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Beolover SyncDrive: DC Platter Motor Replacement for Beogram 4002 and 4004 (Type 551x and 552x)

Late Beogram 4002 and the 4004 (Types 551x and 552x), which have DC platter motors instead of the earlier synchronous AC motors usually suff...

Monday, September 16, 2019

Beogram 4002 DC Motor Restoration

A Beogram 4002 DC platter motor recently arrived from Florida for restoration. It emitted the usual shrieking noises when I ran it from my bench supply. A clear indication that the bearings were dry. This shows the motor as received:
I took the motor apart to extract the bearings (on the black pad):
Then it was time to immerse them in motor oil and pull a vacuum:
Immediately, vigorous bubbling started indicative of air being drawn from the pores of the Oilite bearing material to make room for oil. After about 2 days the bubbling stopped after the oil was replenished in the bearing. I extracted the bearings:
And then it was time to reassemble the motor. I installed it in one of my Beogram 4002s and ran a 24 hrs stability test with my BeoloverRPM device:
The BeoloverRPM can log the RPM over extended periods of time. This is the RPM curve I measured for this motor:
This is as good as it gets for 4002 DC platter motors, i.e. this motor is ready for duty again.





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