Dead Machine CLP-770nd

Hello all i need assistance
I have gone to a clp 770nd which was dead
I was getting 240v at the ac power supply, but nothing at the dc power supply.
so i have changed both dc and ac power supply and still machine is dead but i am now getting power at the dc power board.
i have changed the main board as well still no joy.
can anyone please assist on this matter.

Thanks
Nigel