JCM2000 DSL Silver Edition problems.

[g1]

I think the 70mA per side Leo mentioned will put you right around Enzo's 17watts. Sounds like a real good target.

[Jazz P Bass]

And remember the Univox amps with 700 Vdc (now 750) on the plates.

But they kept the screen voltage at about 350Vdc.

And using 6L6 tubes at that.

[Enzo]

Hell, Music Man amps, with 700, 715, 725 on the plates of EL34s.

[TimmyP1955]

IIRC, with 123V to 125V mains (which seems common these days) I set them for 70mv = 35ma/tube with 500V B+.

[gtrplayr1976]

It is good to 800v with appropriate screens, but you are 300v lower. I mentioned 800v only to point out that the voltages you have will not threaten the tube. Don't focus on 500v as magic, focus on the dissipation instead, as that is what will melt your tube. Your screen resistors 1K or more?

There are milions, or at least many thousands of MArshall amps with your 500v on EL34 plates and screens not terribly lower..

Yes they are 5 watt 1k screens. The owner said his wall voltage is 120 ,so I biased it at 70mA per side at 120. That way if he does take it elsewhere with higher voltage it should still be good.

[gtrplayr1976]

I think the 70mA per side Leo mentioned will put you right around Enzo's 17watts. Sounds like a real good target.

I set it at 70 per side at 120 volts. That's what he said his wall voltage was.

[gtrplayr1976]

Hell, Music Man amps, with 700, 715, 725 on the plates of EL34s.

I have a MM. I had forgotten they ran that high.

[gtrplayr1976]

Too high for what?

'Most' amps have the screens riding darn close to the plate voltage.

The screen tap (and the rest of the preamp) runs through a 270 ohm 7 watt resistor.

I would say it was wise of Marshall to knock down the screens a bit.

That 7 watter is one of the ones that failed ,so guess it was good that it was there. Didn't fry like the others , but it was open.