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820-3115 No Backlight No Video

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RyanLEN

New member
Hi. So, I have a board here that came in with no backlight, but had full video. I replaced C9020 and C9796 because they looked burnt. Also L9080 was missing completely so I replaced that as well. Turned the laptop on to see if it made a difference and I got a chime with a quick flash from the backlight and no video whatsoever. Just darkness. Started measuring around and this is how far I got before things got worse.

U900 PN 4,5 3.2V
LCD_IG_EN 3.2V

Upon measuring pins 2,3,4 on LVDS voltage started at 3.3 and dropped until I noticed that L9004 had pretty much imploded into a bubble at some point during taking measurements. Right now it looks like it could be welded to the board and C9015, C9010 and L9008 dont look so great either. Thanks for any help in advance. Have a good one.
 
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aprendiz

Moderator
Replace all burned and bad looking parts and check LVDS connector, could be shorted inside, my advice is replace it......

After check all this connect your display, do not plug magsafe yet!!!

Check for short in diode mode on L9004, L9008 and on C9020, if no short found, plug magsafe..........

Report result.....
 
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RyanLEN

New member
No Title

Came downstairs this morning to this... This usually takes a long time and cursing for me. does anyone have a method for this that isn't painful?
 

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RyanLEN

New member
No Title

Replaced everything. No short. Now I have same backlight flash at startup but now with horizontal stripes which stay when the backlight turns off.
 

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RyanLEN

New member
No Title

Here is the 1 second of flash before backlight goes off. When I first got this in the only issue was no BKLT. I had full video. I was able to access Recovery mode and diags. Could the demise of L9004 possibly killed my LCD. I am obviously hopingthat not the case, but thats kind of what its looking like. Thanks alot for your help. Have a good one.
 

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RyanLEN

New member
It seems like coincidence that I am having this issue after board damage. Going to give it a shot. The only thing I have handy is a late 2012 Retina A1425 Not sure that will work. Never tried.
 
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dukefawks

Administrator
That is either a bad LCD/cable or 3.3V not getting to the LCD and the LCD getting like 2.5V or something around that value. No a retina LCD is totally different of course.
 
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RyanLEN

New member
In the latest news... New test screen just got rocked. Just plugged it into another machine to compare voltages to this board and nothing. Just black. I don't know if its what ever is wrong with this board or if I'm doing something wrong. All I know is this blows. I don't have another one to continue. Not even sure it would be smart to try if I did. Oh well .Fuck it. Thanks again.
 
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RyanLEN

New member
Hey Duke. Im away from my shop. I keep frying LCD's. Got discouraged and had to walk away LOL Plus Im afraid to try another LCD. Thanks for your response. What could be causing this? I know its possible the first time the lcd blew out could have been my fault. When I was measuring I shorted pins on lvds side and that when the inductor blew up . But since then I have been careful. Thanks again man. Have a good one.
 
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RyanLEN

New member
pn1 0
pn2 .546
pn3 .546
pn4 .312
pn5 .OL
pn6 .579
pn7 .583
pn8 .573
pn9 .574
pn10 0
pn11 .571
pn12 .570
pn13 .0
pn14 .572
pn15 .573
pn16 0
pn17 .580
pn18 .022
pn19 0
pn20 OL
pn21 .557
pn22 .557
pn23 OL
pn24 .599
pn25 .599
pn26 .599
pn27 .596
pn28 .597
pn29 .592
pn30 OL
 
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