MB Air 2015 820-00165A No Green, with fan spin, with power, no backlight

[Kea]

Hello i'm new here,

i have a macbook that a want to repair. It has no green/orange light. When i plug the magsafe in, it starts sometimes. I see the questionmark folder on screen with holding flashlight (no ssd in).

my messurements:

PPBUS_G3H = 8.1V
PP3V42_G3H = 3.428V
PPBUS_G3H_R = 8.2V
PP5V_S3 = 5.1V
PP5V_S0 = 5.1V
SMC_RESET_L = 3.376V
SMC_ADAPTER_EN = 1.0V
PP5_S5 = 5.09V
PP3V3_S4 = 3.29V
PP3V3_SUS = 3.3V
PPVIN_G3H_P3V42G3H = 14.67V
PP18V5_DCIN_ISOL_R = 14.98V
PPDCIN_G3H_ISOL = 15.00V
PPDCIN_G3H = 15.03
PPVPTC_G3H = 3.3V

Later i messured PPDCIN_G3H with a known good charger = 16.40V. Don't know if it say something. Still the same problem.

I'm not a electrician, i'm only interested to repair Macbooks.

Macbook had waterdamage. I have cleaned it with 99% Alcohol.

I would be grateful for advice.

 

[larossmann]

How does the cable between the DC in board and the motherboard look on each side? This is the 821-1722 cable.

Where was the corrosion from the liquid damage? It's important to know where the original corrosion was.

8.1v means the SMC(U5000) is not communicating properly with the ISL6259. Was there corrosion by U5000?

 

[dukefawks]

8.1V is probably with battery connected, check again without battery connected.

What is the voltage on backlight output, C7799.

 

[Kea]

The I/O Cable looks good on each side. I will check that later after work again.
Is the I/O Cable important for green light? Will it go green without I/O Cable?

I didn't see any corrosion, i think the previous owner cleaned it..

I checked the Voltage without battery.
Will check the Voltage from C7799 later.

 

[dukefawks]

Flat cable needs to be connected for light to work. Check PPBUS again as it should be 8.6V without battery.

 

[Kea]

Checked C7799: .010V
Did a beep test on fuse and it dont beep. I think i destroyed the fuse... Because i touched Pin 2 with the Metal Plate from the Chip beside and there was little Spark. Did i destroyed the fuse?

I checked PPBUS_G3H again: 8.18V

Is there corrosion under SMC?
Look at Pictures
thank you

​​​

 

[dukefawks]

I have no X-ray vision so just like you I cannot see under the SMC. Do a voltage and diode mode reading on both SDA and SCL lines on the battery connector.
I can also not tell you if the fuse is dead, a simple check with the multimeter should tell you.

 

[Kea]

The fuse from backlight is dead but thats not the problem now.

the board turns automatically on with magsafe plugged in. Without spin on off on off on off. directly on and spins faster in time.
R5100 is good. 99.1 kohm

PPBUS_G3H: 8.18V with good charger.

What should i do next?

 

[Kea]

Diode Mode SDA and SCL on Battery Connector

SDA: jumps from ~0.088 to 0.762 every second
SCL: 0.768 constantly

sorry for this dumb question but: is it right to do diode mode with power supply? because i have.

 

[Kea]

No Title

Oh my god, i'm so dumb.. i'm so ashamed.. you were right Louis , didnt checked the i/o cable correctly.

There is Pin Numbers 21 Missing and thats the Pin for PP3V42_G3H.

I ordered a new cable now. Hopefully it will fix it and i can use that MacBook for my study.

Look at the picture. Can anyone explaine how this circuit Works? Because i have PP3V42_G3H on the Board without i/o cable plugged in. Does it Go Back to the charger to say "its all okay, Power this Shit Up"?

Thank you for advice.

 

[dukefawks]

3v42 goes to the io board for the adapter sense line protection circuit. Without 3V42 on the io board the protection circuit will not enable the communication with the charger.

 

[larossmann]

The beginning of this video goes over how this all works. https://www.youtube.com/watch?v=xj3y8IhDPOQ

 

[Kea]

Thanks for explaining that.

Replaced the backlight fuse F7700. The I/O Cable will arrive tomorrow so i cant check now if the charger goes green.

Still no backlight. Will it only work with green light?

Checked U7701
VIN: 5.09V
BKL_EN: 4.89V
BKL_PWM: 0V on resistor R7704

Tested with LCD connected

 

[Kea]

I saw that on the DC IN Board is missing the PIN for PP3V42_G3H, so i soldered a jumper wire from L7095 to DC IN Board. Now i have green/orange light but no backlight. PPBUS_G3H still 8.18V with and without battery.

 

[dukefawks]

Get a new flat cable and IO board. SMC_LID is being pulled down by the corrosion. Also expect a dead SMC because of the 8.2V

 

[Kea]

Ordered a new DC in Board. What do you mean with flat cable? The IO cable from DC in Board? Already ordered.

Okay my next step would be to Change isl6259, am i wrong with that?

The MacBook Boots to question Mark folder. Keyboard is working too.

​but it seems to Not Charge the battery. Thats why i would Change Isl6259 next.

 

[JohnB8812]

When you boot into the OS, does the battery have an X through it or does it simply say battery is not charging?

 

[dukefawks]

ISL6259 is the first thing you can try, but in most cases the SMC is dead.

 

[Kea]

Okay i will try ISL6259 first.
Can i use a macbook air 2014 SMC on the 2015 Logicboard? I'm thinking to buy a donor 2014 board because the 2015 are rare and expansive.

And is backlight problem caused of a dead SMC/ISL6259? (will it fixed after PPBUS_G3H have the right voltage?)

john, i will test it when the working DC IN board will arrive.

 

[dukefawks]

As long as it is an 820-00165 board they are all the same. Parts boards from China should be about $20 on Ebay or Ali.