On Thu, 12 Jul 2007 15:44:49 +0100, "Keith G"
wrote:


OK - powered up with dummy loads.

Grid to Ground:

Good Amp - a *continually* changing 0.04 to 0.06 VDC

Bad Amp - steady 202 VDC (???)

Are we on the money so soon?

If you swap the output valves between amps, does the fault go with
them? That grid voltage should be pretty much tied to ground. This one
uses an interstage transformer, yes? Check the resistance of the
secondaries, and make sure it hasn't gone open circuit. That grid
voltage should only move with signal.

d

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Pearce Consulting
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