Bryston 6B original - Overheating channels, distorted output

[cbox83]

Hey DIYers

Desperately need some help with a Bryston 6B.

Have been fighting with this one for a while. Upon turning on, the amp module on the right immediately gets hot (hotter than comfortable to touch within a minute). Output on both channels is distorted. Here's what I've done so far:

Removed all of the outputs transistors and tested them on a tester, all seemingly test good

Replaced all capacitors on the rear input board, as well as fresh power supply capacitors and rectifiers

Replaced some of the coupling capacitors on amp board (mainly the electrolytic ones)

Adjusted the bias to specs (had to work quickly before I felt unsafe letting it get any warmer)

doing the best I can with 7B schematics since this thing doesnt exist on paper or in pdf files. Any suggestions of where I should look next? Its REALLY hard to probe around this thing with a scope.

thanks
Caleb

 

[Audio1Man]

Bryston 6B schematic

Hope this helps.
Duke🙂

 

[JonSnell Electronic]

Download the Bryston 6-BSST manuals for free - Hifi Manuals

 

[jaycee]

Chances are it's oscillating if you have adjusted the bias already.

 

[cbox83]

This one is the original 6B mono block, not the ST or SST. All of the threads I've found on it say there were only about 30 of them made. Atleast 30 years old. Has a special input board and out rigger boards, uses the 3B II amp boards, the values are a hit and miss match or not to old 3B, 4B and 7B values with a few that match neither.

 

[prouthie55]

Hey still need support?

 

[Alex Bokma]

I also need more info about schematic i have 2 6 b mono block’s they need new transistors

 

[prouthie55]

Bryston 6B

still need support ? for you 2 6B mono?