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

[Don Cunningham]

Hi Dave,

Makes one wonder if the switch contacts caused the 26Z5 subs to go bad, 
or if they just went??  I have a set of those I was going to try, but am 
curious what you find now first.  I would hope the builder of those subs 
would give some guidance.
Don, WB5HAK

On 3/30/2020 7:56 PM, R. David Eagle via R-390 wrote:
> Hi Francesco,  I have located the problem and it looks like the sigmapert 26z5w soft starts died on me.  I found the original tubes and put them back in and it works fine now except the power switch issue.  I suspect the contacts got welded...seems to be a common problem.  I have never taken the front off so that will be another challenge!
> Can you send me the info on the filter and cl you put in yours?
> Thanks,
> DaveKb8nnu
>
> Sent from Yahoo Mail on Android
>   
>    On Mon, Mar 30, 2020 at 2:32 AM, fdigio1 at gmail.com<fdigio1 at gmail.com> wrote:   Hi Dave,
> Have you checked the power switch?
>
> 73,
> Francesco - IN3XZP
>
> -----Messaggio originale-----
> Da: r-390-bounces at mailman.qth.net <r-390-bounces at mailman.qth.net> Per conto di R. David Eagle via R-390
> Inviato: domenica 29 marzo 2020 22:09
> A: r-390 at mailman.qth.net
> Oggetto: [R-390] R390A Blowing fuses...newby question
>
> 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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