820-00165-A Overheating and shuts down. It turns on after reflow U7100.

[juhusu]

Hello guys. the macbook air overheats and shuts down in about 10 minutes or less. When I connect the charger it gives me a green light and then a permanent orange but the fan does not move. I go to the U7100 do a reflow or replacement and the mac turns on normally but turns off again after a while and so on.
A detail: When turning on with the charger connected, the battery increases the percentage of charge but the lightning does not appear inside the battery. After a while it turns off as explained above.

 

[Askaleto]

Hello, if you remove battery and plug in charger, normal board booting is this:
1. Fan ON after few sec OFF two times
2. Fan ON and board started.

If there is no FAN spin at all, try exchange the FAN. If touchpad is disconnected, because of palmrest sensor, fan is going to run at full speed. If that is not the case, your fan is probably bad.

 

[piernov]

Fan spin/stop/spin/stop/spin is only on 3435/3437. 00165 doesn't do this, fan should start spinning and stay on when turning on the machine.

 

[2informaticos]

Post exact PPBUS_G3H voltage without battery.
Also check voltage and diode mode to ground for SCL/SDA lines of battery bus.
Check ohm resistance between pins 17/18 and 27/28 of U7100.
Do all these when the board is cold.

 

[juhusu]

PPBUS_G3H voltage without battery = 8.60V
voltage without battery SCL/SDA = 3.42V/3.42V
diode mode to ground for SCL/SDA = 5.53V/5.49V
ohm resistance between pins 17/18 = 4.2 ohm 27/28 = 20.8 ohm

 

[juhusu]

Thanks guys for all the support

 

[2informaticos]

Machine still turns off without battery?
See what happens if you start in SMC bypass; apart of full spin fan, which is normal then.
Be sure the heatsink is good and change thermal paste.
Try clean ME BIOS, just in case.

 

[juhusu]

The machine does not start with battery or without battery. When I turn on SMC Bypass mode it doesn't do anything (the fan doesn't move at all) The heatsink looks perfect and I already changed the thermal paste. The only thing I have not done is clean ME BIOS. But I tried to reflow the wonderful U7100 and the machine started normally. I extracted the original .bin file from the bios in case something happens again.
What is going to drive me crazy is how just by reflow the U7100 the machine comes to life again. Crazy my friend. Another recommendation if the machine dies again?
Thanks for your help.

 

[2informaticos]

Probably the heat affects something else in the board; try another ISL6259, just in case.

If the machine starts in normal mode, then MUST start in SMC bypass too!
It should also start with charger alone (no battery) in normal mode.