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This is a follow up to my recent post about the redesigned Beogram Commander remote control board, which now works in both (DC-motor) Beogr...

Friday, September 11, 2015

Beogram 4000: Adjusting the Gap at the Carriage Servo Pulley Bearing

When I tried out the carriage mechanism of the Beogram 4000 that I am restoring right now after repairing and adjusting the tracking mechanism, I found that the threaded rod that advances the carriage had a lot of longitudinal play. Here is a picture of the setup:

The play manifested itself in an unwanted 'clacking' every time the carriage changed its direction. This turned out to be an easy fix. All I had to do was to remove the servo pulley and remove the damaged locking ring and the worn out plastic washer:

This is the pulley. It is held in place by a setscrew whose threads are in the small brass plate that is inserted into the slot above the shaft receptacle. It should be noted that it usually sits very tightly on the shaft and that it took some careful 'convincing' with a flat head screwdriver to pry it off the shaft.

I replaced the locking ring and the washer by a thick 2-56 nylon washer which fit perfectly on the shaft. The locking ring is not needed since the pulley is locked in place with the set screw:

I also lubricated the shaft in its bearing and the nylon washer with a bit of silicone grease.
Then I put the pulley back on:
Now it has only a fraction of a mm play and the carriage moves very precisely and without strange noises. I added a bit of silicone grease to the threaded section of the shaft and that quieted the mechanism further.

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