[Premium-Rx] WJ-8711A Help Sought

Thu Apr 23 20:22:42 EDT 2020

 Eugene you have multiple errors going on with this radio.
Table 4-6 in the manual lists the errors.  The number that it's displaying is the sum of the errors so you have
8192: PRESEL OVERLOAD2048: RAM FAIL1024: REF ERROR256:  BAT ERROR-------11520
My 8711A seems to always report a ref error on power-on but the reference is definitely good.  Batt error is already being reported.  Does your display report the ref error?

It doesn't appear you have the preselector so not sure why that's indicating an overload, unless there's a pulldown or pullup resistor that's bad.
One thing about 8711s, the yellow tantalum caps tend to short.  Between my 8712 and my 8711A I can't count how many of those damn things I've replaced.
You could try the COLD START procedure detailed in the manual to see if that clears things, but I'd replace the RAM battery first.

Let us know how you progress.
73 John

-----Original Message-----
From: W2HX <w2hx at w2hx.com>
To: premium-rx at mailman.qth.net <premium-rx at mailman.qth.net>
Sent: Thu, Apr 23, 2020 7:29 pm
Subject: [Premium-Rx] WJ-8711A Help Sought

Hi friends,

A few years ago, I picked up two WJ-8711A receivers. One looked nice in a desktop cabinet and the other was clearly a parts mule.

Nice one:
https://w2hx.com/x/Watkins%20Johnson/WJ-8711A/0423201757.jpg

Both units with the parts mule atop the nice one that is out of its nice cabinet
https://w2hx.com/x/Watkins%20Johnson/WJ-8711A/0423201903a.jpg

The nice one has some problems. BATT ERROR (no big deal, probably the coin cell needs replacing) and ERROR=11520
Any idea what ERROR=11520 is?  But probably worse, or maybe related, is an awful squeal coming out of the speaker..
https://youtu.be/aVI5blTALZM

Here are some internal pictures of the nice one.
https://w2hx.com/x/Watkins%20Johnson/WJ-8711A/0423201848.jpg
https://w2hx.com/x/Watkins%20Johnson/WJ-8711A/0423201850.jpg
https://w2hx.com/x/Watkins%20Johnson/WJ-8711A/0423201850a.jpg

Along with the parts mule, I also have tons of other parts including a spare board.
https://w2hx.com/x/Watkins%20Johnson/WJ-8711A/0423201850b.jpg
https://w2hx.com/x/Watkins%20Johnson/WJ-8711A/0423201852.jpg
https://w2hx.com/x/Watkins%20Johnson/WJ-8711A/0423201853a.jpg

interesting that the spare board uses a dallas cheerleader memory chip, whereas the nice one has some other chip in there (maybe EEPROM?).

some heavy encoder knobs and little panel switches (the current knob is garbage, so light)
https://w2hx.com/x/Watkins%20Johnson/WJ-8711A/0423201855a.jpg

Then here is the inside of the parts mule:
https://w2hx.com/x/Watkins%20Johnson/WJ-8711A/0423201907.jpg

This project may be more than I care to take on, but I figure with a parts mule, extra digital board, other various bits and bytes, I might be able to make one working radio. So my question to the group is, anyone have a suggestion on the audio howl/squeal? And what should I know about that error?

Thanks all!
73 Eugene W2HX

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