TSL100 noisy when VPR switch pushed in

[tim]

Sounds like a noisy plate resistor in an old Fender...I have replaced almost all the parts in that VPR circuit, including the switch and noise is still there. I'm beginning to believe I'm barking up the wrong tree. Has anyone ever had this problem? What finally fixed it?

Every time I fix one of these amps, I swear I'll never put another one on my bench but they keep bringing them in.

[The Dude]

If memory serves, the VPR circuit is basically like a fixed PPIMV. I would pull the PI tube out and see if the noise is still there. Narrow it down to the output section or the PI circuit- both of which are somewhat effected by the switch. Also, take a good look at C46 while your in there.

[tim]

crap...I feel like a noob. Brand new set of power tubes...one is noisy.

I hate it when customers buy their own parts...now I have to explain to him that one of the tubes he just bought is noisy...I can swap out my set of known good tubes and show him. He probably didn't keep his receipt either.

[The Dude]

Glad you fig'd it out. I suspect many here have run into this. Not much you can do about it except present the customer with the cold hard facts. Maybe next time he'll buy the tubes from you.