| Hello amazing geniuses, boy do i have an exciting machine with me that needs knowledge I don't posses. Alright so machine was liquid damaged top case side. The board only seemed to have liquid on the backlight decoupling caps. So shorted to ground. So I removed the caps to find a crater. Still had a short to ground on ppvout_lcdbcklt, so I injected voltage and internal short near cp601 and cp604. Then proceeded to dig the short out, lots of grinding and cutting later the short is gone. Yay! However, this was shorted lived as still no backlight. Now the confusing stuff. I have backlight output essentially 51 v on ppvout_lcdbcklt which to me seems like the lcd panel isn't being told to accept the backlight. The screen in question is fine, tested with another board. Also don’t have keyboard backlight if that helps. I have replaced up800 no change. one thing to note i only get about 19mv on up800 pin 4, while comparing with another machine it gets 0.8v. also the i2c data lines are 5.12v Let’s solve this mystery together. I would have loved to show pictures but my old microscope gave out and the sd card failed with it. I will do my best to provide pictures going forward. |
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A2337/820-02016 No backlight
- Thread starter DDVL
- Start date
Thank you for the warm welcome.
Regarding k/dp800 i used 1/cp873 to check continuity. I assumed it would be ok as its the same line when i last checked.
I am about 90% the t-con is good but will check with another one later.
I also thought ALS might be an issue so i had checked lp670 and have 5 volts on both sides.
UP 700 seems good as well.
Regarding the camera not working i am unsure however when i power the screen with a different board it has backlight. Also I tried a different screen to check but no change.
What's next?
also lid open voltage is 1.8
Regarding k/dp800 i used 1/cp873 to check continuity. I assumed it would be ok as its the same line when i last checked.
I am about 90% the t-con is good but will check with another one later.
I also thought ALS might be an issue so i had checked lp670 and have 5 volts on both sides.
UP 700 seems good as well.
Regarding the camera not working i am unsure however when i power the screen with a different board it has backlight. Also I tried a different screen to check but no change.
What's next?
also lid open voltage is 1.8
Camera and ALS are powered from the same line.
I asked about camera, in case of missing power.
Just check if ALS works properly.
ALS problems may be caused by MLB bad circuitry; not only by LCD assembly.
I asked about camera, in case of missing power.
Just check if ALS works properly.
ALS problems may be caused by MLB bad circuitry; not only by LCD assembly.
How would you like me to test that? When i use the other motherboard the screen does light up. I did put the board in a different assembly but same result. I also believe als on motherboard side is at fault but have no idea what else to check. I did change the lcd cable with a known good one but the result was the same.
I was also able to recover a picture of the damage.
But it seems the image is too large to add.
I was also able to recover a picture of the damage.
But it seems the image is too large to add.
Ok so i haven't tried connecting to an external monitor just yet. I will do that and get back to you regarding it.
I don't think i destroyed any data lines. As the short was on the decoupling capacitors. So here is the link to the picture
drive.google.com
I don't think i destroyed any data lines. As the short was on the decoupling capacitors. So here is the link to the picture
20230331_172103.jpg
drive.google.com
I recommend you to confirm continuity from DP800 to JP600.
You've carved the board on the backlight output.
Are you sure the trace is still good all the way?
You've carved the board on the backlight output.
Are you sure the trace is still good all the way?
Ok so ud050 pin 5 and jp600 pin 20 no continuity.
Diode mode with red to grouund -
Rd053-2 --> 0.079
Rd053-1 --> 0.539
Rd051-2 --> 0.005
Rd051-1 -->0.281
Resistances -
Rd053 - 1.78k
Rd051 - 1.39k
Normally i would take of ud050 check diode mode and see what happens and then if readings normal replace it. What do you suggest to do?
Diode mode with red to grouund -
Rd053-2 --> 0.079
Rd053-1 --> 0.539
Rd051-2 --> 0.005
Rd051-1 -->0.281
Resistances -
Rd053 - 1.78k
Rd051 - 1.39k
Normally i would take of ud050 check diode mode and see what happens and then if readings normal replace it. What do you suggest to do?
Well i guess this board is done.
Removed ud050
Rd053 -2 --> 1.7v without ud050
Rd053-2 --> 0.6 on a good board
The bad rd051-2 --> 0.005 even after removing ud050
Rd051-2 --> 0.369 on a good board.
Is it safe to assume the board is fucked?
I shouldn't bother with attempting to fix any traces on jp600?
Removed ud050
Rd053 -2 --> 1.7v without ud050
Rd053-2 --> 0.6 on a good board
The bad rd051-2 --> 0.005 even after removing ud050
Rd051-2 --> 0.369 on a good board.
Is it safe to assume the board is fucked?
I shouldn't bother with attempting to fix any traces on jp600?
You don't need to melt the balls.
Is supposed to burn eventually accumulated crap only.
Is supposed to burn eventually accumulated crap only.
Do i remove the silicon that holds the m1 in place? So essentially just heat it up to 450 mainly in the area that affects the backlight or the entire m1 chip?
If that potentially works i gotta run jumpers for the jp600 connector right?
I don't know if you can tell but i am actually fairly new to fixing motherboards. The biggest bga i ever touched was a cd chip. Also i don't know what temp flux would boil at or remove crap from soder joints. So this information would be helpful.
If that potentially works i gotta run jumpers for the jp600 connector right?
I don't know if you can tell but i am actually fairly new to fixing motherboards. The biggest bga i ever touched was a cd chip. Also i don't know what temp flux would boil at or remove crap from soder joints. So this information would be helpful.
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