[ICOM] IC-765 question
Marc & Tricia Niebergall
mtniebs at gmail.com
Sat Apr 25 10:48:03 EDT 2015
Gary and Rich,
Thank you both for your input. The fuse is cleanly soldered and power
output is normal. At this point while I have the board out, I plan to
change all the electrolytics as they are around 25 years old. The freeze
idea sounds like another good troubleshooting technique and will give it a
try. The rig works marvelously; the only exception being this rather long
pause on first start-up. Sometimes the pause is rather short, a 1/2 second
or so. Other times it may be as long as 2-3 seconds. While 2-3 seconds
doesn't sound like a long time, it seems like an eternity when it happens.
I'm sure I will eventually find the cause.
Marc
On Fri, Apr 24, 2015 at 4:42 PM, Gary Fiber <gfiber at comcast.net> wrote:
> Marc,
>
> If you are lifting the main board in the power supply, look at the bottom
> for a flat bar about 1/4 inch wide by about 1.5 inches long. That is a
> current shunt resistor. Check the solder joints at each end closely for
> cracks. If they are cracked, de-solder that resistor clean up the solder
> and
> reinstall it using some flux and fresh solder. DO NOY flow solder past the
> holes in each end of the bar as doing so will change it's resistance. What
> happens is if there are cracks in the solder the 765 will work fine up to
> about 50 watts but will not output any more power when it is increased as
> the resistor would heat up a bit, the solder cracks would open and develop
> a
> high resistance connection. This was a fairly common fault in that and the
> other Icom supplies of this type like the ones in the IC-761 and IC-751
> series. I wished I remembered other power supply issues but there were not
> that many with those switchers. One good thing though the DC plug coming
> from the internal supply that plugs into the 765 is the very same wiring as
> an external DC power cord for Icom HF equipment, verify this, I remember
> the techs running those radios on the bench using a PS-30 bench supply many
> times when I worked at Icom America.
>
> Gary K8IZ
>
>
>
> -----Original Message-----
> From: Icom [mailto:icom-bounces at mailman.qth.net] On Behalf Of Marc &
> Tricia
> Niebergall
> Sent: Thursday, April 23, 2015 9:08 AM
> To: ICOM Reflector
> Subject: Re: [ICOM] IC-765 question
>
> Rich,
> Thanks for another great idea.
>
> Marc
> On Apr 23, 2015 9:01 AM, "Rich Dailey" <redailey1 at gmail.com> wrote:
>
> > In lieu of a meter, you might try the following: Let the rig run for
> > several hours, or a day, and see if the power cycles on and off
> > without the delay. If it is normal, lightly freeze spray areas of the
> > power supply while cycling power until the delay reoccurs. Then
> > localize the spraying to individual caps, until you find the
> > culprit(s). Sometimes requires heating the area back up with a blow
> dryer.
> >
> > Use to be the 'poor-man's' troubleshooting procedure, but not so much
> > today, considering the prices I'm seeing for freeze spray -hi.
> >
> > Rich, N8UX
> >
> > On Wed, Apr 22, 2015 at 2:08 PM, Marc & Tricia Niebergall <
> > mtniebs at gmail.com
> > > wrote:
> >
> > > When pushing the AC on switch there is sometimes a pause of a couple
> > > seconds before the rig powers up. Other times it comes on almost
> > > instantly. This usually occurs on the first application of the day.
> > Don't
> > > know if it is a relay or an electrolytic capacitor taking time to
> > > charge
> > or
> > > what. I changed two 33uf electrolytics in the power supply that
> > > were swollen, but no change. Any suggestions are welcome.
> > >
> > > Thanks,
> > > Marc-k7wxk
> > > ----
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>
> ----
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