MacBook Pro 13inch 2017mid (A1706 820-00923-A) - liquid damage - USBC and Display short circuit

[rilley]

Hello everyone,
I am new into this, sorry to post it here. I want to make this as a pet hobby project, as this mac is not urgent.

I have (Macbook Pro 13inch 2017mid) A1706 820-00923-A

My mac had liquid damage a long time ago, the connector from J8500 is damaged on pin 46 (PP5V_S0_ALSCAM_F), I guess the LCD/display panel is in short circuit, as I saw the connector from the LCD burned as well.

And the resistor L4004 is literally burned.

From what I see from the schematics, it does not affect any other rails, only the connection to the display port.

(see attached photo L4004-J8500)
(see attached photo L4004-120OHM)

I have sent this mac to a service a long time ago, and they didn't helped me because they said it is way to expensive. I don't believe them.

I have checked, they removed the USB-C port from the motherboard: JB500 ( left side of the board, but USB-C when mac is on the desk is on right side )

(see attached photo JB500)


I have checked the board there where and the connector were removed, and I saw a little bit of small burn/scratch on the 20V+ connectors:
PP20V_USBC_TA_VBUS_CONN
PP20V_USBC_TB_VBUS_CONN

And also on the USBC connector from the mac case on the same pins.

One note, I think they removed CB513 from the left side of the board near the USBC connector. ( as I see it missing, and on the right side, all 4 are there )

(see attached photo CB513)


Usually I charge my mac from the right side, so I think, after the liquid damage, the USBC right side got burned, and also on the LCD side on L4004

Without connecting the LCD or L4004, can I start debugging the board from the USBC that is in place ( J3300 ) and connect it to the charger and start measuring stuff? ( without connecting anything, no keyboard, no battery, no LCD, no nothing, just the board )

Or it will get burned the connector J3300 as well?

(see attached photo J3300)

What do you think?
Thank you in advance!

[rilley]

Hello!

I connected the board to the power supply (61W original apple charger) without any component connected.

Did some measurements:

C6483
PPBUS_G3H
= 13V

C7676
PP3V3_S5
= 3,2v

SW5227
SMC_RESET_L
= 3,3v

R5225
SMC_ONOFF_L
= 3,3v

PP3V3_G3H
= 3,3v

PP5V_s0
= 5v

When shorting the SMC_ONOFF_L to ground, nothing happens. I've also tried to keep the SMC_ONOFF_L shorted to GND for a few seconds, then while keeping them shorted, connected the power supply, waited a few seconds and released SMC_ONOFF_L, and still nothing happens.

Also tried to short SMC_RESET_L to GND, and still nothing happens.

If I connect the board to all the elements from the mac case, the battery is charging, and the trackpad works (has that sounds when 'force' touching).

Do you know how to proceed next? I want to turn it on to see if it works, tried also to connect to external monitor through original hdmi apple adapter, also on the second usb-c connected a mouse with led to see if any activity (no activity so far). Also connected my Android phone via usb-c - usb-c to see any activity (no activity so far).

[rilley]

Sorry to interrupt here.

In theory if I have:
SMC_ONOFF_L = 3,3v

And short this to ground, it should start the board (power button), right?

I'm asking as I have a A1706 that had liquid damage, the short components from one side of the USB-C were removed, and I'm trying to power-up the board.
The Power button, I think it doesn't work, MENU_KEY_L pin is missing from the motherboard flex connector.

Thank you.

[mon2]

Yes.

[rilley]

Thank you for clarification.

Tried to short to ground the SMC_ONOFF_L for a few seconds while the power cable was connected, board outside with no other peripherals connected.

Also tried to start the board with SMC_ONOFF_L bridged to GND for 10 seconds and then connected the power, and released the SMC_ONOFF_L, but nothing happened, CPU heat sink is cold.

I only have a multimeter, I don't have oscilloscope, and I don't have that USB-C multi meter that I can measure the 20V / and amper from cable. (will buy one in the future)

I can't measure PM_PWRBTN_L for activity as the pin is too small and I might mess things up there.. :S

[mon2]

Liquid damage is, of course is dangerous. Liquid spill near lcd connector area can transport the very high backlight voltage onto the cpu low voltage rail which then makes this a no fix case.

Remove all power. Meter in resistance mode. Measure the resistance to ground of the cpu power rail. You can measure this at one of power inductors used by the multiphase power supply for vcore.

Next, one meter probe here, other meter probe to ppbus_g3h fuse. What is the resistance? Checking if the high side mosfet use by the cpu is leaking or not.

[rilley]

Thanks for helping me out!

With board out of any connectivity and cables.


First measurement I did:
- Multimeter in resistance mode, at 200
- Black probe at GND of the motherboard
- Red probe of multimeter at CPUCORE_SW1 ( from L7210 )
- Red probe of multimeter at CPUCORE_SW2 ( from L7220 )

>>>> On both core test had 6.1 ohm

Second measurement I did:

• Multimeter in resistance mode, at 20k
• Black probe at PPBUS_G3H ( from C6483 where I had 13V in the past )
• Red probe at PPVCC_CPU_PH1 and then at PPVCC_CPU_PH2 ( from L7210 respectively L7220 )
• It started to show on multimeter 6 ( I think 6kOHM ), and then it kept rising, and at around 10k I've removed the probes.

*Attaching some pictures with the schematic.

[mon2]

Correcting my incorrect comment - if you have PPBUS_G3H then PPBUS_G3H is not shorted. Respectively, believe your CPU is ok.

Do you have actual pics of your board that can be posted? Not boardview screen grabs. Suggest to pickup a bidirectional USB C meter from Amazon or similar. Then we can know the voltage and current draw of the logic board which can assist in debugging your case. Lots of similar cases on repairwiki, etc.

Any fan spin?

What is the voltage to ground of ALL_SYS_PWRGD? This is a power good signal that should be a logic '1' if all power rails are deemed to be OK.

[rilley]

I'm attaching here some pictures that I took with the board, and will respond afterwards with more details. (sorry if it might be bad quality, took them with my iPhone and the lighting right now is dark here, will do more in the next days if needed)

[rilley]

Thanks for answering about the CPU, this is a relief as this board might have chance to work.

About the bidirectional USB C meter, will try to buy one soon.

I tried also connecting the board with the keyboard flex, and trackpad flex, did the SMC_ONOFF_L and nothing happened, no fan..

What I saw, the trackpad seems to work, when I touch it, it has that "force touch" sound.

What I also noticed if I had the battery + battery status cable connected, it started to charge it, as I noticed the power adapter transformer was warm, and after removing the power cable, the trackpad still worked, also verified the motherboard battery + - connector, and I got voltage there.

(power button I think is unresponsive because I did a test with the board outside of the casing, with only the power adapter cable to the USB-C and pressed the power button, and measured the SMC_ONOFF_L and didn't noticed any change, it was 3.3v there, regardless of the power button press, and I checked the MESA connector from the board, and the MENY_KEY_L pin is missing, not sure if is related or not)

The display connector from the board looks good, but the flex cable that went to the display, on the PP5V_S0_ALSCAM_F is burned, also on the display connector the PP5V_S0_ALSCAM_F is burned, and the only burn that I saw on the motherboard is near the J8500 connector, the L4004 is burned, missing.

Also, the USB-C connector from the board JB500 is missing ( left side ), I think the service that I employed a long time ago tried to remove most of the components that were in short. (I think).

Will try to measure ALL_SYS_PWRGD, a little bit harder as it is too small, but will try to measure.

[rilley]

I've checked at the ALL_SYS_PWRGD test pad, while board connected to the power adapter only (no other cables connected to it), I have 0v on that.

[rilley]

Measured the PP3V3_S0 at R5860, and I have 3.35v

[mon2]

power supply (61W original apple charger)

This is too weak of a power adapter for this model. Use 96W or higher USB Type C adapter with a 100W rated cable. If the cable is not rated for 100W, then the power delivery contract will be lower than required to power this target.

https://boards.rossmanngroup.com/thr...r.65094/page-2
* post # 21

[rilley]

That charger 61W came with the mac, and it worked.

Anyway, recently I've switched to 96W as I have one that works.

[mon2]

Carefully measure the voltage to ground @ C7029. This is the input voltage rail from the external power adapter and is used to create the PPBUS_G3H main rail.

What is the voltage here? Is it 20V or is it 5v? Good if 20v which confirms the PD controller chips (ACE) are working as they should. If not, PD controllers needs to be reviewed.

[rilley]

At C7029 I have 20.4V

[rilley]

I've re-checked the ALL_SYS_PWRGD, black probe to GND, and measure unit to DC red to ALL_SYS_PWRGD, still 0V, when I touched the red probe, I've noticed small changes on the measure unit, but still 0V. ( measure unit set to 20v threshold )

[rilley]

The PPBUS_G3H at C6484 it is 13V stable.

[piernov]

If there was liquid damage in the LCD connector, CPU is most likely damaged anyway as a result of backlight rail arcing with eDP AUX line.

[rilley]

Did some measurements with the board connected to power charger on USB-C.


PPBUS_G3H
= 13V


PP3V3_G3H
= 3,4V


PP3V3_S5
= 3,3V


PP5V_S5
= 5,13V


PP3V3_S0
= 3,3V


PP5V_S0
= 5,1V


PP1V8_S0
= 0V


CPUCORE_SW1
CPUCORE_SW2
= 0V


PPVOUT_S0_LCDBKLT
= 0V


PP3V3_SUS
= 3,2V