[R-390] Collins R-390A, new owner

[Flowertime01 at wmconnect.com]

Rasputin,

Tom pointed out the major two problems.
Power hum leads you to checking the filter caps.

The filter coupling capacitor C553  in the IF deck for the mechanical filters 
is the next major item to inspect for. Considering that if it fails, it will 
let the mechanical filters also be burnt open for no good reason. 

Inspection is a two clamp four green screw and four connector operation.
Cheap and easy to do.

The next item is all the old 0.01 large dia 1/2 inch long 1 1/2 inch likely 
brown but some times black (depending on production run) by pass caps. C553 
listed above is one of these caps. 

If your IF deck has lots  of space and many nice new smaller caps in it then 
you have a deck that has been reworked. If your deck has about a dozen of the 
old large plastic caps then you will want to consider replacing all of them 
over time.

There are also a couple under the RF deck. If you have a need to pull the Rf 
deck off the chassis you will want to replace the large plastic caps under 
that sub chassis deck as well.


There is one small electrolytic in the audio deck that liked to leak as far 
back as the late 60's. You may want to look in the Audio deck as well and 
inspect that cap.

Have you found the R390 web pages with the TM's Y2K manual and the Pearls of 
Wisdom?

Welcome aboard.

Roger L. Ruszkowski AI4NI
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