GON has a subforum which you can try asking
first off.
There is not too much information to go by, I have found an old keyboard for sale thread bearing the same brand and model number as yours. It has some photos as well as some information provided by the seller (at the time). Information
here. The only information that I can extract out of that thread was the PCB as PS2AVR87 PCB again Google was not much of help with the PCB so I do not know what sort of controller it is.
A good idea would be for you to provide some photos, at least photos of the controller and area around the controller. Last but not least if nothing is gained from all of the above you could try swapping the controller to a teensy controller and reprogram it with maybe hasu's TMK for starters.
