Repairing HP keypads



#4

I have a HP-25 that I've taken apart and the keypad seems to be bad. After figuring out the traces and what keys they hook up to I tested the keys with an ohmmeter. Some keys are fine, others either don't make contact or do poorly. There are little holes on the pc board under each key where you can see some kind of contacts coming together. I was thinking of either spraying contact cleaner down these holes or maybe using something very small to reach down in there and clean the contacts. Anybody have any experience with this?


#5

Contact cleaner is worth a try. I fixed an HP-21 with similar problems by this method. Use just the smallest squirt of liquid you can.


#6

I recently purchased an HP-71B on EBAY.

To my dismay, 3 keys didnt work at all and 2 only worked if you would push very hard.

I took the unit apart and sprayed electronics cleaner into the holes three times to no avail.

I then tried a product we use at work called DEOX 2000 which is made to clean and remove oxides, carbon, and corrosion while leaving behind a contact enhancing film.

This worked perfectly after spraying them twice

This product can be purchased at most electronics stores.

GOOD LUCK!!!


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