HP-65 card reader problems

[teenix]

(02-16-2020 08:22 AM)coitboy2000 Wrote:  Ok great

So what controls the voltage sent to the motor when a card is sensed ? That appears to be the issue.

Cheers

When the card is detected in the slot by the CRC on the CPU board, it then sends a Logic LO signal to pin #17 of the sense chip which then outputs the motor drive voltage from pin #1. Some of this voltage is fed back to pin#2 through the 4K64 resistor to regulate the motor speed.

cheers

Tony