[R-390] Troubleshooting Question

[Jim Whartenby]

Roger
I assume that the etc includes the tube heaters are also loosing power?  Could be anything in the primary line from the input filter to line switch to the power transformer itself.  

If I was doing this, I would tack two wires to the power transformer primary and reinstall the power supply module.  Monitor the voltage on the primary to see if it is still present when the radio quits.  If the primary voltage is still present than the power transformer itself is suspect.  If not then move the two wires to the output of the filter and repeat the process.

Regards,Jim

Too much agreement kills a chat.  E. Cleaver

-----Original Message-----
From: Rodger via R-390 <r-390 at mailman.qth.net>
To: r-390 at mailman.qth.net
Sent: Fri, Oct 29, 2021 11:54 pm
Subject: [R-390] Troubleshooting Question

Hey All,

 

I have an R-390 (non A) that has developed the following problem.  When I
turn it on, it warms up and works normally for about a minute or so.  Then
without warning, it shuts down.  Lights out, no B+, etc.  It does the exact
same thing every time I turn it on.  Any thoughts on where to begin
troubleshooting?  How to easily isolate the B+ from the modules, etc. ?  For
the minute that it's on after warming up, the B+ reads 185 volts.  

 

Thanks in advance for any advice.

 

Rodger

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