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HP Forum Archive 21

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HP-85 Keyboard Repair
Message #1 Posted by aj04062 on 18 Mar 2012, 10:06 a.m.

Does anyone have some keyboard contact parts for a 85 or similar units? One of my contacts is busted. I may be able to fabricate one, but a spare one would be much easier.

Re: HP-85 Keyboard Repair
Message #2 Posted by Paul Berger (Canada) on 18 Mar 2012, 3:23 p.m.,
in response to message #1 by aj04062

I assume that you have looked into the service guide for the 85 already so you know what you are up against. This was a very common keyboard technology from around the time the 85 was announced so there are lots of keyboards that used the same design, one that I know of was used in the TI-99 home computer. I have a couple keyboards that I have removed the key modules from the printed circuit board, and now that I have a 85 it would seem that they where keyboards for an 85, however they where likely from prototypes as the key module construction is a little different. A little while ago Bruce Larrabee posted Bruce's post some pictures of components he was looking for help identifying, the first for pictures are contacts that are almost identical to the contacts that are in the keyboard on my 85 the only difference is just above the solder tail there is a tab punched out, this is the same as the keyboards I took apart, and that tab latches into the bottom of the keymodule, if the production keyboards where made this way the process for swapping the contacts documented in the service guide would not work as it would be very difficult to pull them out. Other than that they would seem to be identical and could be used to replace contacts in production level keyboards.

In the service guide they mention a special tool for seating the contacts, I would suspect that this tool would fit around the contact and sit on top of the tabs sticking out of the side for easy insertion, if you try to grasp the contact with pliers to insert it you will likely damage it, I lined the contact up with the hole and pushed it down with the square end of my smooth jaw pliers until I could grasp the solder tail on the other side with these same pliers and pull until it is seated. It would probably be fairly easy to fabricate a tool to seat the contacts. I also found out the hard way you need to be careful installing the keytops as they fit inside the square post and it is possible to snag the contacts and bend them.

I could spare you a couple sets of the old style contacts as I said before they seem to fit in ok and production keyboards do not seem to have the notch the punched out tab fits into so it does not latch them in. If you would like me to send you a couple sets you, email me through the forum with your mailing address.

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