DM42 Battery level always= 1.21v ? Works fine?

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DM42 Battery level always= 1.21v ? Works fine?

Post by FChemRD » Mon Aug 10, 2020 11:37 pm

Good day
I recently purchased the wonderful DM42 calculator and it seems to live up to its billing with one minor exception....the battery indication always reads 1.21v even with a new 3v Duracell (and now a new 3v Energizer Lithium) battery. Obviously this can't be correct. Can anyone here shed some light on this problem? It would be nice to have some battery level indication. Thank you!

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Re: DM42 Battery level always= 1.21v ? Works fine?

Post by grsbanks » Tue Aug 11, 2020 8:49 am

That's a new one for me, I've never seen that fault before.

I'll pass the report on to the right people.
There are only 10 kinds of people in the world: those who understand binary and those who do not.

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Re: DM42 Battery level always= 1.21v ? Works fine?

Post by ijabbott » Sun Aug 16, 2020 9:33 am

It sounds like the same problem as in this thread: BAT indicator stuck on. (That was for a DM41X beta unit, but the electronic components are the same as DM42.)

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Re: DM42 Battery level always= 1.21v ? Works fine?

Post by Gabriele_B » Sat Oct 17, 2020 10:14 am

Hello, I just purchased a new DM42 and received it a couple of days ago.

I had exactly the same problem with the battery indicator (squeezed battery icon and Vdd=1.21V, although the battery is actually good and measures over 3V).
After trying to fix the issue by resetting the device, removing the battery, updating the firmware, etc. without success, I inspected the PCBA components and found that FB1 wasn't properly soldered.

Since I am an electronic technician and have the right tools (soldering iron, etc.) I managed to fix the issue by myself by soldering the lower terminal of FB1 (see picture below).

I hope this can help anybody running into the same problem.
FB1 position on the PCBA
FB1.jpg (136.68 KiB) Viewed 118 times

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Re: DM42 Battery level always= 1.21v ? Works fine?

Post by Walter » Sat Oct 17, 2020 12:42 pm

Great, Gabriele, and thanks for sharing!

This may shed new light on some old cases, too.

BTW, this looks like the third edition of pcb for the DM42.
DM42 SN: 00041 Beta
WP 43S running on this device

HP-35, HP-45, ..., HP-50, WP 34S, WP 31S, DM16L

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