|Re: HP67 - Card Reader Problems|
Message #1 Posted by Matt Kernal (US) on 14 Feb 2001, 12:04 p.m.
Yes, the problem you describe is a disintegrating drive wheel. Even though your 67 has been taken care of, the rubber breaks down with age and becomes gooey (or sticky).
Using the article Warren is referring to (Steve Loboyko's "How to Fix Classic Models"), I just replaced my first 67 card reader drive wheel last week. I varied from his instructions by using two rubber O-rings instead of the fuel line tubing he suggests. You might have trouble finding the same O-rings in Germany (1/4 inch Outside Diameter by 1/8 inch Inside Diameter which means 1/16 inch thickness).
The only problem I found in Steve's procedure was the abscence of any description of removing the Pin which holds the drive wheel/worm gear in the plastic frame (where the motor mounts). This pin "appears" to be a plastic slotted screw head that "looks" like you should turn to unthread it, but it is actually a pin that needs to be pulled to free the drive wheel/worm gear from the frame.
For a better feel of what I'm talking about, first look at this photo of a completed HP41 card reader (similar to a 67 CR) repair with O-rings, http://www.hpmuseum.org/guest/card/cr5.jpg . Notice what appears to be a slotted screw under the black and red wires. This is the pin that must be pulled to remove the drive wheel/worm gear, as shown in this photo, http://www.hpmuseum.org/guest/card/cr4.jpg . These photos can be found in the article "Repairing the HP 82104A Card Reader" at http://www.hpmuseum.org/repair.htm .
As other people have said, accessing the two screws under the back label of the calculator will be the most painful part of the job, because you have to disturb the label to remove it (especially painful on a good condition calculator). And it never looks original when you put it back on (with rubber cement). I used a hair dryer to loosen the adhesive and a long flat knife blade to lift the label without creasing it. Sorry this message is so long.