DM42 dead after a long weekend

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nephilim
Posts: 60
Joined: Sat Sep 12, 2020 10:09 pm

DM42 dead after a long weekend

Post by nephilim »

Today I took my DM42 out of the drawer and noticed that the screen was corrupted (lowest line of the stack empty) and the top row (date, time) was flickering. The unit was not responding to neither keys nor the reset button. I opened it and removed the battery. After inserting it again after a few minutes nothing happened (screen blank). I lightly pushed the foam cover glued onto the battery housing and the unit booted immediately... sort of. It displays the Swissmicros-logo and then shows the About screen, but after pressing "Exit to continue" it just boots again.

It worked fine three days ago. I will take it home and flash it again to see if it can be resurrected. It is running the latest firmware. What could have caused this?

EDIT: after 40 minutes w/o battery I inserted it again and the calculator did boot, asked for date & time, accepted to load a state file and is up and running again.
DM42 (free42, C47), DM15L, HP15C CE, HP35s, HP33s
rprosperi
Posts: 1703
Joined: Mon Apr 24, 2017 7:48 pm
Location: New York

Re: DM42 dead after a long weekend

Post by rprosperi »

These symptoms are consistent with a low battery. Please replace the battery with a new CR2032, and behavior will likely be back to normal.
--bob p

DM42: β00071 & 00282, DM41X: β00071 & 00656, DM10L: 071/100
nephilim
Posts: 60
Joined: Sat Sep 12, 2020 10:09 pm

Re: DM42 dead after a long weekend

Post by nephilim »

Thanks Bob - that fixed it. When I arrived home I saw that my other DM42 had rebooted, too.

When I noticed in the office that the calculator was not working, I felt a little helpless at first. I think that shows quite well how it has grown on me :D
DM42 (free42, C47), DM15L, HP15C CE, HP35s, HP33s
jlgreer1
Posts: 1
Joined: Mon May 22, 2023 2:55 pm

Re: DM42 dead after a long weekend

Post by jlgreer1 »

I have had my DM42 for a couple of years. When I turned it on this afternoon, the entire display was dimming up and down. It didn't respond to any buttons. I tried the reset with no effect. The battery icon has never show less than full battery capacity.

I removed the battery. As usual, I don't have a replacement on hand. I plugged a USB cable into its connector. It rebooted and is working fine.

Now to go buy a battery! ;)

I love my SwissMicro calculators!
rprosperi
Posts: 1703
Joined: Mon Apr 24, 2017 7:48 pm
Location: New York

Re: DM42 dead after a long weekend

Post by rprosperi »

Yep, you fugured it out, it's only a low battery.

The discharge characteristic of most 2032 cells makes it quite difficult to report battery life in any way resembling real warning that it's getting low (and so go buy one to be ready to swap), but as you've figured out, it will operate on USB power just fine until you can install a new one.

Glad you enjoy these machines. :D
--bob p

DM42: β00071 & 00282, DM41X: β00071 & 00656, DM10L: 071/100
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rudi
Posts: 415
Joined: Wed Nov 03, 2021 9:03 am
Location: Denmark
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Re: DM42 dead after a long weekend

Post by rudi »

My DM42 also auto reset the other day, when I had it with me in my coat pocket. It wasn’t freezing, just down to ca 5°C.
Could be the battery, that couldn’t cope with the low temperatures, but it is only a couple of months old.
Can’t find any specs for the devices operating temperature range on SM website or in the DM42 User Manual.
/Rudi

DM-42 (s/n 06999), HP-42S, HP-35s, HP-11c, HP-32SII (ex HP-41CV, ex HP-75C, ex HP-48G + a lot, really lot of a accessories)
Denmark
Panchdara
Posts: 148
Joined: Sat May 15, 2021 9:02 am

Re: DM42 dead after a long weekend

Post by Panchdara »

Just for interest....https://data.energizer.com/pdfs/cr2032.pdf and https://data.energizer.com/pdfs/cr2016.pdf

I reckon enough data here to visualize the battery. Currently I've a CR2016 in DM42.... been a month or so, still working. I expect it to die way sooner than a CR2032 though.
vaklaff
Posts: 29
Joined: Thu Nov 12, 2020 9:23 am
Location: Czechia

Re: DM42 dead after a long weekend

Post by vaklaff »

Panchdara wrote:
Thu Mar 07, 2024 1:07 pm
Just for interest....https://data.energizer.com/pdfs/cr2032.pdf and https://data.energizer.com/pdfs/cr2016.pdf

I reckon enough data here to visualize the battery. Currently I've a CR2016 in DM42.... been a month or so, still working. I expect it to die way sooner than a CR2032 though.
IIRC, you experimented with a CR2025 as well, right? Any interesting experience? Not that I plan to use a 25 or 16, just curious how stable the calculator is with them, e.g. random resets, wrong output etc.
Panchdara
Posts: 148
Joined: Sat May 15, 2021 9:02 am

Re: DM42 dead after a long weekend

Post by Panchdara »

Hiya. Yes. You do remember correctly. Both my 42 and 41 are still chugging away on the CR2016 (edit CR2025)... not used as much as many people do, but the CR2016s (edit CR2025) are still alive.... I'll revisit my post. Anyway, CR2025 do work, but will not last as long. Not sure if there would be a stability issue? I don't have any intensive programs to give the calcs a workout.... ;)

Edit: just opened the calcs.... sorry, using CR2025s.... still alive
https://data.energizer.com/pdfs/cr2025.pdf
BigEd
Posts: 70
Joined: Wed May 03, 2017 9:00 am

Re: DM42 dead after a long weekend

Post by BigEd »

Here's a hideous idea: pack two CR2016s together, perhaps back to back, with wiring to put them in parallel in the space of a 2032 and exposing positive and negative at opposite ends. This will be almost impossible. But the effect will be a lower internal resistance and more current available... would it be better in any sense?
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