Keyboard not working on PowerMac 7100/66

[tokyoracer]

Just posting requiring a little help to get this old Mac to communicate whith the keyboard which it isn't at the moment.
Only reason why I ask is because I'll be donating it to a charity shop at some point and thats the only thing that isnt working on it. Have tried 5 different sorts of keyboards and none are working.

Any light on this issue?

 

[JediMeister]

What port on the Mac are you connecting it to, are you using an extension cable?

 

[tokyoracer]

What port on the Mac are you connecting it to, are you using an extension cable?

Hi JediMeister, I'm using the only port the keyboard plugs into (other 2 are modem and printer ports which have different pin numbers,) and i'm not using an extention cable.
One of my keyboards has the cable fixed onto it it and the other have coiled PS/2 to PS/2 cables. Mice that are connected thru the keyboard work fine too using either port on either side (swapping makes no difference).
Oddly when testing it it did burst into life very breifly once but then stopped again soon after. Also aught to mention that all keyboards I have power it on no problem using that arrow key.

Very strange...