AML 52f50 distortion issues

[andYz00m]

Heyo, looking for help with a pair of AML 52f50 500 series compressors. These are Colin's newer version without the limiter circuit.

Here for the info on the kit.

They built, calibrated and tested fine. I racked them up and then noticed not too long after that they were distorting in a clearly not good way. Happens with the system engaged and when the compression is bypassed or not.

Spoke with Colin and he mentioned it could be some transistors that got zapped due to the way the units handle stereo link in the lunchbox. This is totally possible, but I dont think I connected any of the jacks that would have caused that, only the correct ins/outs for the single unit usage. I ordered some of the BC550Cs in question and will replace and retest.

They are in a Radial 10 slot 500 series rack.

Here is an audio sample. (loud electric guitar warning)

Im not clipping the input and it happens with any audio signal.

Any ideas on what to test would be awesome. I realize it’s super hard to trouble shoot without testing a bunch more and looking at the circuit. I may just send them to Colin to have him check out if it's not an easy fix.

THANKS

 

[Phantasm]

Hey, did you get to the bottom of the distortion? Transistors saturating sounds like where I'd start looking.

J.