It's the keyboard that sends the clock. So when you press a key on keyboard, it will send out data with clock, otherwise if you don't press any keys you won't see anything.

As far as I know, the 8042 is a generic microcontroller, there is no generic pin the clock will go, so any implementation can connect anywhere it wants to.

So you just need to find out where a trace has been disconnected.

Huh. A 286 motherboard with an aux keyboard pinout? That's amazing. Use a multimeter to check for connectivity between the original keyboard port and the pinout on the board itself for the clock.

🤣 I was just thinking that the clock controller might be on the bloody keyboard!

I'm gonna go home in a few hours and take apart a keyboard and check all the connections there - I'm sure it's getting +5 and GND because the LEDS light up. I'll try to feed the keyboard some power (5V source) and see if the LEDS do the same thing (maybe it's a small keyboard POST?)

Any ideas how I would check to see if there's a clock pulse to the MB? I don't have a scope...

OK so here's what it looks like:

Not the prettiest soldering, but it's just temporary (Here I bridged the data line directly to the keyboard controller pin 39)

By the way, all the traces show continuity despite their apparent shape.

I also booted the board without the keyboard BIOS - Didn't POST but keyboard lit up LED - I believe it's a keyboard POST of some sort that just needs power. I put in the other controller from the 386SX board - POSTed but still gave keyboard error.

How many layers do these boards have? I held yet a third board up to a strong light (a 386SX) that is from a similar time to the 286, similar format - It looks like it has two layers, but sometimes I think I can see a middle layer in there. Am I imagining that?

This is a neat 386 DX board I have that works - Notice how you can see all the traces compared to the 286

Should I just go ahead and retrace all the damaged trace lines on the board? What else does anyone suggest?