HP-97 Keyboard entry problem


I have a HP-97 that doubles the entry number from the keyboard on a random basis. (Hit 2 get 22, hit 63 get 633). Anyone know if this is just dirty contacts or more serious? Jim


It could very well be dirty contacts. If you're careful you should be able to dissasemble the keyboard assembly and very thoroughly clean the key contact surface areas. Gentle use of a pencil eraser gives good results. I don't remember everything about how the 97 keyboard is put together but I think each key has a sheet metal spring that makes contact with the underlying board. You have to clean the springs as well as the board, or any other surface that forms a circuit when the key is pressed. Just do it carefully with patience, make a note of where all the keys go and don't leave any bits of pencil eraser behind. Good luck. Maybe let us know if it solved your problem. P.S. don't use an eraser on conductive plastic. It can be washed in warm soapy water and then rinsed and thoroughly dried. I don't remember if the 97 has conductive plastic.


As Steve says, its probably keyboard contacts, and the 97 is one of the easier machines to disassemble, however I would suggest a diagram of the wires and their colours... On the subject of cleaning, eraser has always seemed a little harsh, scrubbing with cotton buds and isopropanol alcohol is an alternative. There is no conductive plastic in sight in a 97.


I had a similar problem on a 97 and it was the result of something spilled into the key board. So in addition to cleaning the contacts, be sure to clean the keys and the hole in the upper case to prevent any sticking.

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