[R-390] Troubleshooting Question

[Jim Whartenby]

Roger
I was concerned that the issue was a failed switch.  Surprised that the problem was simply a dirty fuse contact.  
Just goes to show that experience pays off, good call Jacques!
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
Cc: 'Jacques Fortin' <jacques.f at videotron.ca>
Sent: Mon, Nov 1, 2021 9:35 am
Subject: Re: [R-390] Troubleshooting Question

Thanks to all for your responses on my power supply troubleshooting
question.  Had a taken a quick look at the schematic before posting, I would
have realized there was only a few things that could have caused this
problem.  After tacking wires onto the power transformer to allow for
measurements to be made on both primary and secondary side of the
transformer, I was all set to "catch" the problem.  When it next happened, I
was losing power to the primary side of the transformer.  That left 2
things, both which had been mentioned by list members, the fuse and the line
filter.  The FUSE was the culprit as Jacque suggested.  I didn't even have
to replace the fuse as it wasn't blown, but just had to twist it around in
the socket a few times.  Problem solved.

I am amazed that something as simple as dirty contacts between a fuse and
the fuse holder could cause a problem with such a repeatable symptom.
Before I started troubleshooting, this problem had recurred, probably 25 to
30 times and each time was exactly the same.  The 390 worked for about 2
minutes and then shut down.  

Thanks all for your input and troubleshooting suggestions.  Lots of lessons
learned, including ask this list first!

Thanks,

Rodger

-----Original Message-----
From: Jacques Fortin <jacques.f at videotron.ca> 
Sent: Saturday, October 30, 2021 10:42 PM
To: rodger_adams at yahoo.com
Cc: R-390 at mailman.qth.net
Subject: RE: [R-390] Troubleshooting Question

Rodger, you will surely found my advice strange, but...
Just replace the mains fuse with a new one and retry.

73, Jacques, VE2JFE

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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