Champ Red Plating

[jadams]

Hey all,
I just purchased a silverface champ. It has new tubes and sounds great, however the 6v6gt is red plating and making some popping sounds. That tube is rated for early breakup, so I ordered one rated for late breakup. Will putting in the new tube potentially fix this problem, or is it something else? Any info is much appreciated. Thanks.

[MWJB]

Despite the very high idle dissipations found in SF Champs, this is quite rare. Sure, try the new tube (JJ are pretty bullet proof), if the tube still red plates then it could possibly be a fault with the cathode bypass cap at 6V6 pin 8.

Ensure that the amp has a NOS (not a Russian) 5Y3 rectifier.

[jadams]

Thanks MWJB! The 5y3gt is Russian, but why is this a problem? I'll check that cap too.
Thanks again

[jadams]

P.s. there is also some blue glow coming from the bottom of the 6v6gt.

[MWJB]

Blue glow is normal.

The Russan 5Y3 isn't really a 5Y3, voltages are closer to a GZ34, subsequently your power tube is running at higher voltage than a Champ with a NOS 5Y3. You can still run the Russian rectifier, but it might be best to rebias the amp by replacing the 470ohm resistor, with an 680-800ohm 5W item (I'd change the rectifier, but resistors are cheaper than rectifiers so it's your call). This resistor is in parallel with the cap already discussed. The cap, by the way, should be rated for 50-100v & kept away from the resistor, because the resistor gets very hot & can fry the cap.

[jadams]

Thanks for the help, I think I'll just go ahead and replace the tube. It's terrible that they can call it an 5y3 if it's not the same thing. I bought this Champ because I wanted to learn how to service tube amps, so at least I'm learning some stuff. Thanks again.