[Noris]

Completely stumped here... VCAM POKA is failing!

The voltages on backplane seem fine: 48v is stable, albeit slightly high at 48.8v) and the 5v and 12v rails come up fine during power on but get powered down as soon as controller hits the bad POK from the VCAM board. The power boards are all ok, but io4 error LEDs indicate bad -12v regulator (-5.2v one shows no error). I have tried another IO4 and it is exactly the same so thought it could be dust, bent pins, poorly seated card or something but everything seems good.

The diagnostics document I'm using has a figure suggesting to disable VCAM to find error, which I dont knowhow to do... is this worth trying? Is it just a case of removing the vcam or is there more to it? Will this get me anywhere anyways because that seems to just be removing the troublesome device!

The other curious thing is that the diagnostics roadmap indicates that the io4 draws 48v straight of the backplane but there doesnt appear to be any significant converter blocks on it... is my interpretation of the diagram correct? If not I'm thinking the 512 could not be providing correct voltage, thought LEDs are all amber which I think indicates power outputs are ok.

Also with no cards installed except for controller the system gets through power on but fails with no system clock. Is this referring to one of the dallas timekeeper chips on the controller/io4 or is the system clock elsewhere? It is highly likely the batteries are dead but I thought they were only for nvram etc and noncritical for booting up the system.

This fascinating world has quite a steep learning curve so any advice / experience would really help!

Regards