820-01521 MacBook Air first 5v stuck, now 20v but DFU error

MacLab

Member
Hello, sorry mi English.
This is a 820-01521 MacBook Air that came not turning on whit 5v stuck. Connected the mac in DFU mode and apply a revive option but shows the 75 error . Now the usb meter register 20v but in DFU mode have the same issue.
In some YouTube video saw that maybe the issue was the SSD so i check the rails and only PP2V7_NAND seems low (2.5V)

PP3V3_G3H_RTC =3.3v
PPBUS_G3H = 12.56v

U8600/U8607
PP1V8_SSD = 1.8V
PP2V7_NAND = 2.5V (Seems low)
PP0V9_SSD = 0.9V
SSD0_S4E0_VPP = 2.1V
SSD0_S4E1_VPP = 2.1V
SSD0_RESET_L = 1.8V
SSD0_S4E0_PCI_AVDD_H = 1.8V
 

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2informaticos

Administrator
Staff member
Any history available, liquid sign?

What you did to get 20V on USB meter now?
Tried DFU with charger and battery, both connected?
 

MacLab

Member
Came from another workshop, but no sigs off corrosion or work on the motherboard.
The battery seems death,I will find another to test again

I didn't do anything special to get the 20v. When it arrived, I used the usb tester and it had 5v, then I removed the tester and put the mac in DFU mode and when it recognized it, I tried the revive option without success. Then I tried the tester again and it was 20v.
 

MacLab

Member
When trying to restore I have a different error and it does not complete the process :(
 

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