Dead suitcase amp

[tdrs]

Hello,

Long time reader first time poster.
I own a 73 suitcase model 7054. It's a CBS issue but the amp has the fuse instead of the circuit breaker.
I normally use this for recording and I switch back and forth using the speakers and taking 2 direct line outs to the board from the amp.
If I'm going direct I put a dummy jack in the headphone jack to mute the speakers to better hear the direct sound from my monitors. This has worked great for years, till now. A few days ago I went to turn on the piano and got nothing, no hum no nothing. I plugged the output of the harp directly into my board and that worked but the amp appears to be dead. My first thought was the headphone jack. When I opened up the amp I found the resistors on the jack were fried. After some reading here I removed the resistors and soldered the lines directly to the jack. However the amp is still dead. No sign of life what so ever. I double checked the fuse, power cord and all the other connection but I can't find anything obvious.

So, have I fried the amp with my headphone muting and if so how and what component of the amp is the first place to check. This is my first time inside the Rhodes, I'll keep reading the board here for troubleshooting tips but if anyone can point me in the right direction I would really appreciate it.

[tdrs]

OK, I found Steve's corner. Looks like I have the Peterson 80 watt amp and I have what he describes as the most common power amp failure.
The PCB board on both power modules are blackened with several toasted resistors, one I'm assuming is the output resistor, so..  fried output resistors and all the collateral damage.

So, now I guess my question is, can I repair these myself by replacing the blown resistors, or is this not really a do it your self project. Anyone had any experience with this failure.

Thanks again.

[Electroharmony]

Well, I've never worked on a peterson amp... but what you need is a good digital multimeter to test the resistors, and each component.  It is not a difficult job, but you need to look at the schematics of the board (provided here on this site) and measure yours up to the specified value.  If the resistors are shot to the point where they are blackened, well you may have other bad components such as as bad transistors, or other in-line resistors... again this will need to be verified with a multimeter.  Get a meter, soldering iron, and check out newark.com .

[tdrs]

Thank you, I appreciate your input. I'll check out newark.com .
I have since removed the amp power supply and the two power amps. Both amps have the same resistors all burned to a cinder and blackened the PCB around the area.
I have found some pictures of this failure and it appears to be the classic failure of  one or both of the transistors on both boards. Probably caused by a short in the headphone jack.

I have found CAE's replacement amps at $270.00 each and Vintagevibe's rebuild kit and services (around $110.00 for the rebuild kit and $500.00 plus or minus for the repair service). But before I do that I was wondering if anyone has had experience repairing these themselves by locating replacement transistors, either the Delco transistors or an equivalent and replacing the resistors.  Am I in for more headache time and money, than just replacing the amps?