Tag Archives: reed keyboard

Olympia CD401 Tischrechner: a magnetic keyboard

This marvelous CD401 Nixie-Tube calculator came to me in pristine condition, from a friend, and including all the accessories and even the original power cord. Just that it has some small defects. Numbers 2 and 7 didn’t work, and some of the keys have mechanical issues. Noteworthy, this little calculator came from Japan, despite being branded Olympia (which is a German company no longer in existence), an made by Matsushita Electrics, also known as Panasonic, in the early 70s. It cost close to 1000 Deutschmarks, may be equivalent to a two week’s salary of an engineer at the time…

Someone had apparently tried to fix it before, using inappropriate tools and scratching some internals, and not taking care of proper alignment of the parts.

The non-reactive “2” could easily be traced by a continuity tester, a bad circuit trace (the grease seems to be slightly acidic and has some greenish discoloration in places – copper corrosion).

The trace would be easily fixed with a short wire and some solder. The other defect – maybe introduced by the earlier repair attempts, a broken reed switch. The keyboard as such is a remarkedly complex setup – each key has several metal and plastic parts, and a magnet that operates a reed switch. Clearly, this had been built to a certain standard of longevity at the time, an engineering tool rather than a “pocket calculator”.

I keep a box of reed switches as spares, so luckly found one that is a pretty exact fit of the original.

Some careful re-assembly, some cleaning of old grease, and the instrument can go for a test. Note that there is exposed mains voltage around the transformer – why didn’t they put some cover?? It is right open and exposed and will give you an electric shock when you touch it…

That’t finally the machine all fixed and in best working order, probably soon it will be 50 years old.