[Amps] AL-1200 Grid Current - negative?

[Dana Roode]

Amps folks -

Ok, I removed the tube and the meter still went negative.  I checked the 
filament connections with the tube out, nothing is shorted to ground.

I was suspect of the metering circuit itself.  The left multi-function meter 
measured 300 ohms across the terminals, the right grid meter measured 15k. 
The parts list indicates both meters are 300 ohm 1ma.

I took the grid meter apart, it has a component (a precision resister, I 
assume) in series with each internal meter movement lead.  One measured 100 
ohms, the other about 15k.

I am pretty clueless about this, and Im at a loss as to why a 100ohm 
resister would become 15k, but perhaps this is my problem.

   Dana


Dana Roode wrote:
> What does it mean when you power up an AL-1200 and the grid current 
> meter pins negative (no drive power supplied)?
> 
>   Dana
> 
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