Chosen Solution

Hi First time posting. Can anyone help with this issue. There is also no video using the external video connector. I have tested the LCD with a flashlight and can see the system booting. I have connected another MBP to the LVID cable and it works fine. I am not sure how to test the backlight fuse marked with a P. should I get 12v on both sides of the fuse when the system is powered on? also, in the picture I point to a round component (330) that is a bit loose and one of the plastic “shields” sides is cracked off. There is not water damage on the system. Thanks Kevin

Hi Kevin, I’ve been trying to fix some stuff very much like this lately. I can tell you that yes you should see 12.6V on both sides of the backlight fuse. My guess is that your 11.71 is probably a multimeter error—that’s what mine turned out to be on the last board. Next, you will need to figure out on your own how to source your schematic and boardview for your particular motherboard 820-2915. Once you have those tools, you’ll be able to know exactly which component to test, and where to find it on your board. Your first stop will be to measure the voltages at the LVDS connector itself. I just glanced at your schematic and it looks like you should be seeing 3.3V at pins 2 and 3 on your connector (with display attached and laptop on). And you should be seeing around 27V at pins 39/40 and on a nearby capacitor C9000. On the last no backlight board I had, I saw the same 12V coming through to these pins at the LVDS. This means that the LED backlight driver chip–U9701–was not boosting. Probably because I had burned it up :) Of course if I had not seen the 12V and saw only 0V, that would mean that there was a short to ground somewhere between the connector and the source voltage. This is the kind of thinking you’ll need to learn as you go on this problem. I had to send my board out to my talented friend Louis Rossmann and he of course was able to switch out U9701 and the whole thing fixed within 90 seconds. Curses! I think the backlight circuit on these boards is a very reasonable place to start to try and figure out how to work between the schematic and board to do some troubleshooting. Report back with what you find as you begin measuring around U9701 and the LVDS connector. Start with voltage measurements as you are doing now, and then we can go short hunting if we need to on diode mode later. good luck! jessa

Firstly this makes no sense. You have a picture of a 15" board, with an arrow to the PP3V42_G3H inductor which has nothing to do with backlight. In the title you say a 13.3" board, which would be an 820-2936. Clarify what we’re talking about here! If you have a green light on the magsafe PP3V42_G3H supply works and that part is fine. Chipped plastic means nothing on the casing of a huge inductor. Secondly looking for backlight before there is image is not how we do this. If there so screen activation, meaning you see it blink from black, to a slightly different black, then backlight is not the issue - screen not enabling is. This is a totally separate problem. Does this even chime? The dong when it turns on. If it does, then we begin troubleshooting no image, but most likely we are troubleshooting something else entirely if there is no recognition of a screen via displayport OR internal LVDS!

We the same problem on the MacBook of my wife, first we thought thatcher backlight died and changed the complete screen without success, than I have found this posting :-( We have an early 2011 MBP 13“ with i5 Everything was original no changes