New tubes burned a resistor in my amp

[crokseth]

Hi

Got an old Rivera Thirty Twelve (similar design as Fender amps). Today I decided to put new Tung-Sol EL34s in there. It played for only 5 seconds before the sound dissapeared and smoke was coming from the amp. I opened it and the resistor located close to the EL34 was smoked. (Is this the Screen resistor?)

Any advice? What could have caused this? Should i just replace the resistor and put my old tubes back in?

pictures:

https://www.dropbox.com/s/rs7xw90qjfsjj ... 9.jpg?dl=0
https://www.dropbox.com/s/1y32k8h1khm0l ... 1.jpg?dl=0

[xtian]

Power tubes commonly have two resistors nearby; a screen grid resistor and and control grid resistor. We'll need more info from you.

Did you set the bias after installing new power tubes?

Please post a schematic if you want educated answers.

[Stevem]

I could not track down a schematic for your amp, but it looks like R305 is the one burning up and its looks to be before or after the power supply Choke.

When you say the amp is like a Fender, do you mean it had 6L6GC type output tubes before you stuck in the new 34's?
If that the case then the tube socket may not be wired up the needed way to take a EL34 type tube , no less have the needed reduction in bias voltage.