Beogram 4002 (5513): Gold Plating of Keypad Contact Terminals

One of the design peculiarities of the Beogram 400x series are the mechanical switches that are used throughout the control systems of these beauties. The switches are based on spring loaded contact terminals that are either actuated by the user, or in the case of the 4000 by the carriage as it advances during the playback of a record. The trouble-free operation of these Beograms depends on the proper functioning of these switches. I recently started offering electrochemical gold plating of the contact terminals, since in the Beogram 4000 most control issues originate from oxidized terminals in these switches.

The latter 4002 and 4004 models can benefit from gold plating as well since often their keypads have issues resulting in unreliable switching performance. This shows the keypad terminals of the Beogram 4002 that I am restoring right now in their original condition. 

The thick black coating is oxide which needs to be removed before gold plating can be attempted. I unsoldered the terminals and took them out:

This can be a bit tricky, since it should be avoided to bend them. Once they were out I removed the oxide with 2000 grit sand paper and a fiberglass pen and then plated them with gold:

Then I reinstalled them:

Beautiful!