Ceriatone chupa Red plating

[screamindemon]

Hey guys trying to track down the problem with this 50 watt Ceriatone chupa. It was working fine and while I was playing it started red plating one of the tubes.
This happened over a year ago so I'm I little rusty on the particulars but I am just now getting to trying to fix the thing. I know at the time I tried swapping in another tube and it was lighting up too so I shut it down.
I have pulled the tubes and Checked the bias at pin 5 on both tubes and have about -44.8 volts on V4 and 45.4 on V5 with Bias pots turned all the way up clockwise. Wondering if anyone knows if these are in range ?

Also as I was testing voltages at the tube sockets I put my probe on pin 3 of of V4 the terminal arced and flames shot out of it. Scared the shit out of me. LOL
I think maybe I found the problem with a bad solder joint. I solder sucked it and resoldered the pin.
Here are the voltages at the tube socket.
V4 V5
Pin2 3.31 Pin2 3.31
Pin3 463 pin3 463
pin4 461 pin4 461
pin5 -44.8 pin5 -45.4
pin 6 461 pin6 461
pin 7 3.30 pin7 3,30

As I said wondering if the negative voltages on pin 5 are in range and if anyone has any suggestions to pinpoint the problem.
Thanks

 

[glpg80]

Seems like a high frequency stability problem.

The negative voltages are your fixed bias. They both look correct.

Very well could be a cold solder joint causing the stability problem. Resolder all of the pins of the tube socket. Resolder the resistor connected to pin 5 and also check the ground reference for the adjustable bias for that side.

 

[screamindemon]

Seems like a high frequency stability problem.

The negative voltages are your fixed bias. They both look correct.

Very well could be a cold solder joint causing the stability problem. Resolder all of the pins of the tube socket. Resolder the resistor connected to pin 5 and also check the ground reference for the adjustable bias for that side.

Thanks for the reply, I resoldered all the pins and checked ground reference. Seams to be fine now. I rebiased the amp and rocked it for about an hour last night with no issues.