Hi Jon:
The two weak spots (ok three) of TR-751's that have
manifested over the years are:
1. Volume Pot goes noisy and then fails
2. RF Gain Pot goes noisy and then fails
3. Optical Encoder goes bad.
I have more TR-751's sitting here than I care to admit. I'm
having a real problem with volume pots.
So recently I tried to purchase just the pot or the little
assembly of which it is a part. (The little board would
actually be the easiest repair.)
http://www.kenwoodparts.com/ is the old "Kenwood East"
source. Guess what part they've been out of for years? The
pot AND the little assembly.
I cut and paste the 4 addresses below and I tried all of
them about one month ago for the Pot and the board assembly.
I could quote the Part number and the board assembly if I
was at home. (I'm in Milwaukee) All four of these places
were "out of stock/out of production" on the part we need.
But let me continue.... :-) So I was trying to get ready
for the Jan VHF Sweeps. I spent hours swapping out pots from
some parts rigs I have here. Guess what was failed in each
case? So I sprayed WD-40 all over them trying to leak
enough fluid into them to do some good. Plus I really rocked
the pot back and forth trying to give the "amateur pot
tuneup". One gained "slight" improvement. The rest, no
improvement.
So, then it was time to depart on the rove so I've not taken
the next steps I have planned:
1. carefully drill tiny (weep) holes in the pot case on
opposite sides to flood it with WD-40/contact cleaner.
2. If needed, I'll chop one open to really look at the
failure mode.
3. The worst case will be to keep the pot as an on/off
switch and mod the rig with a new pot.
I'm open to discussion on the last three points and will
report back with results IF/WHEN I get the time to deal with
Bad Pots on TR-751's.
73
Bruce Richardson W9FZ
Herman Electronics
7350 N. W. 35th Terrace
Miami, FL 33122
Phone: 800-938-4376
Phone: 305-477-0063
Fax: 800-938-4377
http://www.hermanelectronics.com
PacParts Inc.
15024 Staff Court
Gardena, CA 90248
Phone: 800-262-1312
Phone: 310-515-0207
Fax: 800-782-5747
http://www.pacparts.com
PacParts Inc.
2114 SE 9th Ave.
Portland, OR 97214
Phone: 800-338-6342
Phone: 503-236-6140
Fax: 800-962-0602
East Coast Transistor Parts, Inc.
2 Marlborough Road
West Hempstead, NY 11552
Phone: 800-776-2626
Phone: 516-483-5742
Fax: 800-733-5904
http://www.eastcoasttransistor.com
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