Troubleshooting amp - help needed
I'm just learning electronics and i'm stuck at this problem. I'm not sure what to test next.
I finally fixed some major power supply issues with my 'learning project' Dynaco Stereo 80 so it runs now. One channel works fine, but the other is very ill. Very low volume with lots of hum and noise.
I measured the voltage at all the test points (see link to service info/schematic below) and the bad channel is reading about double the voltage of the good channel on most rail points, but the problem is not with the power supply since it's offering up the same supply connections through resistors 16 and 17 (which are both fine) to each channel.
Test points #3 & 4 (on PCB-19) should both read the same (36v), but #3 (for the bad channel) is about 70 volts. Points #5 & 6 should both be 37.5 volts, but #5 (for the bad channel) is about 70 volts. I can't figure out why though. I'm not sure where to look next.
Any help is appreciated.