HP-67 Card Reader became very touchy

[AndiGer]

(09-26-2023 10:11 PM)teenix Wrote:  Note the polarity of each as they are polarized and inserting new ones the incorrect way will damage them. (Lots of unpleasant smoke).

Also note that the HP-97 service manual has the +ve marking for C6 to the top of the capacitor, but it should be to the left side as in the image as the capacitor pins are horizontal not vertical.

What I learned lately: HP from some time marked polarity (i.e. orientation) of components by a square pin hole. Pin 1 of chips, anode pin of capacitors, cathode pin of diodes, left pin of transistors. Very cool.
(Before that there is a little triangle on the board you can find in e.g. 35/45/55's.)


Andi