Old 386 and 486 boards cmos bat

[hikaruichijo]

Hi,I have two old boards, one vlsi 386sx25 board and one 486 board with an umc chipset, they are working fine excep for the cmos battery, I changed the battery on bouth boards but they won't retain the cmos setings once they are powered down.
The original battery on the 386 board leaked and I had to clean the board but I didn't see any broken traces.
And another strange thin on the 386 board is that the keyboard is laggy, it delays a bit when you press a key and the computer reacts.
Well I was young when this computers where working so I'm seeking advice from people that has experience with this old hardware.

[kaboom]

Re: Old 386 and 486 boards cmos bat

Try ringing out those traces with a continuity check.

I've had traces that looked OK after caps leaked on them, but were actually open.

[Compgeke]

Re: Old 386 and 486 boards cmos bat

On the first board, what did you replace with? If it's a 3.6V barrel it has to be replaced with either rechargables or a regular batteries and diode. If it has an external battery header that'll be expecting 4.5V, although a CR2032 often works as well.

[stj]

Re: Old 386 and 486 boards cmos bat

pcb foto's ?

[hikaruichijo]

Re: Old 386 and 486 boards cmos bat

Hi, this is the 386 board, is prety damaged around the batt an the bios chip .
I'm thinking in scraping the varnish al around that place to take a look at the traces, but I'm afraid that they may break...
The battery is an 3.6 rechageable nicd but I'm thinking that it may not charge because it may be an new old stock battery,I buyed it as new but...

[stj]

Re: Old 386 and 486 boards cmos bat

did you use vinegar?

[hikaruichijo]

Re: Old 386 and 486 boards cmos bat

No, why? I used an dielectric oil that also repels humidity nothing more.
Is the vinegar usefull for cleaning motherboards or something like that?

[Compgeke]

Re: Old 386 and 486 boards cmos bat

You need something to neutralize the battery leakage.

In this order, do:
1.) Vinegar around the battery. This will neutralize the battery leakage.
2.) Baking Soda\Water mix in the same area. This will neutralize the vinegar.
3.) Distilled or deionized water in the same area, just give it a small rinse. This will clean up residue left from baking soda.
4.) Let board sit for a day or 2 in a warm, dry area. This will ensure all the liquids are dried.

As for the battery itself, it looks like J6 would be an external battery header, although it could be a mouse header. The problem with replacing 3.6Vs is they WILL leak again, it's just a matter of when. They also take time to charge, try leaving the systems on for a few hours then turn off and check battery voltage with a multimeter, if it's not around the rated voltage the batteries are shot or traces gone.

Dig through https://th99.bl4ckb0x.de/ for your motherboards, the odds of the board not being in TH'99 is insanely rare. There's little drawings of boards so look for ones that have the same physical layout (like CPU\BIOS\ISA\etc in the same spots) then click on one that looks to match and see if jumpers line up, like J6 being where J6 is on your board. I work with a lot of 90s stuff and TH'99 is amazing.

[stj]

Re: Old 386 and 486 boards cmos bat

that's long winded.

my method:
throw vinegar over the whole suspect area - so it gets under the bios socket & power socket in your case.
wait till it stops fizzing.
repeat.
once it doesnt fizz with fresh vinegar, boiling water with dish washing liquid in it thrown over the pcb and rubbed in with a big brush.
then rinse well under the tap and shake water off.

finally dry it in front of a fan heater.

in your case, you need to remove the oil to use vinegar - so you have to start with lots of IPA or the dish washing soap.

btw, *always* remove anything in a socket and any jumpers first.
or you will get dirt or cleaners trapped in them.

[R_J]

Re: Old 386 and 486 boards cmos bat

Here is one for sale, the battery is out and it shows the trace goes to the 4 pin jumper, I believe the pins 2 & 3 get connected for the bios to be retained.
http://www.ebay.com/itm/VLSI-311-386...#ht_2052wt_960
I also checked my junk and I have a similar board, ML-765 V5 I think I still have the math coprocessor ic around somewhere

[hikaruichijo]

Re: Old 386 and 486 boards cmos bat

So, it seens that I have a lot of job to do with this board.... if I only knew this two years ago when I got the computer....
So I have to remove everything I can from the board, I'll also desolder the battery and then soak the board with vinegar, wine vinegar is ok??
And then neutralize the vinegar, next check the tracesone by one around that place with the tester...
I'll try to charge the battery with a 3 volt power supply while everything dryes to see if the battery can hold charge.
I'm missing something?
And thanks a lot for the trick I've never heard of that before.
I've never seen a coprocesor with that socket, my boos has one 387dx from it but its other socket, and I never saw one on ebay or other place

[stj]

Re: Old 386 and 486 boards cmos bat

any mild acid is o.k.
i use white vinegar myself.

[R_J]

Re: Old 386 and 486 boards cmos bat

One of my first motherboards was a IBM Opal 486SLC2, I have the manual for it also.
I just saw one listed on ebytes for $395.00 usd, I wonder if he got that for it?

[Compgeke]

Re: Old 386 and 486 boards cmos bat

I can say for sure $395 isn't what you'd ever get for a 386 or 486 board, not even an entire system is worth that much.

I personally couldn't sell them for $30/ea, less yet $395.

[R_J]

Re: Old 386 and 486 boards cmos bat

I can say for sure $395 isn't what you'd ever get for a 386 or 486 board, not even an entire system is worth that much.

I personally couldn't sell them for $30/ea, less yet $395.

http://www.ebay.com/itm/IBM-OPAL-486...#ht_367wt_1181
I know, I've scrapped better working boards than this.

[hikaruichijo]

Re: Old 386 and 486 boards cmos bat

An 386 is useles nowadays but I think that is importan to start from the begining, old pcs where harder to configure, nowadays if you plug everything where it fits, you have a working computer but on the 80's and untill the late 90's it was really fun to mount a pc.
I'll never pay more than 30$ or so for an old board because you also need a lot of other components to have a computer, hard disk and i/o controlers for example.
For me this is sentimental, and I like working computers not a bunch of parts....

[hikaruichijo]

Re: Old 386 and 486 boards cmos bat

You need something to neutralize the battery leakage.

In this order, do:
1.) Vinegar around the battery. This will neutralize the battery leakage.
2.) Baking Soda\Water mix in the same area. This will neutralize the vinegar.
3.) Distilled or deionized water in the same area, just give it a small rinse. This will clean up residue left from baking soda.
4.) Let board sit for a day or 2 in a warm, dry area. This will ensure all the liquids are dried.

As for the battery itself, it looks like J6 would be an external battery header, although it could be a mouse header. The problem with replacing 3.6Vs is they WILL leak again, it's just a matter of when. They also take time to charge, try leaving the systems on for a few hours then turn off and check battery voltage with a multimeter, if it's not around the rated voltage the batteries are shot or traces gone.

Dig through https://th99.bl4ckb0x.de/ for your motherboards, the odds of the board not being in TH'99 is insanely rare. There's little drawings of boards so look for ones that have the same physical layout (like CPU\BIOS\ISA\etc in the same spots) then click on one that looks to match and see if jumpers line up, like J6 being where J6 is on your board. I work with a lot of 90s stuff and TH'99 is amazing.

Hey, thanks a lot for the info about the TH99 database, I didn't know about it and it is REALLY AMAZING.

[hikaruichijo]

Re: Old 386 and 486 boards cmos bat

Hi, the 386 board is fixed,the vinagear does magic, again thanks a lot for the trick. I desoldered the at power connector and the keyboard connector and I found a gift underneath the power connector as can be seen in the photo
I can't believe this board still works.
Now the specs of the system
VSLI 311 386SX-25 motherboard.
4MB in four stick of simm ram
OAK 256kb ram VGA adapter
An unknown brand hard disk controler whit an umc chip.
An original sound blaster 16 bit with amplified speaker output
Quantum prodrive els 122mb hardisk
16x generic cdrom atached to the sound card
and of couse a floppy disk.
Msdos 6.22 and windows 3.11 for wokgroups instaled.
an everythin is working great now, played Prince of persia for a bit for test

When I have time, I'll continue with the 486 board.
Thanks a lot everyone, for the help.