Macbook A1706 EMC3071 (2017 Touchbar)

[kurtspirit]

Hello,

I have a Macbook Pro 2017 Touchbar (A1706) that suddenly shut down for no reason.
So I took it apart and started measuring.
The PP3V3_G3H seems problematic. I traced the line to component U6903 and on Pin 10, I measured 1.9V instead of 3.3V.
Unfortunately, my skills stop there and I don't understand where this type of failure can come from.
I saw on videos of repairers that the failure could come from the U7000 component which would be at the origin of the 3.3V but they have absolutely no voltage. I have a 1.9v...
What do you think ?

Thank you !

[mon2]

Re: Macbook A1706 EMC3071 (2017 Touchbar)

What is the voltage of ppbus_g3h ?

Remove all power. No battery. Meter in resistance mode.

Check the resistance to ground of ppbus_g3h.

Post the measurements.

[kurtspirit]

Re: Macbook A1706 EMC3071 (2017 Touchbar)

What is the voltage of ppbus_g3h ?

Remove all power. No battery. Meter in resistance mode.

Check the resistance to ground of ppbus_g3h.

Post the measurements.

If i'm right, i can do this on "pin 2" of the F7000 right ?

If it's the good place, i have : 0.02V and the resistance to the ground is about 0.97KoHm.

Thank you

[mon2]

Re: Macbook A1706 EMC3071 (2017 Touchbar)

Resistance sounds a bit low.

Remove all power -> desolder F7000 fuse.

Check the resistance to ground again after the fuse is removed @ pin #2 of the PCB fuse pad.

Repeat the resistance check on pin # 1 of the PCB fuse pad.

Now power up without this fuse -> what voltage do you see @ pin # 1 of the fuse pad ?

We are wanting to know if the PPBUS_G3H is working yet the current sense circuit is shutting it down due to an excessive load downstream.

Is the fault at the provider (U7000) or the consumer (downstream; pin #2 of the fuse) ?

Post all measurements.

[kurtspirit]

Re: Macbook A1706 EMC3071 (2017 Touchbar)

Without fuse, on pin 1, it's also very fluctuating... Suddenly I have 13MoHm and it goes down and if I take a measurement a few seconds later, I have 1.4MoHm.
On Pin 2, I have around 0.95kOhm but I sometimes have 1.9MoHm too.
I don't understand the measurement. Could it be a capacitor?
On the voltage side, I have 0.02V on pin 2 and 0.45V on pin1.

[mon2]

Re: Macbook A1706 EMC3071 (2017 Touchbar)

What is the voltage reading for the following ?

PPDCIN_G3H

PP3V3_G3H ; measure @ L6900 (this rail must be 3v3 to get the board started)
* if it is not ~3v3 (or very close to) then remove all power -> meter in resistance mode -> check the resistance to ground of L6900, pin #2

PPVIN_G3H_P3V3G3H ; measure @ D6902 (pin # 3)

[kurtspirit]

Re: Macbook A1706 EMC3071 (2017 Touchbar)

Hello,

Without F7000 :

For the PPDCIN_G3H[/B] : 5.11V

PP3V3_G3H L6900 : 0V - Resistance of L6900, pin #2 is about 4.3koHm but question please: rail on pin #2 isn't PP3V3_G3H but PP3V3_G3H_REG_R on my BRD. Is it the same ?

For PPVIN_G3H_P3V3G3H , D6902 (pin # 3) give 1.05v

I try with F7000 too and result are similars.

Thank you very much

[mon2]

Re: Macbook A1706 EMC3071 (2017 Touchbar)

Post the voltage on D6902, pin #1 and #2.

So red meter probe to pin #1, black probe to ground. Measure the voltage.

Then repeat with red probe on pin #2 and ground.

[kurtspirit]

Re: Macbook A1706 EMC3071 (2017 Touchbar)

On pin #1 , black probe to the ground : 0.025V. With red on ground : -0.025

On Pin #2, black probe on ground : 5.11V, red on ground : -5.11V

[mon2]

Re: Macbook A1706 EMC3071 (2017 Touchbar)

Remove all power. Meter in resistance mode.

Measure the resistance to ground of D6902, pin #3.

What is the resistance?

[kurtspirit]

Re: Macbook A1706 EMC3071 (2017 Touchbar)

on Pin#3 148oHm

[mon2]

Re: Macbook A1706 EMC3071 (2017 Touchbar)

D6902 appears to be defective.

Remove D6902, then check again the resistance to ground of D6902, pin #3 pad on the logic board.

The resistance is a bit low but let us see what it is with this dual diode off the logic board.

You have ~5v going into the dual diode but ~1 volt leaving. There should only be ~0v6 voltage drop here.

This large voltage drop may be due to low resistance on pin #3 which will imply the regulator is the fault.

Do you have spares of the dual diode or can source this part? It is a common part available from AliExpress, Mouser or Digikey or RS electronics.

With AliExpress, you can order the full replacement parts to rebuild this circuit area for cheap.

Can post some ideas later. Back to my beauty sleep...

[kurtspirit]

Re: Macbook A1706 EMC3071 (2017 Touchbar)

Without D6902 onpin #3 pad, i have 214ohm.

I don't have a spare for replace it but i have a 820-2936-B board. Maybe it have this famous diode. I'll check with a brd file.

Thank you very much for your help !

[kurtspirit]

Re: Macbook A1706 EMC3071 (2017 Touchbar)

ok... i find it on my donor board. The D6902. I thought it was the same but the diode burn directly when i put the voltage. I hope it doesn't have to much damage on board.

[mon2]

Re: Macbook A1706 EMC3071 (2017 Touchbar)

The resistance is still low on this pad. In fact, lower than your last reading.

This voltage regulator maybe defective and will require to be replaced.

Check the removed D6902 as follows:

Meter in diode mode. Now place red meter probe to one pin on the side with the 2 pins on this diode. Black probe to the side with the common cathode single pin.

Meter should beep tone. Now reverse the probes and the meter should NOT beep tone.

Repeat with the other leg on this diode.

If you hear beeps after reversing the probes, then the diode is defective. My strong suspicion is this diode is defective. The regulator may still require a replacement due to the low resistance to ground.

In the end, the input voltage to this regulator is too low to enable and yield as ~3v3 or 3v42 as noted in the schematics to power critical rails on the logic board. This is a major and required power rail.

[mon2]

Re: Macbook A1706 EMC3071 (2017 Touchbar)

The new d6902 being killed confirms that the regulator is drawing too much current. The regulator should be replaced.

AliExpress is great for such parts. Check Hong Ming store. Install the AliExpress app or search with your pc on their website. They can also supply the dual diodes. With a bit more on shipping, you will receive the parts in a few weeks or sooner.

[mon2]

Re: Macbook A1706 EMC3071 (2017 Touchbar)

Here is a link to this store we use often:

US $3.33 15%OFF | (5piece) 100% original RT8249CGQW RT8249C 2N=2A 2N=2J 2N= QFN-20 Chipset
https://a.aliexpress.com/_mMFzDV6

Chat them for the dual diode and this regulator. Buy spares to be safe. They can also supply the u7000 intersil part but this area of the logic board requires repair first.

[kurtspirit]

Re: Macbook A1706 EMC3071 (2017 Touchbar)

So I removed the diode again and checked as you explain. I don't have a "beep".
The diode appears to be completely faulty.
The only thing to do is buy a new one, right?
I also need to find out which component is the regulator? Maybe it's better if I buy both.
Thanks a lo

[kurtspirit]

Re: Macbook A1706 EMC3071 (2017 Touchbar)

Thank you for the link.
I'll chat with them because the diode aren't in their store.
Thank you again for all

[mon2]

Re: Macbook A1706 EMC3071 (2017 Touchbar)

yes, the dual diode for sure is required to be replaced. Order spares along with the regulator.

See attached. Remove both of these capacitors off the logic board.

No power to the board -> check the resistance again on D6902, pin # 3 after these caps have been removed.

We are trying to determine which part is causing this line to be loaded down so much. These caps are not polarized so they can be placed back in either direction after this quick test.