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820-4924 - No Power, No Liquid Damage

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bcherdak

Member
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?
 
Last edited:
2informaticos

2informaticos

Administrator
Staff member
Do NOT quote an entire post, visible few centimeters above.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...
 
B

bcherdak

Member
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.
 
B

bcherdak

Member
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.
 
B

bcherdak

Member
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

2informaticos

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

Member
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.
 
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bcherdak

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

bcherdak

Member
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?
 
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