MBP 17 A1297 strange lcd backlight issue

[thortuletz]

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]

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?

 

[thortuletz]

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]

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]

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

 

[thortuletz]

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 ?

 

[pigoo3]

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