Usb or ps2 ? Ports maybe broken.

Freemaxx wrote on 2025-12-14, 12:05:

Hello. I need help about a P2L-B (440lx)
My keyboard don't working correctly since few days. It disconnects after a few seconds or at boot . Thanks

Remove and put on the "KBD" jumper several times.

Where is it located?
Thanks

Freemaxx wrote on 2025-12-14, 14:55:

Where is it located?
Thanks

https://theretroweb.com/motherboards/s/asus-p2l-b-rev.-1.02
https://theretroweb.com/motherboard/manual/35405.pdf

This jumper is OK.
It might be the keyboard connector. I have a spare one. I'll try replacing it.

Freemaxx wrote on 2025-12-14, 18:00:

This jumper is OK.
It might be the keyboard connector. I have a spare one. I'll try replacing it.

I am not familiar with the P2 series, but the next generations of Asus Pentium 3 have an unpleasant feature.
The keyboard is powered by a diode and receives 4.6-4.7 V from a 5 V power supply.
I had problems with a keyboard whose internal capacitor had dried out.
It worked fine with motherboards that supplied 5 V to the keyboard, but glitched badly on Asus.
In other words, the problem may lie with the keyboard itself.

When changing the connector for DIN-5 and PS/2, a double footprint is provided.
When installing PS/2, a more modern keyboard can be used without adapters.

When I swapped the connector, I saw that there were holes for a PS/2 connector. It worked for 15 minutes and then it started again. Ugh. The keyboard voltage seems unstable. I switched to KBPWR, and it seemed better. I modified the BIOS because it wasn't supporting certain processors. I put the SL265 (Klamath at 266MHz) back in place of the SL2S5 (Deschutes at 333MHz) just in case. To be continued...

rain wrote on 2025-12-14, 12:52:

Usb or ps2 ? Ports maybe broken.

Din 5pins

P.S.: The BIOS files found on Asus or Retroweb didn't work. Could my motherboard be an OEM type? ...

Freemaxx wrote on 2025-12-14, 21:36:

P.S.: The BIOS files found on Asus or Retroweb didn't work. Could my motherboard be an OEM type? ...

I have 4.7v...

I have a dead P2-99B.

There's no diode, power connected directly.
The KBD jumper switches the keyboard power supply or from the ATX connector (+5V standby) or to the AT connector.
Check the position according to the PSU you're using.

Near the DIN-5 connector, there are SMD capacitors of approximately 100 pF from keyboard signal lines to ground for filtering interference.
Sometimes they go crazy or simply short-circuit.

Furthermore, these motherboards don't use +3.3V from the ATX power supply at all, only +5V.
If your power supply outputs 4.7V, that's very low voltage.
It needs to be replaced.

Regarding BIOS - go here
Modified BIOSes for ASUS P3B-F, P3V4X, P3V133, CUBX, CUBX-E/L and P3C-E

good luck, what else can I say?