HP-97, Repairing Printer Rollers


Anyone have any luck repairing printer rollers that pull the paper through the printer?

I have an HP-97 that appears to have had the printer set unused for a very long time. The pinch rollers, to the front (the light colored ones) have an indentation (i.e. not a round roller) from the other roller that prevents the paper from being pulled through the printer at that point.

Looks like they could be replaced, if one can get the printer apart. Guess I will have to save this till I get some time.

Anyone have any luck repairing these rollers?


Hi, I just fixed a HP-97 with this same problem. I just pulled the part that has the flattened wheels out of a HP-82143a printer I had for parts. You can usually get these reasonably cheap on ebay or the HP museum site. The only other remedy I see is to find a substitute for the rubber/plastic wheels.


How hard was it to remove the part.

I don't seem to see any way without removing the entire print head. Is that true?


Hi Mike, Yes, it is an involved process. You have to first remove the printer assembly from the calculator. Then there are several printer rods and the print head itself that must be removed. If I remember right, you almost have to take it all apart to get to the part with the plastic wheels. If you do it, watch that you don't lose any of the c-clips that retain the various rods!


I purchased a NIB HP-97 about a year ago from eBay. The unit was in prisine condition. The seller told me he had purchased it for an engineer their firm hired in about 1978. The engineer only stayed about 3 months, so they put the calculator in it's box in closet, until I bought it.

This calculator had the same problem -- a flattened portion on the wheels that caused stuttered paper advancement. It was aggrivating to find this problem in such an otherwise perfect calculator. With the help of some friends, we tried a couple of fixes, but nothing worked for long. I eventually replaced the whole print assembly. Now it works fine.

I should note that the print mechanisms in the 82143 printer, while similar, won't fit in the Topcats. I found this out the hard way. You've got to cannibalize one Topcat to save the other.



Yes, it is true that you can't replace the entire printer assembly for a HP-97 from a HP-82143A. I think the HP-82143A printers ran a little faster so the print head thermal resistors were different, as well as the motor drive and some of the advance mechanism (rubber band drive vs. sprocket drive). But some of the parts are interchangeabe like the plastic carrier (Frame), rods, clips, reed switch, and paper advance item in question.

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