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820-00875 - Backlight Issue

M

mccafe

Member
Hello guys!

I have a MacBook Pro 820-00875 with backlight issue. Customer brought it in because it would not turn on after it went black randomly while browsing.

Plugged in charger and it was giving 20v @ 0 amps. I found a short on PPBUS_G3H. Fixed it by replacing U7430. No more short, PPBUS_G3H = 13 volts, MacBook now turns on, makes charge connection sound, but no backlight (I can see faint Apple logo and it would boot / go to recovery assistant).

There is no sign of liquid.

PPBUS_G3H = 13 volts (12.3 - 12.5 volts if battery is connected)
PPVOUT_S0_LCDBKLT = 55 volts
 
M

mccafe

Member
Luckily I had another display to test, it definitely is the LCD assembly. However, I am unsure if the customer will be willing to bring to Apple for the backlight service program. He took it there initially and now it is obvious that it was worked on.

Anyone have any success in repairing the daughter board for the LCD assembly?
 
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M

mccafe

Member
I compared screen assembly readings and here are my findings. I noticed pin 33 varies a lot on the bad assembly - MIPI_DATA_CONN_P, but other than that everything else seem to check out. I don't think this pin has anything to do with backlight, so it might just be done for.
1591718230754.png
 
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P

piernov

Moderator
Staff member
Just clean your work so that it's not completely obvious that the board has been worked on and bring it to Apple, best course of actions. If it's flexgate they must fix their mistake. If it's not flexgate, eh… still an opportunity not to pay $400 for a replacement LCD assembly.
 
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