I received another set of Beogram 4002 platter motor components and an RPM panel from a customer in the Netherlands to restore. My work started with the motor, as it usually does.

I disassembled the motor to get to the bearings.

Typically, I would show a picture of the bearings being oiled in a vacuum chamber, but I received new Oilite bearings from www.beoparts-shop.com specifically for these DC motors, which I am testing. Here is a comparison of the original (top) and new bearings:

I am very excited to install and test these new bearings!

Next, I restored the main PCB. I replaced every electrolytic capacitor, the RPM relay, the RPM trimmers, and the TR3 transistor with a high-gain version. Here is the restored board:

I also swapped out the incandescent bulbs in the RPM panel with LEDs:

Finally, I tested everything on one of my Beogram 4002s. First, I adjusted the TR3 bias with the 5M precision trimmer that replaced the fixed R26 resistor. I temporarily installed it on the solder side to adjust the collector voltage to 4V:

Then, I moved it to the component side:

Next, I checked that the sensor was working correctly using my oscilloscope:

Each dip in the trace represents one of the platter’s black ribs passing by the sensor.

After confirming that the sensor was working, I used a BeoloverRPM device to run a 24-hour RPM stability test on the motor and new bearings:

These are the results of the test:

This is great! These results are some of the best I’ve seen from Beogram DC platter motors, demonstrating that the new bearings from Beoparts perform as well as the restored original bearings. This will significantly simplify the restoration process!