carvin vl100 problem.

[clearwaysteve]

Had a vl 100 serviced last year because sound went all thin. r34 was replaced. amp was better but still not as full a sound as original. The amp did have new valves and was biased but the service tech said the valves werent the issue, is it possible this resistor has gone again. all the valves are still ok.

[alexradium]

Had a vl 100 serviced last year because sound went all thin. r34 was replaced. amp was better but still not as full a sound as original. The amp did have new valves and was biased but the service tech said the valves werent the issue, is it possible this resistor has gone again. all the valves are still ok.

r34 is responsible just for the reverb send,and that stage is parallel to the main sound so the problem is somewhere else,maybe a preamp tube,some other plate resistor.
If you can measure high voltages in the amp with enough safety knowledge,you can troubleshoot ,otherwise give it to a proper tech.
Other than changing preamp tubes the only other thing you can do externally is clean the fx loop jacks with deoxit.

[clearwaysteve]

r34 is responsible just for the reverb send,and that stage is parallel to the main sound so the problem is somewhere else,maybe a preamp tube,some other plate resistor.
If you can measure high voltages in the amp with enough safety knowledge,you can troubleshoot ,otherwise give it to a proper tech.
Other than changing preamp tubes the only other thing you can do externally is clean the fx loop jacks with deoxit.

The tech mentioned replacing a screen resistor but Im not sure which one /s. And thanks for the reply. Ive tried 6 different preamp tubes with no change.

[qwerty]

Could replace all of them.i think 470k.check shematic.

[The Dude]

Can you post a gutshot of the amp? If memory serves, the output tube screen resistors hang upside down in this amp (I think it's this amp, anyway). There are holes in the circuit board and you can see them from the top. There's enough heat in the amp to melt the solder joints for those resistors and they literally fall out. You can resolder them 'till the cows come home and they'll just keep falling out. The solution I've found is to replace them with 5W wire wound resistors that are better able to dissipate the heat and solder the resistors from the top side so they can't fall out. This all assumes I have the right amp in mind.