Mesa F-50 Combo Problem

[HoboMan]

My Mesa F-50 1x12 combo has no sound in the gain channel. Clean channel works fine but nothing from the gain channel. This just started last night. New tubes have less than 8 hours on them.

I'm going to take it in to the shop but I was just wondering if anybody had any ideas of what it might be?

 

[recto-robbie]

Hey Hoboman,,, you should have kept the f30 you sold me,, she is working like a charm, damn fine amp!!!.
Anyways I have a feeling that the preamp tubes V1 or V2 are the problem.
Even though they are new tubes doesnt mean that both sides of the tube are working correctly. I have a feeling it might be V2 because thats the boost stage tube for both channels. Swap some known good preamp tubes in V1,V2 and V4. I would think this may solve your problem.
Good luck, see ya around.

 

[HoboMan]

Glad that F-30 is working out for you. Those are GREAT amps, destined to become a classic (IMO).

Thanks for the tip. These are new tubes and I still have the old ones. I will try putting them back in tonight to see if that fixes it.

I'll keep you updated.

 

[HoboMan]

Robbie,

THAT WAS IT! Bad phase inverter tube. Glad I saved my old ones.

If we ever meet at McDonalds again lunch is on me!

Thanks,

Dave

 

[HoboMan]

OK, update. When I put the new tubes in from Eurotubes I put the Balanced Phase Inverter tube in the wrong socket. Shouldn't have made a difference but when I put it in the correct socket everything works fine.

Thanks again Robbie.