Beomaster 8000 Terminal: Replacement of Corroded Battery Terminals and the Design of a New 3D Printed Battery Cover

The Beomaster 6000 that I just repaired came with a non-working Beomaster 8000 Terminal remote control. It turned out that a simple replacement of the corroded battery terminals was enough to restore power and with that the functionality of the unit. However, this Terminal was also lacking the battery cover and the rubber bumpers that keep it from sliding off polished furniture surfaces. Since this is not the first Terminal that I saw with lacking battery compartment cover, I decided to design a 3D printed replacement part. Here are a few impressions of my progress:

This shows the original corroded battery terminals:

and the installed replacement:

After a few design iterations I had a fitting battery compartment cover:

This shows it in comparison with the cover I extracted from one of my Terminals. Here the outside surface of the part:

The part has rubber bumpers like the original. Thir location is slightly different due to stability considerations, but they do their job very well.

This shows the part installed:

Pretty, eh?? The latch works exactly like in the original part. The cover can be extracted from the ouside by inserting a small flat blade screw driver and then lifting it out.

But why in orange you may wonder?!? I usually use orange for prototyping since I have an ample supply on hand these days for filling CleanerVinyl orders. Orange also reveals more details than black in photographs. But of course the final version was printed in black. Here in comparison with the original:

And in more detail:

If you are lacking the battery compartment cover on your Terminal, this part is available for purchase. Just send me message (use the contact form on the left).

The remaining task was to replace the worn/missing rubber bumpers at the lower end of the Terminal body. This shows a newly installed bumper (right) in comparison with a broken off original bumper (left):

And both replaced:

The final step was to clean the unit. I employed my ultrasonic cleaner (another benefit of the CleanerVinyl project...;-) and the buttons and housing came out in a fairly pristine condition:

What a lovely classic design! This is Beolove!

Beocord 9000: Replacing the RAM Battery

The Beocord 9000 has a 3V battery that supports the 16 word memory chip (an interesting MCM144102 chip that is mentioned as a peripheral memory unit in the Motorola 6804 manual, but whose detailed data sheet appears to be unavailable on the web). This chip stores the calibration settings (and may also back up the system time...not sure at this point - need to play a bit more with it). Here is a snapshot of the circuit:

The good news is that the battery is secured against connecting it with reverse polarity via D27. This suggests that replacing it with a battery holder instead of a soldered in tabbed version is a good way to proceed. 

The battery is located right underneath the TIME CAL indicator cabinet. The original battery started leaking the Li compound from the inside (that is the green-grey stuff around it). When I unsoldered the battery I suffered a small explosion due to this leaked compound. One should keep in mind that Li  is a highly reactive compound where a bit of heat immediately causes an exothermal reaction with the oxygen in the air. Luckily, I wore a magnifying visor and glasses, so nothing bad happened. But I would definitely recommend to cut the battery off with a wire cutter before starting to remove the tabs. Also wiping the area with ethanol would probably be a good idea to remove as much of the stuff as possible. Anyway, here is a picture of the vacated battery location after cleaning it as good as possible:

I used a 1/3N battery holder since tabbed 1/3N batteries are rare and pretty expensive. Also, a battery holder will enable to replace the battery in a few years without much fuss (the glass panel is removed very quickly without the need of a screwdriver, and then the battery can be accessed). Here is a picture of the new battery and the holder:

And the holder (Newark 25T0455) magnified:

Here is a picture after soldering it in. It is important to note the correct orientation that the + and - symbols match up with this on the PCB to avoid confusion down the road:

And with battery inserted:

Looks nice! Like it was designed that way (sort of strange to find a soldered battery in such a rarefied device, but then engineering of consumer devices usually assumes a 10 year use horizon...).