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MB Air 2015 820-00165A No Green, with fan spin, with power, no backlight

K

Kea

New member
checked voltage again.
Backlight issue:
C7796: 40.0V
C7797: 40.0V
C7799: 40.0V
C8317: 40.0V

I think the LCD Connector is bad. Because the macbook will power up the backlight so the voltage is high.

I Think the last thing is PPBUS_G3H.. it will not charge the battery and dont start with battery only. SMC bad and/or ISL6259 bad?

can i reflow the smc to bring him to life?
 
D

dukefawks

Administrator
40V means an open line to the LEDs inside the LCD. Usually damaged cable or bad connector.

SMC or ISL is bad, you can start with replacing the ISL as that is easy, but be prepared for a SMC replacement.
 
K

Kea

New member
I read in another thread "do not connect ac without ISL6259" from you duke. I had some problems with soldering the isl and than i testet with removed isl too.
Did i damaged something now?

I still have soldering problems.. the solder (60sn40pb 3.5 flux + no clean flux) won't stick to the pads. Ordered a new "weller wt 1010" soldering station now with a small tip because my soldering station is a cheap one.
 
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dukefawks

Administrator
In the case of the ISL6259 it will not do damage. In case of any other controller chip it can be an instant write off as the high side FET on the PPBUS rail may start to conduct and get PPBUS voltage on the low voltage output. With the controller missing there is no way to regulate the output voltage.
 
K

Kea

New member
I think i killed some Fets with my bad soldering. I have a new Weller soldering Station now, soldered the isl6259 again but now i have no ppbus_g3h and no pp3v42_g3h

PPDCIN_G3H jumps up and down fast and stops at 0.446V for a few Seconds and Starts jumping again..
 
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dukefawks

Administrator
One thing I can not fix is bad soldering. Replace ISL and the FETs again. Also check the resistance between pins 17/18 and 27/28 of the ISL.
 
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