820-00165 MacBook Air 2015 green light/no power/no fan

[galvestonmac]

I have an 820-00165 MacBook Air 2015 board liquid damaged with green light/no power/no fan. Damage was centralized on U7501. Via to C7500 to pin 23 on U7501 burned.

Replaced U7501. Voltage at pin 14 on U7501 .75v before chip changed. No change in voltage after chip changed, still .75v
Replaced C7500 & C7503

Restored via with jumper on pin 23. Now have restored 8.65v after jumper installed.

PP5V_S5=.75v measured at C7505
PM_SLP_S4_L=0v
S5_PWRGD=2.96v
PM_DSW_PWRGD=3.42v measured at R1451
PP5V__S4RS3=0
PPVRTC_G3H=2.88V measured at R1450

Any thoughts on what I need to track down to get this thing to turn on?

 

[Dukky Repair and Recovery]

Test with a battery plugged in. i know its silly but the past few 00165s have not been starting up without a battery for me.

 

[galvestonmac]

OK. Thanks. Could very well be! I'll check it out!

 

[galvestonmac]

More measurements:

SMC PM G2 EN=3.42 at R5198
SMC_BC_OK=3.09v

 

[JohnB8812]

Ok so for one yes always test with battery once you get the S5 rails but this seems like more to it. 2.88 volts on PPVRTC_G3H is no good need to replace clock chip and inspect that area. After that, need to figure out why only 0.75 volts on 5V_S5

 

[galvestonmac]

Do you think that if I inject 5v on the PP5V_S5 line at maybe C7505 I'd have a better chance of finding the short? I also tried with the battery but there is no change.

Looking for the short:
Removed 4820-.75v
Removed C4810-.82v
Removed C7505-.81
Removed C7400-.81

 

[JohnB8812]

Yes but you need to address your PPVRTC problem first. That may even fix the problem

 

[dukefawks]

What short?? What is resistance to GND on 5V_S5?

 

[galvestonmac]

I’ll check out the clock tomorrow and report findings. I will also measure in diode mode on 5V line.

 

[galvestonmac]

PP5V_S5 diode mode measured at C7505=.479Ohms
PPVRTC_G3H diode mode measured at C1910=.472Ohms
Looking for a replacement clock chip in my donor boards to replace this one with

 

[galvestonmac]

Changed clock chip out and now I have 3.41v on U1900 pin 1. Now have .04v on U7501 PP5V_S5. I've already changed out the chip. Do you think that something else cooked it while I was messing around with U1900? Ugh

 

[JohnB8812]

No that means you have fixed the clock issue if it's a stable voltage, but now measure resistance to ground on PP5V_S5 could be bad soldering on U7501 but that sounds like a short

 

[galvestonmac]

Got the clock issue fixed but then suddenly now I have a short on PPBUS_G3H. It was measuring 2v at F7140. I was looking around for something that was getting hot but couldn't identify anything. I injected voltage to the PPBUS_G3H line and slowly added voltage up to 1v. The CPU was heating up but I couldn't find any components that were hot via the old alcohol trick. I plugged in the AC adapter and the green light came on and then I heard "pop". The top of the CPU popped off right under the microscope. What transistor allows voltage to pass directly to the CPU? This repair has been a PITA.

 

[JohnB8812]

High side fet was shorted or you bridged something but RIP to that board

 

[dukefawks]

This is now fried, RIP.