HP 65 card reader

[burkhard]

(07-24-2019 09:02 AM)Namir Wrote:  

(07-24-2019 07:31 AM)NoEqualsButton Wrote:  I just scored a HP 65 in immaculate condition. Cosmetically near perfect and works perfectly with the exception of the card reader. I have replaced the batteries and fully charged them. When a card is inserted the motor does not start. No noise. The display just blinks 0.00.

Any ideas? I know the gummy wheel needs replacing anyway, but I'd expect it to at least try and read the cards.

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!