DC-3 Problem once amp warms up

[ant_riv]

Hello and thanks for checking out my thread.

I have had my DC-3 for a number of years and love it.

The last two times I used it though, once it warmed up and is played for about an hour, the clean channel starts to distort (like I am in the gain channel). The gain channel gets fizzy also.

Additionally, it seems as though the amp gets excessively hot. Once I let the amp cool down, it works fine again, but the cycle repeats.

Is this something I can fix (bad tube or ???) or is it time to take it to a real tech?

Thank you for any advice you may have!

 

[kekam35]

If its tube related and in both channels it's either the P.I. or the power tubes. If you have a spare 12ax7 try swapping out the phase inverter first(cheaper). Could just be a tube isn't fully seated in the socket as well. When looking at the amp from the back the P.I. is the last one on the left.

 

[ant_riv]

Thanks kekam35!
It is on both channels. I will swap out the PI and let you know if that solves the problem.

I expect that if I swap out the power tubes I will need to bring the amp in for bias adjustment, correct?

 

[kekam35]

Not if you use Mesa tubes

 

[ant_riv]

I replaced the PI and the problem went away!

Thank you very much kekam35! I really appreciate the advice/solution!

I definitely owe you one!

 

[kekam35]

Glad to help.