Winged C EL34s = smoke :-(

[sdhnc123]

I purchased a matched quad of Winged C SED EL34s for the VH4S.
The switch was set to "EL34".
I put the Winged C EL34s in the amp and used the Weber Bias Rite to check the bias with the new tubes.
I noticed that one of the tubes had really low current (4-7) while the other tubes were much higher (32-38).
I heard a popping noise in the speaker even though the amp's volume was at zero.
Then I noticed smoke coming from inside the amp.
I quickly turned off the VH4S.
I removed the Winged C EL34s.
I put a matched quad of Tung Sol EL34b in the VH4S.
Now one of the tube sockets is not putting out adequate current. It is always between 4-7.

Any ideas what is broken?

I have a friend that is a qualified amp tech. He hasn't looked at the amp yet, but based on on symptoms, he suspects it might be a screen grid resistor. Does this sound reasonable, and is the screen grid resistor easily accessed on this amp?

Thanks.

 

[Jens Kruse]

Please send me an email so that we can discuss this problem (see signature)

Jens Kruse

 

[Peter Diezel]

If it is a grid resistor it´s easy to replace.
Get a 1 kilo ohm / 5 watt type.

Best,
Peter

 

[sdhnc123]

I tested the Screen Grid Resistor and it is broke.
I'll buy a new one and my friend (amp tech) will help me put it in.

Thanks!

 

[Peter Diezel]

....... and don´t trust in new tubes