MBP 17 A1297 strange lcd backlight issue

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hi guys

i have a weird prb i searched it over and over, i didn't find the same issue...

So here i go ...

about 1 year ago i had the fuse burned because of water spill, so i just soldered the pin together , all was perfect till 1 month ago when this time my cat spilled water on it.

Now the actual problem i replaced 3 screens, 3 cables all new, but my backlight is not working like it should... is working till 4 dots on the slider if i press the 5th time is like on the 1st dot.

Here is my laptop to see exactly what i mean : https://www.youtube.com/watch?v=1Z0LsgiRDD8
 

cwa107


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Before we could even speculate as to the cause of the problem, we'd need to know more about the modification you made. Specifically, what fuse did you bridge exactly?
 
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i soldered the F9800. but yesterday i put the original F9800 "p" back in its place nothing change

On external screen all is good, lvds connector is clean all is good there also ...
 

cwa107


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I don't assume LED-backlit displays still use an inverter, since they don't require the same kind of voltage that a typical CCFL-backlit display would. But assuming there is some kind of a step transformer in there, I'd be looking at replacing it.

Hard to say with liquid damage, it could be just about anything.
 

pigoo3

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Agreed Chris.:) Just checked. The A1297 identifier covers all 17" Unibody MacBook Pro's back to 2009 (2009 thru 2011)…and all displays were LED. I also checked Powerbookmedic.com…and they did't list any sort of display inverter (like old backlit LCD display's had).

- Nick
 
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ok guys i just discover something else, when the battery is full or charging ii can reach 4 dots of brightness sometime even 5, if i have less then 50-40% battery i go till 3 dots on slider maximum...
it could be a capacitor? i want to check them but i don't know what are the normal values do u know them?

if i post some pictures with the board can u locate the step transformer ?
 
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pigoo3

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This is a difficult situation. Two liquid spills and non-standard soldering of pins together. It's amazing that the computer is still working at all.;)

To be honest…with other folks two liquid spills would have meant two new computers (a total of three)…and you're still working with number 1.

- Nick
 

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