[ICOM] IC-765 on 220 VAC

[Gary Fiber]

Mike,

I know enough to be dangerous. I am not real good at troubleshooting 
that switcher supply. Lots of the questions here were exactly as I 
fielded on the phone for 11 years. The newer products escape me as I 
have limited experience with them.

To your question actually thats they way the power supply was built. 
I doubt someone has messed with it.I actually forgot about the grey 
plastic sheet. It provides insulation and heat sinking.
The plastic screws isolate those two transistors from grounding to the chassis.
Icom has been using thermal pads for some time. The 781 power supply 
has them too.

Like you I am from the old school, white heat sink thermal compound 
every place. Most generally more of it ended on up on my hands and 
clothes than in than on the device that needed I think. ;)
So for power devices like those transistors I generally think of 
thermal grease when assembling.


Gary K8IZ



At 09:00 PM 6/28/2006, you wrote:
>Gary, you seem to know the IC-765 PS pretty well.
>Maybe you can answer a question for me.  When I got
>into my PS last weekend to re-solder the copper strip,
>I took the four screws out of the solid state devices
>that were screwed down to the chassis so that I could
>lift up the circuit board.  Two of the screws were
>metal and two were plastic.  I noticed that there was
>a grey plastic sheet between the four devices and the
>chassis.  This struck me as odd.  I would have thought
>that these would have been screwed down directly to
>the chassis with heat-sink grease between them and the
>chassis.  I am just trying to figure out if my PS is
>normal or if it has been "messed with" prior to my
>ownership.  Any help is appreciated.
>
>Thanks,
>Mike, WC0L
>
>--- Gary Fiber <gfiber at comcast.net> wrote:
>
> > Hi Tim,
> >
> > Going from memory.......
> > Get the electric screwdriver warmed up.
> >
> > Remove the power supply from the 765.
> > Remove the bottom cover, about 20 screws.
> > Take note of the transistors and insulators, remove
> > the mounting
> > screws from them and circuit board from the power
> > supply case.
> > Look and you will see two jumpers that are marked
> > 110 / 220. Move
> > each jumper to 220 Volts, Requires soldering.
> > Under the Full Wave bridge there is a jumper that
> > connects the AC
> > inputs together, cut it. Try to leave enough so you
> > can revert back
> > to 110 Volts if desired.
> > While you have the board out inspect the current
> > shunt resistor,
> > about 1.5 inches long by 1/4 inch wide flat bar on
> > the bottom of the
> > circuit board.
> > If the solder joints are cracked or look bad, de
> > solder, clean up
> > area and reinstall the current shunt resistor. Do
> > not solder past the
> > holes in the resistor.
> > Reassemble the power supply, maybe using some new
> > grease under the transistors.
> > Reinstall it into the rig
> > Change the plug on the end to a proper 220 Volt
> > plug.
> >
> > Praise the good job the electric screwdriver did :)
> >
> > Enjoy.
> >
> > I think mods.dk has this on it
> >
> > Gary K8IZ
> >
> > At 01:40 PM 6/28/2006, you wrote:
> > >Has anyone ever done this?
> > >I see some schematic notes in the service manual,
> > but no step by
> > >step procedure.
> > >Any help would be appreciated.
> > >Thanks and 73,
> > >Tim K3LR
> >
> > Gary Fiber K8IZ
> > GROL PG-19-6691
> > Washington State Resident
> >
> >
> > ----
> > Your Moderator: Dick Flanagan K7VC,
> > icom-owner at mailman.qth.net
> > Icom Users Net: Sundays, 1700Z, 14.316 MHz
> > Icom FAQ: http://www.qsl.net/icom/
> >
>
>
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Gary Fiber K8IZ
GROL PG-19-6691
Washington State Resident