Imac 21.5 A1418 820 3302, On and Off cycling!!

[Noguinfor]

Hey,

This machine when i press start, fan spin 1 sec and off.. Cycling!

no water damage, board looks well! But when i dismounted the machine i saw that it was full off dust!

could be a power supply ??

 

[aprendiz]

PP12V_G3H present and stable? Usually is a shorted USB port.....

 

[Noguinfor]

PP12V_G3H = 11.8V.. i will check usb's!

 

[Noguinfor]

usb's OK.. but without ram's the machine stay's on!! with rams = looping!

 

[Noguinfor]

i already test ram's and no short in PP1V5_S0!

 

[dukefawks]

Does it beep without the RAM?

 

[Noguinfor]

Good Morning Duke,

Yes, the machine beeps without a Ram!

 

[dukefawks]

Pffff, could be anything....Known good power supply first and check all rails for shorts.

 

[Noguinfor]

tested with a new power supply and can't fin any short in power rails !! I think it's going to be another imac that I can't solve.=(

 

[dukefawks]

Last thing to try is BIOS. SAFE THE OLD DUMP!!!