820-01987 20v 0amp

Kappy

Member
I've got an 820-01987 which the customer says just switched off. I've had a look under the microscope and there is no sign of any liquid damage to any of the components. It's been ultrasonic cleaned and after probing around I've noticed that all the AWAKE and SLPS2R rails are pulsing. These all come from the U7800. I'm getting a stable 3.3v on PP3V3_G3H_PMU_VDDMAIN and PPBUS is also stable 12.27v.

Am I correct in saying that the U7800 is faulty or is there anything else that it could be or I could check.

Thank you in advance
 

2informaticos

Administrator
Staff member
SMC/PMU_COLD_RESET_L stay low, or pulse?
Looks like no communication between T2 and U7000.

Check for short at all U7800 surrounding coils; also at any big coil from the board.

Did you try with known good batery?
 

Kappy

Member
PMU_COLD_RESET_L is also pulsing

Not tried it with a battery as I would have thought it would work fine with just the mains plugged in.
 

Kappy

Member
With is showing 0amp I was a bit sceptical but tried it anyway. I used a brand new battery which has 60% charge on it and it's still showing 20v 0a
 

Kappy

Member
Yes same as before.. I really can't think it's anything else than something around the U7800 or the chip itself. Do you know if this chip is firmware locked to the board?

I'm just waiting for the go ahead from customer to remove the shielding that covers the U7800. The other option will be to sending back to Apple for a replacement under the Consumer Law.
 

2informaticos

Administrator
Staff member
Check if machine is covered by some Apple warranty first.

"The other option will be to sending back to Apple for a replacement under the Consumer Law."
Sounds like best option...
 
Top