1708 EMC3164 macbook have power issues

[itzusman]

Hi Masters.

My 1708 EMC3164 macbook have power issues. First it was working fine but a bit slow in booting. Net day i turned it on and it didn't powered on. And i tested with usb meter it suddenly @ 20v it takes 2.6 ampares and cpu gets hot. Then i checked the baord and PPBUS_G3H was short to ground. I injected 1v to it it takes 350ma and cpu gets warm. After opening L7410/20/30 there was inly L7420 line was short then i injected 3v to PPBUS_G3H and it takes 2.5 amps and U7420 got hot and i desolder it. Now after that in the start it takes 0.580 amps and goes to 620-30 mili amps. And then drops to 310 to 330 mili amps. No display. Fan starts slowly and gets fast by time.

L7410/20/30 0V

PPBUS_G3H 13v

Cpu gets hot by tiime and fan gets fast

Usb c meter 20v 580ma to 620ma

"The macbook came for bios password"

Any suggestions .

Please.

[mon2]

U7420 needs to be onboard. This is one of the multiphase power supply controllers. Each such controller contains internal high and low side mosfets. They will switch on/off to dial down the PPBUS_G3H high voltage to a safe voltage for the CPU.

On this note, never never inject a high voltage onto any board. The highest voltage for injection should be the lowest voltage used by the board. So keep it 1 volt or lower. The reason being that the injection voltage can reach the CPU. In your case, 3v may have reached the CPU or GPU and killed it.

Remove all power, no battery. Measure the resistance to ground of inductor L7420. What is the resistance value?

Suggest to measure the resistance to ground of each inductor on the board. You are checking for a potential short on the board which can cause the local power supply rail to turn off.

Check the power sequence charts below. Also, the CPU should be powered up with a heatsink and fan for normal diagnostics.

[mon2]

U7420 needs to be onboard. This is one of the multiphase power supply controllers. Each such controller contains internal high and low side mosfets. They will switch on/off to dial down the PPBUS_G3H high voltage to a safe voltage for the CPU.

On this note, never never inject a high voltage onto any board. The highest voltage for injection should be the lowest voltage used by the board. So keep it 1 volt or lower. The reason being that the injection voltage can reach the CPU. In your case, 3v may have reached the CPU or GPU and killed it.

Remove all power, no battery. Measure the resistance to ground of inductor L7420. What is the resistance value?

Suggest to measure the resistance to ground of each inductor on the board. You are checking for a potential short on the board which can cause the local power supply rail to turn off.

Check the power sequence charts below. Also, the CPU should be powered up with a heatsink and fan for normal diagnostics.

[itzusman]

Thanks for reply.
Ok i will check and report back. Power sequence values

[itzusman]

U7420 needs to be onboard. This is one of the multiphase power supply controllers. Each such controller contains internal high and low side mosfets. They will switch on/off to dial down the PPBUS_G3H high voltage to a safe voltage for the CPU.

On this note, never never inject a high voltage onto any board. The highest voltage for injection should be the lowest voltage used by the board. So keep it 1 volt or lower. The reason being that the injection voltage can reach the CPU. In your case, 3v may have reached the CPU or GPU and killed it.

Remove all power, no battery. Measure the resistance to ground of inductor L7420. What is the resistance value?

Suggest to measure the resistance to ground of each inductor on the board. You are checking for a potential short on the board which can cause the local power supply rail to turn off.

Check the power sequence charts below. Also, the CPU should be powered up with a heatsink and fan for normal diagnostics.

I have tested it again . and i opend all 3 inductors

L7410/20/30 and cheked voltages. On the U7410 / 20 / 30 Side it is giving about 10 volts it looks high voltages for CPU_VCC_GT and then i give 1 volt to the cpu side and connect charger and it gives display but didn't comlete boot at the final stage it restarts. And on the power supply it consume 1v 800 ma.

How much voltages should be on CPU_VCC_GT
?

And what cand cause 10 volts on U710/20/30 output?

[mon2]

CPU and GPU will always be a very low voltage. Both are heavy current consuming devices and for this reason, the semiconductor, by design will operate at a very low voltage of 1 volt or even lower.

Having such a high voltage on the noted rails means that at least one of the high side mosfet is leaky and allowing for the high voltage to enter this region. To produce a safe and lower voltage (buck regulator design), there will be a high side and a low side (to ground) mosfet. Each will switch on / off to create a lower and safe voltage for the powered device(s).

In your testing, do you see the Apple logo during power up? Try booting in Safe mode if you do.

[piernov]

Crappy multimeters won't understand the fast switching of the MOSFETs, nothing wrong there.
No way iGPU survived getting PPBUS_G3H *then* 3V from lab PSU anyway.

[itzusman]

I opened all 3 inductor s l7410/20/30 thease are open voltage. 2 of sic635 ics are short i have pulled them out. And now it is third one that is making 10volts. Now is it possible that ISL95828 is also faulty? Now i have conected a buck converter 1.07v 5amps. It shows display even it installes os. But when it comes to final booting display turns off.