buttons that don't register well

If you're having problems with the hardware of a DM41X or DM42, post about them here.
Helix
Posts: 31
Joined: Sat Jun 24, 2017 12:59 am
Location: France

Re: buttons that don't register well

Post by Helix »

inautilus wrote:
Thu Sep 26, 2019 1:44 pm
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.
Rmollov
Posts: 37
Joined: Wed May 03, 2017 7:55 pm
Location: Sydney, Australia

Re: buttons that don't register well

Post by Rmollov »

Helix wrote:
Fri Sep 27, 2019 1:42 am
... 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 :(
Rmollov
Posts: 37
Joined: Wed May 03, 2017 7:55 pm
Location: Sydney, Australia

Re: buttons that don't register well

Post by Rmollov »

jaykstone wrote:
Wed Sep 25, 2019 5:14 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,
jaykstone
Posts: 4
Joined: Wed Sep 25, 2019 4:42 am

Re: buttons that don't register well

Post 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.
dirtcooker
Posts: 1
Joined: Sun Feb 23, 2020 4:42 pm

Re: buttons that don't register well

Post by dirtcooker »

jaykstone wrote:
Wed Sep 25, 2019 5:14 pm
Has anyone tried replacing the dome switches?
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 purchased a DM42 in Dec 2019, s/n 4124, and it is a fantastic machine. However, like many on this forum, I have trouble getting used to the keyboard. I have to press quite firmly and deliberately to avoid a missed keystroke. Light key presses, with normal tactile feedback, sometimes do not register. So I replaced the key domes with these: https://www.aliexpress.com/item/32644675443.html 300 gf 7mm snap domes. Although the action is stiffer now, there is never a missed key. The height of these domes is 0.3mm, the original domes I measured at 0.2mm. I am not a dome expert, but I suspect that the longer "throw" results in more reliable action. If I can find a similar height dome of lower force, I will try them. However, I am quite satisfied with the action now as is. It is stiffer than my hp41cv, but so far just as reliable.
Something from Snaptron may work better, if anyone wants to experiment: https://www.snaptron.com/products/stand ... /f-series/
2020-2-23 dm42 dome replacement1.jpg
2020-2-23 dm42 dome replacement1.jpg (155.85 KiB) Viewed 8666 times
2020-2-23 dm42 dome replacement.jpg
2020-2-23 dm42 dome replacement.jpg (152.51 KiB) Viewed 8666 times
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Stefan Karlsson
Posts: 26
Joined: Thu Apr 04, 2019 10:26 pm

Re: buttons that don't register well

Post by Stefan Karlsson »

xmehq wrote:
Fri Sep 28, 2018 3:29 pm
The shift key on my DM 42, sn 03805, has always been tricky to use, it seems to register about half the time. This morning I noticed that there is a slight gap between the upper and lower parts of the case in the corner nearest the shift and exit keys. I opened the case to see if something was misaligned but found nothing amiss. I carefully aligned the slots and tabs and reattached the back and the gap is still there. Is seems like the keyboard bezel may be slightly warped. Any suggestions on what I might try next?
Is the serial number of your DM42 really 03805? Mine has the same number ...
xmehq
Posts: 2
Joined: Mon Sep 04, 2017 11:41 pm

Re: buttons that don't register well

Post by xmehq »

It really is. SN:03805 etched on the case. It makes me believe that the serial numbers are irrelevant.
gopper
Posts: 21
Joined: Tue Mar 05, 2019 11:18 am

Re: buttons that don't register well

Post by gopper »

dirtcooker wrote:
Mon Feb 24, 2020 3:22 pm
jaykstone wrote:
Wed Sep 25, 2019 5:14 pm
Has anyone tried replacing the dome switches?
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 purchased a DM42 in Dec 2019, s/n 4124, and it is a fantastic machine. However, like many on this forum, I have trouble getting used to the keyboard. I have to press quite firmly and deliberately to avoid a missed keystroke. Light key presses, with normal tactile feedback, sometimes do not register. So I replaced the key domes with these: https://www.aliexpress.com/item/32644675443.html 300 gf 7mm snap domes. Although the action is stiffer now, there is never a missed key. The height of these domes is 0.3mm, the original domes I measured at 0.2mm. I am not a dome expert, but I suspect that the longer "throw" results in more reliable action. If I can find a similar height dome of lower force, I will try them. However, I am quite satisfied with the action now as is. It is stiffer than my hp41cv, but so far just as reliable.
Something from Snaptron may work better, if anyone wants to experiment: https://www.snaptron.com/products/stand ... /f-series/
2020-2-23 dm42 dome replacement1.jpg2020-2-23 dm42 dome replacement.jpg
I've just ordered the same key domes in Aliexpress and I'm wondering if you use the old adhesive sheet (of DM42) or a new one. If you used the DM42 sheet, did you have any problems with it? (lost of adhesive properties, dust...).

Thanks for sharing your solution!
Panchdara
Posts: 148
Joined: Sat May 15, 2021 9:02 am

Re: buttons that don't register well

Post by Panchdara »

Helix wrote:
Fri Sep 27, 2019 1:42 am
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.
Actually, I had an issue with the 3 key on my new DM41X. Gordon sorted me. Now works a treat.
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