help with unidentified trackball

[civic83]

Hello, I am relatively new to MAME, and have a very little bit of electronics experience.  I have started to gather components to build my first cabinet and want to use a trackball for mouse movement.  I have read several messages about the compusa crystal trackballs but they seem to be discontinued (if anyone has one or more they want to sell please email me!).  I was rummaging though some junk and I came across an old unisys computer with an integrated 2.5 inch trackball which i removed, now i am faced with trying to interface it to the ps2 port (or serial if thats easier).  The casing says alps on it, and 647b seems to be the model, it has a 7 pin molex connector on it, now the first 2, and last 2 pins are marked x+, x-, y+, y-, but the 3 in the middle are not marked, i assume they must be +5v, gnd, and CLK? but i am not sure.  
The only other markings i can find are on the pcb board, they are a series of numbers:
2L100470
SZ
HRO
YS8506

Any help would be greatly appreciated, Thanks!

[PacManFan]

Post a picture if you can, and I'll take a look. The x+, x-,y+,y- are probably the signal leads for l/r u/d, try to trace the other leads on the pcb to figure out which ones are power and ground, The 7th one may be unused (but who knows?) I don't think a trackball uses a clock, at least, none that I have seen.
-PacManFan

[unclet]

I believe www.computergate.com has the crystal trackball available:

http://www.computergate.com/products/item.cfm?prodcd=JTBSCT

[civic83]

Here is a picture of this mystery trackball with the cover removed