[ICOM] IC-745 Repair / Help

[Ed]

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