HP-67 Card Reader Repair Question


What would cause the motor to slowly rotate in the direction of reading a card?

Edited: 7 Aug 2013, 10:51 p.m.


The most logical source of trouble would be a fault in the sense amplifier. Pin 17 of the amp goes low to run the motor, this is controlled by the CRC. If that pin is not at the level of either rail, I suppose that could cause motor creep but that's speculation as I don't know what the circuitry is inside the sense amp.

BTW, if you replace the amp, don't forget to take the timing resistor with it, otherwise motor speed will most likely be wrong. If you have a later 67 with a pot, measure the resistance of the timing resistor in the device where you get the sense amp then set the pot in your 67 to that resistance.

Edited: 8 Aug 2013, 11:18 a.m.

Possibly Related Threads…
Thread Author Replies Views Last Post
  Reasonable price for a 41C, Quad Mem, Time, Navigation and Card reader module? Eelco Rouw 10 4,766 12-12-2013, 01:52 AM
Last Post: Eelco Rouw
  hp-67 card reader problem. Marcel Samek 5 3,233 12-09-2013, 09:09 PM
Last Post: Paul Berger (Canada)
  HP-67 keyboard repair davorin 1 1,186 10-04-2013, 04:09 AM
Last Post: Katie Wasserman
  HP-97 card reader pinch roller axle davorin 2 1,627 09-15-2013, 08:47 AM
Last Post: aj04062
  HP-97 Card Reader davorin 3 1,905 09-13-2013, 04:21 PM
Last Post: Stephan Matthys
  HP-15 LE Key repair question Namir 2 1,466 06-10-2013, 10:42 PM
Last Post: Namir
  Hp-67 card reader: tantalum capacitor identification Ignacio S├ínchez 8 3,269 06-02-2013, 07:26 PM
Last Post: aj04062
  Testing card reader motor for 65 Michae Altmann 2 1,637 03-17-2013, 09:24 PM
Last Post: Randy
  Repaired HP-97 card reader doesn't show any signs of life jbssm 6 2,673 02-17-2013, 03:15 AM
Last Post: Alberto Fenini
  HP 65 card reader problem H Fischer 3 1,544 11-24-2012, 12:11 PM
Last Post: H Fischer

Forum Jump: