Beogram 4002 (5513): Restoration of the DC Motor - Oil Infusion of the Oilite Bearings

After rebuilding all the components of the DC motor control system of the Beogram 4002 (5513) that I am restoring right now, it was time to look into the DC motor. Just spinning it by hand created scraping bearing noises, i.e. it was definitely time to re-infuse its Oilite sleeve bearings with oil. Most Beogram DC motors need this treatment at this point in time to be able delivering stable RPM performance again. This shows the motor as extracted from the Beogram:

I took it apart to extract the two bearings:

The bearings are the two 'donuts' up front on the black pad.

I submerged them in motor oil and pulled a vacuum. Immediately air bubbles emerged from both bearings:

After about 24 hrs the bubbling came to an end and I extracted the bearings from the oil and put the motor back together. This shows the 3D printed tool I use for installing the top bearing:

After the motor was together again, I installed it in the Beogram and ran a 24 hrs RPM stability test with the BeoloverRPM device. It allows logging the RPM over extended periods of time. A great feature to detect intermittent RPM instabilities. This tool is available to other B&O enthusiasts. Just send me an email or use the contact form on the right.

This shows the BeoloverRPM in action (it is also great for adjusting the RPM precisely):

This shows the resulting 24 hrs RPM graph:

This is as good as it gets with a DC motor Beogram. The slight variations of the RPM are probably caused by temperature variations of the ambient (or the moon phase...;-). They are within the specs of the Beogram and are not audible. The joys of analog technology of the 70s! This Beogram is getting close to a first test drive!