DM42 early units vs. current?

[Dave Britten]

I've got a DM42 that I bought from the first release batch in 2017, and I've never been in love with the keyboard. "Willing to live with" is probably a better way to describe it. Has anybody used one of these early units, as well as a fairly recent one (i.e. 2020), and can offer a comparison of the keyboard feel and reliability between the two? I'm considering buying a second one, but only if the keyboard quality has improved to at least match the DM41L and other Voyager clones from SM.

[lrdheat]

Have you seen any improvement in your 2017 example? I have noted that the key presses have become reliable on my unit over time, that all of my key presses register. That said, it is not as satisfying keyboard experience as on other calculators...I still find myself checking, to make sure that all the key presses registered...

[lrdheat]

The original HP-42S, which I was very fortunate to be gifted is a true joy to use, keyboard is just right.

[Dave Britten]

(09-06-2020 05:12 PM)lrdheat Wrote:  Have you seen any improvement in your 2017 example? I have noted that the key presses have become reliable on my unit over time, that all of my key presses register. That said, it is not as satisfying keyboard experience as on other calculators...I still find myself checking, to make sure that all the key presses registered...

I had to open mine up, peel up the keyboard sheet to clean the clean contacts, flex the key "hinges" to loosen them up, and put some shims under the lopsided ENTER key to make mine livable. It's still far from ideal - I'd honestly much prefer a keyboard like the TI-85 or the original TI-36X Solar - but it's fine for short sessions.

[lrdheat]

I was fortunate in not having to open mine up...would not do so in any case as I would likely make things worse...!

[lrdheat]

Further note...my DM 42 has become dependable with keyboard presses while on a desktop, but I still note undetected presses when holding the unit. The 42S has no such worry...

[Logan]

Sorry Dave, both my DM42s are from the first batch in 2017. I didn't have as much trouble with mine as you seemed to though. Just flexing the keys seemed to do the trick for me.

[johanw]

I recently got a DM42 (SN 05370) and have noticed no problems with stiff or non responding keys. So they might have improved the production process here.

[Sylvain Cote]

(09-06-2020 01:56 PM)Dave Britten Wrote:  I've got a DM42 that I bought from the first release batch in 2017, and I've never been in love with the keyboard.
"Willing to live with" is probably a better way to describe it.

This is exactly my thought.

(09-06-2020 05:25 PM)Dave Britten Wrote:  I had to open mine up, peel up the keyboard sheet to clean the clean contacts

I have flex the keys but did not go to the extent to peel up the contact sheet.
It is slightly better but then again we are a world apart from the HP-42S or the HP-41.

(09-06-2020 05:25 PM)Dave Britten Wrote:  and put some shims under the lopsided ENTER key to make mine livable.

I should do that, because the enter key only works when I press on one side.

(09-06-2020 01:56 PM)Dave Britten Wrote:  I'm considering buying a second one, but only if the keyboard quality has improved to at least match the DM41L.

My DM41X beta unit is better but key miss is frequent enough that I do not trust it forcing me to look at the screen all the time.
On the standard HP-41, I type with two hands and I am faster than what the calculator can handle and that includes the 41CL at 50X.
So for me the DM41X keyboard is very, very frustrating, but I understand that I am probably not the targeted audience for it.

Still I will buy the DM41X when available in the hope that the keyboard will be better on the production units.
Like you, I am still on the fence about buying a second DM42 and for the same reasons.

What is still puzzling me is that the keyboard on DM1xL series is very good in general.
I use a HP-16C and a DM16L daily and I have no issue at all with the DM calculator.

Sylvain

edit: I wrote DM41L but DM41X was intended, now corrected

[Dave Britten]

Hey Sylvain, sounds like we've had similar experiences, then. The missed/bouncing keystrokes were the reason I peeled up the keyboard and cleaned the contacts. It wasn't a perfect fix, but it's vastly better in that regard. It's strange that the Voyager lookalikes are so much better. They aren't quite at the level of real HP keyboards, but they're perfectly fine, enough so that I'm considering a DM15L just for the faster speed and increased memory.

Based on johanw's response, though, it sounds like more recent units might be a bit better than the early ones.

[pinkman]

I was reading this thread of the SwissMicros forum: https://forum.swissmicros.com/viewtopic.php?t=2328

It is described that the key click and false clicks are improved in recent DM42 units, and I thought you might be interested, but as you can see you are a participant of this discussion.
Too bad!

[Sukiari]

I have an early DM42 and the keys used to either not register sometimes, and give double bounces at other times. But either through normal use, me “learning” how to press the keys, or software updates to the key handling and debouncing or a combination of these, it seems to work well now. But I have been using it pretty often.

Maybe some day they will make a 48 clone.

[Dave Britten]

(09-12-2020 08:20 AM)Sukiari Wrote:  I have an early DM42 and the keys used to either not register sometimes, and give double bounces at other times. But either through normal use, me “learning” how to press the keys, or software updates to the key handling and debouncing or a combination of these, it seems to work well now. But I have been using it pretty often.

Maybe some day they will make a 48 clone.

They did release an update with rewritten keyboard handling, and it improved the debouncing tremendously.

Personally, I'd like a DM67.

[jklsadf]

David at Swissmicros rewrote the keyboard handling code for the DM 42 in July 2019 (DMCP v3.14 and newer should have the new code), and the rewritten code significantly reduces key bounces causing buttons to register twice.

Note though that early versions of the DM 42 keyboard have hardware problems which sometimes make keys not register at all (when hooked up to a scope there is no visible change), and these hardware problems can't be fixed by the keyboard scanning code.

In summary: in many cases updating the firmware can help with repeated keystrokes from key bounce, but will not improve missed keystrokes on early hardware.

[lrdheat]

Thinking more about my experience, my DM 42 purchase, inspired by my HP-42S, still is problematic concerning key presses registering when hand held. It is much more reliable when on a hard, substantial surface such as a desk. The HP 42S is a joy to use hand held or on a desktop. The HP 42S is my shirt pocket gem.

[trojdor]

(09-11-2020 01:39 AM)johanw Wrote:  I recently got a DM42 (SN 05370) and have noticed no problems with stiff or non responding keys. So they might have improved the production process here.

No, I think you just got lucky.
I have an even later DM42 (SN 05401) than yours, and the keyboard on it is a complete nightmare.
I tried cleaning the contacts, and flexing the buttons, but if anything it seemed to have made things worse.
SwissMicros was kind enough to send me a new plastic sheet of the contact 'domes' to try....but right now, it's just sitting. (Can't trust it for any important calculations.)


(OTOH and FWIW, the DM15L I have, has a perfect response rate .... I don't think it's ever missed a keystroke.)

[pascal_meheut]

(09-21-2020 02:41 AM)trojdor Wrote:  and the keyboard on it is a complete nightmare.

Same here. Mine is older and I tried all the tricks I read here but the Enter key works only if I press it on the left, not the right. Maybe it is a political statement?

But joke aside, I do not understand how the keyboard can be so bad.

[johanw]

(09-21-2020 02:41 AM)trojdor Wrote:  No, I think you just got lucky.
I have an even later DM42 (SN 05401) than yours, and the keyboard on it is a complete nightmare.

Fortunately for me. Although I agree the DM15L keyboard is better, I think it's even better than the keyboard of my original HP12C (2nd hand unit, SN 2741A08800, that is made in 1987 I thought).

The only issue I have with it is that the yellow paint from the "o" in "complex" is partially missing but that does not bother me enough to send it back for that (and maybe get a replacement with a bad keyboard?)

[Sukiari]

(09-12-2020 11:53 AM)Dave Britten Wrote:  

(09-12-2020 08:20 AM)Sukiari Wrote:  I have an early DM42 and the keys used to either not register sometimes, and give double bounces at other times. But either through normal use, me “learning” how to press the keys, or software updates to the key handling and debouncing or a combination of these, it seems to work well now. But I have been using it pretty often.

Maybe some day they will make a 48 clone.

They did release an update with rewritten keyboard handling, and it improved the debouncing tremendously.

Personally, I'd like a DM67.

I was able to eventually find both a 67 and a 97, and I've gotten my printer and card reader rejuvenation kits from the kind people who sell them (probably all members here) on the auction site but since that time I've been struck with a terrible anxiety about trying to fix them. My 97 looks so new that it's doubtful it was even used, I'd like to say the same 'bout the 67 but it still works great.

But there's a DM-15, that's kind of a superset of the 67 no?

[Sukiari]

(09-17-2020 09:07 PM)jklsadf Wrote:  David at Swissmicros rewrote the keyboard handling code for the DM 42 in July 2019 (DMCP v3.14 and newer should have the new code), and the rewritten code significantly reduces key bounces causing buttons to register twice.

Note though that early versions of the DM 42 keyboard have hardware problems which sometimes make keys not register at all (when hooked up to a scope there is no visible change), and these hardware problems can't be fixed by the keyboard scanning code.

In summary: in many cases updating the firmware can help with repeated keystrokes from key bounce, but will not improve missed keystrokes on early hardware.

I don't have any keys which fail to register any more but if I did I'd contact Michael and I'm sure he would help me out. I've bought about a thousand dollars worth of his calculators by now lol.