Featured Post

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, November 23, 2020

Beogram 4002 DC Platter Motor Restoration

I recently received the DC platter motor from a Beogram 4002 located in Iowa. This shows the motor as received:

I took the motor apart to get to the bearings:
They are the two small donuts on the black pad. I immersed them in motor oil and pulled a vacuum. Immediately strong bubbling started:
This indicates that air is being drawn from the empty pores of the bearing material, making room for the inter-diffusion of oil. When all the pores are full with oil the bubbling stops. In this case it took about 72 hrs until the process was complete. This shows the bearings after extracting them from the oil:
I put the motor back together and installed it in one of my Beogram 4002s for a 24 hrs test run with my 
BeoloverRPM device, which allows logging the RPM in 10s intervals over extended periods of time:
This is the curve I measured after about 24 hrs:
This is pretty much as good as it gets with the Beogram DC motors. This motor is ready for duty again!

No comments:

Post a Comment

Comments and suggestions are welcome!