Voltage Check Question

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Hi Doc,

We have completed all the steps for assembling the amplifier and are at the voltage check step (page 65). All the terminals seemed to be within tolerance besides two. Terminal 4 reads 160 mV and terminal 17 reads 40 mV (both should be 0 V).

Is this a reason for concern?

*Some more info after a few mins of observation:

T4 voltage slowly goes down from 1.2 V to 160 mV, while T17 voltage goes up from 30 mV to 50 mV during the span of about 5 mins.

Also, the C4S LEDs do not turn on during testing. Is this normal? T7 and T14 voltage are 215 V, so they are within range. All other voltages are also within the expected range.

Thanks!

[Paul Birkeland]

I think in an adequately dark room that you'd see the LEDs illuminated. 

0.160V and 0.040V are close enough to 0V in a kit with ~400V or so available.  These two terminals will be slightly above 0V when the 2A3s are conducting, as there is a bit of grid leakage present that will make those voltages not quite 0.

[premiumcookie]

Hi Paul,

Thanks so much for clarifying about the two terminals. We did end up seeing a faint light from the LEDs as well.

Cheers.