[ICOM] need assistance with 761

[bonddaleena at aol.com]

Hello. I have a nice 761 that is driving me crazy. I would like to chat 
with someone off-line about this issue. Hopefully, someone has 
sufficient knowledge.
I would ask for advise from Scott at MTS or Clif at Avvid, but the 
problem is so trivial, I don't want to waste their time. I have used 
both of these gentlemen before, and I cannot say enough good things 
about them.

I will describe the 'problem' briefly, but like I said, I would prefer 
to correspond off-line so I won't bore everyone.....

When the radio is FIRST turned on, everything is perfect. A short time 
later (seconds or minutes), the receive sensitivity drops way off. 
Abruptly. Tapping the top of the radio very gently, restores it. As the 
radio warms up, it 'improves', and after a 1/2 hour or less, the 
problem never returns.

Here's the part that bugs me........ I have had the radio out to my 
test benches several times. I have tightened all the screws, plugged 
and unplugged every connector on the RF and Main board. All seems well, 
but then a couple of days later, it starts all over again.
In addition to the gentle tapping, I have found that putting the 
'preamp' switch 'on', temporarily fixes the loss of sensitivity. Also, 
engaging the Tuner has the same effect.

Today, I was looking at the block diagram and the schematic. (I have 
the Service Manual). I was hoping that there was a relay that switched 
the preamp in/out, but it's done with diodes. I 'kinda' suspect RL1...
Before I 'go back in', I thought I'd ask the experts here.

Yes, I realize there could be a cold solder joint somewhere (!!), but 
there a LOT of parts in one of these babies. If the problem was more 
consistent, I'm sure I can find it. It's just too touchy right now.

Sorry for the long post, but it's difficult to explain in one sentence. 
ha ha

tnx

ron

N4UE