how to open it ?

The scan convertor boards can be accessed by removing the screws at the top back of the system, and sliding the cover off. Then remove the card cage cover.

To access the scanner boards and the scan convertor power supply, there are two screws on the right side where the upper and lower sections come together. Remove the screws, and carefully lift the upper half of the unit up and to the left. There should be a cable that retains it. Be careful with the scan convertor and monitor raised up so that it doesn't accidentally come down. Loosen the screws on the card cage cover and remove it to acess the scanner boards.

There is also a power supply tray on the bottom of the unit. It comes out the rear of the system after removing the 4 bolts and the filter bracket. There is an analog DC and a switching power supply in the tray.