DM15 ground reset issue

Discussion of hardware issues related to the DM1x/DM41. Please ensure that you specifiy whether the issue is related to a credit card size unit or a "Voyager" unit (DM1xL/DM41L).
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keithdalby
Posts: 495
Joined: Mon Apr 24, 2017 6:38 pm

DM15 ground reset issue

Post by keithdalby » Thu Jan 11, 2018 10:21 pm

When I drop my DM15, which I do from time to time from a low height, the battery dislodges slightly and causes the reset issue when pressure is put near it from the front. Michael has in the past said it is because the battery or housing comes into contact with the metal case, which is grounded.

Would it be a good idea for me to put some electrical tape on the inside of the metal case where the battery housing sits so that if the battery does become slightly dislodged there is no way it can come into electrical contact with the case? Has anyone tried it? What are the tolerances: is there enough space for the thin layer of electrical tape?

Michael
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Re: DM15 ground reset issue

Post by Michael » Thu Jan 11, 2018 11:04 pm

The battery holder should have a E.V.A. foam pad 1mm thick.
It's no problem if there is some stress on the battery holder.

keithdalby
Posts: 495
Joined: Mon Apr 24, 2017 6:38 pm

Re: DM15 ground reset issue

Post by keithdalby » Fri Jan 12, 2018 5:02 am

It does have a foam pad but I worry it isn't big enough

keithdalby
Posts: 495
Joined: Mon Apr 24, 2017 6:38 pm

Re: DM15 ground reset issue

Post by keithdalby » Fri Jan 12, 2018 4:16 pm

The foam pad covers a lot of the battery housing, but the battery can slip a little bit if the calculator is knocked too hard (dropping from a small height onto a tabletop will dislodge the battery slightly). I believe the battery dislodges by just enough to come into contact with the metal case. The symptoms of the problem I was encountering matched what Michael described. When certain buttons were pressed, the calculator would reset. If they were pressed very very lightly, it wouldn't, but it was too light a press to be practical.

I have put a layer if insulating tape on the inside of the case. I actually just used sellotape because my electrical tape is at the bottom of my toolbox and I'm too lazy to find it. So far, the calculator has not reset itself. I will monitor it closely, but I suspect it will not reset itself again now. I don't want to test my theory by deliberately dropping my calculator, so I will just wait for entropy to play out - disorder will win in the end.

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