took it over to my amp and plugged it in, but it still sounds the same, so the problem is elsewhere.  

I'm open to places to check.  

Retested all the voltages as follows, though I am using a different power supply, the one by my amp, it is 9.11 volts at the input.

guitar cables plugged in this time, but no signal going in.

IC1 (top left)
RC4558p    
1. 242 mv        8. 15.54 V
2. 41 mv          7. 0.48 V
3. 41 mv          6. 16 mv
4. -14.51 V       5. 16 mv

IC2 (bottom left)
RC4558p
1. 1 mv            8. 15.53 V
2. 1.4 mv         7. -14.1 mv
3. 1.4 mv         6. 1.2 mv
4. -14.51 V       5. 1.4 mv

IC3 (bottom right)
RC4558p
1. -13.2 mv     8. 15.53 V
2. 1.6 mv        7. -0.47 mv
3. 1.7 mv        6. -13.6 mv
4. -14.50 V     5. -13.2 mv

IC4 (top right)
LT1054ip
1. 1.45 V       8. 8.8 V
2. 4.08 V       7. 1.4 V
3. 1.9 mv      6. 2.57 V
4. -4.27 V      5. -8 V