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Full Version: HP-41 Card Reader Error
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I recently rebuilt my Card Reader. The card runs smoothly, but I consistently get Card Err or Malfunction or Checksum Error.

Some threads point to the 2 contacts. I swapped and checked to make sure they are flat. I applied contact cleaner as well.

I tried a different calculator, but that didn't work.


Hi Adam,

If you get inconsistent results, then I'd say there is hope. And I presume you had never seen such errors before the rebuild /

My guess is that you need to spend more time adjusting the roller pressure.

Is the motor struggling ?


I swapped the rebuilt drive assy with another card reader I had.

This assembly works great. So, I presume from browsing older posts, the cause of these errors/malfunctions could be the capacitor adjacent to the sense amplifier chip. I will try this next after I rebuild another drive unit.