HP 65 card reader

[[kby]]

Assuming it doesn’t immediately blink zero, that is normal behavior once the calculator decides the card didn’t read correctly.-kby

(07-24-2019 12:58 PM)burkhard Wrote:  

(07-24-2019 09:02 AM)Namir Wrote:  Your HP-65 needs a gummy wheel repair job. This happens due to age and regardless of usage and/or "expectations".

Well, yeah, but he acknowledged that. He was asking why the motor wouldn't turn on.
There are several reasons why this could be --
a) Problem with switch that detects card insertion
b) Problem with motor itself
c) Problem with wiring for a) or b).
d) Something related to the display just blinking zero -- some greater brain damage?

I think you will need to investigate once you get in there to fix the certain gummy wheel anyhow. With a DMM you ought to be able to check out the switch function and continuity throughout. Directly power the motor with 3.6 VDC and verify that works as well.
The display blinking 0.00 I am more at a loss on... At the very least, when you have it open, clean all the contacts with IPA and DeOxit. Oh, does it ONLY blink zero when you insert a card, but otherwise works fine? Maybe it is detecting a stalled (gooed / glued up) motor?

There are lots of posts here about removing and reattaching that foil label without ruining it. Be sure to check them out in advance! I'd then leave the label off until you are sure everything is working 100%.

Good luck!