Re: Kenwood PS-40 switching PS ?

From: sofie (sofie_at_olypen.com)
Date: 01/18/05 

Date: Tue, 18 Jan 2005 15:07:49 -0800

Henry:
It is your power supply and your pocket book. If you continue to run it
until it quits altogether the repair will be more involved and probably much
more expensive than just replacing electrolytics or resoldering connections.
It might not gradually get "worse" than it is now, But rather it might have
a catastrophic failure of other parts that are stressed by the high ESR
electrolytic(s) or cracked board connections.... parts like diodes,
switching transistors, integrated circuits, opto-isolator, etc, etc.
Takes your choice and pays your money. 

-- 
Best Regards,
Daniel Sofie
Electronics Supply & Repair
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
\
"Henry Kolesnik" <kolesnik@sbcglobal.net> wrote in message
news:uCdHd.20046$iC4.15802@newssvr30.news.prodigy.com...
> The power supply was turned on this morning at 8 am and shut down in less
> than 10 minutes.  I turned it back on about 9:30 and it is still on,
that's
> over 4 hours.   I'm not that versed on ESR but I have a tester and cm
> curious if high ESR can be an intermittent condition and if so what would
> the physics of that phenomena be?  At this point I'm not willing to do a
> shotgun replacement of all the caps.  I do keep running the power supply
and
> the condition is not getting worse.  I wish it would fail so I might find
> the failed component.  The way it is now it's impossible to troubleshoot
> without shotgunning.
>
> -- 
>
> 73
> Hank WD5JFR
> "sofie" <sofie@olypen.com> wrote in message
> news:10uqn75tb4oc77f@corp.supernews.com...
> > Henry:
> > As long as it is still w"working" the problem is not likely anything
more
> > than either cold or cracked solder connection OR electrolytics that have
> > dried out or have developed high ESR.   If you do not have an ESR meter
> > then
> > you will have to use the "one by one" substitution method... or just
> > replace
> > all of the electrolytics at once.   Just about all other methods of
> > testing
> > electrolytics will not provide the crucial ESR test needed especially
for
> > electrolytics in switching power supplies and other high frequency or
> > critical circuitry.
> > DO NOT keep running your power supply with this problem.... it will only
> > get
> > worse to the point that it will fail all together and be a much more
> > involved repair.
> > -- 
> > Best Regards,
> > Daniel Sofie
> > Electronics Supply & Repair
> > - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
> >
> >
> >
> > "Henry Kolesnik" <kolesnik@sbcglobal.net> wrote in message
> > news:mU9Hd.19989$iC4.2906@newssvr30.news.prodigy.com...
> >> This is a 20 amp switching power supply for their 12 volt ham
> > transceivers.
> >> I used to leave it on 24 hours a day on receive pulling less than an
amp
> >> with no problems but about a month ago it started to shut off.  You
have
> > to
> >> turn it off first and  wait about 15 minutes and it'll come back on,
> >> sometimes for an hour or longer and other times for 5 to 10 minutes.
> > After
> >> it goes down you have to turn it off and then wait 10 to 15 and it'll
> >> come
> >> back for an unpredictable time.  It doesn't seem matter if it been on
for
> > an
> >> hour or sometime 5 minutes, it'll shut down. It doesn't seem to be a
cold
> > or
> >> heat problem and  flexing the board or tapping components won't turn it
> > off
> >> or make it come on quicker.  I don't have a schematic and can't find
one.
> >> It must have some kind of logic that senses something and makes it shut
> > down
> >> and then time out.  One thing I have noticed is that if I turn it on
when
> >> its not ready to come on I can hear a very, very faint noise (like
static
> >> discharge)  that goes away as soon as the switch is turned off.  It has
a
> >> TL494CN.  Any tips appreciated.
> >>
> >> -- 
> >>
> >> 73
> >> Hank WD5JFR
> >>
> >>
> >
> >
>
>

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