[R-390] AGC Voltage Continued

[Flowertime01 at wmconnect.com]

Mike,

You wrote:

I can't figure out a way to isolate the faulty filter except by unsoldering 
the common wire to each filter one at a time, turning the IF deck over a few 
times while watching the ohm meter.


Hard work but the only way to do it right.

You could just clip that wire into sections and then just replace it when you 
fix the filter problem.

The "foam insulation" inside the filters has turned to crud at this age.
That crud gets conductive.

You can unsolder the filter cans (another subject) and clean them out and 
rebuild the filters.

You can also get used filters that may or may nor have problems after being 
bumped around in the mail or UPS truck on the way to your location. Just buying 
an another filter these days is not as nice as it use to be. There are some 
rebuilt filters out there that have had the crud cleaned out and new stuff 
inserted. For a price but cost effective.

Roger AI4NI

> 
> I think I'm onto something.  The resistance at pin 6 of J512 was 22K when it 
> should be infinity, by continuing on I found that the resistance on the 
> outputs of the filters was zero, when it should also have been infinity. 
> (The filter outputs are all connected together on one side according to the 
> schematic)  After moving the IF deck around a bit the resistances were 
> normal - yep, one of those.
> 
> I can get the resistance on the filter output to  change from zero to 
> infinity by turning the IF deck over a couple of times.  Likely there's 
> something loose inside one of the filters.
> 
> 

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