Kantack,
Try this link below:
[Link: yamaha.com]This gets you to where you can download a few things including the Remote Control Instruction Guide. If I am not mistaken, it will show you how to convert codes like 7A DE to pronto hex.
oop. I think you can find the instructs here as well:
[Link: yamaha.com]I used these instructs to get the discrete on & off for the Yam DVD-S550