Gary Schafer wrote:
>Check the meter shunt. Hook a known good meter in series with the plate
>current meter circuit to see if they read the same. Keep your fingers
>out of the high voltage.
Don't even plug the power cord into the mains! There is a better, much
safer way to do it.
Working with a completely 'dead' amplifier, you can connect a small
external power supply to deliver an accurately known current through the
meter circuits. It isn't necessary to power up the amplifier, or even
to disconnect any of the existing wiring.
The exact details of the test hookups will depend on the individual
amplifier, but you can see the general idea in Section 6.1 of the Triode
Board user manual, downloadable from the address below.
73 from Ian GM3SEK
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