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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...

Sunday, March 17, 2019

Beogram 4002 DC Motor Restoration

Another Beogram 4002 DC platter motor arrived for restoration. This one came from New Zealand. This shows the motor as received:
I disassembled the motor and extracted the bearings:
The bearings are the two small donuts on the black pad. I immersed them in motor oil and pulled a vacuum:
Immediately air bubbles emerged from the bearings. The vacuum draws the air from the pores of the Oilite bearing material. This enables the diffusion of oil into the bearing. Once all the air has been replaced with oil, the bearing is replenished with lubricant and can be used again. These bearings needed about 48 hrs for the bubbling to stop, after which I extracted them for re-installation:
After assembling the motor I installed it into one of my Beogram 4002s for a 24 hrs RPM stability test with the BeoloverRPM device. The BeoloverRPM allows logging the RPM in 10s intervals over extended periods of time. This is the curve I measured for this motor:

This is as good as it gets for a Beogram DC platter motor, i.e. it is time for this motor to travel back home to New Zealand!

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