Macbook Air 5V 0.340A

scoman123

New member
Hello, I will start this by saying I am VERY new to logic board repair, I know basics and learn best by doing but have found this difficult as I can't find my exact problem and just chunks of it which makes things hard to track for me.

It's a Macbook Air 2019 A2159 820-01598.

It was apperantly used for 3 months then randomly stopped, I was asked to repair it a year or so later as Apple wanted to charge too much.

It started off with 5v 0amps, I tracked down a problem with U7000, U9080 and U6903. When I replaced these I started getting 5v and 0.340A. I can't seem to get any further than this and have gotten a bit confused in the process, I can't remeber exactly what lead me to U7000 as this was about a month ago while waiting for new chips but U9080 was shorting to ground.

Voltages:

PPBUS_G3H: 5.02V
PP3v3_G3H: 0.00V
PP3v3_G3H_RTC: 0.00V

No short to ground that I can find anywhere, no visible damage, no liquid damage.

Any help is massivly appriciated.
 

2informaticos

Administrator
Staff member
First of all, welcome to the forum!

"PPBUS_G3H: 5.02V"
Are you sure about this?
Isn't PPDCIN_G3H instead?
We need accurate information...

Post diode mode to ground readings on PPBUS_G3H (F7000), L6900 and L9080.
 

scoman123

New member
Hi,

Yes I get a specific and constant 5.02v on every point for PPBUS_G3H according to open board , specifically: F7000, R6700, F84000, CD770, CD771.

PPDCIN_G3H gives 5V at F3000, CD720, R7015, R7071.

For the resistance multimeter set at 2k ohms:

L6900: .381 & .389
L9080: .411 & .412
F7000: .466


What I have now noticed just by chance is that Q7040 (SIZ342DT) is producing a small amount of heat, not sure if this is a sign of a issue or just because the board was plugged in.
 

2informaticos

Administrator
Staff member
Check for short between R7020 and F7000.
You should chabge Q7030/40 anyway.

BTW, I said "diode mode", not 2K, or other ohm scale...
 

scoman123

New member
Sorry, readings were all OL diode mode so thought the actual readings would be mroe helpful.

So yes, I think there is a short? This is where I'm still new to everything and to what to do next, If i put one probe on F7000 G3H and one on R7020 pin 2, PPDCIN_G3h_ChGR I get a short (a beep).
 

2informaticos

Administrator
Staff member
Beep is not equal short!
Multimeters beep until 0.050-0.075 (diode mode), depending by model.
However, such low value is not good at all between PPDCIN_G3H and PPBUS_G3H.
I hope you did the test without power applied on the board.

Now change Q7030/40.

"readings were all OL diode mode"
With red probe connected on ground y black on test point???
 

scoman123

New member
Just rechecked everything to be sure, power supply not connected at all.

Diode mode readings are all "1 . " with red probe on a screw hole and black probe on point.

It will be next week sometime before I can change Q7030 & 40 because I have to order the components in.
 

scoman123

New member
I have changed Q7030 & 40 and no change except there is now 1. instead of a beep between F7000 & R7020 and PP3v3_G3H now has 0.15v.
 
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