I posted another thread with a lot of questions how to upgrade the ibook CD with a combo drive.
I got a lot of help. Thanks.
Still I ran into a lot of problems. I now solved them and want to share them here
First of all the optical ribbon cable wich has printed "To cd-rom" on it works with any kind of drive. Its a standard cable.
Never the less apples ide-plug has two extra pins. I'm not shure what they do, but they are placed at the jumper-section of the drive and covers the first two jumper-pins. Both on the harddrive and on the optical drive.
The haddrive is set to master and the cd-rom to slave.
The Combo -drive I used first time was a toshiba sd-r2212. I could't make it work at all. Maybe it was broken.
I goty my hands on a g4 ibook combodrive, the one without tray I forgot the name of it (Matshita CW-8124). This drive is set to master and has no jumper, so I needed to set the harddrive to slave.
It now runs great and it even boots.