[Johnson] Invader Low Voltage Problem

[David C. Hallam]

Problem solved.  In spite of the fact that the filter capacitor showed 
no leakage on my capacitor tester, it was bad.  I replaced it and things 
are back to normal.

David
KC2JD/4

David C. Hallam wrote:
> I have an Invader 2000 with a low voltage problem in the 330VDC supply 
> for the exciter section.  It is running about 60 to 70VDC low in both 
> standby and transmit.
> 
> The transformer is supplying 620VAC to the rectifier.
> 
> I tried two different 5U4 rectifier tubes with no change.
> 
> I checked the filter capacitor for leakage and found about .1 mA at 
> 450VDC, so I would say it is OK.
> 
> I did a resistance check and didn't see any values which were out of 
> line from the last time I did it.
> 
> I checked all the tubes on my tube tester and the all tested good 
> (whatever that means).
> 
> I tried tube substitution of some but not all of the tubes.
> I have not done any testing or substitution the 6146's.
> 
> Another symptom that may or may not be related is when I switch the amp 
> section on, the finals draw no idling plate current.
> 
> I am sort of stumped as to where to go next.  Any suggestions would be 
> appreciated.
> 
> David
> KC2JD/4
> 
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