Powerbook g4 15" fw800 dual display issue

[philparis]

I know some posts here and there covered this issue but not exactly the same way
so i take my chance
I bought this PB used from Ebay, i had to switch back from System 10.5 to 10.4.9 (actually 10.4.11 due to internet updates) for software compatibility (FCP)
I have never been able to use the external video capability,
i bought a first cheap dvi/vga cable but it looked like some pins were not there so i bought an original apple one
now when i plug it in, the internal screen of the laptop goes black for one second then blue then black again and then back to normal display
The pref panel never showed any external monitor, clicking "detect monitors" is no help
Also the S-video cable does'nt show like it is working
F7 key does'nt do anything either
I did almost anything i found possible to do after my internet searches:
resetting PRAM, NVRAM,PMU
nothing worked
The video card is an ATI Radeon Mobility 9700

Does anybody here have a clue about what is happening to this laptop ?

Any help would be greatly appreciated as i will have to use it for a presentation

Thanks a lot everybody

Philippe, Paris, France

[ElDiabloConCaca]

...so i bought an original apple one...

Are you absolutely positive you bought the correct adapter?

[philparis]

I am quite certain it is an OEM (white and all...), i used to work with a production company who had the same PB and the adapter was exactly the same (it came even with the same plastic covers on both ends)
As i said, i already had bought one which was NOT the same as some connecting pins were lacking on the DVI side. This one has ALL the pins

[philparis]

Any idea anybody ??????

[ElDiabloConCaca]

What kind of external monitor are you hooking up to the laptop with the adapter?

[philparis]

thanks fory answering
apparently my problem has not been so frequent !
in fact i am trying to hook it up to a TV set through a second adapter from vga to composite video
so from what i read the computer is not receiving any information from the outside through the vga
Any hint ?

[ElDiabloConCaca]

Yikes... try hooking up the computer to an external monitor to begin with (not a TV) -- this will determine whether the PowerBook and adapter are working correctly.

If you can get it working correctly first with an external monitor, then we can move on to getting it working with the TV. TVs and monitors are quite different in their specs, resolutions, refresh rates, etc. Some TVs just won't work, while others will work flawlessly.

The fact that the internal monitor goes to blue, then black, then the desktop appears again indicates that the adapter and Mac OS X are working correctly, but the TV may not have a resolution/refresh rate supported by the hardware.

[philparis]

i will give it a try immediatly
i keep you posted
thanks