[ICOM] IC-745 Repair

[Ed Myers]

Also, unplug and plug back in all the connectors inside on the boards, etc.
These can get corroded. I recently fixed an IC-735 this way, as well as the
board screw fix.

Ed WC4TT

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Today's Topics:

   1. IC-745 Repair / Help (Ed)
   2. Re: IC-745 Repair / Help (Vladimir Sidorov)
   


----------------------------------------------------------------------

Message: 1
Date: Tue, 27 Jan 2009 12:53:17 -0500
From: "Ed" <edanderson1 at verizon.net>
Subject: [ICOM] IC-745 Repair / Help
To: <icom at mailman.qth.net>
Message-ID: <ACB0E313C3E046A1A8F658B72EE2BD4C at Profit>
Content-Type: text/plain;	charset="us-ascii"

Hi All:

This is my first post.

I picked up a very nice looking IC-745 at an estate sale this past fall.

When I got the radio home and put it on the bench it didn't work.

The symptoms are no RX/TX, no display, and no response from front panel
controls.

The light on the S-meter does illuminate, I can vary the RF gain and the
receive led does go on and off

when I rotate the squelch (SQL) control.

I have no history about this radio.

I replaced the RAM board with a ICOMPROM from PIEXX, but that did not help.

I think the problem lies somewhere on the logic board.

All of the VCC voltages look good.

There is a good clocking signal on the CPU (IC3) pins 30 & 31.

There is no clocking signal on IC2 (CPU input control) pins 18 & 19.

Since this same basic design is used in a number of older ICOM radios, I was
wondering if anyone might be able to 

give me some pointers before I just start guessing at what components might
be bad.

I have down loaded the service manual, all of the board layouts and circuit
diagrams.

This would be a good winter project and I would love to bring this radio
back to life.

Thanks in advance.

 

Ed / N1IWV

 

Edanderson1 at verizon.net



------------------------------

Message: 2
Date: Tue, 27 Jan 2009 13:07:36 -0500
From: "Vladimir Sidorov" <vs.lists at gmail.com>
Subject: Re: [ICOM] IC-745 Repair / Help
To: <icom at mailman.qth.net>
Message-ID: <0E3EB49AFDFC448989882A265D046B34 at VladimirPC>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
	reply-type=original

Ed,

You may try to clean up plates of the boards where they are connected to the

common bus, i.e. the TRX body, just under and around respective screws. As 
time goes, these areas get oxidized and it causes problems similar to what 
you describe.

GL anmd 73,

Vladimir VE3IAE

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