[ICOM] need assistance with 761

[Dave Edwards]

Perhaps use the radio, but leave the covers off. Then when it whigs 
out...you can touch various suspect areas with a probe or eraser side of 
pencil...to see what area makes it come back to life.
....Dave
----- Original Message ----- 
From: <bonddaleena at aol.com>
To: <icom at mailman.qth.net>; <n4ue at arrl.net>
Sent: Thursday, September 25, 2008 10:22 PM
Subject: [ICOM] need assistance with 761


>
> 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
> ----
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