820 - 00165 A liquid damage, green light but no fan spin no boot

[estelanim416]

Hi,

Bath submerged macbook air,
Obvious damage to the backlight circuit and both the lcd connector on the board as well as the lcd cable.
Put through crest, replaced dodgy looking bits in the backlight circuit, changed the lcd connector.
New io board and flex.
When I plug it in with only lcd and ssd connected, I get green light but nothing else

Also not sure about the keyboard, I am guessing there a pins I can short to turn the power on, tried a few that are labeled smc on but no difference

 

[2informaticos]

Test the board alone, only 5 pins DC cable connected.
It should start automatically when charger is connected.


Try first to start in SMC bypass mode.
Post SMC_ADAPTER_EN, PM_BATLOW_L, PM_SLP_SUS_L, 3V3_S5, 3V3_SUS.

 

[estelanim416]

OK, no green light for some reason when I left only the 5pins in.
SMC_ADAPTER_EN 0v
PM_BATLOW_L 0v
PM_SLP_SUS_L 0v
3V3_S5 0v
3V3_SUS 0v

I was checking a few other things

g3h is 8.2v

U5110 lloks a bit dodgy and few smaller bits around it

 

[2informaticos]

"no green light for some reason"
Of course, no LIO flex connected.
You don't need the light at this moment.

Confirm if you really have 3V at SMC_RESET_L.
Do you get 3V at both pins 5/8 of U5110?

If missing SMC_PM_G2_EN, you may need to reball SMC.
Reflow it with good flux first...

 

[estelanim416]

Thanks 2informaticos, just shows you how little I know

SMC_RESET_L 0V unfortunatelly

U5110 0v on both 5 and 8 pin

SMC_PM_G2_EN is missing

OK, I will reflow SMC and see if that makes it any better

 

[2informaticos]

Don't torture SMC yet!!!

"U5110 lloks a bit dodgy and few smaller bits around it"
Clean its area, resolder, change corroded components...

"I get green light"
With SMC_RESET_L at 0V???

 

[estelanim416]

Cheers

I redone the U5110 and the bits around yesterday
Yes, I still get the green light when the flex cable is connected.
Checked SMC_RESET_L with and without flex cable, still 0v, I checked on 2 points far away from each other

Tried reflowing SMC, 200 Celsius with my quick 861da and mg chemicals flux but no difference :/

 

[2informaticos]

Missing SMC_RESET_L blocks the SMC.
Strange to get Magsafe light in this case; maybe fake charger used...

You MUST get steady high level at SMC_RESET_L to continue.
Check resistance to ground there.
Be sure R5100 is good.
Remove U5110 and check voltage level.
Remove R7100 and check again.
Also clean/remove J6100.
Then only SMC remains to change; try reflow it first...

 

[estelanim416]

Ow yes, the charger is 3rd party :/

SMC_RESET_L resistance to ground goes up and down 300 -400 k?
By accident I discovered that there is continuity between SMC_RESET_L and CHGR_RST_L, not sure if that supposed to be the case.
I will follow your advice and report back
Fingers crossed

 

[estelanim416]

R5100 comes up as 96.7k omhs so it seems fine

removed the u5110 and I am getting 3.4v SMC_RESET_L - looks like good direction

SMC_PM_G2_EN 3.4v

the pads for u5110, pad 5 3.4v, pad 8 0.42v ( thats without u5110 in place)

SMC_ADAPTER_EN 3.44v

PM_BATLOW_L 0.03v

PM_SLP_SUS_L 3.32v

PP3V3_S5 3.32v

PP3V3_SUS 3.32v

I guess I need a new U5110, right?

 

[JohnB8812]

Your problem is also going to be the battery after you fix PPBUS so definitely get a known good OEM 85 Watt Magsafe 2

 

[2informaticos]

Change U5110 and comment the result.

 

[estelanim416]

Tried that with a U5110 from another board but same results. I cant be sure about that one so I ordered a few ICs.

 

[2informaticos]

SMC_REST_L goes down when you've soldered other U5110?
Then change C5101 and post voltage for pins 6 & 7.