Macbook 13.3 Screen Issues?

I had an issue something like this a while back

I discovered that the plug for the LCD itself wasnt making a good connection... I wiggled it around and it came on and I havent had a problem sense but I expect I may be replacing it in the future

 

What inverter cable do you have? Is it 4-wall or 3-wall connector?

4-wall


3-wall

 

I have exactly the same problem with my cousins laptop. On connector J9000 I discovered that logic board sends wrong signal to the inverter. Normally Pin4 on J9000 gets various voltages depends on brightens level. It ranges from 0V to 3.3V. Unfortunately after first hit to F2 it goes back to 0V. It should stay on 0.6V or if you keep presing F2 it should go up to 3.3V where screen is on maximum brightness. I got 3.3V from Bluetooth connector (J4810 Pin1 with ">") and by connecting Pin4 on J9000 to Pin1 on J4810 I managed to get back-light back to acceptable (maximum?) level. J9000 is the connector on the logic board where you connect inverter cable. Pin1 is marked with ">" it should have 12.5V, Pin2 is Ground, Pin3 should have 5V and Pin4 is the one responsible for brightness level. Voltages as above. Why the type of connector is important? With 4-wall connector it would be impossible to check voltages because pins are completely covered. What you can do is to check Pin4. If it stays on 0V all the time or if it goes to 0 immediately after you hit F2 (and screen goes blank) than you can try to do what I did - get 3.3V from Bluetooth directly to the inverter and see what happens. Unplug Bluetooth module as it may cause voltage drop.

J9000 here:
http://www.mylivegallery.com/50299-152423931-31.html
J4810 here:
http://www.mylivegallery.com/50299-2342348240-31.html
I used this schematic:
http://www.scribd.com/doc/122474146/Apple-Macbook-a1181-k36c-Mlb-Schematic

 

You could have purchased a screen with a failing backlight. Keep in mind that these stopped being produced damn near six years ago. Screen that comes on, but light fails shortly thereafter could be bad backlight.

Bad backlights also occasionally kill inverters.

And the fun goes on and on.

 

Jacek GENIUS GENIUS GENIUS! ! ! I have been thinking and thinking of a hardwire method but just gave up as I had no clue where to get started.Thanks!This is a widespread problem with this model macbook I think so many people have interment success due to the connection only seating properly for a limited about of time so they think a new inverter board fixed it (me) but then is seems like it bad after a couple days(me) I am going to try this next weekend and I'll update

 

g4manimac

You have to be sure what is actually broken. Test everything you can.

My screen with inverter powered from Blutooth connector worked well for about an hour. Then it started to blink as before. I got scared that Blutooth killed the inverter. In the mean time a brand new inverter arrived and I tested it immediately. Screen still dead. I wanted to be completely sure that inverters are OK. See here is what I did: http://videobam.com/OBNSV

Inverters are OK, Bluetooth power appears to be safe. New inverter is going back to the supplier. Money saved.
I did the same test but with Macbook screen connected to Philips inverter and the screen blinked once or twice and thats it. It does blink every time I power-on the inverter but after that it reminds dead no matter what I do. Conclusion: CCFL is gone after months of stutter - new LCD already ordered.

I need to do another test with Philips screen and brightness control from the Mac's logic board but I need to order a new inverter cable. The one from my sis Macbook is converted to get power from Bluetooth and I want to have both options available when new LCD arrives.

Also if others are interested in inverter voltages. Here is a video of what brightness control Pin4 voltage looks like on a fully working Macbook:
http://videobam.com/yvcLZ

If you have a 4-wall connector you can read Pin4 voltage directly from the inverter. Just cut that yellow film protecting inverter board.

 

A new screen has arrived. Hurray! I had some problems with connection, it has an unusual adapter for VGA cable and first it didn't work but after several attempts it worked OK. I will post pictures of that adapter later - others may have similar experience/problems.
Now please take a look how it works when inverter is powered by Bluetooth and how brightness control does not work.
Video here: http://videobam.com/tQXYW

 

One noteworthy point to people troubleshooting these machines. It can be one of four components causing the no backlight problem.

a) Inverter cable

b) Inverter board

c) LCD backlight

d) Logic board backlight powering circuitry.

These parts are, at this point, mostly 5+ years old. So, even if you get one of each, there is a good possibility that it won't work because it's old, used, crusty junk. It doesn't mean the component you replaced is not the problem, it could simply mean that you got a dud.

 

Hi,
i wonder if you can help.
i have same issues as above,first hit on f2 i get flick of light then nothing afterward,i've tested the 4 pins from logic board and from the end inverter board,the voltage i get is right.
pin1 12.5v.pin3 5v,pin4 from 0v to 3.3v gradually everytime i hit F2.
does it mean the inverter and logic board are fine?
is it the screen?
many thanks