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HP-71b keys recording double key press issue
07-29-2019, 04:54 AM
Post: #1
HP-71b keys recording double key press issue
Hi All

One of my 71b's has an issue with the A and D keys regularly recording double press's. Its a real pest. The calculator is in fantastic condition otherwise. Is there a potential fix ? Probably not given the way it is made but I would welcome any suggestions.

Regards

Richard
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07-29-2019, 01:04 PM
Post: #2
RE: HP-71b keys recording double key press issue
(07-29-2019 04:54 AM)coitboy2000 Wrote:  Hi All

One of my 71b's has an issue with the A and D keys regularly recording double press's. Its a real pest. The calculator is in fantastic condition otherwise. Is there a potential fix ? Probably not given the way it is made but I would welcome any suggestions.

Regards

Richard

I've never encountered this on a 71B, and I've used over a dozen machines, so it is somewhat unusual. One approach, though not guaranteed to work, is to get a drop or two of DeOxit (Red) contact cleaner under the affected keys. When you cannot access keys from the inside, I use a wet brush to scrape along the bottom edge, thus collecting some DeOxit on the bottom lip, then hold the machine inverted at angles to get the liquid to drip to the center, all the while working the key.

Depending on the actual cause of the problem, this may not help, but if the issue is any form of corrosion or dirt between the key and the contact dome, this likely will eliminate the issue, but in any case will not hurt. It's an easy and non-invasive technique worth trying before resorting to disassembly, etc.

--Bob Prosperi
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07-29-2019, 10:30 PM
Post: #3
RE: HP-71b keys recording double key press issue
Thanks Bob. I will give that a try.
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07-30-2019, 10:56 PM
Post: #4
RE: HP-71b keys recording double key press issue
I get this too, with my 'B' key; thanks Bob.

Cambridge, UK
41CL, 12C/15C, DM15/16, 71B, 17B, 28S, DM42, 48GX, 17bII+, 50g (& newRPL), 35s, 30b (WP 34S), Prime G2
& Casios, Rockwell 18R :)
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08-05-2019, 08:25 PM
Post: #5
RE: HP-71b keys recording double key press issue
For me it is the "6" key, and I find that it is a sign that I need new batteries.
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