[R-390] R390A Blowing fuses...newby question

[Glenn Little WB4UIV]

The lights being on may be welded contacts on the microswitch.
There have been many posts about this.
Search the archives.


73
Glenn


On 3/29/2020 4:08 PM, R. David Eagle via R-390 wrote:
> I have been working through the alignment procedures outlined in my manual and am now on day 3 of it.  Everything was going great with the alignment yesterday and receiver was on WWV and sounded great.  I came in this morning and flipped the switch on to warm it up, and poof the fuse blew.  I was extremely blown away because it was working fine when I shut it down for the evening.
> So I went through and pulled all of the plugs off the modules except main power supply plug.  I put a new fuse in and poof...it blew again.  I pulled the rectifiers which are actually the soft start upgrades from sigmapert, put a new fuse in and everything seemed ok as the transformer powered.  I then became suspicious that that the soft starts went bad and I plugged one of them in  and it powers up fine with it in either socket.  Here is the weird part - I did the same to the other one and it works fine as well, BUT if  I have both plugged in it blows the fuse.
> So I then pulled out the original 26Z5W's and plugged them in and all is good until one of them warms up and the fuse blows.  I then verified the wiring on the drawing and traced one wire that comes from the rectifiers to CR102 and unsoldered that and still get the same results.
> Another odd thing that has transpired is that when the radio is switched to the off position, the frequency lights are on....???
> Has murphy decided to come play for the weekend or has my radio been plagued by the Corona?
> Thanks again,
> Dave
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-- 
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Glenn Little                ARRL Technical Specialist   QCWA  LM 28417
Amateur Callsign:  WB4UIV            wb4uiv at arrl.net    AMSAT LM 2178
QTH:  Goose Creek, SC USA (EM92xx)  USSVI LM   NRA LM   SBE ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"