[R-390] Re: R-390A Problem

[Flowertime01 at wmconnect.com]

 jdkopke,

First step is this is a tube receiver.
The usual suspects to round up for questioning are all the tubes.

There is no such thing in an R390 or R390/A that cannot be isolated and fixed.

Sure hope you have access to a tube tester and lots of time.

The other choice is some spare tubes to do substitutions.

A quick test will not do for this problem.

The tube may be intermittent flaky. So you need to leave each tube in the 
tester long enough to give things a chance to flaky.

Unplug the RF deck and the IF deck.
Leave the receiver on and listen to it.

If it still goes bad then you are only looking at a few tubes in the Audio 
deck.

If the problem does not appear then plug the IF deck back in.

If the problem pops up then you are looking at an IF deck problem.

If not then your on to the RF deck.

Is the power supply solid stated or do you still have 26Z5's in the power 
supply?

These tubes will arc and pop and give you all kinds of noise problems.

After you get all the tubes checked and are sure you are just not looking at a
simple old tube gone bad, then you have to consider a cap going intermittent.

The R390/A have some big fat plastic caps that are known to be going bad as 
they are over 40 plus years old. The nice silver metal looking caps are OK. 
Some of your caps may need to be replaced.

The plug in power supply filter caps on the audio deck are also suspect but 
these do not tend to go intermittent. They mostly go with a full failure.

Check the Tubes first and see what you find.

Roger AI4NI



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