Amplifier Repair help needed- Perreaux 6000b

Does anyone think those little transistors on the main board and little side board could be guilty ?
 
im getting to the point where im scared and spending alot of time and bucks on it and it failing on me, but I simply can't pass it up on an amp like this
 
If you want to do this yourself, you're going to have to learn to use a meter. :smoke:

It sounds like there might be an open emitter resistor on one of the output transistors but we can't really be of much help if you are just going to guess. :yikes:
 
I just want to have happy beautiful sound again :banana:


Can I just add you guys have been such a sensational help :beerchug:
 
The big Perreauxs are very tough. It's hard to kill them, but that said, you have some very high rails and big caps in there. Don't go poking about until the main caps are thoroughly discharged. Mosfets are unobtainium in that unit so be careful.
 
is it possible that those "pre drive transistors" or any transistors for that matter can be causing this issue? Can the MOSFETs also cause distortion? Ive got my cart laid out to order all new caps in hope of going foward in this issue
 
GENTS I have sourced the problem - 126.4 MV dc offset. How to lower??
that might be the cause as apposed to the problem .. i see where you are coming from though but saying that it might be a red herring . i have had amps play fine to the ear with almost that offset .
 
I think it may be the lead to the actual Issue, petehall. Im just in a knot from where to go here onwards
 
Thanks for all your help petehall, a sit a think and a drink is needed on this one. im knocking it down to a transistor being dodgy and I will do my best to solder new ones in
 
Look, you can't just throw a bag of capacitors and parts at the problem and hope it will go away- you need to locate the fault.

I asked you to inject a low level signal directly into the channel with the 'distortion', right on the pot wiper terminal and report back. Have you done that? You need to rule out the balanced front end opamp. Can you confirm there is a TL084 or similar on the balanced PCB or front end?

They are a fragile little FET input opamp and often fail in their old age. Not only that, you have had some vaporised parts around that part of the circuitry.
 
yes replacing parts willy nilly will only bring problems . thus making it even harder to put right .. understanding how things are supposed to be working is the key here . seeing a schematic can make it so much easier .
 
When I get home I will see the model number on the op amp. I agree with what you're saying completely I am being a little hopeless. I wouldn't have a clue on how to inject a low level signal onto the pot wiper.
 
On that little PCB to the side there is this op amp it reads

MC14093
bcpfr8451
 

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Black chip in between pots reads

MC14093

BCPRR8443
 

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