[ICOM] IC-765 question

[Gary Fiber]

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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