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[W4AJF]

Hi all, I have an old Yaesu radio with trimmer capacitors that may be able to be revived somewhat with a cleaning (they are obsolete), does anyone know how I can attempt to clean these so they work properly and not skip?

I have pictures but can't see how to post them.

Thanks for any help.

Adam Farber W4AJF
Cooper City, FL

[W4AJF]

And I did of course adjust them back and forth several times but that did not help.

[WA2EIO]

I am not sure what type of trimmers they are, but Collins gear suffers from stuck and dirty trimmers, and there have been methods described for them:

http://www.collinsradio.org/wp-content/uploads/2015/05/Repairing-Frozen-Trimmers-Zook-Copywrite.pdf

https://www.qsl.net/k7rld/Fixing%20a%20stuck%20ceramic%20trimmer.htm

Might give you some ideas; good luck!

[W4AJF]

Thank you Very much. I did see those but neither works for the type of trimmer cap that I have. I very much appreciate the attempt. Adam W4AQJF

[WB6BYU]

I am confused by the phrase “and not skip”.
That’s not usually a problem with trimmer
capacitors, depending on the type.  It is
possible for some types that have a wiper
contact if it is corroded.

One of the best cleaning methods for variable
capacitors is an ultrasonic bath - my wife has
a jewelry cleaner that probably would work,
but I haven’t had the need or the courage yet
to try using it for that purpose.

I had one ham friend who ran his variable
capacitors through the dishwasher, but that
is probably better for the larger types.

In either case, they need tp be thoroughly
dried afterwards, which may be problematic
with some types.

[W4AJF]

Hi, when I say skip, when attempting to adjust it it shifts around at certain points and I can see the frequency jump on a frequency counter when attempting to align this portion and hear the sound change. Cleaning it after is not something I can do but thanks, Adam

[KB1GMX]

That style appears mostly in Japanese gear, The give away is a
what looks like solder blob on top next to the adjustment slot.

What that blob does is connect the rotor to the top plates plating
(the rotor part of the cap).  The failure mode is the plate locks
(welds from crud) and rotating it breaks that solder loose.  The
fix then is replacement.

Variable Caps with similar value and pinning can be used and are available.
Value and all usually is noted in service manual.

Finding direct replacement is possible but much hunting is likely.  Places like
Jameco MPJA and others are a starting point.

The other source of that is underside where the rotor rides a plate
and gets oxidized resulting is discontinuous contact. If you get it out in
one piece cleaning is a maybe thing.  however they fail over time,
replacement assures less long term pain.


Allison

[W4AJF]

Thanks for the post. Finding a right angle trimmer is virtually impossible, I will have to just get a standard one and see what I can do with it. Thanks Adam

[K4LIX]

If they're silver or silver plated, then a drop or two of TARNX will brighten them up!

[W4AJF]

Hi, thanks, don’t really care how it looks if it works, thanks Adam

[KC3TEC]

Cleaning them can be done but its an iffy proposition.
Use of a good plastic safe contact cleaner and a soft artist paint brush can work to remove crud but may leave a thin film behind.
Trimmers with mica dialectric should be cleaned with alcohol only and litely at that.
Any other cleaner may delaminate the mica.