ilmazzo wrote on 2023-06-11, 22:44:

Hi guys, […]
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Hi guys,

this U-GREEN socket 3 mobo (UMC 491F chipset) does not want to see my keyboard at boot...

I checked the 5V on the keyboard connector and I get 4,97V so seems ok there....any damaged traces maybe?

Love to see some thoughts about this....it's for a new full tower 486 build I have in progress...

Cheers

Lot of questions here....did it/does it have a leaking battery? Are there damaged traces in that area? I assume you've tried more than one keyboard.

ilmazzo wrote on 2023-06-11, 22:44:

Hi guys, […]
Show full quote

Hi guys,

this U-GREEN socket 3 mobo (UMC 491F chipset) does not want to see my keyboard at boot...

I checked the 5V on the keyboard connector and I get 4,97V so seems ok there....any damaged traces maybe?

Love to see some thoughts about this....it's for a new full tower 486 build I have in progress...

Cheers

Pictures please!

eesz34 wrote on 2023-06-12, 16:37:

ilmazzo wrote on 2023-06-11, 22:44:

Hi guys, […]
Show full quote

Hi guys,

this U-GREEN socket 3 mobo (UMC 491F chipset) does not want to see my keyboard at boot...

I checked the 5V on the keyboard connector and I get 4,97V so seems ok there....any damaged traces maybe?

Love to see some thoughts about this....it's for a new full tower 486 build I have in progress...

Cheers

Lot of questions here....did it/does it have a leaking battery? Are there damaged traces in that area? I assume you've tried more than one keyboard.

Yeah it had a leaking battery that I removed and I'm using a external battery pack instead

There were some acid marks near the DIN connector, after cleaning I could not see a damaged trace but I'm not an expert 😀 I would like to workaround the traces doing a wire bridge from the DIN to the KB controller and see what happens....but I don't have the pinout of the KB controller and the pinouts on the bottom of the PCB where the DIN is soldered either.... I recall a youtube video where someone had the same issue I have and he was forced to rework the voltages on the pinout fo the KB controller due to same damage on the board, but I don't find it anymore to get some inspiration. I thought that it was from Necroware yt channel (very interesting channel on retro repair projects) but maybe I'm wrong....

The keyboard I'm using is perfectly ok for the other 10 pcs I used in between with it 😀

Nexxen wrote on 2023-06-12, 16:41:

Pictures please!

Yeah, I can't find any on my phone right now so I'll make some photos of the RTC battery area and the KB controller this evening....

Seems the gods won't let me have a 486 build: 2 socket 3 mobos I have around they both have various issues that are preventing me from having a stable or working build...they are VLB so are quite rare and expensive and I really want to fix them and improving my skills in the process.....fingers crossed 😀

Ops don't know what happened but I was sure to have posted yesterday with the picture but... I can't see it!

So, here it is the photo of the area near the keyboard connector and I have to say that I was wrong...to me that trace is completely corroded by acid and I think the issue is there....funny enough I have found a webpage with this exact mobo of a italian fellow with the same keyboard issue

https://pcrebuilding.altervista.org/44/344/MO … 486-VL+486.html

in the third photo you can see almost the same acid damage that I see on mine... and it complains that the keyboard is not detected! what a surprise!

I tried to understand where that broken trace go to in case to bridge it in some way but I can't get figure it out....

The DIN 5 pinout is this

I have the 5v reading as already said, so the issue must be on the clock or data trace (pin 1 and 2, pin 3 NC means?!?)