I did this :
Try the following:
Boot without startup-sequence. At the DOS prompt enter the following commands:
cd devs/monitors
rename #? :storage/monitors
cd :prefs/env-archive/sys
delete screenmode.prefs
delete overscan.prefs
Now wait for the HDD to finish its work and a few seconds more, then reboot.
You should now see the normal Workbench on your TV.
Open the Devs/Monitors drawer as well as the Storage/Monitors drawer. Drag the icons labelled Multiscan and VGAOnly to Devs/Monitors and reboot.
This did not give me any other options than what I had before (NTSC) ....
Any help?