powerbook 5,7 boots only after pmu reset, does not wake up from sleep

Hello,

my PB 5,7 wont boot normally. I got to reset the pmu every time i try to power on, even when i put it into sleep it will not wake up - only after the pmu reset.

What i tryed until now is:

reset pram, disconnect: HD, optical drive, PC Card, Soudboard, Airport, right USB board, left USB Flex cable, fans – no other reaction.

I changed: Topcase with keyboard, DC-IN board, power cables, batterie cable, RAM and right USB board with the pram batterie - every time it will only start with the pmu reset.

I installed a new tiger system and also a new leopard from orig. DVDs and updated both via Airport with the combo updates.

Now i dont have any further idea. Every help would be appreciated! Did i have overseen a crucial thing? Thank you all!

Must I replace the Logicboard?

Best regards

siebo