please help me identify this 4B board

Discuss the dual-mono 4BSST² and all previous versions of the Bryston 4B amplifier

please help me identify this 4B board

by paulstef » Fri Nov 25, 2016 6:14 pm

Hello,

I got this amplifier for repair and somebody already seems to have worked on it.

4 power transistors (one of each branch) are blown. Here they use 2N3773 and 2N6609.

My question is, as you can see in the picture on the middle board they have two PNPs on the right and two NPN to the left.

There is not one schematic on the net I could find where there is two PNP or NPN in one branch on the middle board. (there is the otrigger boads where they are the same and base and collector are together, yes)

So, if somebody could help me to find the right schematic or tell me if this is indeed the right configuration that would be awesome.

One thing I can tell, this thing is OLD.

Thanks guys
Attachments
wrong schematic 4B.PNG
not consistent with PCB
wrong schematic 4B.PNG (88.08 KiB) Viewed 6230 times
IMG_20161125_125008867.jpg
module flipped
IMG_20161125_125008867.jpg (249.1 KiB) Viewed 6230 times
2016-11-19 13-53-39.637.jpg
2 NPN left - 2 PNP right
2016-11-19 13-53-39.637.jpg (155.93 KiB) Viewed 6230 times
paulstef
 
Posts: 2
Joined: Fri Nov 25, 2016 5:55 pm

Re: please help me identify this 4B board

by paulstef » Fri Nov 25, 2016 8:59 pm

I think I found the schematic
Attachments
Schema-4B-small.png
Schema-4B-small.png (213.37 KiB) Viewed 6224 times
paulstef
 
Posts: 2
Joined: Fri Nov 25, 2016 5:55 pm


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