PS3 HDMI to scart rollback... HELP

Hi guys,
Have fat PS3, used to live in a house with tv that had hdmi connections....
Moved out, and am now using a small portable that only has a scart connector on rear or yellow/white/red connectors on front.
So I connected up everything, power, and av-multi cable with scart adapter - nothing appeared on my av channel on tv.

My problem Ithink, is that my ps3 is set up to HDMI output, and I need to set it to revert to output on the av-multi out.
Can this be done without having to connect machine to another tv with HDMI, or is this my problem at all???
Any help gratefully appreciated
Thanks, Alan.