Alright, looks like I found the culprit. Bad solder joints on the control board, tightly attached but bad electric connection. If anyone stumbles upon this thread for debug, make sure to test all your components, not directly on the part but from its connections on each end.
I'm gonna call it a night, long long work day tomorrow. All output transistors are in, bias is testing at 0.235v on both channels with both trimpots full-CCW.
I do have a question about DC offset, which is testing 0.007v on the right channel with full voltage input. It was 0-0.002v on both channels until the last transistor row. Normal ? Just a slight difference between output transistors/emitter resistors ? All the emitter resistors are good and nicely connected.
Pictures coming by the end of the week
Thanks
