So you are telling us that if the pwr. supply board is unplugged from the DVD's controller board, the fuse does not blow open? If that's the case the fault is on that controlelr board. However if it's like most control/processing boards, it's a bunch of surface mount components and specialized IC chips making for a difficult repair. You could look for obvious signs like bloated capacitors, solder connections that show signs of arcing, or poor conductivity, etc. Remove the DVD mechanism's power wires from the control board so the motor(s) do not run. If fuse remains good, the problem is in the DVD transport itself.