820 00138 A , Don't turn on

[Noguinfor]

Hey,

This one don't turn on because to the typical CPU vcore drop-out issue!

PPBUS down = 0,700V and when i plug the charger in the area of U7330 get's hot!

my questions, i must replace All FDMF6808N ??

CAn i replace for a new on FDMF6808N ?? or i must replace for FDMF6708 ?

thanks

 

[2informaticos]

New FDMF6808N does NOT exist.
That chip is Apple proprietary; wasn't sold new for anybody else!
Of course all chinese sell "NEW" refurbished chips.

Change all with new FDMF6708N from serious online store; forget chinese sellers...

 

[Noguinfor]

Hey,

the components just arrived and already replace all FDMF6808N for a new ones FDMF6708N and no lucky!! PPBUS shorted in the same!

If i remove U7330 short goes away!! and if i measure resistance on L7330 i have 0 ohm!

already soldered a wire on L7330 with 1.1V and consume 2A. Still hoped it was a capacitor but i'm wrong! nothing burn!!

More ideas?? Processor dead??

thanks

 

[JohnB8812]

Very likely the CPU is dead. When those fets short, they send 12 volts to the CPU. The dropout issue is only if the board is randomly shutting down not if PPBUS is directly shorted to ground. This sounds like an RIP.

 

[2informaticos]

New U7330 cannot short again by itself; even if CPU is shorted!
Probably problems with R/C7331, or bad U7200.

 

[Noguinfor]

You are right one more time mr.Vali! U7200 problem. replace u7200 and the machine turn's one but with DC power suply only consume 0.100A!

i have 0v and 3.3ohm on 3 coils L7330, L7320 and L7310!

already soldered the 3 FDMF6708N again but only consume 0.100A.

CPU fail ? any time anyone have the same issue ??

thanks

 

[2informaticos]

Likely bad CPU, after overvoltage recieved.
Resistance to ground looks good at VCORE.
As last option, try new BIOS.