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Full Version: HP97 cant read card but writes fine
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I have a HP97 that had the classic card reader gummy wheel problem, I changed the wheel to square O rings and assembled it again, but every time I try to read a card I get "Error".

I have tried to adjust everything according to the manual, the small plastic rod so that the motor draws about 200mA and adjusted the gold contacts so they make contact when the card is fed through, but I cant get it to read.

But It does write with no problem.

I have another HP97 that I made the same procedure on and It reads the programs I write on the cards in the first machine just fine, so what can be the problem?

I have measured the resistance on the heads and its the same on both machines, about 45 Ohms or something around that on both the read/write coils

anyone has any experience on these things? its damn annoying that one of the machines does not work as it should.

I changed the wheels on my HP41 readers just fine, why cant the HP97 reader be as simple as those.
Your motor speed might be too high. this will make the card fly through before all of the data is written, becuase writing is simply timing controlled and not bound the the cards movement. i had that once with a 41-card reader, and i adjusted the motor speed down. it worked ever since.

also the card might get pulled through too slow, which would make all data on only part of the card. this is far less likely though as those cards can usually be read on the machine they were written on (though not on any other machine).


Card too fast
|||||||||||||||||||||||||||||||||||||||||    Data
[---------------------------------]          Card

Card too slow
|||||||||||||||||                            Data
[---------------------------------]          Card
All 5 wires of the head connected? Once I had a loose blue wire on a 67 or 65, but don't remember what didn't work
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