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MBP 820-00281 A1707 - Not turning on after thermal paste replacement

j.seyvecou

j.seyvecou

New member
Hello,

I may have shorted something during the process of thermal paste replacement. No sign of magic smoke or apparent damaged component.
The Macbook doesn't want to turn on anymore (screen, keyboard and touch-bar stays black). I do have fans spin and track-pad feels clicky when powered on. A long press on the touchID button turn it off. I doubled-checked all the connections and everything seems to be plugged in the right place.

I took some measures if it can help, based on one of the video I found here.

PPBUS_G3H -> 12.6V
PP3v3_G3H -> 3.4V
PP3V0_G3H -> 3V
PP5V_S4 -> 5.1V
P5VS4_EN_RCD -> 3.3V
PM_SLP_S5_L -> 3.3V

PP5V_S0 -> 5.1V
PP5V_S0SW_LCD -> 0V

PP3V3_S5 -> 3.3V
PP3V3_S0SW_LCD_R -> 0V
LCD_PWR_SLEW_3V3 -> 0V
PP3V3_S0SW_LCD -> 0V

BKLT_SD -> 5.13V
LCDBKLT_EN_L -> 11.3V (Shouldn't d this be 12.6? )

Any idea what could go wrong?

In advance thanks,
Justin
 
2informaticos

2informaticos

Administrator
Staff member
Try the board alone, with no device connected.
Just connect charger and check for S3/0 voltages.
Also try to start in SMC bypass mode.
Check for knocked off components, or damaged traces near the heatsink screws.
 
j.seyvecou

j.seyvecou

New member
Thanks for the quick answer,
I tried the board alone with only the charger plugged-in. As I said in my previous message, no damage apparent on any components, doesn't smell like burned or what so ever. Heatsink feels hot when plugged-in which I guess is a good sign.
 
j.seyvecou

j.seyvecou

New member
The USB-C adapter LED lights when board turned ON
Unfortunately nothing shows on the monitor...
 
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j.seyvecou

j.seyvecou

New member
Well, got in a very dusty environment, run hot for a couple of years and the old thermal paste dried out... After reinstalling the OS (nothing running in the bg) and fans set to 100%, I measured idle temperatures at 90 degrees C. This was unacceptable...
This laptop was always kept dry, and no green/blue signs on the board.

I don't know if this could be a clue where to look at, but everything around U8500 and U8501 don't get the right voltage, see my first post. I get PP5V_S0 at 5V and PP3V3_S5 at 3.3V but nothing out.
 
2informaticos

2informaticos

Administrator
Staff member
Why do you bother with internal LCD, if don't have external video, nor even USB activity?
Do you get CPU voltages?
 
j.seyvecou

j.seyvecou

New member
To be honest I have no idea where to look at exactly but I assume the CPU gets power, since it gets hot when the board is powered on.

Edit:
PPVCC_S0_CPU is 1.11V
PPVCCIO_S0_CPU is 0.97V
PPVCCSA_S0_CPU is 12.6V
 
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