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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...

Friday, October 15, 2021

Beogram 4002 DC Platter Motor Restoration

I recently received the DC platter motor of a Beogram located in Massachusetts for restoration. A quick bench test revealed the usual squealing indicative of dry Oilite bearings. This shows the motor:

I took it apart to get the bearings out:
The bearings are the two small donuts on the black pad. I immersed them in motor oil and pulled a vacuum. Immediately, strong bubbling started:
This shows that the vacuum pulls the air from the empty oilite pores making room for oil to diffuse into the bearing material. After about 48 hrs the bubbling stopped and I removed the bearings from the oil:
Then I reassembled the motor and installed it in one of my Beogram 4002s for a 24 hrs RPM stability test with the BeoloverRPM device:
This is the curve I measured. It shows the RPM in 10s intervals over 24 hrs:
This is as good as it gets with the Beogram DC platter motor. This motor can be sent back to its owner for another tour of duty in his Beogram!


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