Fixing logic board? LED lights up steadily, Fans turn, no chime.

Hi there,

my sisters Mac Book just died while in normal use, running cool with no tell-tale signs in beforehand. No mechanical abuse or liquid damage occured.

Machine:

- MacBook Core Duo, Late 2006, black

- 2 GHz

- 2x512 Meg RAM

- Three-Walled connectors

Symptoms after pressing the power button:

- Fan spins

- Display flashes shortly as usual. Stays black

- No chime sounds. Ever.

- When RAM is installed, LED turns on and stays on.

- When all RAM is removed LED flashes rapidly.

- Swapping RAM/Reseating and using known working RAM does not change the Situation

- Shuts down after holding down the power button for a longer period. Does not power down by itself.

Things I did:

- Removed the board, cleaned with professional PCB cleaner fluid (Kontaktchemie LR)

- Removed the SRAM-Battery for a few minutes

- Tried booting with and without HDD, Airport-Module, Battery

- Symptoms change slightly when removing RAM altogether (see above)

- Mechanical an electrical inspection done, no visible damage or signs of severe corrosion.

- All fuses I was _able to find_ seem ok.

- No signs of liquids or scorches

So basically I'm running out of ideas how to "simply fit it". I'm an electrical engineer and am able to fix complex things with a schematic. Having worked a lot with SOT323, BGA, 0402 SMD and all it should be doable, but without a schematic I'm screwed.

Maybe someone could give me a hint towards a schematic. If I get it working I will keep you informed for others who might to come this way, too.

Thank you in advance!

Peter