[ICOM] 756Pro Tuner "mystery" solved, inconsistencies

[David S. McCallum]

Tom have you been using the rig on 6m's at all and maybe attempting to
run the tuner in auto position?
  
On Thu, 3 Jun 2004 15:29:28 -0500 Tom Norris <r390a at bellsouth.net>
writes:
> No, the adjustment menu remains a mystery as
> does the inconsistency between manual and actual
> menu, but I did find the problem.
> 
> Yes, the radio is out of warranty.
> 
> When physically inspecting the tuner board I found
> 2 relays that looked "swelled" - further investigation
> proved them to be shorted - their contacts welded
> together. Either mismatch or a lightning blip, and I
> am afraid it could indeed be the latter - when initially
> checking the relays/board, by using the inputs to
> the 54562 ICs to drive the relays, I also found
> an output on IC-2 that does not go "all the way high"
> and does not *always* activate RL-6. Easy enough to
> replace chip and relays, perhaps socket the new ICs.
> 
> Photos of the dead relays --
> http://www.fernblatt.net/mystery/756tuner/2relays.jpg
> Note the melted hole in the foremost relay - which was
> RL-11. RL-13 also had a deformed case, but no hole.
> 
> http://www.fernblatt.net/mystery/756tuner/friedRelay.jpg
> Note the burned contacts of RL-11
> 
> Now, to the next inconsistency in the manual. *all* the
> relays on the tuner board are marked with the part number
> "NY-12W-K" as is the schematic. The parts list gives
> relay 13 and 14 different part numbers The commercial
> pn of these according to the manual are "AG 2011344"
> with the Icom part being 6330001330 versus xxxxxx1510
> for all the rest.
> 
> The good news is that while I had it apart I did a full
> alignment check, and other than the S meter and one
> more adjustment, it was fine. Very clean output even at
> full power, looking at the spectrum analyzer.
> 
> I'd still like to know more about the "top secret" adjustment
> menu, though.
> 
> 73
> 
> Tom NU4G
> 
> 
> 
> 
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David S. McCallum/USAF RET./Chief Mac/W7SAC/4