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...).