yamaha m-4

Hey all, first post here. I recently picked up a Yamaha M4 amp on Facebook. When we tested it it sounded good (BA A200 speakers) but had dirty pots. I have since cleaned the pots with deoxit and they turn smoothly. When I plugged everything in the right channel (speaker A) would go in and out...

Hello! Long time lurker, first time poster. I recently purchased a Yamaha M-4 which I've been running through the speaker B output as the speaker A button was stuck (but not engaged). I've been experiencing output issues where the audio will get extremely quiet in one or both channels or become...

Hello ! I noticed that my M4 Bias current needs to be re-calibrated somehow “often”. All electrolytic capacitors were replaced recently. Any idea ? Thanks

Hello everyone, I completed the replacement of all electrolytics on my unit purchased in 1980, and noticed that once I power up the relays are not connecting. I measured on Left channel the voltage, instead of getting +65, I got 28.5V, while on the Right channel I got 44.4V instead of 65V. I...