more HP97 card reader followup.


I had last posted that my newly acquired HP97 was all working, except the card reader, which was pulling cards slowly with hight current (>300 mA), and producing errors. It was looking like the tubing I had used to repair the gummy wheel was too large diameter.

I ordered the correct O-rings, and received them today. Replacing the tubing with the O-rings, there is slight improvement; the card pulls through slowly, but not as slow and jerky as before, and the current is still high (about 250 mA) regardless of the cam position. I will spend some time next trying to get this resolved, but I would be most grateful for any additional suggestions.




Hi Dave,

I have fixed the same issue on my HP-97, with O-rings too.
I have currently not in mind the exact size of O-ring I choose (I tested several), but I will keep in mind to check this as soon as I will be back at home.
I didn't mesure the current though, but the card reader did read and write correctly, so, no more investigations were needed to my opinion.

Kind regards.


What is the motor current with the gear removed? If it is higher than about 40ma, the screw is bent or not centered on the motor shaft.


Duoh. Is the 250ma with or without a card present? If it is card present, is it card stalled (held back) or card moving?


Thanks for all the help!!!

I just checked it--about 20 mA. Interestingly, the reader is now working! I had to put the machine away so I can use my bench for work over the weekend, so I assembled the whole unit, and popped in the battery I bought (from Mark via Ebay), and just for kicks, I slid a card in and it went through smoothly this time, but gave an "ERROR". I wondered if perhaps the card contained garbage data, so I tried the Diagnostic Card from the Standard Pac, and it read both sides, then wrote both sides of that same blank card, then read the card back. I ran the program, and it gave me the -7.777777770-77 as expected, and printed out 1.+07, 10.000+06***, 1.0000+07***.

However, the manual indicates it should leave a -8.888888888-88, and instead I see 1000000.00

I am assuming the last is a display test. Why would the calc not show it?

Also, I notice that the printer paper tends to jam a bit while loading. I had to thread a piece of tape beneath the platic sheild to try to fish the leading edge of the paper up and through. Afterwards, it seems to feed along nicely, although the printer makes a bit of a whining sound.

All the keys work beautifully, and the display is excelent, except that part of the middle segment on the rightmost digit doesn't light.

Best regards,


Edited: 3 Dec 2011, 12:06 a.m.

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