Arcade experts urgent!

Hi I have a dedicated Killer instinct 2 cabinet and I've sold it to a guy who is picking it up in a couple of hours, I also sold him a Killer Instinct 1 board to play on the cabinet. The Killer Instinct 2 plays fine in every way. The killer instinct 1 board plays fine on all of my cabinets other than the dedicated KI2, for some reason there is no sound. The test mode on the KI1 sez the sounds roms are bad when in the KI2 cabinet, but on the other cabinets the KI1's sound roms are fine in test mode?!?. The KI1 and KI2 boards are indenticle other than different Roms and Harddisc's. So why work on one and not another and the other works on both when they are techincally the same??
My first thought was to try adjusting the power and I turned it up a little and down a little but no difference.
Can anyone else recomend anything I could try, its probably a simple silly reason but cos I'm in a hurry I can't think straight!
Any suggestions would be great!

HELP!!

Thanks Paul

Have you tried changing the psu, you have tried adjusting the 5 volts but perhaps the supply regulation is not working well and screws up #1 more than #2 for some reason ??? Thats the only logical explaination imho.
As you say the hardware is the same, just different roms and hd as far as I know.

Hi, thanks for the reply, I'm 99% sure its power related as the KI boards are a little dodgy when it comes to getting the power correct. I'll try changing the power supply and see if that helps.
Any other ideas?
Thanks Paul

Phew sorted it, the Power supply wasn't earthed properly, there is like a braided earth strap that runs through the machine so I bolted the PSU onto it and it works fine now
Thanks anyway
Paul

Just for the record, KI1 and KI2 are *slightly* different. There is 1 chip that is different. I think it's the IDE controller. Anyway, KI1 boards can have an addon pass through cable with a new chip on it going to the hard drive that will allow it to run the KI2 ROMs/drive, however, KI2 can't be downgraded to run KI1.

Yep correct, the boot up chip will only run with an original KI1 or KI2 Seagate hard disc. One of my hard discs died and I got a new programed hard disc and 'any hard disc' chip from this guy:-
http://www.revisionx.com/\kiproject\ki1.html
Highly recomended! Its a shame there is no back up for KI2 and although most people prefer KI1 I actually like KI2 better, the tunes are pumping and Sabre Wolf is much better
I was told you can downgrade a KI2 to 1 you need the harddisc bootup chip and all the sound roms, as the mother boards are the same, but I may be wrong as I don't know anyone thats done it.
Cheers Paul

No, a KI2 board will only run KI2.

A KI1 board can run KI1 or KI2 if you have the pass through adapter.