A1466 820-3437-b not turning on

[Biggtechman]

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  Hello everyone.
  last week I got a macbook air a1466 820-3437-b with reports that it stopped working.
  
  was told a few months prior to this that it was exposed to a tiny bit of water.
  
  also was told in the last 2 months prior to it dying that it was turning off earlier then what battery says.
  
  my findings.
  upon examination I checked one wire circuit and it works.
  checked 8v line and it works.
  no 5v ot 3.3v line work.
  nothing on top side stranded out as corrosion..
  however on the bottom side I noticed corrosion around r1661 and the 3 test point closest to it were completely dead. So r1661 pin 1 that runs to the test point was down. I could not solder a jumper back to it because the pad was so corroded l. Also line for r1663 pin 1 line was down to test point, same for r1669 pin 1 to test point.
  
  forgive my boorish question, I'm unfamiliar with board view. I normally fix iPhones.
  
  is that test point the only means of communication that the resistors have ?
  
  can I use board view to check what is on the test point line for that specific resistor and run a jumper to closest component?
  
  also am I wasting time ?
  will any of these resistors causeing no power on ?
• thanks again. Any advice or help is appreciated

 

[2informaticos]

These resistors I don't think to be related with start sequence.
Check presence of PPVRTC_G3H and the 4 derived RTC signals: RTC_RESET_L, PCH_SRTCRST_L, PCH_INTRUDER_L and PCH_INVTRMEN.
Post voltages for SMC_ADAPTER_EN, PM_BATLOW_L, SMC_PM_G2_EN, SMC_RESET_L.
Do you get magsafe light?

 

[Biggtechman]

Yes one wire is active.
I'll check all them points and get back to you.
thanks for responding

 

[Biggtechman]

3.329v on ppvrtc_g3h
3.321 on rtc
3.321 on pch_srt
3.011 on pch_int
3.217 on pch_inv

3.410 on SMC_ADAPTER_EN
3.325 on PM_BATLOW_L
3.440 on SMC_PM_G2_EN
3.408 on SMC_RESET_L

I just checked ppvcc_so_cpu and it reads 0 volts.
I seen some other guy with a similar issue out a post up.

Could I please have some guidance as to what direction I should take next ?
this is my first macbook air board level repair.
I have repaired a fair few iPhone board issues, but am a bit lost with Mac's.

thanks again for any advice or guidance you can provide.

 

[Paul Daniels]

can I use board view to check what is on the test point line for that specific resistor and run a jumper to closest component?

What boardview program are you using? OpenBoardView and FlexBV should bring up all the other points on the board that share the same network, including parts.

I suspect with R1669, what you're finding is that the other part on the board one side is connected to is the CPU on the directly other side of the board (see the faint blue line and ring, they indicate the connection on the other side)

 

[2informaticos]

Short SMC_ONOFF_L to ground and see if PM_PWRBTN_L reacts (3V-0-3V).
You can use R5115/16 pads.

PM_SLP_SUS_L is present?

 

[dukefawks]

"no 5v ot 3.3v line work."

Is 3V not present on L7560?

 

[Biggtechman]

Hey guys. Crazy day with the family.
I will post findings in next few hours.
thanks again you guys rock, appreciate all your support

 

[Biggtechman]

PM_SLP_SUS_L is there.
mag light won't come on when I short R5116
it seems the only line that is right is 3.450

 

[2informaticos]

"Is 3V not present on L7560?"
Is importanbt to reply, in order to get more help...

 

[Biggtechman]

Yeah. Sorry been juggling work and family lately.
wife is pregnant.
l7560 is 0v
thanks again
talk soon. I'm off to bed. Night

 

[dukefawks]

SMC_PM_G2_EN present? No short on 3V3_S5?

 

[2informaticos]

"upon examination I checked one wire circuit and it work"
-----
"mag light won't come on"
So, don't you get magsafe light???
Your affirmations are contradictory...

"3.440 on SMC_PM_G2_EN"
U7501 should then generate 3V3_S5.
Post exact values at U7501, pins 23, 12, 21, 22, 29, 13.

 

[Biggtechman]

Hey guys my apologies
what I meant is when I short r5116. So I short it and plus mag in and no light.
take short away and plug it back in and it works.

so 3v3_s5 is there at 3.304

 

[Biggtechman]

Reading for u7501 are as follows
pin 23=8.59v
pin 12=3.440v
pin 21=3.440v
pin 22=3.315v
pin 29=5.02v
pin 13=2.002v

 

[Biggtechman]

Was I meant to short r5116 while mag was plugged in ?

 

[Biggtechman]

Bingo!!!

short on c7500 which is ppbus_s5_hs_other_isns
would it be correct to say this would stop it from running !!?
now I just got to find where the short on that line is coming from.
anyone got any suggested places to start looking ?
thanks again

 

[Biggtechman]

Ok... what da...
the short disappears after a few minutes of no power..
it comes straight back once mag is plugged in???
why would this be so?

 

[Biggtechman]

Got to go to bed guys.
will be back in the morning
it's nearly 10pm and I've got the kids fr the morning while my wife goes to her friends.
will be back asap when we gets back.
thanks again. I think we are making progress
talk soon.

 

[2informaticos]

"l7560 is 0v"
---
so 3v3_s5 is there at 3.304"
Did you really check it at L7560?
Is there stable 3V3?

When I talk about R5115/16 means temporary short; is like pressinbg power button.
So again
"Short SMC_ONOFF_L to ground and see if PM_PWRBTN_L reacts (3V-0-3V)."