Dynaco stereo 400 distorted channel repair

[robc23]

Hello, left channel is distorted at any volume. Found the emitter resistors to be brittle and cracked. I have a mouser cart to be filled. Any other known 400 issues? For now I've ordered 2. New pc-28 boards but if I can fix with a few mouser parts, I'd save $170. Which I'd prefer. Thanks yall.

 

[robc23]

Right channel has been replaced it seems. Looks newer

 

[llwhtt]

All of the big Carbon Comp resistors need to go. Replace with some 3W metal film or metal oxide. The 300 ,750, and 1K Ohm resistors, the 1K Ohm resistors take a beating in this circuit.

Craig

 

[robc23]

Thanks. Yes. They look it. I'm on the fence. Would it be a wise decision to just use the brand new pc28 boards from eBay I also ordered the power supply board from update my dynaco along with the speaker relays.

 

[llwhtt]

I ordered boards for my ST-400 or ST-416 but haven't had the time to work on either. The early boards, like yours, have the big resistors standing on end so those are the boards I will probably replace with the after market boards.

 

[levier]

I completely rebuilt my Stereo 400 with Ed Fantasia’s PC-28 boards and assorted other parts he recommended. Also rebuilt PC-29. Ed provides excellent service on his products via eBay messaging. Highly recommended.

 

[robc23]

I completely rebuilt my Stereo 400 with Ed Fantasia’s PC-28 boards and assorted other parts he recommended. Also rebuilt PC-29. Ed provides excellent service on his products via eBay messaging. Highly recommended.

Yes. I ordered 2 28s, power board and relays.

 

[robc23]

What's the best sub for the bc308b? I've decided to rebuild the old boards

 

[hamrules]

I could be wrong but I believe the PC28 kit had BC307B’s to replace those. I did a 416 and used BC556B’s.