Following the repair of the Beogram 4002 (5513)’s arm lowering and tracking mechanisms, the next stage of restoration involved the electronics and platter drive. As usual, the process commenced with the replacement of all electrolytic capacitors on the printed circuit boards (PCBs) with new, high-quality Japanese capacitors rated for 105 degrees Celsius. To ensure the DC motor operates smoothly and without speed variations, the RPM relay was upgraded to a modern, enclosed unit, and 25-turn precision trimmers were installed for precise RPM adjustment.

The main PCB’s original condition is depicted, highlighting the capacitors slated for replacement in red and blue:

The main PCB after capacitor, RPM relay, and RPM trimmer replacement:

A detailed view of the ‘RPM section’:

A relay breakout board was used to accommodate the modern surface-mount relay, a part that is offered to other enthusiasts. A version compatible with the National relays found in some 4002 models is also available.

The output PCB (#8) was also addressed, providing an opportunity to replace the worn keypad with a meticulously refurbished one. A closer look at the original PCB#8 is shown below:

The rebuilt output PCB is shown below:

Replacing the original output relay is advisable, as they can become stuck on a single channel, effectively transforming the turntable into a mono device. A switch that permits the connection of system and signal grounds was also added. This connection can aid in reducing grounding issues.

The motor will be rebuilt next by re-lubricating the Oilite brass sleeve bearings. This should leave the platter drive in excellent working order.