Mains to 12 volt DC

Power good has been on PC power supplies since the original IBM PC and it's *from* the PSU to PC not the other way around.

Yes, Dell were (are?) A rule unto themselves as far as PSUs were concerned, same connector - different wiring; they could at least have keyed them to make them incompatible,

That's why I first avoided mentioning colours and used pin numbers.

Either way, a PC PSU isn't really ideal for this when 12V DC PSUs are easy to come by.

Simply because they will be given the option to "Press and Hold" an ordinary bell push.

I HOPE (excuse upper case) that it will be enough incentive NOT to knock on the window!

Mathew, thankyou for your input, this is just the information I needed, I shall order one forthwith, Thanks again, Peter.

My thanks to all who have responded, I really appreciate your giving of your knowledge and expertise.

I think the problem is solved thanks to Mathew and I look forward to fixing the warning light.

Regards, Peter Charles Fagg