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HP Forum Archive 04

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Re: HP65 card reader problem
Message #1 Posted by John Robinson (Australia) on 24 Sept 2000, 10:06 p.m.

My switch now turns the motor on OK when I insert a card, but I am having problems getting the card to feed properly. I either have a situation where the motor works hard,a passes the card slowly, in which case I think my roller is too big, or the motor runs unevenly, in which case I think the roller is too small and is slipping. I noticed that the nylon part of the motor clutch is broken in two, so I am not sure if the motor clutch is slipping, but when I take the motor out, and run it, and hold the worm gear, it doesn't seem to slip.

Is there any way I can eliminate all other causes and convince myself that it's just me roller making skills need honing ?. Can anyone sell/give me a roller that is known to work fine ?

I am yet to try the "fall through" test, perhaps someone can explain it to me ??

Thanks - John

      
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)

ohn,

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.

-Katie

            
Re: HP65 card reader problem
Message #3 Posted by John Robinson (Australia) on 25 Sept 2000, 2:18 a.m.,
in response to message #2 by Katie Wasserman

Hi Katie,

The nylon part of the motor clutch is referred to in Steve Loboyko's repair document. It's on the motor shaft, and goes into a metal sleeve before the worm gear.

I'll try rotating the nylon shaft as you suggest to see what difference that makes. I'll also take a look at the 97 repair manual.

Cheers, John

                  
Re: HP65 card reader problem
Message #4 Posted by Katie @wasserman on 25 Sept 2000, 11:49 p.m.,
in response to message #3 by John Robinson (Australia)

John,

I understand what you're talking about now. The "clutch" is really the coupling between the motor shaft and the worm gear. It's a nylon bushing inside of a metal cup and supposely allows the motor shaft to slip if the worm gear becomes jammed.

I've fixed a couple of these (before I even read Steve Loboyko's article) in a manner similar to what he describes. However I found that the best glue was quick setting epoxy (crazy-glue and the like just didn't work for me). Just a tiny drop of it is all you should use or you run the risk of getting it inside the motor. The motor shaft will not slip with the expoxy in there, but I've never found that to be a problem.

-Katie

            
Re: HP65 card reader problem
Message #5 Posted by Matthew Riehl (U.S.A) on 25 Sept 2000, 5:53 p.m.,
in response to message #2 by Katie Wasserman

Katie,

You refer to the HP-97 repair manual (. . . If you read the repair manual on them (see the 97 repair manual) . . .) in your post.

Where might I find this manual? Is it available online or possibly on the museum's CD set? It sounds like a great reference to have. Thanks for mentioning it.

Matt Riehl

                  
Re: HP65 card reader problem
Message #6 Posted by Katie Wasserman on 25 Sept 2000, 11:09 p.m.,
in response to message #5 by Matthew Riehl (U.S.A)

Matt,

Yes, the HP-97 repair manual is on the CD set available for purchase here. I don't know of an on-line copy of it.

-Katie


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