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A few suggestions to improve the hardware DM41.

Posted: Sun Oct 31, 2021 6:24 pm
by agusDM41
Just a few suggestions to improve the hardware of the swissmicros DM41.

The plastic between the LCD and the transparent keypad window is not necessary, it also creates problems by sticking to the LCD and giving a water print underneath due to sticking. I have removed it.

If you press too hard on the keyboard area on the battery, a short circuit can occur sometimes and the memory is erased and I think it is due to a not very good soldering of the battery box with the PCB when PCB is hard pressed.
In any case, the anti-short circuit sticker seems unnecessary since titanium is a very poor conductor and I tried to create a short between the + pole and the titanium housing without plastic sticker over battery and it was impossible produce a MEMORY CLEARED but touching with copper cable pole + and the house of screws produce a MEMORY CLEARED.

I think that the battery box and the pressure and deformation of the PCB in that area should be studied to prevent resets.
Test it without titanium housing and deform gently a little the PCB and in certain cases ... reset.

I have solved these problems with a good cleaning of the battery box and putting a conductive metal type washer between the + pole of the battery and the battery case so that there is no gap and the battery is firmly seated no matter how much pressure is applied on it from the keyboard.

Improve the soldering of the + pole with the PCB and the internal contact of the battery on the negative pole since it looks dirty even after cleaning it and does not see gold or silver.

Less glue near the domes of the keys since pressing hard sometimes they stay stuck and you have to detach the keyboard and stick it again to release them.Now is working fine to me after two times remove keyboard and put again.

Just 1mm or 1,5mm of glue grid around the keys I think would improve tactile feedback and prevent keyboard issues and noise when the key is lifted and "dragged" on the keyboard giving an unpleasant adhesive noise.

The screws 0,5mm or 1mm less long to prevent push keyboard up.
Write on the back of DM41 RESET hole to not confuse the two holes RESET ... PGM.

After all a great product and idea that can be better with some improvements in hardware.

Re: A few suggestions to improve the hardware DM41.

Posted: Sun Oct 31, 2021 10:58 pm
by agusDM41
A correction to the previous comment.
A short circuit does occur when touching the titanium case with the battery case.
I forgot to attach the titanium case to the battery negative to check this :roll:
I just realized right now. Sorry for the mistake.
The insulating sticker is necessary although I have put a very thin insulating adhesive strip all over the inside of the titanium case.
The rest of the comment is correct in my appreciations.

Re: A few suggestions to improve the hardware DM41.

Posted: Mon Nov 01, 2021 2:45 pm
by agusDM41
As an additional note to say that I like this "old" type of electric welding much more for the battery house ... see attached photo. I don't know if one type of welding is better than the other.
As for the sticky sound of the keyboard, only sometimes in some key happens but is an ugly noise.

I value much more the robustness of the calculator than those small details but the tactile sensation of the keyboard could perhaps be improved with another type of adhesive that in case of loosening a little does not make a sticky noise.
Maybe a very thin layer of adhesive silicone around the keys could give it some fluffiness without sticky noise?
I don't know, for sure SwissMicros has tried the most things. I just contribute a few ideas.
It works well for me by ignoring those little details and I love the size and light weight.

A great idea to have put all this in such a small space.

Re: A few suggestions to improve the hardware DM41.

Posted: Thu Dec 30, 2021 8:13 pm
by johanw
I noticed something like this myself - my DM41 suddenly stopped working so I assumed a flat battery. I opened it - which required some force because one of the screws didn't cooperate - and saw suddenly some memory resets occuring. When I just reassembled it it has kept working normally since then, on the same battery so something must have short circuited or broken a circuit before. I've never had this with my DM15 which has the construction as shown in the last pucture.