Help: HP97 key not working


I just bought and received a mint (and I mean mint!) HP97 with case, manuals, battery pack. The battery pack looks mint. I started performing some basic exponential decay calcs here at work with it and quickly found out that the zero (0) button does not work at all. What can I do. This looks like a keeper but I really want it to work properly. I don't think I can find one as nice as this. I've never opened up an HP, so I don't really feel comfortable trying to fix it, and I only want an honest person that won't mark it up with a screwdriver.


It's probably a very simple fix. The HP-97 keys merely press down on a set of contacts printed on a PC board. I imagine removing the keyboard and cleaning the contacts and the bottom of the key switch would fix it-- it's worked on my 97s.


The 97 is easy to open. From memory: 6 small phillips screws on the back and 7 to pull the internal frame off. The pcb pulls off a bunch of spreading connector pins with only your fingers as tools. There is no label to peel up. If i can do it then you can.
There is a post by waterhosco in the articles forum on the sticky wheel repair and that will get you deep enough to atack the keypad from the back with some cleaner. You might do the sticky wheel fix while you're in there, if it hasn't already been done.


Thanks, guys! I don't mind sending it to someone competent to fix it and even do a little preventative maintenance. I would gladly pay the person.



If you're still nervous about opening your HP-97 to clean the keyboard contacts, you can send it to takes < 30 minutes if you've done it before.

No guarantees, of course, but it sounds like a simple fix.


Of course, the reader will need to be rebuilt.

Also, if the printer was never used the printer drive cam will probably be so screwed up it will need to be replaced also (you can use one from an 82143A). On machines that were never used, the rubber tended to degrade much worse than on machines that were used.


Actually, the HP97 (and other Topcat) keyboard is easy to dismantle fully. There are no heatstakes.

Once you've removed the bottom cover and the chassis plate, undo the 2 screws inside, one at each end of the keyboard. Unclip the display window from the top case, then take the whole lot out (it comes out from the outside, not down into the case. Bend the display cable as little as possible, it can be fragile.

Then take off the 7 screws on the back of the keyboard. Lift off the PCB. Don't lose the contacts for the slide switches. Take off the plastic spacer sheets and the gold-plated contact sheets. It's now obvious what to clean -- I use propan-2-ol (isopropanol) for this.

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