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PCChips M747 motherboard not detecting CMOS battery

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First post, by MrMateczko

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Hello!

I have a PCChips M747/Amptron PII-3747 PCB V1.5 motherboard.
It works fine, except it doesn't want to detect a brand new CMOS CR2032 battery I am inserting in it acting like it's not there, showing the CMOS Battery Low error.
I've tried cleaning the battery contacts with Isopropyl alcohol, updating the BIOS, and using many new and working batteries to no avail.
Can a broken diode that's next to the battery compartment cause this? I've tried measuring it with a cheap multimeter I have and I'm suspecting it might be faulty because measuring the reverse bias in the diode doesn't show off limits resistance, but I'm not trusting the results, and I do not have a soldering iron to try measuring it outside the motherboard, and I do not want to force rip it apart 😀

Reply 1 of 4, by Repo Man11

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I'd start by making sure the battery holder's contacts are good by measuring the voltage on the back of the motherboard. Take a look at this thread: Motherboard BIOS wont save

"I'd rather be rich than stupid" - Jack Handey

Reply 2 of 4, by MrMateczko

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I've tested the battery holder and it outputs stable 3V all the time so it's not the issue. There are no signs of corrosion or any issues with it.
I've re-tested the diode next to it and it measures high resistance in both directions, so I assume replacing it would fix the issue?

Reply 4 of 4, by MrMateczko

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So now I am using this motherboard with CWT200 AT PSU and...everything seems to be working fine, I was using an ATX PSU before.

Could a PSU really cause such an issue? Maybe motherboard fixed itself, some solder joints, capacitor or something?

The previously mentioned diode seem to be actually fine once it was actually properly tested 😁

EDIT: I've switched back to the ATX PSU I was using before, and it is still working fine...computers are weird 😁
I have updated to the latest BIOS as well, even if it fixed itself on the older BIOS, just in case. 😀

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