Problem: iMac does not turn on, no post, no power, no fan, DEAD

Diagnostic:
Check U7600 for 5V, 3.3V – 0V on both
Check C7650 – 0V, resistance to ground 50Koms (OK)
Check Q6970 pin5 – PP12V_G3H - 11.6V, pin4 FET_EN_P12V_S5_R – 0V (missing enable signal), pin123 PP12V_S5 – 0V (no 12V output to U7600, gate is closed)
Check U6970 pin2 SMC_PM_G2_EN – 0V (missing enable signal from SMC)
Check SMC Power input, C5002 PP3V42_G3H – 3.4V. SMC is powered.

Conclusion:
Main issue, missing signal SMC_PM_G2_EN from...

Re: help acer 5733 probleme work only 7 min then shutdown

this acer model is known for bad heatsink pipes. if heatsink pipe temperature at cpu is different than pipe temperature by radiator then you need to find another heatsink. once they lose gas its useless, no more convection.

Re: please need help

I work in computer store, when people bring us acer for repair we always try to recycle them (as in; put them in garbage). I suggest you do the same.

Re: Boardview for Dell Alienware M18x R2, LA-8321P

well that one is hard to find...
however you can find this one easily: Compal LA-B751P schematic.
many things are same and also labeled same between these boards.
look up page 60 for DC IN and BQ batt charger, page 61 for 3V and 5V LDO. good luck!

Re: Alienware M17x R3, LA-6601P is missing +VCC_GFXCORE_AXG CPU voltage

you need to check pu800, it makes +VCC, I just fixed similar board (LA-C912P).
often this chip is shorted because of bad caps that fail under heatsink heat. check caps near pu800. Easiest way to locate short, you remove 5V coil by DC input (it will be next to 3V coil, leave that one. remember if shorted 5V line then your coil will be 0V, look up schematics for exact location, its like one coil away from DC jack connector) then measure resistance on each pad. If its 50+ oms/koms then its fine, if low number...