Traynor YSR-1 Popping and Screeching question

[shanetram]

I have an early 70's Traynor Custom Reverb (YSR-1) that pops and screeches when taken out of standby. I warm up the amp for 5-10 minutes and then switch out of standby then it immediately starts to pop for a few seconds then screech once or twice and then it stops and runs fine with no noise. I can play for two hours with no problems. If I take a break and put the amp back into standby that same thing happens when I switch to operate again. It doesn't last long and it's only brief (5-10 seconds) but it seems to be getting worse.

Any suggestions? Thanks in advance for your advice.

 

[shanetram]

Anybody?

 

[Blue Strat]

Microphonic preamp tube? See what happens if you turn down all volume controls before switching it on.

 

[donnyjaguar]

It *may* not be the same problem, but my 1978 Traynor had the same symptom. Except it would pop and screech and eventually blow the breaker. It turned out to be a bad output tube (original) that had the heater shorting to the cathode. I had to replace the two resistors on the filament leads too, which it had smoked, but all has been fine since. Found also bad socket that needed re-tensioning, but don't think this was the cause.

 

[shanetram]

It's got all new tubes but maybe I have a bad one. It passes the tapping test. I'll swap some tubes and see what happens.

Any other suggestions? Thanks!

 

[Chute Amps]

Is it a very high pitch screech?
It could be noise induced into the power section by a dying filter cap, have you checked them out?