Amp power drop off to zero, buzzing

[ExitThirteen]

If you decide to let it go as it sits, let me know. If you decide to repair it, we'll be here to help.



~Cheers~

 

[AudioShockwav]

Those are nice amps and worth a little time to keep.
Don't see many with regulated bias any more.
The rest of the amp looks clean, just that one area is suspect to a sloppy repair.
If you take plenty of time to disassemble the amp and get the board off the heat sink it is not that bad.
I like that style of amp, built much like the Palomar and Sommerkamp amps from days of old.
73
Jeff

 

[Big Kahuna]

If you decide to let it go as it sits, let me know. If you decide to repair it, we'll be here to help.



~Cheers~

If you want it just PM me an offer

Those are nice amps and worth a little time to keep.
Don't see many with regulated bias any more.
The rest of the amp looks clean, just that one area is suspect to a sloppy repair.
If you take plenty of time to disassemble the amp and get the board off the heat sink it is not that bad.
I like that style of amp, built much like the Palomar and Sommerkamp amps from days of old.
73
Jeff

Yeah these and the Cobra 350 XL's are one of my favorites. I tested it when I took it in on trade and it worked fine, just found the issue when I hooked it up again last week and talked for longer than 5 mins. I think these were a little older than the Cobra 350 but similar layout.

 

[dave457]

this resistor looks burnt as well

 

[dave457]

It may just be flux...

 

[Tallman]

View attachment 35883this resistor looks burnt as well

It is just a shadow from the black wire just above it.

 

[dave457]

I see the shadow... On the side of resistor facing the transistor

 

[dave457]

It looks burnt or maybe just flux

 

[Tallman]

I see the shadow... On the side of resistor facing the transistor

Flux

 

[Big Kahuna]

Yeah it was flux - didn't find anything obviously burnt. Crazy thing is in person I have trouble seeing details on the parts with my bad eyesight but when zooming in on the photo it's like I'm walking around in the amp. Photo technology blows me away I can still remember getting my film developed and now I can take a picture with my phone and see things 1 mm big.

 

[2NC995]

Definitely worth fixing and holding on to as it's not getting any easier to find amps like this.

It's nothing more than a sloppy job on replacing the keying transistor...not a major issue, and the rest of the board looks great.