The Museum of HP Calculators

HP Forum Archive 13

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More info on 41c card reader problem
Message #1 Posted by Steve on 27 May 2003, 9:54 a.m.

It looks like it was the alignment of the LED with the card slide hole and sensor. I adjusted the LED (from the board) to be in the center of the opening (near the wheel) and it has started to work. I never realized the positioning was so critical (I only moved it a couple of millimeters) but I guess it is. I believe this would explain why it runs for ~5 seconds: if the sensor does not detect the LED light, it thinks it has a card, but since the card may be stuck, it turns the motor off after a few seconds. I've seen this with bad wheels that can't pull the card through.


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