Sonavor is currently restoring four Beogram 4002 turntables and recently asked for assistance in refurbishing the DC motors.

The restoration process involves removing the motor bearings, cleaning them, and applying fresh oil. To ensure effectiveness, a vacuum is used to draw the oil into the porous bearing material. The bearings are then cleaned of excess oil and reinstalled.

After reassembly, each motor undergoes a 24-hour RPM stability test using a specialized device. All four motors performed well, demonstrating consistent speed stability within acceptable tolerances.

Minor variations in RPM between the motors are attributed to the unique friction profile of each motor, which influences the analog speed control system. Interestingly, motor performance tends to improve over time, possibly due to the motor shaft gradually smoothing the bearing surface.

With the restorations complete, the motors will be returned to Sonavor for installation.