The Beogram 4002 (5523) restoration continued with a focus on the PCBs after addressing the decayed transport lock bushings. The main PCB was first, as shown below:

In addition to replacing all electrolytic capacitors, the RPM relay and trimmers were targeted due to their susceptibility to corrosion and impact on RPM stability. The following image highlights the RPM section in its initial condition:

Modern, encapsulated 25-turn trimmers replaced the old ones, and a new relay was installed (interested enthusiasts can obtain a replacement relay by email or through the contact form). The upgraded components are shown here:

The main board after its restoration is depicted below:

The output PCB also received attention. The electrolytic capacitor responsible for the output relay’s time constant was replaced along with the relay. The restored board is pictured here:

A red switch located in front of the output connector offers a way to connect the system with the signal ground, mitigating potential hum in the amplifier. This situation typically arises when using RCA adapters that lack a separate ground connection.

The main reservoir capacitor, crucial for power supply stabilization, was the last component to be replaced. Its original state is shown below:

A smaller, modern capacitor was used as a replacement, mounted with a 3D-printed adapter to ensure compatibility with the existing mounting clamp. This setup is visible here:

Measurements of the old reservoir capacitor revealed a capacitance of only ~3100uF, falling short of the specified 4000uF. This finding suggests that the capacitor was nearing the end of its lifespan and would have soon failed completely.