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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...

Wednesday, November 6, 2019

Beogram 4002 DC Motor Restoration

A Beogram 4002 DC platter motor in need of restoration arrived recently from Australia. This shows the motor as I received it:
I took it apart to get the bearings out for oil infusion:
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:
The bubbling indicates that air is being drawn from the pores of the Oilite bearing material to make room for diffusing oil. After about 72 hours the bubbling stopped and I extracted the bearings from the oil:
Then it was time to reassemble the motor for a RPM stability test in one of my Beogram 4002s:
I ran a ~24 hrs measurement with my BeoloverRPM device. This is the curve that I measured:
This is pretty much as good as it gets with the DC motor of a Beogram 4002. This motor is ready for duty again!

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