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[AMPS] sb 220 update that was bounced the first time sent in...

To: <amps@contesting.com>
Subject: [AMPS] sb 220 update that was bounced the first time sent in...
From: nospam4me@juno.com (nospam4me@juno.com)
Date: Wed, 10 Nov 1999 21:33:35 -0800

>I removed the chassis from the case to first find the ALC 
>electrolytic capacitor strewn about the bottom in confetti and 
>foil. 

:There is no such capacitor in the ALC circuitry  -- in the 110VDC
supply, 
:yes. 

Correct, wrong label and most of the 110 volt supplies measure close to
120 vdc resting.

>Parasitics and or a tube problem might be the next thing to 
>investigate.

: Parasitics that are intermittent are not easy to investigate.  

It's interesting that the excessive voltage happens after both tubes have
been sitting on for a few minutes.  As soon as I get more time to set
things up, I'll have the spectrum analyzer log what it sees. 

>The unit fired up without tubes showed no problems at the 
>alc point, then each tube was tried in individually at both 
>locations. Again, no abnormalities observed. 

:Be sure to remove the wire between the bias contacts on the relay and
the 
:110VDC power supply.  If you don't do this, a shorted tube can easily 
:destroy the filament transformer.  

In your opinion, would a series glitch resistor in the bias supply
prevent xmfr damage?    Since the meters are near hens teeth to replace,
I'd like to protect the movements if possible. I hope to work up a
circuit to do that properly.   Notes in the original owners manual about
the meter movement values to follow once I confirm them.

thanks
skipp 

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