Today’s teardown subject is another vintage find: a 1974 Casio Personal-Mini.
Still in the original box
Oddly enough the packaging foam is still good
Hmm, I bet it’s been more than 20 days since purchase
Interesting board to board interface with soldered pins. Probably good for a couple bends.
Going around the converter pins with a scope, I see a few voltage rails, interestingly enough all negative relative to the battery negative terminal: -6.5V, -18V, -23.5V
Along the same line, notice color coding of the battery wires: Red is Negative, White is Positive:
And some more closeups of the VFD:
Slow thinking video
To illustrate how this thing behaves, I made a short video. Let’s just say it takes its time thinking
And here are some shots of the user manual: