The final major task in the Beomaster 1900 restoration, detailed in the previous post, has been completed. This post covers the last board requiring capacitor replacements: the Tone Control & FM Tuning Board. Replacing the ten capacitors on this board is straightforward due to their accessibility. The true challenge lies in cleaning and fixing the three slider controls: Bass, Treble, and Balance.

Before images of the Tone Control & FM Tuning Board are shown below.

Work began by cleaning and restoring the slide controls.

Disassembling the Bass and Treble sliders revealed a prior repair attempt, likely performed alongside the main board’s bridge rectifier replacement, although the two are unrelated.

The slide controls have a design flaw where the control contacts attach to the sliding control bridge. The bridge’s small black plastic piece, which houses the contacts, is prone to breakage. A glue repair on the bass control bridge points to an attempt to address this issue.

The treble slider control is depicted below.

A reliable slider control bridge repair kit was likely unavailable at the time of the glue repair, which likely provided a temporary fix. Given the eventual failure of such repairs, the current solution involved using a replacement bridge sourced from Martin Olsen of Beoparts.

The photo below showcases the new Beoparts bridge alongside the original bridge intended for the bass control slider.

The image below shows the bass slider control contacts mounted on the new bridge.

Cleaning and lubricating the rails on which the contacts slide is another crucial step in the slider control repair.

Deoxit and conductive carbon grease were used. The bass control slider is now ready for reassembly and reinstallation on the Tone Control & FM Tuner Board.

The treble slider control is now ready for reassembly.

Anticipation to listen to this Beomaster receiver grows. However, some tasks remain.

The last slider control, the balance control, differs in style from the others. While visually similar, its design eliminates the need for repairs required by the bass and treble controls. This balance control slider style is preferable due to its enhanced durability.

Nevertheless, it still requires cleaning and lubrication.

Before-and-after pictures of the balance slider control cleaning are shown below.

Moving on to capacitor replacements, the electrolytic capacitors in this Beomaster, similar to others, were found to be out of tolerance.

Below is the one in the worst condition, a 2.2uF capacitor.

It measured a staggering 6.27uF.

Below is a photo of the fully restored Tone Control & FM Tuning board.

The final steps before testing involve replacing the Beomaster 1900 indicator lamps, a task scheduled for tomorrow.