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Re: buttons that don't register well

Posted: Thu Sep 26, 2019 11:42 pm
by Helix
inautilus wrote:
Thu Sep 26, 2019 11:44 am
PS ... makes one wonder how many others out there (world-wide) are also reluctantly sitting on their money, really wanting to purchase, but ...
I am in this situation.
I know the response of some members here: only a small percentage of DM42 users has a problem with the keyboard, the vast majority is happy, and it's probably true.
But on the other hand, I never see complaints about the HP Prime, the DM1x, the DM41… Why this difference?
For a 200€ calculator, I would expect 100% reliability.

Re: buttons that don't register well

Posted: Fri Sep 27, 2019 2:09 am
by Rmollov
Helix wrote:
Thu Sep 26, 2019 11:42 pm
... I never see complaints about the HP Prime ...
Recently I had a chance to play a little bit with a colleague's HP Prime. Not impressed at all let alone not being RPN/L, but the keyboard is really, really nice. Which is exactly opposite with my DM42 SN 00849. Some time ago there was a word of (after market) replacement dome sheet with different domes to make keys working with less force. So far nothing to support it :(

Re: buttons that don't register well

Posted: Fri Sep 27, 2019 2:21 am
by Rmollov
jaykstone wrote:
Wed Sep 25, 2019 3:14 pm
Has anyone tried replacing the dome switches?
I purchased a DM42 and received it last weekend. I immediately loved everything about it except the keys. Keys were hard to press, and many of them could click without registering unless i pressed harder after the click. I decided I was intent on keeping this calculator and really did not want to send it back.
First I tried the gentile key bending. this did reduce the required force, but keys could still click and not register. Next I put a dab of UV curable plastic on center of each dome. this helped on some keys, but was too thick on others. I gently ground down the added plastic until all keys worked. This was better than when I started, but I would still miss some keystrokes where a click was felt but the press did not register.
I took the DM42 to work for a day and decided the keyboard was just causing too many mistakes.
I peeled back the sheet of domes, and everything looked perfectly clean. I cleaned with Isopropyl alcohol anyway, and still no change.

Finally I decided to remove the plastic I had added on and replace the snap domes. first I peeled off the plastic bits I had added with tweezers. The only domes I had on hand was some 6mm domes I was able to salvage from some scrap keypads at work, but it looked like they might work even though they are smaller. I carefully removed half of the original 8mm domes (from top half of keyboard)and replaced them with the domes I had on hand, carefully centering each one and sticking it on the plastic sheet. Upon re-assembly, all of the keys with the new domes worked perfectly. I could not get a key to click without registering. I repeated this on the remaining keys with the same result. Now every key works great.

Has anyone else tried this? I suspect there may be other domes (from Snaptron etc) to consider from a feel perspective, but based on my results it seems like replacing the domes could be promising. Any thoughts?

Jay
I envy you for what you've done, I'm far less skilled than needed to do so with my DM42. Anyway, how is the keyboard feel now after all? I taught smaller domes would make keys tougher - requiring more force to register, at least so was suggested here in the past (replacing domes with larger ones in order to make keys "softer").
I'm still hoping someone will come up with a solution like prefabricated sheet with better domes and if so happens I'll probably start using it.

Cheers,

Re: buttons that don't register well

Posted: Fri Sep 27, 2019 6:48 pm
by jaykstone
I envy you for what you've done, I'm far less skilled than needed to do so with my DM42. Anyway, how is the keyboard feel now after all? I taught smaller domes would make keys tougher - requiring more force to register, at least so was suggested here in the past (replacing domes with larger ones in order to make keys "softer").
I'm still hoping someone will come up with a solution like prefabricated sheet with better domes and if so happens I'll probably start using it.
The feel is fairly firm with very definite clicks (but not in a bad/unreliable way like say a late 1970s TI). I am not much of a dome expert. From what I have read, i believe they make domes of various actuation force travel and tactile ration in various sizes. I think larger domes are supposed to have longer operating life (more cycles) for a given actuation force. I would certainly consider trying a larger lighter force dome at some point if I heard good feedback on a particular one.. The ones I have now are just what was on hand. I don't really want to keep peeling it apart over and over just to try things that may or may not work well so I'll probably just stick with what I have for now.