Super Champ X2 mystery

[matt mincer]

Hey All,

I have a Super Champ that's got an odd problem. The screen grid resistor (R79) burns up intermittently. I'll replace it, check everything and it'll work again for a few weeks. The kicker is, I've actually seen it happen. I cut the old one out and used jumpers to put one in for testing. At some point, it started smoking and burning so I cut the power. When I turned it back on, it was fine again. The voltages to the resistor are fine. The bias voltage is fine. Well, I say that but I haven't been able to test voltages while it's smoking. Does anyone have any ideas? I'm thinking I have a shorted tube but my tester is down so I can't check it.

Thanks
Matt

[sluckey]

Maybe you need a fresh set of 6V6s in the amp. Maybe replace the resistor with a 3W metal oxide resistor or maybe even a 5 or 10 watt resistor. Or maybe C40 is acting up occasionally. My first bet would be the tubes.

[shooter]

   you keyboard better than me

[purpletele]

I reluctantly worked on a Super Champ X2 recently.

I consider myself lucky after removing and replacing the board approximately 10 times due to experimentation, and not breaking any critical parts.

I was sort of frustrated with the time and energy I put into that amp, I could have put a nice Princeton in the Chanp chassis and have a cool amp.

So that is what I am doing now is fitting a Princeton into a Champ as a surprise that he may not get for free, more like $1300.

[Colas LeGrippa]

bad solder: check for a bad solder at tubes sockets

[matt mincer]

I put some known good tubes in and let it cook overnight. So far, so good.

Thanks for all the tips.

Matt