Just a quick update.

The tester PCB and PIC arrived on Thursday. So of course I spent all day putting it all together.
Took about 3 hours to assemble the tester and another 5 or 6 hours putting together all the neccessary cables  to test my Williams 11b CPU board.
This board is from a Cyclone machine which has power issues and I have already rebuilt the power supply board but still getting low 5 volts at CPU board.

Using a computer power supply and the tester to boot the CPU on the bench has allowed me to rule out further power supply issues. 
Basically it's like swapping the cpu to another machine and see if the faults go with it, which they did.
Also working on the bench is certainly alot easier than working in the backbox.

The tester has a built in DVM and logic probe which are useful for tracking down faults on the board.
I found the logic probe function particularly useful, as I am learning as I go, and being able to see the various voltage and pulses was a big help to me.

Overall I'm very impressed with the tester so far.

Here are some Pics.