Tube amp issues need to troubleshoot please help

[Jasondunn81082]

Ok I have a bugera 333xl (I know it's not a Mesa or a Marshall but I love it lmao) the issue I have is I'm new to tube amps and the problem is that it has three channels clean,crunch and a lead channel each with it's own eq....the eq for the clean channel works fine but the eq's for the lead and crunch do not work....could this be caused by a blown preamp tube?? Maybe someone drove an input signal to strong while in the overdrive channels and blew one or something?? Idk but I just picked up the amp for cheap and I'm just trying to figure out what's wrong with it....thanks to anyone that could help!

[M Fowler]

It's hard to say what the prior owner has done. Sounds more like a switching problem or tone stack bypass switch stuck. Do you have the pedal switcher?

Mark

[Jasondunn81082]

No bought it without the foot controller it switches to the different channels fine and I can adjust the gain and volumes but the eq section is un-adjustable or doesn't change enough to really notice...and the problem is the same for the lead channel and crunch channel only, eq for the clean works fine

[M Fowler]

If the tone control pots are PCB mount it could be copper trace cracked/broken.

I opened a new Blackstar combo and found a ribbon cable socket had come looose. Tech's poke around inside to fine trouble but unless you have knowledge of high voltage inside tube amps I don't recommend you look the amp over.

Mark