Re: Dell XPS 15 9550 no backlight

Ok I did it, it works now the capacitor CV168 was defect. This is what gave me the 378 Ohm. A guy took it off the board for me and now it works. Should I replace that or can I leave it off?

Re: Dell XPS 15 9550 no backlight



I don't quite understand what you want me to do. Should I test with or without the battery? Also the left resistor is at 99.3k Ohm. That is pretty much what RV120 is supposed to be and I am fairly sure that this is RV120. I measured points with 0 Ohm resistance between them and found this [url]https://puu.sh/EHfVc/1ecd75c6b8.jpg[/url] (all measured without power). From what I can tell the 378 Ohm resistor is supposed to be RV 119 which is supposed to be 1m Ohm?

[url]https://puu.sh/EH4PO/88f0016834.png[/url]
...

Re: Dell XPS 15 9550 no backlight



Here are all the measurements to ground [url]https://puu.sh/EHeG6/96f5696cc6.jpg[/url]

Actually the 0v is more like 0.4mv, measured multiple times at that place just to make sure.

edit: Right resistor is 382.6Ohm, left one is 99.2kOhm

edit2: accidentally swapped the ohm valuesRe: Dell XPS 15 9550 no backlight<br...multiple times...

Re: Dell XPS 15 9550 no backlight



4 is 13.6v right now and 3 is 13.55v right now. All the other pins are still at like 8.7mv.



From all sides to ground?...

Re: Dell XPS 15 9550 no backlight



I have also managed to measure QV12. It has 2 pins on one side and one on the other side. The left pin is at 3.38v, the right pin is at probably 0mv? Sometimes it shows 0.1mv or 0.2mv and then goes back to 0. The top(or bottom?, the one that is alone) pin shows 0.4mv (constantly)....

Re: Dell XPS 15 9550 no backlight



How do I know which pin is 3 and which one is 4? Also I have just shorted one of the pins next to it to 3 or 4, no idea for just a split second. I hope that didn't make anything worse. I definitely wasn't careful enough and got a short spark between the pins I think. Screen is still on with no backlight.

One of the pins is at around 13.53v and the other ones are still at around 9mv. The other pin (again 3 or 4) is at 13.48v....

Hello,
first of all I am a total noob with board level repair. My Dell XPS 15 9550 backlight died. I tried to replace the screen but it is still not working. I found the schematics online (only for rev 0.0, I have 1.0) but no board view which means I basically can't find anything really on the board. Not to mention that I have never really used a schematic.

Either way I managed to measure the backlight voltage on the 40pin connector. It is 9mv and supposed to be 25v. Any idea what I should try out next? No matter how much I look at the schematics I don't get any further....

Re: New Members - please post your introductions here

Hello

I am a student with no money that hates to have his stuff break even though it is still in great condition. I am mainly here to try to fix my Dell XPS 15 screen backlight but I guess I will come back here in the future as well. Sadly I have no real soldering experience so this will be interesting.