1. remove barrel battery and use alcohol vinegar to remove the "green" stuff
2. do you have a video card installed?
3. you have to use FPM memory. Newer EDO isn't supported by 99% of 486 motherboards.

Yes, the memory you have is definitely EDO RAM.
Also, when you do get FPM RAM, be sure to check the configurations that your motherboard support (for example, some motherboards only support double sided RAM in certain slots).

Keppu wrote:

Hello, […]
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Hello,

I'm quite new in dealing with this old hardware. I recently got my hands on an old 486 which I stripped to bare minimum to get it working again.

UMC UM8498 mobo

Am 486 DX2-80

I found some random memory from same location and tried them on. Good thing is that the PSU and mobo seems to be in good condition and bios battery still alive as I hear 2 beeps 8 beeps and 2 beeps when starting the computer with the memory. According to the http://www.techspot.com/community/topics/the- … eep-guide.95391

8 beeps seem to indicate "short Display memory read/write error- The system video adapter is missing or defective"
2 beeps seem to be "Memory parity error- A memory parity error has occurred in the first 64K of RAM. The RAM IC is probably bad"

Bad thing is that apparently I need to be getting some new memory. Here is the current memory type. I have 2 pieces of these and I've tried them in different sockets.

Any help is appreciated about what memory and how much of it I should be getting. I can also post more pictures for anyone interested. 😀

I have some RAM if you need it. PM me

kixs wrote:

1. remove barrel battery and use alcohol vinegar to remove the "green" stuff
2. do you have a video card installed?
3. you have to use FPM memory. Newer EDO isn't supported by 99% of 486 motherboards.

So is there a safe way to detach the battery? I don't have much tools in my disposal and I feel that the battery will rip something with it if I just pull it off.

I suppose that green stuff is corrosion of some sort and needs to be removed?

Also it's safe to use alcohol mixed with vinegar?

Video card currently detached.

There are some threads about how to remove a barrel battery (you can either desolder or cut off the connectors).
Here's a link to a webpage that provides a number of options available in replacing CMOS batteries: http://pc-restorer.com/replacing-cmos-b ... in-old-pcs

There's no need for any tool, just use your hand. Move it gently from side to side faster and faster as you go, eventually it will come off. Use vinegar and then alcohol.

Battery came off nicely as I detached the legs. There had been some corrosion in various places and as well as one broken(split) component in C2. Hope that's not crucial

Your motherboard looks alot like the one I wrote about here: 486 VLB UMC-Chipset, what is it?
Type number "TK 8498F /GP 4N D24".

gerwin wrote:

Your motherboard looks alot like the one I wrote about here: 486 VLB UMC-Chipset, what is it?
Type number "TK 8498F /GP 4N D24".

Yeah it looks quite identical, except the memory slots. Interesting read! 😀

The broken capacitor is EMI related (keyboard logic line) and probably not important. But this level of corrosion may already have killed the board.

You may want to use a toothbrush with your vinegar scrub and get around those components in the battery area. Notice the green around your keyboard connector in addition to surrounding components. The traces aren't looking so hot either. Mmm. H-a-l-9000's concern is legit. You may have a bit of an electronics repair project on your hands

This calls for a bath in thinned vinegar essence (until the green is gone) and a wash under clear water with a toothbrush and soap afterwards. Remove any socketed components and jumpers before doing that and put them in the bath for their own if corroded. After that, swing it around to remove large spots of water and ideally heat it to 100°C to dry.

The mobo and jumpers are now enjoying their vinegar path. Thanks for the help.

After cleaning I can't really test the mobo before getting the memory, is that right?

Without memory it may emit a beep code which would be a good sign of life.

h-a-l-9000 wrote:

Without memory it may emit a beep code which would be a good sign of life.

I had 2+8+2 beeps before(my first post). I need to test it again yes, but to fully test it and get some picture for my vga monitor, all that I would need memory?

At least you scored a nice vlb graphics card though but some of these board that have gotten that bad often end up not working due to traces getting eaten but still fixable. Get some fpm ram and be sure that you get several sticks as some boards get picky and ram does go bad time to time from age. Take pictures of everything on the board then remove all the jumpers and the bios rom from the socket as you need to clean up the acid in those areas near the cmos cancer (battery) as you don't want any more rot. Once you are done put everything back as it was before but with fresh jumpers as a few of the ones there got some acid exposure.

The mobo is now out of the vinegar bath. It seemed that the corrosion was neutralized by the vinegar quite well over night.

After some soap and scrubbing, mobo is now enjoying 100°C sauna.

After drying process I have to put everything together again and test if I get some beeps out. I ended up ordering some cheap FPM ram for testing.
http://www.ebay.com/itm/331863174752

And also a new battery as was suggested in the guide that jesolo linked.
http://www.ebay.com/itm/381091351366

This sure ended up being quite an adventure, but I guess it was expectable as the computer was lying around in an old barn for 20 years. 😀

486 boards are well worth this effort! I hope it all works out because 486 is very special and cool 😀

PhilsComputerLab wrote:

486 boards are well worth this effort! I hope it all works out because 486 is very special and cool 😀

They sure are. 😀

Very useful site you have btw.