820-4924 - No Power, No Liquid Damage

[bcherdak]

Hey guys, I have here a 820-4924 with no power.

Green then Orange light, when pressing power CPU heats up, then trackpad is clickable for a few seconds.

then the trackpad is not clickable and CPU cools back down.

I have tried original 60w magsafe 2, I have tried multiple charged batteries, that are fully OEM, pulled from other machines, I have tried a working/tested trackpad, and trackpad cable.

ppbus_g3h - 12.27V // 250 ohms
PP3V42_G3H - 3.4V // 10k ohms
PPVRTC_G3H - 3.4V // 18k ohms
PP5V_S5 - 5v // 18k ohms
PP5V_S3 - 5V <--- WHEN POWERING ON, BUT THEN IT GOES DOWN TO .2V
PP5V_S0 - 5V // 13k ohms <--- WHEN POWERING ON, BUT THEN IT GOES DOWN TO .2V
SMC_LID - 3.4V // 87k ohms
PP3V3_S5 - 3.4V

Board is completely clean, never been messed with, all screws were untouched.

Any other voltages I can test?

 

[2informaticos]

Try if board stays on starting in SMC bypass mode.
Test the board disconnecting anything.
Just keep DCIN board and use USB mouse for test.

"ppbus_g3h - 12.27V"
Incorrect voltage"
Post exact resistance between pins 17/18 and 27/28 of U7100.
Also post voltage and diode mode on SCL/SDA lines of battery bus.

 

[bcherdak]

Try if board stays on starting in SMC bypass mode.
Test the board disconnecting anything.
Just keep DCIN board and use USB mouse for test.

"ppbus_g3h - 12.27V"
Incorrect voltage"
Post exact resistance between pins 17/18 and 27/28 of U7100.
Also post voltage and diode mode on SCL/SDA lines of battery bus.

Hi and thank you for responding, I have tried SMC bypass mode and that does not work, is the correct way of doing SMC bypass by unplugging the laptop, holding the power button for 10 secs, plugging the computer back in while holding the power button for an additional 10 secs and then releasing and pressing it again to get it to boot.

Also, doesnt the 2015 macbook pro need a good battery, trackpad, and keyboard attached to start up, I heard they act kind of funny.

Also post voltage and diode mode on SCL/SDA lines of battery bus.

I am not 100% sure what those mean, are you talking about the SMBUS_SMC_1_S0_SDA and the SMBUS_SMC_1_S0_SCL line?

Will report back with resistance between pins 17/18 and 27/28 of U7100.

 

[2informaticos]

Do NOT quote an entire post, visible few centimeters above.
Maintain forum aesthetic, please.

This board should start by itself when charger is connected.
You can trigger SMC_ONOFF_L signal for test to check other reactions on the board.

I was reffering to SCL/SDA lines common to battery, ISL6259 and SMC...

 

[bcherdak]

Sorry about quoting,

I will Use R5115/16 pads for that.
Solder a tiny wire on SMC_ONOFF_L and simulate power button touching some metal plate from chassis, is that correct?

When it comes to SCL/SDA Lines do you mean

ISL(U7100)
PIN 10 which is SMBUS_CHGR_SCL
PIN 11 which is SMBUS_CHGR_SDA

SMC(U5000)
R5351 which is SMBUS_SMC_0_S0_SCL
R5350 which is SMBUS_SMC_0_S0_SDA

Battery
Not sure about the scl/sda lines, if you can let me know.

Please let me know if I am heading in the right direction.

 

[2informaticos]

Is correct, but still waiting to post the values...

 

[bcherdak]

Thank you, I will post the values once i get back into the office, thank you for your help, I will reply with it later today.

 

[bcherdak]

ISL(U7100)
PIN 10 which is SMBUS_CHGR_SCL = 3.4V // 12.5k OHMS
PIN 11 which is SMBUS_CHGR_SDA = 3.4V // 12.5k OHMS

SMC(U5000)
R5351 which is SMBUS_SMC_0_S0_SCL = 0.08v // 33.5K OHMS
R5350 which is SMBUS_SMC_0_S0_SDA = 0.08v // 33.5K OHMS

Shorting SMC_ONOFF_L to ground does nothing at all.

 

[2informaticos]

To be more specific, -SMC SMBus "5" G3H- is the battery bus.
And I was expected diode mode readings, not ohm scale.
Should be good, ohm values are equals too.

"Will report back with resistance between pins 17/18 and 27/28 of U7100"
???

Do you get 3V3_SUS?

 

[bcherdak]

"Will report back with resistance between pins 17/18 and 27/28 of U7100"

u7100
pin 17 = 70k ohms
pin 18 = 7.2k ohms
pin 27 = (OL) Open Line
pin 28 = (OL) Open Line

"Do you get 3V3_SUS?"
yes I do 3v3_SUS = 3.42V

thank you for your support.

 

[2informaticos]

I meant resistance between specified pins, not to ground.
However, your readings show problem with R7150-52 network resistors, at least.

 

[bcherdak]

U7100
Resistance between pin 17 & 18 = 4.0 Ohms
Resistance between pins 27 & 28 = 20.7 Ohms

You do not think it is problem with SMC? As it might be dead?

 

[2informaticos]

Something wrong with SMC-U7100 communication.
Please podt diode mode readings (red probe at ground) on SCL/SDA lines.

 

[bcherdak]

Hi diode mode readings

u7100
PIN 10 (SCL) - .52v
PIN 11 (SDA) - .52v

SMC
R5350 (SDA) - .73v
R5351 (SCL) - .73v
are these the right resistors to test from? I cannot find any others.

 

[2informaticos]

You still mix the things here.
If we talk about the SAME (common) bus between different chips, why do you check R5350/51???
Battery bus is SMBus 5.
And which is the reason to try measuring the same line in different points?

The readings look good.
In this case I recommend to change first U7100.
If no result, reball/change SMC...

 

[bcherdak]

"If we talk about the SAME (common) bus between different chips, why do you check R5350/51???"

I was just measuring all the SDA, SLC lines that I see with that substring included in openboardview and the schematic pdf, I do apologize.

Question, what are the smbus_smc_0, smbus_smc_1,smbus_smc_2, smbus_smc_3, smbus_smc_5?

Do you want measurements for all of them?

 

[2informaticos]

Why all, if are totally different buses??
I specified you to FIX on battery bus (SMBus 5).

 

[bcherdak]

"I specified you to FIX on battery bus (SMBus 5)." I will replace u7100 and reball the SMC, will post with results. Thank you!!!!!

 

[bcherdak]

Replaced u7100, and reballed SMC, trackpad clicks for a few seconds then stops. CPU gets warm and then cools back down,

After that I replaced SMC from another board 820-4924 and same thing, trackpad clicks for a few seconds, (taptic feedback) and then stops.

Same issue, any more suggestions?

 

[2informaticos]

Didn't get 12.5V on PPBUS_G3H yet?