Fender Prosonic Cutting in & Out after several minutes of warm up

[tiaka]

Seeking Answer: My Fender Pro-sonic Combo starting cutting in and out at a live gig. Fortunately I had a backup Amp. When I unplugged it it was freaking "HOT" im reading this is quite common so not surprising

So next day I threw in some spare tubes I had laying around starting with the GZ-34 didn't do anything then a single 6L6GC, no change then the next 6L6GC, bingo worked for an hour into rehearsal then started cutting in and out again. The sound is indicative of a Bad guitar input jack or guitar chord sound that you have to jiggle every once in a while with the volume up. Tried another guitar and guitar chord same deal.? Anyone have any clue as to what this could be?. I'm not an electronics schematic professional so I have no clue where to look. Any I don't want an amp tech to burn me for something simple and easy to repair.

Any help or insight appreciated

[52 Bill]

Try plugging in a spare cord from the FX out to the FX in jack.

[jrfrond]

Another problem that I've seen a couple of times in the ProSonic that can cause all kinds of problems is the Rectifier Select rotary switch on the rear of the amp. The contacts burn open and become intermittent.

[Amp Kat]

If it's not the above which are great suggestions monitor all of the tube heaters when it drops out and see if they are staying lit or dying when the amp dies.