MacBook Air 820-00165-A PPBUS-G3H <1V

[Gpl]

Hi all, i would like to learn to repair pcb, i'm tring to repair a macbook air 1466 with mb 820-00165-A

I got ppbus_g3h about 0,9-0,8V, fuse is ok,
PP3V42_G3H present

the only thing i can notice is a burn on the cable of the display

What can i check ?

thanks.

[luckydip]

Re: MacBook Air 820-00165-A PPBUS-G3H &lt;1V

check voltages without anything else attached - only dc-in board. Measure resistance on ppbus_g3h.

[Gpl]

Re: MacBook Air 820-00165-A PPBUS-G3H &lt;1V

check voltages without anything else attached - only dc-in board. Measure resistance on ppbus_g3h.

Thanks, 0,9V is without anything attached, i will check resistence

[Gpl]

Re: MacBook Air 820-00165-A PPBUS-G3H &lt;1V

Resistance to ground on ppbus_g3h is 600ohm

[Gpl]

Re: MacBook Air 820-00165-A PPBUS-G3H &lt;1V

Removed fuse F7140 still have low voltage on ppbus_g3h

checked PPDCIN_G3H, 1,7V goes down to 0,8V

PPDCIN_G3H_ISOL : 15V

hope to find the sort :-)

[piernov]

Re: MacBook Air 820-00165-A PPBUS-G3H &lt;1V

checked PPDCIN_G3H, 1,7V goes down to 0,8V
PPDCIN_G3H_ISOL : 15V

Not possible. PPDCIN_G3H_ISOL is derived from PPDCIN_G3H.

[Gpl]

Re: MacBook Air 820-00165-A PPBUS-G3H &lt;1V

Sorry, my mistake,
PPDCIN_G3H = 15,04V and also PPDCIN_G3H_ISOL

PPDCIN_G3H_INRUSH = 0,9V
CHGR_SGATE_DIV = 0,9V

PP5V1_CHGR_VDD = 5,14V
PP5V1_CHGR_VDDP = 5,14V

[piernov]

Re: MacBook Air 820-00165-A PPBUS-G3H &lt;1V

What about ACIN and DCIN of U7100? Resistance between pins 17/18 and between pins 27/28 of U7100?

EDIT: and resistance between pins 26/27 of U7100 as well

[Gpl]

Re: MacBook Air 820-00165-A PPBUS-G3H &lt;1V

CHGR_ACIN = 3,92 V
CHGR_DCIN = 14,72V

resistance between pins 17 and 18 is 3,4 ohm
resistance between pins 26 and 27 is 164,9 kohm

Thanks

[piernov]

Re: MacBook Air 820-00165-A PPBUS-G3H &lt;1V

And between 27/28? If it's 20 ohms you can try replacing U7100.

[Gpl]

Re: MacBook Air 820-00165-A PPBUS-G3H &lt;1V

Yes, between 27/28 of U7100 resistance is 20,1 ohms

can i use a new U7100 ?

I also have another board with fan that spins but not boot