Alright, I tried again making sure the drive was spun down, no luck. My empeg is bone stock with a single 12G drive. I will unfortunately be busy for most of the weekend but I will check the powerfail line as soon as possible. Thanks for the technical info on the CPU lines (don't suppose part of a schematic would be available?) I will post as soon as I have been able to try what you've suggested.

Thanks again
Nick