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macbook air no power 820-3437-a

J

john

New member
this board was water damaged i put it in ultrasonic cleanner and then tested
PPBUS_G3H -> 8.164V
PPDCIN_G3H -> 15.126V
PP3V42_G3H -> 3.42V
any ideas?
 
J

john

New member
found a problem the:
L5001 was 0V pin one pad was gone
R5193 was 0V on pad 2 and the pad was gone

from R5117(pad2) -> 3.42V

I put a wire from R5117(pad2) to L5001(pad1) and R5193(pad2)
Now I have a green light the fan is spinning and there's no chime

I'm back to square one. any advice?
 
A

aprendiz

Moderator
Where was water damage before ultrasonic cleaner?? Inspect under microscope, look for more missing pads or resistors....
 
D

dukefawks

Administrator
Corrosion somewhere, look closer, may also be corrosion under the SMC. No way for me to tell over the internet.
 
J

john

New member
I've receive my new microscope witch is fantastic apart from the camera I paid for 5mp camera it it looks awful. I found on u1950 pad 8 missing also the c1950 didn't had a pad. I puled a wire from c1950 to pad 8.
after a closer look I found q1840 and q1842 problems and i replace those. After I fix it I plug it and the fan is spinning and I hear a dong this was without the screen. I connected the screen and when I tried to boot a second time it didn't work anymore. the fan is spinning for 3 seconds and it stops and it repeating and no dong this time. any thoughts?
 
J

john

New member
I replaced the u1950 and I looked like a 100 time and still can't fine any problems. So all the rails g3h are present all the time and S0 S3 S5 they work for a few seconds when the fan is spinning and when the fan isn't spinning i have no S0 S3 and S5
 
D

dukefawks

Administrator
Are you getting CPU Vcore? If yes then check all resistors in series with the data lines from SPI ROM. But really this could be anything at this point....
 
J

john

New member
I'm getting CPU VCORE
This is a list with the rails that are 0V:
PP15V_TBT
PPHV_S0SW_LCDBKLT
PP0V6_S0_DDRVTT 0.6V insted of 0.75V
data line from SPI ROM are ok
This time the machine has a full fan spin but no dong when I turn it on
 
D

dukefawks

Administrator
PP0V6 is at 0.6V......seems fine with me. The rest is of course not of any interest for now.
Also in your post from 4 days ago it was doing on/off and now you have a stable CPU Vcore?
 
J

john

New member
That's the problem. Last time I heard a few times a dong and then on off thing but i did reflow a few chips and now is stable but no sound when I power on and the cpu is stable
 
J

john

New member
This is the second bord with the same problem I found u1950 at pin 8 bad trace the pin 8 was burned. replaced the u1950 and the same thing i have a fan spin but no dong no imagine nothing.
PPDCIN_G3H_ISOL and PPDCIN_G3H are 15V instead of 18.5V
 
J

john

New member
PPBUS_G3H 8.6V
PPBUS_S5_HS_COMPUTING_ISNS 8.6v
PPBUS_S5_HS_OTHER_ISNS 8.6v
PPDCIN_G3H_ISOL 15.04 V
PPDCIN_G3H 15.04 v
PP3V42_G3H 3.42 v
PPVRTC_G3H 3.33v
PP5V_S5 5.1v
PP5V_S4RS3 5.1v
PP5V_S0 5.1v
PP3V3_S5 3.33v
PP3V3_S4 3.33v
PP3V3_SUS 3.33v
PP3V3_S3 3.33v
PP3V3_S0 3.32v
PP3V3_S4SW_SNS 3.33v
PP3V3_S0SW_SSD 3.33v
PP3V3_S4_TBTAPWR 3.33v
PP1V8_S3 1.78v
PP1V2_S3 1.2v
PP1V05_SUS 1.06v
PP1V5_S0 1.5v
PP0V6_S0_DDRVTT 0.6v
PP1V05_S0 1.049v
PP1V05_S0SW_PCH_HSIO 1.048v
PPVCC_S0_CPU 1.73

Am I missing something?
what should I test next?
 
J

john

New member
u3210 had a pin that was looking strange. I did reflow and then i replace it and q1840 and q1842. I checked under microscope both board like 100 time and if I saw something strange i replace it and the same issue...it powers on i have green light the fan is spinning but no dong when is booting
 
J

john

New member
if all the rails are present and I can't find any corrosion the fan is spining but i don't hear a don where do i have to look next?
 
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