[Collins] Reluctant filter switch on 51J-4 - Solutions?

[Gerald]

On Sun, 2005-12-18 at 17:24 -0800, Chris Kepus wrote:
> My 51J-4 plays and works very nicely with a few odd exceptions: (previously
> noted on this list) but the one thing that now concerns me most is the
> amount of effort that it takes to switch from one filter position to the
> next.  It seems like that small switch lever behind the knob is about to
> bend or break every time it finally moves to the next position (regardless
> of rotational direction).  Out of concern that the lever might break, I have
> stopped using the switch until I have time to pull the unit out of the rack
> and examine it.  Is this rotational resistance just one of the switch's
> characteristics...or ???.  For those of you who use a 51J-4, is it "easy" to
> change filter positions using your filter switch lever or do you feel like
> the lever is about to bend or break each time you use it? If the normal
> state of affairs is a switch on which the positions can be easily changed,
> does anyone have an idea of where I should look for a problem with my switch
> mechanism?  If anyone has successfully corrected a similar problem, would
> you be kind enough to share your method?
> 
> Thanks, 73, Merry Christmas, Happy Hanuka, and Seasons greetings to all!!
> Chris
> W7JPG
Sounds to me as if there's a lubrication problem on the concentric
shafts and the switch detent and shaft bearings. I had that problem
recently with a switch on a Heathkit soldering iron station. I was able
to free the switch shaft temporarily with heat. I tried adding solvent
in the form of PB Blaster while hot. When the switch cooled that
combination of gelled oil and PB Blaster made even better glue. I had a
useable replacement switch that I wired in and junked the old switch.
I'd wish that a solvent would reduce the friction in your switch shaft,
bearing, concentric shafts and detent. It may take something strong like
acetone (but don't get a drop of that on a dial or paint!) best to start
with something more gentle like denatured alcohol or naphtha before
going to lacquer thinner or acetone. What works will depend on the
nature of the original (and perhaps subsequent as a mixture) lubricant.

The filter switch should be no more difficult to operate than any of the
other switches on the panel of the radio.
-- 
73, Jerry, K0CQ, Technical Advisor to the CRA
All content copyright Dr. Gerald N. Johnson, electrical engineer