The hard drive will not start ,scanning etc all ok .I found that there is 12volt leaving the power board but when it gets to the hard drive it is 10.5 volt and varying.Does anyone know the circuitry from the socket PL451 and PL402 .Hard drive checked on a PC and spins ok .Alternative Hd fitted with the same symptoms

Have you read http://forums.digitalspy.co.uk/showthread.php?t=1309563? First thing to check would be the capacitors on the PSU board.

Thank you futaura have had a good look at all the capacitors all look ok .Had a feeling it might be off the power board and some component on the PCB between the two sockets there .Still has 12v leaving the PSU board but 10.5 at the HD

Just to update in case it helps other people .I found that s314 on the PCB was open circuit .This prevented 12 v being passed to the hard drive ...Short circuited it and all is working again .