A Pair of Beomaster 1900 Receivers for Restoration: Recapping the Tone Control & FM Tuning Board (Unit #1)

The most time consuming tasks of the Beomaster 1900 restoration were completed in the last post.
This post shows the final board that needs capacitors replaced....The Tone Control & FM Tuning Board.
The capacitor replacement is easy. There are just ten capacitors and they are easily accessible. The difficult task on this board is cleaning and repairing the three slider controls (Bass, Treble and Balance).

Here is the Tone Control & FM Tuning Board before photos.

I started with the the cleaning and repairing of the slide controls.

After some disassembly of the Bass and Treble sliders I could see that an early repair attempt had been made in the past. Probably at the same time the bridge rectifier on the main board was replaced (though the two items are not related).

These slide controls have a weak part of their design and that is where the control contacts mount to the sliding control bridge. The small, black, plastic piece of the bridge the contacts fit into tends to break.
You can see where there was an attempt to repair that problem with some glue on the bridge of the bass control.

Here is the slider control for treble.

A good slider control bridge repair kit was probably not available when the glue repair attempt was made. That repair probably worked for a while. Eventually that type of repair will fail again so the fix made today is to use a replacement bridge that is supplied by Martin Olsen of Beoparts.

This photo shows the new Beoparts bridge next to the original bridge for the bass control slider.

Here are the bass slider control contacts mounted on the new bridge

Another task of the slider control repair is cleaning and lubricating of the rails the contacts mate with.

I use some Deoxit and some conductive carbon grease. This bass control slider is ready for reassembly and installation back on the Tone Control & FM Tuner Board.

Here is the treble slider control ready for reassembly.

I am starting to get anxious to listen to this Beomaster receiver.  Still a little ways to go though.

The third and last slider control, the balance control, is a different style of slider. It looks similar to the others but its construction is such that it does not require the repair that the bass and treble controls did. I prefer this style of slider that the balance control has. It seems to be more durable.

It does require cleaning and lubrication though.

Here are the before and after photos of the cleaning of the balance slider control.

Now for the capacitor replacements.
Like the other electrolytic capacitors in the Beomaster these were out of tolerance.

Here is the worst one, a 2.2uF capacitor.

Wow... 6.27uF.

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

The final restoration tasks before testing the results is to replace the Beomaster 1900 indicator lamps.
I will do that tomorrow.