Macbook 820-3115 missing 3V42_G3H

[mon2]

Re: Macbook 820-3115 missing 3V42_G3H

Good.

Resistance to GND on L6995 (PP3V42_G3H_REG) ?

[Nuld_]

Re: Macbook 820-3115 missing 3V42_G3H

Pin 2 on L6995 is someting about 135kohms, L6995 is still removed from the board.

[mon2]

Re: Macbook 820-3115 missing 3V42_G3H

That is a much better resistance than before. If the other side of L6995 is also a high reading, then proceed to solder back L6995 so that it can perform its job.

The voltage output of L6995 should be ~3v42 if all is well on this rail.

[Nuld_]

Re: Macbook 820-3115 missing 3V42_G3H

The other side is reading O.L,
so should be good i guess.

[Nuld_]

Re: Macbook 820-3115 missing 3V42_G3H

Both Pins on L6995 are around 125k ohms now that L6995 is soldered back.
Is it safe now to plug in the magsafe connector?

[mon2]

Re: Macbook 820-3115 missing 3V42_G3H

I think it is. Do measure the output of the L6995 and it should be ~3v42 if all is well.

[Nuld_]

Re: Macbook 820-3115 missing 3V42_G3H

Still reading nothing on L6995 and U6990 isn´t producing PP3V42_G3H.

[Nuld_]

Re: Macbook 820-3115 missing 3V42_G3H

And U7941 is now shorting again on Pin 1.

[mon2]

Re: Macbook 820-3115 missing 3V42_G3H

Confirm the input voltage to U6990, pin # 7 - measure @ D6990, pin # 3 (PPVIN_G3H_P3V42G3H).

[Nuld_]

Re: Macbook 820-3115 missing 3V42_G3H

Pin 7 is reading 16,6V and Pin 3 is at 15,1V.

[mon2]

Re: Macbook 820-3115 missing 3V42_G3H

Are you using an official magsafe adapter ?

Remove all power, check the resistance to ground of L6995, pin #2. Be sure that L6995 inductor is soldered in properly and mating with the PCB pads.

[Nuld_]

Re: Macbook 820-3115 missing 3V42_G3H

It reads around 3 ohms again. I guess it fried the U7941 again.

It´s not a official magsafe adapter but it worked with the samelogicboard in the past.

[mon2]

Re: Macbook 820-3115 missing 3V42_G3H

I would buy a Costco lot of U7941 devices from Aliexpress. Do ask if they are valid for macbook repairs but believe this is a fixed function device that should just operate as expected upon soldering. Silego has many programmable devices and you need special tools and IP to configure them otherwise.

Remove all power and check the resistance to ground of the 3 x outputs of this device (pin 4, 3 and 8).

What are the readings ?

[Nuld_]

Re: Macbook 820-3115 missing 3V42_G3H

Pin 4 is at 15Mohms, Pin 3 is at 15,6Mohms and Pin 8 is at 15,6Mohms aswell.

[mon2]

Re: Macbook 820-3115 missing 3V42_G3H

The resistance is ok.

Very strange, yet this part dies.

What are the resistance readings to ground for the input pins 2, 6, 7 ?

Would not be a bad idea to source & replace U6990 (PM6640). If nothing else, you will have spare parts for future repairs.

[Nuld_]

Re: Macbook 820-3115 missing 3V42_G3H

Readings on U7941 are:
Pin 1: 2,6 ohms
Pin 2: 16.1 Mohms
Pin 3: 16 Mohms
Pin 4: 16 Mohms
Pin 5: 2,5 ohms
Pin 6: 676 ohms
Pin 7: O.L
Pin 8: 16 Mohms

Readings on U6990:
Pin 1: 1,2 Mohms
Pin 2: O.L
Pin 3: something around 2Mohms
Pin 4: something around 2,2 Mohms
Pin 5: 0,3 ohms
Pin 6: 2,9 ohms
Pin 7: something around 2,2 Mohms
Pin 8: O.L
Pin 9: 2,4 ohms
Pin 10: 167k ohms

[mon2]

Re: Macbook 820-3115 missing 3V42_G3H

Remove U7941 off the board.

Does the low resistance disappear @ L6995, pin # 2 ?

If yes, power up (without U7941) and confirm if the voltage @ L6995, pin # 2 = +3v42.

[Nuld_]

Re: Macbook 820-3115 missing 3V42_G3H

Pin 2 of L6995 is reading 130,5k ohms
Voltage is reading 0V.

[Nuld_]

Re: Macbook 820-3115 missing 3V42_G3H

Uhm, now Greenlight is on with 3,4V on Pin 2 of L6995 without U7491 even attached.
And U7200 is getting hot too.

[Nuld_]

Re: Macbook 820-3115 missing 3V42_G3H

U7200 Ohm Readings:
Pin 1: 115k
Pin 2: 8,32k
Pin 3: 383k
Pin 4: 1M
Pin 5: 3,92k
Pin 6: 78,6k
Pin 7: 3,1
Pin 8: 1M
Pin 9: O.L
Pin 10: 43,4
Pin 11: 3
Pin 12: 106,5 k
Pin 13: O.L
Pin 14: 382k
Pin 15: 0
Pin 16: 4,5
Pin 17: 37,5
Pin 18: 800
Pin 19: 106,7k
Pin 20: 6,4
Pin 21: 106k
Pin 22: O.L
Pin 23: 10k
Pin 24: 6,2