Genz-Benz El Diablo 100

[The Dude]

I'm working on one of these for a customer. I've checked and/or sub'd all the tubes, checked for cold solder, etc., etc. The thing biases fine. Here's the PITA part. The customer, who is a reputable/intelligent guy says that the amp cuts out and the volume goes low (usually after warmup). I've not been able to duplicate this in the shop. The amp works fine even after an extensive burn in. I do however believe there is a problem. The customer says he switched over to another amp using the same cords/pedals/cabinet/etc. and the problem went away.

Not asking anyone to troubleshoot this for me. My question is simple. Does anybody know of any common problems with these things. Just hoping maybe someone here has delt with this amp before and knows of "issues".

Thanks for reading.

[Enzo]

Does it have and FX loop, a power amp in jack, or an insert jack?


If so, poke each one with a plug while music plays through i9t. Does poking any of them cause the symptom? It should cut out the signal when the plug is in, but we are more interested in whether pulling it back out happens clean or intermittantly. I don;t usually poke in all the way, just enough to push the tip contact aside some.

Also, on those jacks, measure resistance across the cutout contacts. it must read less than half an ohm. If it measure4s even just 2 ohms, it will work fine, but the fact it is up to the 2 ohms means the contacts are not pristine, and can be a problem at another time.

[The Dude]

Thanks for the quick reply and help, Enzo! I did check those already. That's usually one of the first things I look at. It could be that I've unknowingly fixed it already just with all of my poking around in the thing. Still a bit uncomfortable kicking it out of the shop without knowing "the real deal".