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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, December 6, 2019

Beogram 4002 DC Motor Restoration

A Beogram 4002 DC platter motor arrived from California for restoration. This shows the motor as received:
I disassembled it to extract the Oilite brass bearings for oil infusion:
The bearings are the two small donuts on the black pad up front. I immersed them in motor oil and pulled a vacuum:
Immediately, strong bubbling started indicating that air was being extracted from the bearing to make room for oil diffusion into the porous material. After about 3 days the bubbling stopped and I extracted the bearings from the oil bath:
I reassembled the motor and installed it into one of my Beogram 4002s for performing a 24 hrs RPM stability test with my BeoloverRPM device:
This is the curve I measured:
This is pretty much as good as it gets with Beogram 4002 DC motors. This motor is back in business!





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