DM15L loses memory contents

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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ultrarunner
Posts: 1
Joined: Sat Jun 22, 2019 3:35 am

DM15L loses memory contents

Post by ultrarunner » Sat Jun 22, 2019 9:47 am

My DM15L (S/N 482) has recently developed a little problem: About once per week it loses all memory contents and settings when powered on. Two interesting facts: When this happens …
  • … it does not show "Pr Error".
  • … it reverts to the default font (which it doesn't do when manually reset by "ON + minus")
The battery voltage is 2,49 V, and no battery warning is displayed. The RTC is not affected. A firmware update from V26 to V29 did not help.
Has someone any idea what could be the reason for that behaviour?

grsbanks
Posts: 856
Joined: Tue Apr 25, 2017 9:23 am
Location: Preston, Lancs, UK
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Re: DM15L loses memory contents

Post by grsbanks » Sat Jun 22, 2019 9:55 am

Interesting.

It could still be the battery if it's a cheaper brand. One way to find out is either to replace it anyway, they're not expensive, or to switch the calculator CPU clock to 12 MHz instead of 48 MHz ([ON]+[9] key combo). It will reduce overall battery drain and maybe prevent the supply dropping below the threshold that might be causing this.

Cheaper batteries tend to have a higher internal resistance than batteries from a good brand, which means that the voltage delivered by them drops more when under load than it would with a better battery.

If it's still the original battery that came with the calculator then it's probably a Panasonic, which is good, but it means the problem is elsewhere...
Not SwissMicros staff, just an enthusiast.

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