|Re: Repairing the hp 82104A Card Reader |
Message #2 Posted by Randy on 10 Nov 2007, 2:18 p.m.,
in response to message #1 by fred moon
The spring in the front half (the one without the motor) acts to press the card against the head. The half-moon spring on the back half presses the card down again bottom guide rail.
Hitting the wall comes from following the directions... it's really the method described to reassemble the two halves as IMO it doesn't work most times.
I find the better way is to hold the parts is with the front half in one hand with the two leaf springs facing the floor. With the other hand and a small screwdriver or something similar, wiggle the head spring into position such that it is straight in its slot and when the high free end is flexed downward, it enters the recess underneath. Now, without rotating the front half, lower the inverted back half with the motor down onto the front and engage the pins. Holding the halves together, install two screws, one from the front and the other from the back. Once those two screws are tightened, put it down and find a tester card. Slide the card into the reader from the right side and just keep pushing. If the head pressure spring is in the right place, the card will pass between it and the head. If it moved before you got the halves together, the card will hit the spring and not go past. Tear down and reassemble if you have to but once you see what the jamb point is, it's easy to fix. I've never had to rebend a spring, you only need to insure it is installed and aligned correctly.
Once card passes through, install the contact board with the three remaining long screws.
Rather than trial and error, you can set the correct drive wheel force by running the motor with a 3.0 VDC supply and adjust the eccentric cam for 180-200 ma draw with the card stalled. This is the same for all readers and is documented in the 97 service manual.