Marantz 4070 - Super Shrieking

[ZCurves]

Greetings ! I have a 4070 Quad Amp with the SQA-2 board. It was working fine- plays for a while then out of the blue it starts Shrieking and Screeching at very high volume. There is no way to turn it down, it is just full-on Shrieking and Screeching assault. I have to power off to preserve my speakers and my hearing. So I if anyone has experienced similar, I am looking for ideas.

 

[Steven Tate]

Not an expert, but sounds like some kind of oscillation, which can seriously damage the unit and/or your speakers. I wouldn’t test it on speakers I care about. Someone more experienced might be able to help you chase it down - or get it to a qualified tech. Good luck!

 

[ZCurves]

Update - basically I had a burnt transistor. I paid to have the whole bloody thing cleaned, recapped and biased. Running my Marantz 6200 and Garrard DD75, it really delivers. So Good!