Following the PCB restoration of the Beogram 4002 (5523), the next step was to swap the RPM trimmer illumination bulbs with LEDs. This change enhances the Beogram’s long-term stability and the DC motor’s RPM consistency. The RPM trimmers are integral to the DC motor’s feedback circuit, which maintains a steady RPM. Incandescent bulbs generate heat, affecting the trimmers and potentially causing RPM fluctuations. The cooler-running LEDs effectively address this issue.

This image shows the extracted RPM panel from the back:

Removing the covers exposes the bulbs:

Once the bulb leads are unsoldered, the bulbs can be extracted, and the LED boards can be put in their place:

The image displays the LED boards, designed as direct replacements for the light bulbs:

These boards are available for other enthusiasts. Interested individuals can get in touch via email or the contact form provided.

The covers can be placed back over the LED boards:

The LEDs illuminate the RPM trimmer indicators with a natural, incandescent-like glow while maintaining the red indicator color. This is achieved using red-green LEDs calibrated to emit a spectrum similar to that of an incandescent bulb: