I have seen many 286 boards fail to POST without battery power. Try to add a new battery and see if that helps.

appiah4 wrote on 2024-05-07, 10:32:

I have seen many 286 boards fail to POST without battery power. Try to add a new battery and see if that helps.

thank you for your answer. I have soldered there a new a battery but the board behaves the same 🙁
Any other idea?

thank you, tomas

In that case, assuming the board has an AMI Bios, 0E is sending the BAT (Basic Assurance Test) command to the KBC, and 0F is initializing the KBC after BAT. That means there is probably still a broken trace that stops the KBC from initializing. Check that the KBC is actually connected to the Keyboard socket, power and cmos properly - you probably still have a broken trace somewhere..

tsalat wrote on 2024-05-07, 10:22:

Any suggestion what to try? I have no idea if the jumper settings are fine.

Check all the VIAs in the spill area. I've seen these big 286 mobos develop via cracks and the battery corrosion sure doesn't help. This looks to be another 286 mobo where they put in a 10MHz CPU and factory overclocked it to 12MHz. Could be an issue but it's unlikely the mobo would stop on the exact same code every time. So unless you have a CPU for swap don't rush to buy another one.

Seems to be some OEM mobo but based on Suntac chipset. Chances are the DIP switches are configured in similar fashion. These include clock speed, I/O wait states (that could be a separate jumper), BIOS size, EMS page port, and 3 switches select RAM size and EMS or XMS configuration. Since your mobo seems to have some socketed RAM there might also be jumpers that select between these chips and the SIPPs.

The keyboard controller is not as close to the battery as it is on other mobos and any issues with the keyboard itself (or the clock/data lines) would be detected and reported well after BIOS initialized the video card. If there are still broken connections on the mobo the code might be unrelated so don't limit yourself to the KBC. Use RESET switch to reset the mobo, see if changes anything (and if the POST card LED reflects the button state).

appiah4 wrote on 2024-05-07, 11:39:

In that case, assuming the board has an AMI Bios, 0E is sending the BAT (Basic Assurance Test) command to the KBC, and 0F is initializing the KBC after BAT. That means there is probably still a broken trace that stops the KBC from initializing. Check that the KBC is actually connected to the Keyboard socket, power and cmos properly - you probably still have a broken trace somewhere..

you were right, I have found 3x traces broken next to the battery and the board started to post and beep, ending at Post code 2625 and two short beeps. Without the VGA it started to issue the VGA missing beep code.
I did not connected it to a monitor and thus I am not sure if there is picture or whats going on but it definitely moved forward.

I will test it later on but at this moment I am very thankful for the idea!

br, Tomas

Deunan wrote on 2024-05-07, 17:11:

Check all the VIAs in the spill area. I've seen these big 286 mobos develop via cracks and the battery corrosion sure doesn't he […]
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tsalat wrote on 2024-05-07, 10:22:

Any suggestion what to try? I have no idea if the jumper settings are fine.

Check all the VIAs in the spill area. I've seen these big 286 mobos develop via cracks and the battery corrosion sure doesn't help. This looks to be another 286 mobo where they put in a 10MHz CPU and factory overclocked it to 12MHz. Could be an issue but it's unlikely the mobo would stop on the exact same code every time. So unless you have a CPU for swap don't rush to buy another one.

Seems to be some OEM mobo but based on Suntac chipset. Chances are the DIP switches are configured in similar fashion. These include clock speed, I/O wait states (that could be a separate jumper), BIOS size, EMS page port, and 3 switches select RAM size and EMS or XMS configuration. Since your mobo seems to have some socketed RAM there might also be jumpers that select between these chips and the SIPPs.

The keyboard controller is not as close to the battery as it is on other mobos and any issues with the keyboard itself (or the clock/data lines) would be detected and reported well after BIOS initialized the video card. If there are still broken connections on the mobo the code might be unrelated so don't limit yourself to the KBC. Use RESET switch to reset the mobo, see if changes anything (and if the POST card LED reflects the button state).

I was not expecting the Keyboard controller to be the issue since the location but have found some more broken traces and it started to post and beep.
As mentioned above, I need some time to test it with the VGA, have some more boards to test but I will report after 😀

thank you both for your help! Appreciate it!

br, tomas

tsalat wrote on 2024-05-07, 18:42:

you were right, I have found 3x traces broken next to the battery and the board started to post and beep, ending at Post code 26 […]
Show full quote

appiah4 wrote on 2024-05-07, 11:39:

In that case, assuming the board has an AMI Bios, 0E is sending the BAT (Basic Assurance Test) command to the KBC, and 0F is initializing the KBC after BAT. That means there is probably still a broken trace that stops the KBC from initializing. Check that the KBC is actually connected to the Keyboard socket, power and cmos properly - you probably still have a broken trace somewhere..

you were right, I have found 3x traces broken next to the battery and the board started to post and beep, ending at Post code 2625 and two short beeps. Without the VGA it started to issue the VGA missing beep code.
I did not connected it to a monitor and thus I am not sure if there is picture or whats going on but it definitely moved forward.

I will test it later on but at this moment I am very thankful for the idea!

br, Tomas

At this point I am 95% confident it will POST successfully with a VGA. Glad I could help, enjoy your 286!

appiah4 wrote on 2024-05-07, 18:53:

tsalat wrote on 2024-05-07, 18:42:

you were right, I have found 3x traces broken next to the battery and the board started to post and beep, ending at Post code 26 […]
Show full quote

appiah4 wrote on 2024-05-07, 11:39:

In that case, assuming the board has an AMI Bios, 0E is sending the BAT (Basic Assurance Test) command to the KBC, and 0F is initializing the KBC after BAT. That means there is probably still a broken trace that stops the KBC from initializing. Check that the KBC is actually connected to the Keyboard socket, power and cmos properly - you probably still have a broken trace somewhere..

you were right, I have found 3x traces broken next to the battery and the board started to post and beep, ending at Post code 2625 and two short beeps. Without the VGA it started to issue the VGA missing beep code.
I did not connected it to a monitor and thus I am not sure if there is picture or whats going on but it definitely moved forward.

I will test it later on but at this moment I am very thankful for the idea!

br, Tomas

At this point I am 95% confident it will POST successfully with a VGA. Glad I could help, enjoy your 286!

To close this topic, I have tested the board today and it works! It complains sometimes with the keyboard detection but the keyboard works - could be the keyboard itself.
The BIOS is something I have never seen before, very simple, nothing to set in total 😁, one page only - have enclosed some pictures and the BIOS together with the NSSI report.

thank you all for your help and direction!

br, tomas