[R-390] RF Deck B+ short (390A)

[Grayson Evans]

Hi Dennis, 
I agree, make sure you remove the tubes, there could be an internal short in a tube element.  
All the coils are “isolated” from B+ by resistors of fairly high value compared to 60 ohms, but it would not hurt to see if turning the band switch changes anything.
When resistors are damaged, they usually go UP in value, so I would not expect a bad R.

I would trace the B+ line from where it comes in on J208 through the chassis and disconnect it someplace in the middle of it’s run to help isolate the low resistance.    

This could easily be a pinched B+wire someplace. 
I am overhauling my RF chassis as well, it happens to be on the bench now.  I was replacing some caps and giving it a clean.   I will poke around and see what looks like a likely suspect.

Grayson,
KJ7UM/TA2ZGE

On Nov 19, 2014, at 8:59 PM, Dennis Wade <sacramento.cyclist at gmail.com> wrote:

> Thank you all very much.  I've already isolated the short to the RF deck
> with the unplugging modules technique.  I will pull the tubes and do the
> measurements possibly tonight, more likely tomorrow night.
> 
>       Thanks again....I love this list.
> 
>                Dennis