820-00840 / No boot / PP3V3_G3H Short to ground


Hello everyone,

Firstly sorry for my english, french guy inside.

I brought a macbook pro A1708 - 820-00840 logic board inside, wasn't powering on.
History is a day, nothing happened when opening the laptop, that's all.

Nothing special inside, no corrosion, no liquid damage, never opened, pretty good state.

First, with the logicboard alone on my desk, mesures are :
5v017 and 0.000 amp.
Finding a short on the PP3V3_G3H_VR, but not on the PP3V3_G3H (0.540 on diode mode)
PPDCIN_G3H_CHGR_R present (5,1 volts) PPVIN_G3H_P3V3G3H around 4.1 volts. PM_EN_P3V3_G3H around 2 volts.

To isolate the CC, removed L6995.
Short was not before it, but after, on PP3V3_G3H_VR. No short on PP3V3_G3H (at this time).
Removed all caps C6996/5/7/8/C6988/9, but short still there.
Decided to remove R6999. Then no short on PP3V3_G3H_VR (happy) but now PP3V3_G3H is shorted ! (around 0.002 on diode mode)e

Resoldering L6995, plug-in USB-C charger => 5v017 on charger, 0.00 amp, but PP3V3_GH3_VR now present (3.42 Volts).
Resoldering R6999 (the real mistake?) but nothing else. No short on PP3V3_G3H_VR (Pin 1 of R6999 shows 3.42 volts) but sill present on pin 2. I suppose resistance can isolate a short, because nothing is connected to the ground.

Removing C7080 on PP3V3_G3H (the most easier before thinking at U7000) and... nothing more. I decided to leave the board beside.

This morning, i plug the charger to make new tests, and, without touching nothing since the last day, charge stays at 5v017 but amp drop from 0.3 to 1.8A ! Nasty smell around U3100 and U3200... touching in the zone and burning my finger on Cap C3100... Damned !

Charger pulling down to 0.6 amp and 4.7 volts on first usb-c port, stay around this values and, around 5v017 and 0,3 amp on other port...

So i decide to take the voltage of PM_EN_P3V3_G3H => 5,17 volts !! how it's possible !

I decided to remove C3100, C3200, and U7000. Unfortunatly there still a short on PP3V3_G3H, and now another on the PP3V3_G3H_UPC_XA and XB.

So i remove the R3000 and 3001, one by one.

Short is gone on PP3V3_G3H_UPC_XA and XB, so i suppose U3000 & U3001 chips are fines.

But short on PP3V3_G3H is still there !

I remove R6999 to be sure again, but no difference...

Also tested keyboard connector who looks perfect, nothing special.

However, values are below :

Resistance from pin 15 to ground => around 2,6 ohms
Resistance from pin 16 to ground => around 0,9 ohms (same as shorting my multimeter)
Resistance from R6999 (pin 2) to ground => around 2,6 ohms

So Pins 15 & 16 aren't shorted together, connector seems fine.

A idea for the nexts steps (without more destruction?)

thanks a lot for your help


Staff member
First of all, welcome to the forum!

Please don't write so much in a post.
Try to go in the repair process step by step.
This way you can save time, avoiding wrong steps.

You've created a big confusion with 3V3_G3H short to ground.
How can you get short one side of 0 ohm resistor, but not on other pin???
Is 0 ohm value man, between its pins.
EXACTTLY same value to ground should be on its both pins; unless resistor is open/burnt!!!
Short to ground on 3V3_G3H will burn R6999, of course.

"So i decide to take the voltage of PM_EN_P3V3_G3H => 5,17 volts !! how it's possible !"
What's strange there?
Don't make confusion between a power rail and its enable signal!

Post diode mode to ground on all LDO lines of both CD3215 chips.


Thanks a lot, and sorry again for my mistakes.

So values requested are below (diode mode, red pin on ground)

PP3V3_UPC_XA_LDO : 612
PP1V8_UPC_XA_LDO : 639

PP3V3_UPC_XB_LDO : 617

(please note as C3000/3100 and R3000/3001 are still unsoldered from the board)


Staff member
Which is actual resistance to ground at 3V3_G3H?
Check it in ohm scale (not diode), on both pins of R6999 (to ground).


Staff member
First, as already said, R6999 is burnt/open.
2 ohm is low enough to find the short using voltage injection method.
Do not solder new/good R6999 until eliminate the short...


If I understand right (sorry if I ask for details) next steps are :
- remove r6999
- inject voltage directly on r6999 pin 2 (or any other pp3v3_g3h spot on the board)
- try to find shorted component on the board, with fingers or isopropyl.

Never done that, but understand how it work. major question is : how many voltage and amp may I have to inject to find it ?



I injected from 1v to 3.3v at 5A limit. Board take 0.17A at 3.3v max.

Nothing warm.

Retry to mesure my resistance to ground on PP3V3_G3H => now it's 127 ohms !
Diode mode => 127

The only thing i removed before injecting is R6999

Any idea?
Last edited:


Staff member
You should get 0.300 in diode mode approx; and much more in reverse way.
R6999 is already open/burnt in your board; doesn't influence in any way.

Did you inject voltage in the side with short to ground?


In diode mode i got 0.127 (sorry i don't write 0.xxx, my multimeter doesn't show the 0.)

U7000, C7080, R3000, R3001, C3100 & C3200 are still unsoldered, i don't know if it affect the value.

In reverse (ohm's mode) i read around 126 ohms, not more.

Injection done directly on PP3V3_G3H rail (in test point right of R5168), witch was in short before injection (around 2,6 ohms)


Staff member
Reverse way means black probe at ground; still in diode mode.

Resolder all the components and put new/good R6999 (0 ohm).
Then post again diode mode readings on 3V3_G3H and all LDO lines of CD3215 chips.


Thanks for explanations.

Is there a way to find new smd resistors & capacitors equivalence for apple products? And how to find exact value? (Don't have a donor board and my U7000 is dead, new one is on the way)


Staff member
For resistors/caps, schematics show nominal value and package size; like 0201, 0402, 0603, etc.
For the caps you should pay atention to nominal voltage, apart of capacitance.
Then you can search in any other boards, not only Apple stuff.


Ok. So if i understand right, R6999 is a 0 ohm resistor (0 under the name on schematic seems to be the resistance in ohms) so, in this case , it's just like a strap ?


Right! more easy to bypass.

So, i put back C7080, R3000, R3001, C3100, C3200 and all caps C6996/5/7/8/C6988/9.
U7000 isn't there.

Before strapping R6999, value for PP3V3_G3H_VR (diode mode) => 0.767 and PP3V3_G3H => 0.040

I've made a strap to replace R6999 :

PP3V3_G3H_VR (diode mode) => 0.040
PP3V3_G3H (diode mode) => 0.040

PP3V3_UPC_XA_LDO : 0.542
PP1V8_UPC_XA_LDOA : 0.635
PP1V8_UPC_XA_LDOD : 0.581
PP1V1_UPC_XA_LDO_BMC : 0.612

PP3V3_UPC_XB_LDO : 0.544
PP1V8_UPC_XB_LDOA : 0.627
PP1V8_UPC_XB_LDOD : 0.576
PP1V1_UPC_XB_LDO_BMC : 0.609

Note : before resoldering R3000/3001 and C3100/3200 i've taken PP3V3_G3H_UPC_XA and XB, each around 0.560 in diode mode.
Last edited:


Staff member
You still have a problem with 3V3_G3H power rail...
040 in diode mode could mean 50-80 in ohm scale.
Not too low to heat something with voltage injection.
You can try, in case some IC enters in thermal avalanche.
Using IR cam may help you to see small temp differences.


PP3V3_G3H is actually around 40,5 ohms.
In reverse diode mode, around 0.036 (Note that the R6999 strap have been removed to take these values)

Is it normal to have the same value in diode mode and ohms mode for this rail?

So, if i understand right, next step is to inject again directly on PP3V3_G3H around 3.5 Volts at Max Amp and pray for a notable short somewhere, that's it?

It's really strange that a firstly massive short to ground (around 2,6 ohms) becomes a short not so significant, don't you think? i haven't changed anything on the board, nothing replaced, only removed U7000 to be sure...
Last edited:


Staff member
"Is it normal to have the same value in diode mode and ohms mode for this rail?"
Depends by multimeter used.

You may have a capacitor partially shorted; its "ohm" value changes after burnt some part of internal layer.