Locked shafts and volume controls

ID: 241858
Locked shafts and volume controls 
09.Jan.11 12:55
17

Emilio Ciardiello (I)
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Articles: 533
Count of Thanks: 7
Emilio Ciardiello

When servicing old radios or old turntables, often shafts of volume or tone controls,
variable capacitors or of small synchronous motors are locked. The problem is caused by
hardened grease between the shaft and its bushing(s). Usually these parts cannot be
disassembled for cleaning. A lot of patience is then required to slowly dissolve old grease,
adding from outside drop after drop a very fluid solvent, as turpentine, until it penetrates
deep inside the bushing. Nevertheless in many cases bushings are not easily accessible even
using a syringe and anyway several hours or even days are required for the solvent to reach
internal surfaces.

Since the dried grease has the same properties of tar, it can be melted by heat. Using a
powerful soldering tool, put the tip in contact with the bushings for few minutes leaving
the heat to reach the shaft inside. The shaft can be now easily unlocked. Unfortunately tar still
remains in the bushing and must be removed. When cooled again rotation remains sticky
but the shaft can now be rotated back and forth, helping solvent to penetrate deep inside
more quickly than before.
 

Do not apply solvents when parts are still hot!

 

Regards, Emilio

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 2
Locked shafts and volume controls 
09.Jan.11 14:33
17 from 3143

Bill Rowse (USA)
Articles: 7
Count of Thanks: 5

 Thanks Emilio,

Your tip makes a lot of sense. In such instances I will do as you suggest.

Best Regards

bill r

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