Just to get obvious stuff out of the way - Have you tried clearing it?

naujoks wrote on 2023-08-24, 16:04:

I have an MS6183 Pentium III board that gives me a CMOS checksum error. I replaced the CMOS battery, cleaned the contacts, reflo […]
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I have an MS6183 Pentium III board that gives me a CMOS checksum error.
I replaced the CMOS battery, cleaned the contacts, reflowed solder joints, checked the BIOS chip, flashed a later revision BIOS - all to no avail, the error remains.
Two more curious symptoms that might give a hint what the error is:
The beeper doesn't beep.
They PS/2 keyboard doesn't work. The lights on it blink very dimly. I connected a USB keyboard, which works, but only in the BIOS. There's actually a setting in it which reads "Enable USB keyboard", which is defaulted at "no", so when I save the settings, the settings do NOT get saved and once the board boots, consequently the keyboard does not work.
It boots into a MS DOS 6.22 floppy fine and finds the HDD, but as the keyboard doesn't work, that's as far I get.

What could be wrong?

do all the settings in BIOS not get saved ? even date and time and other info or is it just the keyboard ?

If you cant save any bios data then it is definitely something on the battery circuit ... or the CMOS chip
check if the battery wasn't drained by some short circuit and follow the battery traces to the chip to see if the CMOS chip gets power...

Ohh and is the keyboard controller one of those big ones ? 40 pin ? is it the original one that came with the board ?

Good luck !

No settings are getting saved, not the date or time either
The keyboard controller is not the fat one, but I also don't know which IC takes over the keyboard functions. They board is amazingly miniaturised for 1998.
The battery does not get drained by a short.
How do I find out which chip is the CMOS chip? Am I supposed to get 3V at the VCC at all times?

-

Hey mate cmos located in south bridge and if it fails you have to replace south bridge unfortunately. As for ps/2 keyboard it's winbond super io chip responsable for it.

For the ps/2 problem, inspect the area around ps/2 connector for missing/broken/burnt components/traces and probe all inductors and fuse you see there with multimeter for continuity.

P.s. you say the keyboard LEDs are very dim... I suspect the inductor or fuse on the +5V line to the ps/2 keyboard connector is lose or malfunctioning.

Edit:

What's the deal with the capacitor on the right side of the mb atx connector, underneath the psu atx connector ?

weedeewee wrote on 2023-08-25, 10:24:

What's the deal with the capacitor on the right side of the mb atx connector, underneath the psu atx connector ?

Pwned by the ATX plug )

This dude had the same problem. Turned out he had the CMOS jumper left in the "clear" position, moving it back fixed it.

However, in your photo, in the place where the manual says yours should be I can't make out a pin header at all, so I can't tell whether that might be it.

And in case anyone else is wondering, the empty socket at the bottom left is a red herring, that's a place to put some security extension module, but it seems to be entirely optional. Weird how some boards have a socket there while some seem to have something else soldered right in, but whatever.

Made some progress on the keyboard. One of the jumpers that's repsonsible for wake on keyboard was corroded and not conducting. Cleaning the contacts and using a new jumper brought the keyboard back to life.
I've checked all other jumpers for corrosion, but they were fine.
The jumpers concerning the CMOS seem to be slightly different on this board compared to the manual. I think I located the proper ones, but I'll triple check.

elszgensa wrote on 2023-08-25, 10:42:

However, in your photo, in the place where the manual says yours should be I can't make out a pin header at all, so I can't tell whether that might be it.

Waddayamean no header? J26 and JBAT1 are right there, close to the CR2032 battery holder.

I can't tell from the photo if JBAT1 has the jumpers on the right pins. J26 has the jumper set correctly.

https://theretroweb.com/motherboards/s/msi-ms … 3-wh9#downloads
use rev 1.1 of the manual

Oh and yes, I had to move the caps near the power socket out of the way because the plug wouldn't fit otherwise. I'll make it pretty sometime later.

The JBAT1 jumper isn't in between the PCI slots as in the manual but sits towards the edge of the board. There's actually an arrow pointing towards it (which you can't see on the picture).