Repair of a Bombay Co. quad watch winder

[robmack]

Hi,

I recently purchased a previously-owned quad watch winder to keep my automatics fresh overnight.  The price was very attractive and the pictures were good but, since the article was in a different city, I was not able to see it in person before I purchased it.  When I received the package, I found out that one of the winder motors spun without driving the watch holder.  The seller hadn't disclosed this problem, even though I specifically asked.  It was an obvious mechanical problem which I set about to repairing.  I'm documenting my findings here so that if someone in the future experiences the same problem, they might have a clue as to how to repair the problem.  These winders are common and manufactured in China as per the "Made In" sticker.

The winder consists of two 6V DC 10 RPM universal motors configured to drive a dish shaped watch holder.  Each motor is capable of winding up to two watches simultaneously.  In my winder, the right watch holder just remained stationary as the motor spun, indicating that either a belt had slipped or a clutch mechanism had failed.  In either case, it was necessary for me to extract the motor assembly.  I began by removing the watch holder from the shaft of the motor (remove the foam insert and then loosen the screw holding the part to the shaft of the motor).  Then I removed the bottom panel since there was no other means to access the insides.  Once opened, I disconnected the motor from the driver board and removed the four screws holding it to the baseplate (see photo 1 below).

Once extracted and on the bench, I proceeded to inspect it.  The motor is clamped in a plastic base and is coupled to an axle using a drive dog (see photo 2).  When I disassembled the plastic base and removed the motor, the cause became apparent - the rubber drive dog was stripped. You can see the rubber residue that was dug out by the shaft. The receiving hole for the motor shaft should have been shaped to fit the keyed shaft  (see photos 3 & 4).  The rubber dog was just too soft to accept the torque of the geared-down motor.  Any stalling of the watch holder transferred to damage to the dog.  My solution was simple.  I drilled a hole in the coupling housing and inserted a screw that would act as a key to prevent the motor shaft from rotating relative to the coupler (see photo 5).  I decided to do this to both motors to prevent a similar fate for the operational assembly.  Once repaired and back together, the winder was as good as new.

Edited December 9, 2018 by robmack
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