macbook pro a1707 dead

[jesi]

hi all techs

require some help on this 820-00281-A macbook motherboard came in dead and the pch bga U1100 (SR2NH), u5000 , Q7056 , U7000 and bios U6100 ,looks like these have been tampered with ..also the battery is swollen..

adapter usb c 20.5v 4.7a 96w , i persume it should power on mb without battery..

update:

when adapter plugged in , power switch which 3.3v on it , when power button pressed both fans come on after 6 secs for about 20secs approx then goes off , nothing on the display stays as blank.. the voltage at the usbc out start from 4.96v to 20.25v after 2 to 3 secs they drop to 19.77v

attached a photo of the mb with all the voltages on the top side which i managed to note down are wdotted down on the attached photo of mb,

i only get these voltages when the battery is disconnected and the adapter is connected, when battery flex is connected the macbook does not respond to anything no voltages except the usb c voltages

i was thinking of flashing the bios to start with but not able to find the right one for it , so have not touched until i get a repnse from yourside

these voltages i only get when the battery flex is disconnected from the mb

thankyou in advance

[mon2]

Check if PPBUS_G3H and 3V42 rails are stable.

[dariusgc]

Hello,

i've got the same mac. Want t know, maybe someone knows what normal resistance are on L7960 and L8000 phase inductors?

Thanks in advance. 🙏

[mon2]

These are low voltage rails so the resistance is expected to be low as well. Remove all power. Measure their resistance to ground and post the results.

[dariusgc]

Those two inductors show ~50 Ohms. Is it normal?

[mon2]

Yes. To me, these are ok.

What is wrong with the unit? What is the voltage to ground of PPBUS_G3H?

Also measure, ALL_SYS_PWRGD voltage to ground.

[dariusgc]

It powers on, fan spins non stops, cpu not hot.

PPBUS_G3H = 12V.
ALL_SYS_PWRGD = 3.3V.

Maybe bios is coruppted?

[mon2]

Fan spin often is linked to missing the detection of the sensors in the trackpad. This results in high fan spin and the CPU will be throttled.

Disconnect the trackpad cabling and test if the results are the same. The logic boards should feature shorting pads to mimic the power on/OFF button using tweezers.

[dariusgc]

Without trackpad the fan spinning super fast, like turbine. Shorting pads of DEV-POWER BUTTON do nothing.

[mon2]

Try the bios in post # 2 here:

https://www.badcaps.net/forum/troubl...2159-820-00281

Backup the original 2 times and verify the contents before erasing and using the new image.

[dariusgc]

Thanks , i'll try. Let you know.

[dariusgc]

Hm, the same problem, fan spining, cpu is cold...😏

[dariusgc]

I've found very low resistance to ground, it is ~0.7-0.8 Ohm on L7330 inductor. This is PPVCCSA_S0_CPU rail. Is that resistance is normal or cpu is dead?

[mon2]

It may be, review this thread:

https://boards.rossmanngroup.com/thr...a_s0_cpu.6401/

[mon2]

Wait, you have ppbus_g3h so cpu is not dead from the high side mosfet. The cpu will heat up normally without a heatsink. Test the vcore voltage to ground.

[dariusgc]

There is no voltage on vcore rail . cpu is cold as ice. I meassured PPVCCSA_S0_CPU more accuratley there is 0.2-0.3 ohm reading...