Model A1181: 1.83, 2, 2.1, 2.13, 2.16, 2.2, or 2.4 GHz Core 2 Duo processor

1418 Questions View all

Flickering Backlight after replacing inverter and inverter cable.

I have a black Macbook Core 2 Duo A1181 (last 4 # of serial are: F0P2) running Mac OS X 10.6.8

I started having trouble with the backlight on my screen a few weeks ago. The screen would go black after opening it up occasionally. (Note I could see my desktop and icons, it was just as though the brightness has been turned all the way down.) This problem became more frequent as time went on. I could usually fix it by closing it and opening it a few times. Then it would for for a variable amount time before going dark again.

I started with the two cheapest parts I thought it could be based on my research on this site. I replaced the inverter cable first, which seemed to make things better (darkness came less frequently), but did not fix the problem. Next I replaced the inverter board, also which did not entirely fix the problem. Now when the backlight goes out, I can usually make it come back on by turning the brightness all the way down and then back up again. Sometimes I have to do this 2 or 3 times before the back light stays on. Just reset my SMC again (which I had done before I replaced any parts). Haven't had it go out again, but I only reset my SMC 10 minutes ago.

I am wondering what I should try next to fix this problem? Could this be the CCFL backlight lamp? If so any guides for replacing that? (I understand there may be some soldering involved, but I'm pretty handy. I hope its this, as its a relatively cheap part). Or is it the whole LCD screen going bad? Lastly could this be the logic board (even though I can always see the icons on the screen even when its completely dark? I'd hate to spend another $150 replacing the screen (when I'm already in it $75 and haven't fixed anything yet) only to find out its the logic board (which I am not willing to pay >$500 for on a laptop of this age).

Oh, by the way, sometimes the screen will flicker as it goes dark or as I am turning the brightness down and up.

Thanks.

Answered! View the answer I have this problem too

Is this a good question?

Score 3

Comments:

By the way, Resetting SMC and PRAM did not fix the problem. Backlight has gone out since.

by

Sounds like you've isolated the problem down to the display

by

Just a little follow up: I successfully repaired it by replacing the LCD screen (purchased off amazon for $80, just fyi). Thanks for the advice.

by

Add a comment
Mac RAM Kits
Speed up your Mac. Max out its memory.
Mac RAM Kits
Get more memory out of your Mac.

2 Answers

Chosen Solution

Click here, for a generic tutorial on how to replace a CCFL bulb. The gist of the procedure is similar for most LCD screens. I suggest you wear non powdered rubber gloves when you do this. The oils on your skin can/will leave hot spots on the bulb and discolor what ever else it gets on. Take care when removing the silver tape holding the "tray" the CCFL bulb sits in. You will need to use it again for the install. If it gets crinkled it will reflect the light unevenly when the job is through. Click here, for a tutorial on the soldering technique to attach the wires to the CCFL bulb. This repair is not as hard as many would think, I've done a number of them on other models, though it is not a job for the faint at heart. If you live in the US click here to get one from a reputable seller for $4.00USD. If you live outside the US do a Google search for A1181 CCFL bulb to find offering in your area.

ADDING WITH EDIT

Machine in question: 2.4GHz - Early 2008 - MB404LL/A - MacBook4,1 - A1181 - 2242

With the parts you have replaced and the symptoms you give, I really suspect that the CCFL is the faulty component here. If you decide to replace the bulb instead of the whole LCD, I suggest you buy one with the wires already soldered on, unless you have excellent soldering skills. "Cold" solders make for bad connections that can/will cause screen flicker and/or humming noise. You also need to make sure the connections are insulated properly. They carry 500 - 600 volts. If not well insulated that voltage can jump/arc to the LCD frame and cause a great deal of damage.

To test the inverter cable. Preform a continuity test using an analog multimeter/multitester (One with the needle.) while moving the wires around. Do this for each wire in the cable. If the needle sweeps hard at any point, it is a break in the wire and the cable needs replaced. Digital multimeters usually have to slow of a reaction time for this type of test and/or have circuitry in them to ignore quick fluctuations in a reading.

NOTE: The following is for reference only.

You have a "3 wall" backlight header/socket on your logic board. With the upper case off when you look at the header socket there are 4 pins to it. The first one to the left is pin #1 and should read 12VDC or a little more (This is the supply line.). Pin #2 should be 5VDC and is what opens the gates on the inverter. Pin #3 is ground - Since the backlight is controlled by PWM (Pulse Wave Modulation) it is actually connected to a tank circuit and with power off may show a difference in potential difference from chassis ground. If the inductor or capacitor is bad in the tank circuit you will only have ground during half a wave cycle. If they are both bad you will have no ground, unless one of them is shorted. Pin #4 is the control voltage and should read 5VDC when the backlight is set to full brightness and something less than that on lower brightness levels. Unless you have special probes for your multimeter/multitester I would only test the voltages on the outer two pins (pin #1 and #4). Most test probes are too large for testing the inner pins (#2 and #3) and risks shorting out parts on the motherboard - and/or inverter, if hooked up.

Was this answer helpful?

Score 3
Add a comment

Sorry to say you'll need to swap out the display unit.

If you have access to a junker you might luck out, otherwise it's a new unit (buy online and do it your self) or an exchange out (if you bring it into an Apple repair center)

Was this answer helpful?

Score 1

Comments:

What about the CCFL backlight lamp?

by

The CCFL's are part of the display unit

by

Add a comment

Add your answer

rheller84 will be eternally grateful.
View Statistics:

Past 24 Hours: 1

Past 7 Days: 4

Past 30 Days: 17

All Time: 3,852