|Re: HP65 card reader problem|
Message #2 Posted by Katie Wasserman on 25 Sept 2000, 12:35 a.m.,
in response to message #1 by John Robinson (Australia)
Your 65 card read problems are not uncommon in my experience. If you read the repair manual on them (see the 97 repair manual) you'll get a better understanding of how they're suppose to work.
Briefly, what's going on here is that the spiral gear on the motor shaft should never, ever slip. It should stop the motor if you hold it. The gear it drives should also never, ever slip and the pinch roller should never slip either.
So when you run a card through the machine it's going to put a load on the motor. In fact, it's a pretty significant load depending on how hard the pinch roller rubs against the card and the hard nylon roller underneath the card. The manual notes this and tells you to adjust the system for a specific current draw. It's not at all obvious, but the way you adjust this is by turning the nylon shaft that holds the drive gear and pinch roller. It's actually not a symmetric shaft in fact it's called the "eccentric cam" in the manual. The screwdriver slot in the end of this shaft is for adjusting this cam through 360 degrees.
It's been my experience that some card readers are much more sensitive to this adjustment than others. Most don't care at all how the eccentric cam is turned, but others will give radically different card speeds based on the cam position.
I'm not quite sure what you mean by the "nylon part of the motor clutch". However, I would consider using a soft rubber pinch roller that's a tiny bit more than 1/4" O.D.. I've found that the O-rings are very hard, much harder than the original pinch roller and therefore, generally mean that the drive speed is more sensitive to the cam position.