Super Mario wrote on 2021-04-22, 13:28:

Hi […]
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Hi

I'm trying to get my old PC working but ran into few problems. The lights on the keyboard flashed when I start the PC but the keyboard didn't work and I also got these error messages:

CMOS system options not set
CMOS battery state low
keyboard error

The original blue battery had some stuff coming out of it so I replaced it with a new one. Now I get these error messages:

CMOS system options not set
CMOS display type mismatch
Keyboard error

Run setup utility
Press F1 to resume

Since my keyboard doesn't work I'm unable to continue. Any tips?

it looks from the pic like some of the stuff coming out of the battery may have gone onto the motherboard, maybe corroded or messed with the traces

of course it may be nothing of the sort, but you may want to take a closer look or take a top down zoomed pic of the area

there could well be some cleaning up and repair needed

Well, you'll need to clean that up and fix any traces that are broken.

here's a starter vid https://www.youtube.com/watch?v=CrD6hALcbkc

gerry wrote on 2021-04-22, 13:33:

it looks from the pic like some of the stuff coming out of the battery may have gone onto the motherboard, maybe corroded or messed with the traces

of course it may be nothing of the sort, but you may want to take a closer look or take a top down zoomed pic of the area

there could well be some cleaning up and repair needed

I took this picture earlier. Have to check the motherboard more carefully when I get back home.

That blue 'stuff' is leaked alkali from the battery and its very corrosive. In your photos it is obvious that it has corroded several traces going from the power connector to the ISA bus as well as connectors from the battery to the CMOS and AT port to the keyboard controller.

You need to remove the battery, neutralize and clean the board thoroughly, expose the affected traces and possibly remove affected ICs to chec traces beneath them, check for continuity over all of them, and fix broken traces.

Welcome to the horrible nightmare that is NiCd barrel batteries..

Remove the battery completely. The new one will also start leaking at some undefined point the the future. They are just not a good idea.
Check if the mainboard has an "external battery" connector and use that, alternatively install a coin battery holder and a diode to prevent the board from charging the new coin battery.

here's a video of a repair of a mainboard with the same symptoms as yours.

https://www.youtube.com/watch?v=3Yjy8isi5A0

the person who made this videos is also on the forum, maybe same name, can't recall.
enjoy & good luck

if you do manage to sort it out post a pic, always nice to see a success 😀

if not don't give up, plenty of know how around here

@weedeewee his name here is Scorp 😀

Deksor wrote on 2021-04-22, 17:24:

@weedeewee his name here is Scorp 😀

thanks 😀

Looking carefully, there is also "blue" corrosion on the ISA slot connector itself.

You need to remove that battery NOW, otherwise the board may not be able to be saved. Even as it is, it may be quite a bit of work to clean and replace all the affected components.

megatron-uk wrote on 2021-04-22, 17:32:

Looking carefully, there is also "blue" corrosion on the ISA slot connector itself.

You need to remove that battery NOW, otherwise the board may not be able to be saved. Even as it is, it may be quite a bit of work to clean and replace all the affected components.

Super Mario wrote on 2021-04-22, 13:28:

The original blue battery had some stuff coming out of it so I replaced it with a new one. Now I get these error messages:

Thanks for the help guys 😀

I measured the components and it seems like L4 is the problem since all other components get connection from the keyboard port. The L4 trace is hair thick so it will be pretty tricky to repair. I was thinking about connecting it airborne using coated wire.

Before you worry about fixing that trace I'd use some vinegar and give that board a good cleaning and then a rinse with some IPA and then some distilled water. As long as the alkali material from the battery is still on the board it'll continue to corrode and eat away at the motherboard.

Speaking of repairing traces, I have a bunch of 286, 386 and 486 boards I have to do this work with.
What do you guys (or anyone) use for sealing repaired traces after you've done the trace repair?

I've used clear nail polish in a pinch. But you can buy a bottle of solder mask or a bottle of conformal coatings

ThisOldTech wrote on 2021-04-22, 19:45:

Speaking of repairing traces, I have a bunch of 286, 386 and 486 boards I have to do this work with.
What do you guys (or anyone) use for sealing repaired traces after you've done the trace repair?

Transparent nail polish.

If I don't get the motherboard working, can I connect the hard disk to any 486 and access the files, run programs etc on DOS and windows or should I use the exact same motherboard / components?

Main reason why I try to get the PC working is to copy stuff I made in the 90's to my new PC, but I would also like to check windows and run the programs I used back then.

Super Mario wrote on 2021-04-22, 21:01:

If I don't get the motherboard working, can I connect the hard disk to any 486 and access the files, run programs etc on DOS and windows or should I use the exact same motherboard / components?

Main reason why I try to get the PC working is to copy stuff I made in the 90's to my new PC, but I would also like to check windows and run the programs I used back then.

For dos, any 486 will do, for windows you'll get the usual problems with drivers for soundcard, graphics card ... unless you take those along with you from the old pc, if possible.

is it really necessary to seal the traces? Isn't tinning them not enough?