2
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toke182
25
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Very rare backlight issue
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Hello to the community, I have a very rare issue with the backlight of my macbook.
Firstly I have changed the inverter board for fix it but didn't works, the inverter wasn't the problem.
Then, I have tested the continuity of the four pin cable of the inverter and all of them were right.
After that, i noticed that passing a magnet over the magnetic lid, the backlight sometimes turns on, so i thinked that the problem was there.
I have checked the continuity from the magnetic lid to the inverter cable pins and found that the continuity was in the second pin beginning the count from the right side. I have cut this cable and soldered it to the "bronze S" that is at the right side of the inverter cable on the logic board. It solved my problem and i can use the laptop hours and hours, shut down it and turn on, shut down the backlight from the keyboard and put it in the sleep mode without problems, but when I shut down it for a long time (30 min to 1 hour) when I turn it on again the backlight doesn't turns on and i have to pass a magnet reapetedly over the magnetic lid until the backlight turns on.
The last thing i tried is disconnect from the logic board the magnetic lid but the problem still doing the same.
Here is a video to see what is the state of the macbook right now:
http://www.youtube.com/watch?v=f3XMqnRxL...
Someone can help me? I'm really desperate already.
Thanks to someone.
Please tell us more about what it was doing prior to these modifications - backlight not work at all, backlight work with LCD at different angles, backlight only work if you adjust brightness, backlight only work when comes out of sleep mode, etc... The bronze S is going to be a ground. Please show us a picture of the magnetic lid - I am not sure what you mean by that. Please show us a picture of where you pass the magnet. Did you use an analog (with needle) or digital multimeter to test for wire continuity?
ABCellars,
Thank you very much for your response. Before I did all that stuff the backlight not work at all, it wasn't a problem with the angle of the display and adjust the brightness doesn't do anything. Sorry for my level of English, I'm Spanish, I call "magnetic lid" to the first piece I show in the video, now I have disconnected this piece for testing. This piece is used to put the laptop in sleep mode when you close the display. I use a digital multimeter for test the continuity. I will upload more photos very soon. Really thanks!!
toke182,
There are the pics: The "magnetic lid": http://flic.kr/p/b9veyz. The soldered cable: http://flic.kr/p/b9vhtr. I have seen that I have the same issue with the backlight when it is shut down for a long time (30 min aprox) after using the combination cntrl+shift+eje
toke182,
There you can see what is the problem with the backlight, the first i do with the screwdriver is put the laptop in sleep mode. The second thing I do is shut off the backlight with cntrl+shift+eje
toke182,
If I understand it correctly, what you try to explain me is the same as unsoldering the cable from the piece of bronze and solder it to the pin where it was. I do that but the same issue persist. This is a pic of what I do: http://imageshack.us/photo/my-images/543...
toke182,
Then, to be sure, i have to buy the resistor and the capacitor of the diagram, soldering them to the bronze S (gnd) and after that soldering the cable I have soldered to the second pin beginning the count by the right side (is the same of the inv_gnd pin? in the diagram) to them in serie?Other question, how can I give you score points?
toke182,
It is an inductor/coil and a capacitor - no resister. They absorb and give out on opposite sides of the PWM wave, keeping power and ground constant - switching points - giving equilibrium to the circuit. You are better off with a straight ground than putting one without the other in the circuit as you will end up in a worse position. The backlight is controlled by Pulse Wave Modulation (PWM) - learn about it. The value of the capacitor is given in the diagram. Study the LC tank circuit to find the value of the inductor - frequency should be 25k. I believe you will get this working, most will not. I thank you for wanting to increase my points for the information I have given you. I have done this in a manner where you can't.
ABCellars,
Hello ABCellar i have studied the things you have commented in your posts and i think i have understood them. Can you say to me if this is correct? http://img39.imageshack.us/i/imageloj.jp...
toke182,
Hello ABCellar i have studied the things you have commented in your posts and i think i have understood them. Can you say to me if this is correct? http://imageshack.us/photo/my-images/39/...
toke182,
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