Video Signal lost during bootup.

I am working on a Gateway Profile 4b LS. It is an “all-in-one”. When the computer is turned on the splash screen comes on and then immediately (about 1.5 sec. later) the screen goes blank. Window XP sounds like it contiues to boot,the disc drive continues to access and the “Window’s ta-da” sound blairs, as it boots. Still no video. No message on the screen and no beeps either.

I have:

* Tried to access the BIOS. No video, so it may be there but can’t tell.

* Changed the HDD. No change.

* Tried to boot from a emergency disc. No video.

* Connected another monitor to the external monitor port. The extra monitor starts then displays “no video signal”.

This model has an AC adaptor. no PSU.

I am trying to avoid getting a video card.

Any help? Thank you.