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keyboard Error - <Solved>

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First post, by 90skidJohnny

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So I'm trying to bring this 486 board back from the dead.. I now have video, and can boot! yay

But im getting an error when I boot. CMOS battery was bad when I got this, so I've replace. Getting some bios Errors, and it also states
"Keyboard error"
And wants me to either f1 to continue or Del for setup.. Keyboard is totally unresponsive.

On boot the keyboard lights flash bright, but then go dim. All lights are on keyboard, just dim tho..
This motherboard also has a keyboard lock. Currently its on a test bench, nor do I have the original lock / keys

I believe I have successfully shorted the right pins, as if it short again, I get 2 errors...
Keyboard Error..
And keyboard locked.,..

After shorting, I just get keyboard error.

Any ideas?

EDIT: Some trouble shooting I've done.
1>. Unseated and reseated the keyboard bios chip
2> tested continuity between the keyboard clk and keyboard data pin. tested fine.

More things I've tried:
Removed Keyboard Bios All together. Did not post.
Used a keyboard Bios from a known good 386 board. - Still gave keyboard error, but would hang, normally I would get the keyboard error, and then it would try to load the floppy drive etc, but with the other bios it would not get any farther except for the Hit DEL for setup
Rechecked Traces. Everything looks good. Multimeter shows continuity. The battery had leaked prior to me getting this board, but cleans up nicely, and I can't find any damaged traces.

Last edited by 90skidJohnny on 2019-04-23, 04:28. Edited 1 time in total.

Reply 1 of 4, by 90skidJohnny

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Welp. Did it again. Tiny tiny tiny little trace that connected into the keyboard bios and goes though a series of capacitors. Minute trace broken.
Soldered directly from the cap to the previous break and No more Keyboard error.

I can post pic for reference if anyone is interested for anything. if not let ill let it die.

Time for bed. nearly 1am and work in the morning!

Reply 2 of 4, by pico1180

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This is an interesting thread for me... I replaced the CMOS battery recently on a 386DX-40. Keyboard was working fine before, Keyboard not working now.

I did have a few mishaps during the process that caused my soldering iron to skip across the local traces.

I thought I damaged a trace as the keyboard connector is right next to the batter. But none of the traces seem to be severed (although I did mar a couple of them).

Can you upload some pics of what you did and where your problem was?

Reply 3 of 4, by 90skidJohnny

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I sure can. Im at work right now but will do as soon as I get home. Grant it, im sure most boards can be layed out different, but the only way I was able to detect it was with the multi meter.
I removed the keyboard bios and there were 2 lines that one the top appeard to go right into a capacitor, and then into the socket for the bios. From the capacitor to the socket, i could get continuity, however, from the start of the trace, nothing. You could just barely see some corrosion on the base of the capacitor, and at the start of the trace, it seemed to intersect with a trace on the bottom of the board.

Ill upload some pictures tonight and it should make more sense 😀
Actually kinda proud of this repair. im usually terrible at motherboard repairs. practice makes perfect I guess.

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