Texas Beomaster 8000: Restoration task on the control panel

The Beomaster 8000 from Texas has been playing music beautifully while I have been working the restoration tasks for the Canada Beomaster 8000 unit. However, a couple of issues popped up during the functional testing.

The first problem happened when moving the microcomputer board and display board out of the service position. All of a sudden the Beomaster wouldn't switch on the +15V power supply again. I have gone over the solder joints of the microcomputer board a number of times now and here it goes off again. Quite disappointing.

To confirm the problem is still with this original microcomputer board I substituted one of my spares again. Just like that the Beomaster was working again. Due to this flaky behaviour I am not ready to trust this microcomputer board in completing this project. I feel like this board needs to be stripped completely down and all of the traces (and vias) reworked from scratch.

For this project I am going to go with one of my spare microcomputer boards. It hasn't failed me yet so it will be perfect for this project.

The second problem happened at the same time and was the volume control wheel ceased to work. The Beomaster volume worked just fine via the remote control so the problem had to be in the control panel. Either the wheel sensors or the cables.

The cables are the most likely suspects as this Beomaster has gone through some rough cable repairs in the past.

On these Beomaster 8000 control panels the two ribbon cables and the (blue) wires for the rotary wheel sensors can work loose in their small solder joints.

I had to resolder the connections but I decided to go ahead and replace the two ribbon cables with new replacement cables I get from Beolover. That is the best option for success here.

Interestingly, I hadn't noticed this before, the control panel utilizes a flat, metal spring to hold the panel secure in the center. That spring is the same as the flat springs that are used on the Beomaster press bar that opens the Filter & Tone Controls. Perhaps a substitute can be used here and this spring would be free to replace one of the missing press bar springs.

Here is the control panel button board removed and the installation of the new ribbon cables.

Instead of re-assembling the control panel in its final, permanent configuration I will just tape it in place temporarily so I can test that the control panel works and the volume control problem is gone.

Success, both the volume wheel and the FM tuning wheel function properly now.

Tomorrow I will start putting these components back into their permanent positions in the Beomaster cabinet.