AT to PS/2 Keyboard Help

WalkingContradiction

Hello all,

I recently resurrected my Socket 7 motherboard, and everything is working fine except for one thing. After POST, the computer tells me there is no keyboard connected. The motherboard uses the older AT keyboard connector, and I do not have a keyboard that uses that standard at the moment. However, I do have an AT to PS/2 adapter. Even though I know that the adapter works, the system does not detect any keyboard no matter what PS/2 keyboard I use. I have also tried to use the on board USB connector as well as a PCI USB1.1 expansion card with no success. I was wondering if anybody could help me troubleshoot this issue, because I'm not sure whether it is the connector on the motherboard that is bad or the adapter.

Thanks,
TheWalkingContradiction

SomeGuy

USB keyboards won't usually work properly on a system unless the USB port is on the motherboard and the BIOS supports PS/2 keyboard emulation. Even then, many earlier motherboards had that option disabled in the BIOS so you had to enable it - using a PS/2 keyboard

If you get the OS booted and it supports USB keyboards, it may recognize the keyboard even from an expansion card, but you will not be able to control the bootup of the computer or enter the BIOS setup.

AT-PS/2 keyboard adapters are just straight-though connectors. You can test them with a volt/ohm meter. Also check that plug pins are long enough and nothing is dirty.

I thought that any PS/2 keyboard could use an adapter to talk to almost any "AT" style computer (not XT), but it would not surprise me if they found some way to break compatiblity.

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By any chance, does this board use the old cancer barrel CMOS battery? If on the off chance that it does, the battery acid may have leaked onto the board and corroded the traces.

If not, have a look at the traces by the keyboard connector and see if the traces have been severed for some reason.

WalkingContradiction

Well it turns out the issue was the adapter, and I was able to confirm this by plugging the PS/2 keyboard to AT port adapter into an AT keyboard to PS/2 port adapter and then the keyboard into that. The adapter I was using turned out to be faulty, and I am going to be swapping out the connector on the MOBO with a PS/2 miniDIN port. Also, thankfully the MOBO doesn't have that awful piece of cancer barrel battery, because I would've swapped it out for a CR2032 battery holder the second I got the chance.

Thank you all for your help,
TheWalkingContradiction

SomeGuy

WalkingContradiction wrote:

and I am going to be swapping out the connector on the MOBO with a PS/2 miniDIN port

I would not recommend any kind of soldering on that kind of motherboard unless there is already a good reason to do so (such as a damaged connector). ~486 and later boards are usually really good about redistributing heat, which makes de-soldering a bitch.

It is usually much easier to swap out the cable on the keyboard, or just obtain another adapter.