A Beogram 4004 DC platter motor arrived recently in the mail for some TLC. I bench-tested it and it ran quite rough. It seems these days there are not many Beogram DC motors that do not need their dry Oilite bearings infused with fresh oil. We make it a point in our restorations of the 4000 series Beograms to always rebuild the motor. Over time the oil that is in the pores of the Oilite brass material is drawn out into the motor and the bearings run dry.
Fresh oil can be infused under vacuum, but for this the bearings need to be extracted from the motor. Here are some impressions of the process in this 4004 motor. This shows the motor extracted from the Beogram as received:
After taking it apart and immersing the bearings into motor oil:
This shows the bubbles coming from the bearings after pulling the vacuum:
After about 24 hrs the bubbling stopped and I assembled the motor again. This shows the 3D printed tool I use for pressing the top bearing retainer back into the housing:
I tested the motor in one of my Beogram 4002s and measured a 24 hrs RPM stability curve with my BeoloverRPM tool (which is available to other aficionados and repair shops - just send a message using the form to the right or via email). This shows the curve:
A perfect result. This Beogram 4004 motor is back in business!
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