[ICOM] IC-F-521s

[Kenneth G. Gordon]

Good morning from snowy Idaho:

I am a long-time tech here, age 79, have been into electronics since 1956 when I was first 
licensed as WN7EKB.

I eventually worked for over 30 years at the University of Idaho as their Electronic Instrument 
Specialist, Sr so I have lots of experience with making reclacitrant electronics eventually 
work.

My present issues have to do with some IC-F-521 transceivers which a good friend has 
asked me to look at. We/they have bought several for fairly low prices. Most work quite well, 
and we are impressed with their many features.

I discovered several things about them which needed addressing: for one thing, the heat-sink 
compound used at the final amp was much too "spare" in some cases, but that was easily 
remedied.

My present problem is that we have more than one of these rigs in which the TX audio works 
just fine, i.e., they transmit just fine, and can be easily copied with good quality, but the RX 
audio is simply non-existent. They are completely deaf. It is as if there is simply no signal 
getting to any detector, but that is probably just intuition on my part.....or wishful thinking.

I have as much of the service information as I could find, but it really isn't too helpful in this 
situation.

Might anyone here be familiar enough with these rigs, and their history, to point me in a 
plausible direction to get them working? Was there a common problem with these rigs in the 
RX section somewhere? I suspect either a blown IC, or some damaged connection to the 
CPU.

In one case, I replaced the front-panel with a known good one, which did not help, and tried 
to trace the RX audio back to a source, but had to set that aside for a more important job at 
the time.

I have, and am experienced with all the necessary test equipment. 

Any suggestions out there? Thanks in advance.

Ken W7EKB
www.w7ekb.com