Ok well after feeling like a knob for having the multimeter on ac I've retested the board and have 5.0v @ the 5v point & 4.9 @ the dmd & only 10.2 @ the 12v point. I've changed the bridge rectifier #3 and have the same readings. I have noticed that the fuse holder f5 looks a bit corroded so ill change that over next. Any other ideas? Where else should I check/test ? Thanks guys

don't worry it must be a baywatch thing I had a plug flipped and it didn't work so I felt the same, at least we learn something from it.

Check the fuse holders as well as Beaky found a cracked one on the power board so can play a small effect. Check the fuse holder near the BR3 as well that is linked to the display.