Re: MacBook Air 820-01521 Backlight
I did some test using repair.wiki as a reference and it's pointing to the CPU being bad. Should I try anything else before ending this repair attempt? Or can I do a CPU replacement with this model and it be reasonable with a hot air and soldering rework station?
eli302
Member
Last Activity: 08-10-2024, 11:32 PM
Joined: 11-30-2021
Location: Wilmington, DE
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Re: MacBook Air 820-01521 Backlight
So before I took off the jumper R8451 read 5.13V then dropped to 0V after testing. Now it's at 5.13V on both sides consistently.Leave a comment:
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Re: MacBook Air 820-01521 Backlight
Do I need to resolder the jumper cable to continue testing? Or should I resolder the resistor?Leave a comment:
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Re: MacBook Air 820-01521 Backlight
I have to resolder my jumper wire but R8450 is reading 5.13V on both sides.Leave a comment:
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Re: MacBook Air 820-01521 Backlight
I'm back working on the board.Leave a comment:
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Re: MacBook Air 820-01521 Backlight
I believe the issue is between R8400 and Q8400. Everything but pin 6 on Q8400 is at 0V.Leave a comment:
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Re: MacBook Air 820-01521 Backlight
PPVOUT_S0_LCDBKLT_F is at 0VLeave a comment:
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Re: MacBook Air 820-01521 Backlight
No backlight still. The voltage is steady at 20.1V and the current ranges from ~1.5 to 1.77A.Leave a comment:
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Re: MacBook Air 820-01521 Backlight
After I solder the jumper, completely reassemble and test the screen?Leave a comment:
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Re: MacBook Air 820-01521 Backlight
^in 20M setting.Leave a comment:
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Re: MacBook Air 820-01521 Backlight
Bklt_en_r the resistance starts at 1.67 then climbs to 3.3 then drops. This is over about a 15 second time frame.Leave a comment:
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Re: MacBook Air 820-01521 Backlight
Yes you can see everything with a flashlight.Leave a comment:
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Re: MacBook Air 820-01521 Backlight
Both sides of R8442 are reading 0V.Leave a comment:
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Re: MacBook Air 820-01521 Backlight
I believe EDP_BKLT_EN comes from U0500 but I don't think I can test for it as it is a soldered on chip. Or should I try something else?Leave a comment:
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Re: MacBook Air 820-01521 Backlight
EDP_BKLT_EN is reading 0V. So the enable isn't working.Leave a comment:
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Re: MacBook Air 820-01521 Backlight
F8400 is reading 12.6V on both sides.Leave a comment:
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Re: MacBook Air 820-01521 Backlight
Also I didn’t read PPVOUT_S0_LCDBKLT_F from F4800 is read it from the other side of the board. Could the reading at the fuse be different? Also I don’t know how to test the fuse without using my bench since the fuse is on the other side of the board when testing using AC power. When I did have the board completely out though the fuse had beeped in diode mode so can assume it’s still good from this and it’s not the issue or do I need the exact resistance to determine?Leave a comment:
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Re: MacBook Air 820-01521 Backlight
The voltage and current draw is 20.1V and 1.47A.Leave a comment:
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Re: MacBook Air 820-01521 Backlight
Test each pin on the connector?Leave a comment:
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Re: MacBook Air 820-01521 Backlight
So go ahead and order and replace the connector and fuse?Leave a comment:
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