MacBook Air 13" A1466 820-00165 - Backlight

Good evening,
I need these 2 small IC (see photo) for a motherboard MacBook Air 13 "A1466 820-00165.
It's 2 small ICs (mosfets normally) are for backlighting.
I do not know where to order them.
I also have another 820-00165 that starts, but no backlight.
The 2 IC are OK, the chip on the back of the screen connector (the driver of the backlight) is OK too, the fuse too, but still nothing.
I suspect maybe the IC U8300 (on the diagram of the motherboard, a mosfet too) but I can not locate it.
It's a shame, on the MacBook Air there are no inscriptions to locate the components, not like the MacBook Pro (17 "anyway).
Cordially.
 

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2informaticos

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The small one is Q7707 and the other is Q7706.
Why do you supose them bad?
What did you measure?
Boardview available for this board, so easy to locate them.

There could be other reason for missing backlight...
Post their voltages for diagnose; with LCD connected, of course.
 
Thanks for the reference of the components.
I just need it because they miss me for a motherboard.
I have a client who passes my 5 motherboards 820-00165, I have already repaired 3 (including one where I miss the Q7707).
One HS (the BCM15700A2 chip overheating and the motherboard that starts, turns off, starts looping, even if IC remove, the CPU heats up abnormally too) and the other, backlighting problem (Q7707 and Q7706 that works, voltage compared with a functional motherboard), OK fuse and IC backlight OK driver too.
But no backlight yet.
What is Boardview?
I found the OpenBoardView software on Google, but I only have schemas in PDF, not in .PCB as for iPhones / iPad.
Sorry I just arrived on the forum.
 
Yes, I saw the XW7720 on the diagram (thanks for that).
But on the motherboard, between the coil and the diode, I have nothing.
I saw after that I could test it differently by measuring on the capacitors, I would do that.
Motherboard : 820-00165-A.
 

2informaticos

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You can find "real" pictures of XW7720 searching the forum.
That small point gets corroded many times...
 
Good evening,
I saw that it was actually a pad.
It is present on the motherboard, and it is not oxidized.
I tested with a functional motherboard and connected screen, I must have 25V at this place.
But on the motherboard with HS backlight, I have nothing in this place, and even the surrounding components.
I have the 8.5V that comes out of the fuse and goes to Q7706 and Q7707.
But I have nothing in XW7720, L7701, D7701, C7797, C7799 ...
 
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Q7706:
I have 8.5V on pin 4, so I get the power of F7700.
I have 8.3V on pin 3.
And I have nothing, 0V, on others.
Q7707:
I have 2.45V on 6 and 4 out of 5 I have 3.29V.
On 3 I have 5,12V, 2 I have 3.29V and on 1 (GND) I have 0V.
For BKL_EN and BKL_PWM I have 0V.
Sometimes I get to have a voltage on XW7720, just now I managed to have 8.5V after cleaning, while it was clean, then nothing after.
There earlier, I had 2V then the voltage dropped, at first I had nothing, the tension came after a while.
I have already changed 2x U7701 in doubt, the same.
 

2informaticos

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Do a PRAM reset and post again BKL_EN (R7715) and BKL_PWM (C7704).
Be sure U7701 is properly soldered.
Check continuity from its ball A5 to D7701.
 
On R7715 I have 2.5V.
C7704, 2.80V.
I have continuity between A5 U7701 and D7701.
I also realized that I have nothing, 0V, on XW7720, but I have 8.5V on the components around.
I have rechanged U7701.
 

2informaticos

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Put the working board in same case and test LCD assembly.
If you have BKLT_EN and BKLT_PWM at U7701, backlight circuit is enabled.

"I have nothing, 0V, on XW7720"
You must have the same voltage as in cathode of D7701; what voltage is there?
 
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When all assembled, the same, I have an image but no backlight.
I only have 8.5V in the backlight circuit.
I have nothing on XW7720, but I have 8.5V on D7701.
 

2informaticos

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"I have nothing on XW7720, but I have 8.5V on D7701"
This is not possible, unless XW7720 is open circuit.

Check schematic, XW7720 is between D7701 and U7701.
A tiny trace connects the dot of XW7720 with D7701, is that good?

Click image for larger version  Name:	xw7720 fix.jpg Views:	0 Size:	522.5 KB ID:	45765
 

2informaticos

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"Put the working board in same case and test LCD assembly.
------------------------
When all assembled, the same, I have an image but no backlight."
Working board no image with the same screen???
So bad screen.
I hope you've tested properly...
 
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