820-000165 Dead

[fusioninfo]

Hello, i have this macbook air here 820-00165 which was dead, clean no signs of water anywhere. Found out with some help that smc_reset_l was low (0.9v) and replaced U5110 and this voltage got back to it's normal value. Got green and orange light on magsafe, it booted but was sluggish to death. diagnostics says everything is ok, recovery environment is awefully slow and it's unusable in the os.

I have to keep power down for a long time for it to boot, after the chime otherwise it shuts down.

Left it charging and it went dead again, so i tried replacing again u5110, but it didn't change anything. New to these things, i'm not sure where to go from here. Thanks in advance!

 

[2informaticos]

First of all, welcome to the forum!

You should try clean ME BIOS.
Does it boot normal in Windows, or Linux?

 

[fusioninfo]

Hello ! Ok, what do i need to be able to flash this bios ? I haven't tried to boot it in windows or linux, but the hardware still has an issue since i have to hold the power down no ? It also goes dead and comes back alive for no apparent reason - some day it powers on - next day it's dead and voltage to smc_reset_l is down to 1v or so again..

 

[2informaticos]

Seems that only boots on SMC bypass mode.
If you short press power button, check for pulse at PM_SLP_Sx signals.

SMC_RESET_L is not stable?

 

[fusioninfo]

It oscillates from 1.6 to 1.8vdc and the magsafe light goes from green to amber by itself constantly with a few seconds delay.

How can i press the power button and at the same time poke on the board with both meter leads ? there's some tricks i don't have it seems.

 

[2informaticos]

Solder a wire on convenient point of SMC_ONOFF_L and touch the ground; usually R5115/16 pads.

You MUST get correct SMC_RESET_L signal first.
Remove U5110 and check if is stable.

 

[fusioninfo]

Ok, will report back. thanks