HP-65 low keys


Hi all,
I have a HP-65 wich is in very good condition except the keys. Mainly at the center of the keyboard, around the "8" key, those keys are very low, I would say almost at the half height. They don't make good contact also. I've open the calculator already and cleaned the keyboard PCB using a wet contact cleaner spray and blowing it with an air spray too, which improved the electrical contact but the keys are still down. How could I solve this problem (if there is a solution...)?
Thanks in advance for any suggestion!


Hi Luis, It sounds like it could be one of the following problems: 1. Keypad pcb is warped. 2. The plastic insert that goes directly over the keys is not properly seated. 3. One or more screws that retain the black plastic piece that inserts over the keyboard pcb are stripped out. My guess is that it is #2.


I have seen quite a few HP65's with the same problem. Don't know the cause though. I don't think it is any of Erik's 1/2/3 suggestions. I have not worked on any that had the problem, but suggested the same things to others that have... they didn't help.


Another common problem I forgot to mention is that the spring part of the key pad may have broken. You can usually fix these by soldering in a replacement from another parts machine.


Again, a no go from past experience. The machines that I was familiar with had reasonable clickage.


Yes, I guess that's the failure. I think the spring plate for many keys (maybe the most used ones) are weak and they aren't strong enough to rise them back. Any idea to make it strong again? What about decrease the clearance between the spring plate and the keys installing some kind of spacer behind the keyboard PCB?


Is the spring plate broken? If so, it needs to be replaced.


Hi Erik. No, it's not. I still guess the problem is because the spring plate keypad are weak due to its usage.

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