Following the restoration of the Beogram 4000’s control panel (keypad), the next step was to focus on the carriage position switches. These switches are vital for the Beogram 4000’s digital control system, and even one faulty switch can render the entire device unusable. Similar to the keypad switches, these are prone to oxidation, making gold plating a reliable solution to prevent future contact problems. The image below displays the circuit board with the switches after detaching the carriage position indicator component.

After disconnecting the servo motor leads and removing the two screws holding it, the board can be lifted:

Although the contact tabs may appear clean at first look, removing them exposes oxidation in the contact points, visible as small black marks:

The presence of humidity in the air acts as an electrolyte, facilitating electrochemical reactions. This leads to the oxidation of the terminal metal at its point of contact with the corresponding terminal. Applying a coating of a noble metal such as gold is a practical solution because it significantly hinders this oxidation process. The terminals, following the electroplating procedure, are shown here:

And after reinstallation:

With the carriage position switches successfully restored, attention now turns to the main PCB and the capacitors for the reservoir and motor.