A2337 new M1 MacBook Air problem Logic Board related, no video backlight 820-02016

[mon2]

Review the first pic in post #80 of this thread.

Move the red meter probe to the other side of the caps. What is the resistance?

[corintosh]

Review the first pic in post #80 of this thread.

Move the red meter probe to the other side of the caps. What is the resistance?

I hope the pictures show everything well enough. Flipping the side and measuring there gives the exact same values.

[mon2]

Can you share the pic for the CP600 block of parts?

[corintosh]

Can you share the pic for the CP600 block of parts?

I should have included more info, it is already part of the ones I already uploaded. They are at the top.

[corintosh]

Do you have another idea / anything I could try or check or is it time to assume the board is internally shorted?

[inflex]

Do you have another idea / anything I could try or check or is it time to assume the board is internally shorted?

There's more caps off to the side of the screen connector and near the main storage caps that you've already removed.

Do you have the boardview & schematic and a boardviewing program? This is FlexBV5 ( https://pldaniels.com/flexbv5 ) which has a free edition which may help you out here.

[corintosh]

There's more caps off to the side of the screen connector and near the main storage caps that you've already removed.

Do you have the boardview & schematic and a boardviewing program? This is FlexBV5 ( https://pldaniels.com/flexbv5 ) which has a free edition which may help you out here.

Thanks, I do already use flex and the schematic for my board. I removed all caps that flex showed to be part of the lcd backlight out. This includes the ones next to the screen connector and the 4 on each side next to the main storage caps.

I included photos of the board with the caps taken off of all the regions.

If it is time to stop trying other things I will likely sell it for parts. I don‘t think it is worth to buy a replacement logic board as I probably would have to replace married parts.

[inflex]

Right, sorry about that one - I misinterpreted your pictures where you had the LCD connector + removed caps next to them in the next picture, definitely my bad there.

Did you also remove RP831 ? It's a resistor that takes the voltage back across XWP801 (internal link) to the controller. If you remove that and the short remains, then I'd say you've got a bad board likely. If the short disappears then look at the FB line parts and the controller

[inflex]

Thanks, I do already use flex and the schematic for my board. I removed all caps that flex showed to be part of the lcd backlight out. This includes the ones next to the screen connector and the 4 on each side next to the main storage caps.

I included photos of the board with the caps taken off of all the regions.

If it is time to stop trying other things I will likely sell it for parts. I don‘t think it is worth to buy a replacement logic board as I probably would have to replace married parts.

I just realised, YES, you already have removed those parts

Try remove the controller, just for the hell of it too.

[corintosh]

I just realised, YES, you already have removed those parts

Try remove the controller, just for the hell of it too.

Thanks for staying on it with me!
The controller would be UP800? I will try it. I am still quite sure that when injecting voltage the very first time (still with RP831 on) it created a mark on it. Refering to post 76 in this thread.

[inflex]

Thanks for staying on it with me!
The controller would be UP800? I will try it. I am still quite sure that when injecting voltage the very first time (still with RP831 on) it created a mark on it. Refering to post 76 in this thread.

Correct, yes UP800. Normally I'm not one to subscribe to the notion of pulling chips without first determining a viable cause to blame them but sometimes after all this sort of work you end up just throwing caution in to the air and trying. At least it's a comparatively simple chip. Other possibility of course is the display connector itself.

[corintosh]

Correct, yes UP800. Normally I'm not one to subscribe to the notion of pulling chips without first determining a viable cause to blame them but sometimes after all this sort of work you end up just throwing caution in to the air and trying. At least it's a comparatively simple chip. Other possibility of course is the display connector itself.

Alright I will give it a try. I am trying to learn as much as possible - could you explain your thought process behind this? I would have guessed the chip was out of the equation since we removed the path to it when RP831 was removed.

[mmglipetsk]

Hello. In my case there was no display backlight due to the CP870 capacitor. It's surprising that the Led driver didn't fail

[kamil83]

MacBook Air A2337, motherboard number 820-02899-A. In short, this Air had a damaged backlight. The screen has been tested and works fine on an external monitor. I reinstalled the operating system, but nothing changed. PP5v_BKLT_A/B 5V
PP5v_BKLT_D 5V
PP5V_S2 5V
PP5V_SW_LCD 5V
P5VS2_PWR_EN 1.8V
P5VS2_BST_R 8V
P5VS2_SW 5V
PPBUS_5VS2_VIN 5V
PPVOUT_LCDBKLT - Doesn't short 0V
FP800 - Both sides 13v
BKLT_EN_R & BL_PWR_EN - 1.8v
IPD_LID_OPEN_1V8
PP3V3_SW_LCD
QP800 3pin 13v 4 pin 12.8v 6521pin 0v i changed

LP800 0.014V On both sides (should be 12? / no short)
UC300 & UP800 Replaced with tested one - no difference.
Just to clarify, no backlight - I can see display very dim.