Tube Amp Problem. PLEASE HELP!

[billskisalot]

I have a Fender 300ps and am having issues with it. I can turn it on and it plays normally for a time then it will suddenly start fading out until there is no volume. It will stay like this for a few minutes then will get louder until it is back at the original volume. It will do this over and over with no real pattern to when it does this or the time in between. Any thoughts to what could be the problem?

Thank You.

[r9player]

Perhaps the tubes are going bad? If you have a spare set, you can try replacing the tubes one by one see if it resolves the issue. Or dirty pins
The other thought would be that perhaps you have a bad solder connection somewhere. You can try the 'chop stick' technique. Take out the chassis, turn it on, tap the components see if any cause the fade in/fade out.

[Rosewood]

I just took a quick look at a schematic and I would say when it loses volume try moving the preamp tubes slightly to see if there is a bad connection at the tube sockets. Also if your not using a footswitch with the amp plug a cord in and out several times to see if it brings the volume back. This amp has quite a bit more to the circuit than a standard Fender amp so I didn't spend much time with the schematic but suggest starting with the tube connections first.

[Groovey Records]

Swap the power tubes or

Try a visiting a tech

if you swap ptubes it may need rebiasing I dunno if your amp is fixed or not