Apple MacBook Air 820-3437-B

[mferna14]

Hi all., I am working on a MacBook Air logic board 820-3437-B. It came in as liquid damage & I revived the logic board. All work & turns on fine & display is perfect, boots up OS well. But there is one problem, if I removed the magesafe 2 jack & put it back in the socket, no green light for a while, & if I leave the magsafe jack connected with no greeen light, automatically after about a min or so the logic board turn on by itself & all voltage are back & logic board works fine. I replaced the clock chip where the corrosion was & I see no broken traces. Since I was not getting any votalge on Fuse F7140 (PPBUS_G3H), I assumed, after a lot of diagnostic that the SMC is acting with the 1-wire circuit. I replaced the SMC but still the same. I replaced know good Cables & the Magsafe/USB/audio board & the J9500 connector too as green corrosion was on that too, but no luck at all. Hope someone can help me out in this. Maybe some Tantalum Cap gone bad??? Thanks in advance for the help.

[luckydip]

Re: Apple MacBook Air 820-3437-B

A few things:

was the smc from the same model donor board?

did you check around isl, do you get stable acok voltage?

are R53801 & R53802 resitance and volatge ok on bus line?

if they're ok try running asd and look for any errors.

[piernov]

Re: Apple MacBook Air 820-3437-B

I'm confused, machine works without PPBUS_G3H? What about PPDCIN and PP3V42_G3H?
Why replace SMC if PPBUS_G3H is missing?

Make sure you are using a good Magsafe2 AC adapter.

[mferna14]

Re: Apple MacBook Air 820-3437-B

Thank for all the replies., I will check & let you guys know...

[mferna14]

Re: Apple MacBook Air 820-3437-B

& Lickydip are you relating to these resistors R5380 & R5381 right!!! you got one mumber extra..

[luckydip]

Re: Apple MacBook Air 820-3437-B

& Lickydip are you relating to these resistors R5380 & R5381 right!!! you got one mumber extra..

Sorry, yes they're the ones

[mferna14]

Re: Apple MacBook Air 820-3437-B

No problem buddy., all tips are great. Ok now I found that the R7006 on PPBUS_G3H line was blown, replaced it but still not luck till now. I am feel I am so close, yet so far. I find resistence reading differences in R7012, R7011 & R7010. I checked with a known good board & the meter shows the difference. I will remove them tomorrow & check., maybe this might be the problem. R7010 & R7011 both show 10K whereas one should be 100K & the other 10K. & R7012 should be 68K, the meter reading is fluctuating between 34K~51K.. Lets see tomorrow where the problem lies. Any more tips will be much appreciated. Thanks once again

[luckydip]

Re: Apple MacBook Air 820-3437-B

Go through it step by step. Is there any voltage on D7005 pin 2? I've seen a lot of boards where D7012 is the issue.If yes then look to see if there is anything on L7095.

[mferna14]

Re: Apple MacBook Air 820-3437-B

Thanks luckdip., I will check all step by step & inform you once done.

[mferna14]

Re: Apple MacBook Air 820-3437-B

Ok., I checked the resistance., after removing Q7010, all the resistances readings were prefect. So 100% Q7010 was defective. I replaced it, now turns on fine & PPBUS_G3H line voltages are all ok. Now the fan spins & no self test mode of the logic board, i.e the fan spins then stops & this happens twice & then get the display. Now this does not happen, the fan is spining continously with any pauses & no display, where as first I was getting the display. Any tips now.

& one more help, just received a 820-00165-A logic board, liquid spill on it. I cleaned very well. Turned on & the display fuse F7700 blew. I saw green stuff on the LCD connector J8300. As it was corroded, I replaced both of them. Now the fuse did not flow, the logic board turned on & I get all the voltages, but as soon as I see the backlight the logic board turns off by itself. Any further tips on this.

[luckydip]

Re: Apple MacBook Air 820-3437-B

Ok., I checked the resistance., after removing Q7010, all the resistances readings were prefect. So 100% Q7010 was defective. I replaced it, now turns on fine & PPBUS_G3H line voltages are all ok. Now the fan spins & no self test mode of the logic board, i.e the fan spins then stops & this happens twice & then get the display. Now this does not happen, the fan is spining continously with any pauses & no display, where as first I was getting the display. Any tips now.

try a smc reset. Changing Q7010 should not stop the display, unless something else was disturbed by the heat

[luckydip]

Re: Apple MacBook Air 820-3437-B

& one more help, just received a 820-00165-A logic board, liquid spill on it. I cleaned very well. Turned on & the display fuse F7700 blew. I saw green stuff on the LCD connector J8300. As it was corroded, I replaced both of them. Now the fuse did not flow, the logic board turned on & I get all the voltages, but as soon as I see the backlight the logic board turns off by itself. Any further tips on this.

Need to check voltages on backlight boost circuit. The fuse blew for a reason, make sure all pins on the LVDS connector are soldered properly and there is continuity.

U7701 often gets liquid damaged, check the balls under a microscope for corrosion.

[piernov]

Re: Apple MacBook Air 820-3437-B

820-3437 is supposed to spin/stop 3 times after losing battery power.

820-00165: Please open another thread for a different issue.

[mferna14]

Re: Apple MacBook Air 820-3437-B

Thank you very much... will try all tips later...

[mferna14]

Re: Apple MacBook Air 820-3437-B

Ok., as soon as I install the SSD, the problem starts again. Even with known good SSD, same!! & with the SDD all works fine, display is ok & get all known voltages. Anyone got a problem like this?? Do you think BIOS is the issue, but battery charges well to 100%