[Collins] 75A-2 Receiver Ceramic Trimmer Repair

[Jim Walker]

I have had a number of ceramic trimmers in my 75A2 that were either
stuck or the ceramic piece between the rotor and stator broke away from
the olive drab rubber base of the trimmer.  The stuck trimmers were
repaired using a modification of the article in The Collins Journal Vol.
12, No.1 "Repairing Ceramic Trimmers" by KF7TY.  Since all of the 75A-2
trimmers are riveted in the receiver, I could not drop them in a cup of
boiling water.  What I did do was to soak some paper towel and saturate
the trimmer for about fifteen minutes then used a Weller heat gun with
the small nozzle used to flow surface mount components from a printed
circuit board.  I applied enough heat until any residual water on the
trimmer disappeared.  I did it twice and presume the water was wicked
into the trimmer and caused the sticking material to easily break loose
when I carefully turned the trimmer rotor.
 
The more difficult trimmers have required unsnapping the under side clip
that hold the rotor on the trimmer.  The rotor and the stuck ceramic
piece that was originally glued on the stator / riveted piece in the
receiver both fall out ... fortunately in two pieces separated from one
another.  I have tried GC Bond, GE Silicone II and Super Glue to glue
the ceramic piece back in position on the trimmer olive drab stator base
with varying degrees of success.  After applying the adhesive I would
reassemble the rotor and retaining lip to hold everything together until
the glue dries.  I have not tried Super Glue Gel.  Has anyone found the
ideal adhesive for this application?  I am not satisfied with the long
term fix of these trimmers.