LSC Screen grid resistors

[plan-x]

Here's the story again, I had a bad arcing outer power tube. Followed by the something's burned electrical smell. I found a cracked screen grid resistor on my outer power tube. So I got some 470ohm metal oxide 2watt resistors. Matched 2 of them @ 463ohms, replaced the 2 outer ones, fired up the amp and now one of the inner tubes started arcing. Followed by the something's burned electrical smell. So I presume, I now have to go in again and replace the inner socket resistors. The amp did work after this on 50w setting not using the inner pair. So I guess I'm half way home.

First off, I'd like to thank you guys, Charles, ja22y, and all of you screen grid resistor brethren for your help. But I have a couple more questions.

Is there a definitive wattage value for these resistors??
With all these screen grid resistors going down around here, you'd think we'd get these values precise for the diy'rs. I googled up a schematic that has no more than a 470 written on it.

While in 50w mode, the ones I have already replaced, one of my outer tubes was running extremely hot, like burn my hand hot, while the other outer wasn't and was at a fairly normal temp. The hot one was not the original arcing tube, but the other side outer. Could this be related to the wattage values of those resistors again? Needless to say, I've pretty much depleted my back stock of 6l6's thru all of this.

 

[plan-x]

Ok, talked to an authorized tech who gave me the wattage value. 1 watt. He said 2-3 watt is ok also. I was concerned about that cause I actually bought 2 watters. He said the reason these resistors go south is because of a bad tube.

 

[Charles Reeder]

Hey Plan-X!

Glad you're at least half way there!
The reason the tube opposite the one that was arcing is running so hot is because the arcing tube finally burnt out it's screen resistor....as a result the push/pull mode was lost and an ininordinate amount of power is now being fed through the surviving tube (and it's screen resistor)!

That's why you'll want to always replace both screen resistors in a pair. If the screen resistor opposite the tube which was pitching a fit with a 'light show' isn't burnt out yet and cracked...it's well on it's way. Replace 'em both.

Also check that tube (or have it checked by someone with the equipment). If it's still good...keep as a spare...but replace both inner output-tubes with a new matched pair.

Regards: Charles

 

[plan-x]

Ok, talked to an authorized tech who gave me the wattage value. 1 watt. He said 2-3 watt is ok also. I was concerned about that cause I actually bought 2 watters. He said the reason these resistors go south is because of a bad tube.

New info. 1 watt only. A higher wattage can damage the amp.