The Apple LED Cinema Display features a 27-inch (2560x1440) glossy LED-backlit TFT active-matrix LCD display. This is the Mini DisplayPort model, which came in both 24' and 27'. There were 2 generations released. Apple 27' LED Cinema Display (MDP) MC007LL/A.
It may not supply the power to the LED backlight. May be there, you can also not rule out the power supply. Just because the power /sound/etc. You do want to check your logic board over and see if you find any bulging or leaking capacitors. Monitor Type Description: The 27-inch Apple LED Cinema Display, featuring a stunning 2560-by-1440 resolution, LED backlighting.Jason, this is not as easy as just recommending a certain part that has failed.
The chart below provides the estimated greenhouse gas emissions for the 27-inch LED Cinema Display over its life cycle. I would also suggest that you try the Apple Deep Dive for Blank / No Video, No Backlight:Apple seeks to minimize greenhouse gas emissions by setting stringent design-related goals for material and energy efficiency. Post a couple of hi-res images of your logic board with your question, so we may look at it and see if we can come up with something more concrete. There should also be a fuse for the backlight, which may have failed.
Connect Mini DisplayPort, MagSafe and USBConnectors into a known good, supported, powered-up portable. Connect display to AC power source. Featuring a response time of 12 ms and 1000:1 contrast ratio, this 27-inch LED model delivers the screen performance required for optimal viewing experience.1.
Verify that theSuspect no power to LCD. Unplug and replug Mini DisplayPort connector into a known-good, supported,Powered-up portable system and monitor the portable’s display. Remove glass and LCD panel screws, slightly pivot LCD panel and verify that the internal DisplayPort cable (part of all-inone cable) and function cable are fully connected to LCD panel and logic board.Reseat DisplayPort connection to LCD panel and/or function cable connections between logic board and LCD panel and retest.For any damaged cable, replace affected cable before testing again:4. Go to step 7.Suspected no power to LCD panel or no DisplayPort connection with system. Verify that thePortable’s display briefly turns off then back on.LCD is powered and detected by system. Unplug and replug Mini DisplayPort connector into a known-good, supported, powered-up portable system and monitor the portable’s display.
Suspect no LCD power from logic board.6. Go to step 7.LCD panel still not detected by system. Verify that the portable’s display briefly turns off then back on.LCD panel powered and detected by system. Unplug and replug the Mini DisplayPortConnector into a knowngood, supported, powered-up portable system and monitorThe portable’s display. Replace all-in-one cable and reinstall LCD.
Shine bright (low heat) flashlight into the front of the LCD. Check whether video is present on LCD. Replace LCD panel.LCD panel is detected by system but no backlight.
Apple Cinema Display 27 Driver Cable Connections
Set digital multimeter to DC and correct range, and verify that a 23.3–25.7 V DC voltage is present between logic board test point (24 V DC) and chassis ground (GND).24 V DC power for backlight is present on logic board, but no backlight. See Functional Overview.If connections are OK and secure and there is still no backlight, go to step 10.If any cable is damaged, replace affected cable and retest:- LED backlight driver cable (part of LCD panel)10. Remove glass and LCD panel screws, lift LCD panel to verify that the function cable, and LED backlight driver cable connections are secure. Go to step 9.No image displayed on LCD Replace LCD panel.9.
Replace LCD panel, (makeSure that you don’t pinch the LED driver cable from LCD panel) and retest. Also remove the logic board and verify if one or more of the three square inductors or adjacent components on top of board show signs of overheating.LED backlight driver cable on LCD panel found damaged. Verify if the LED backlight driver cable (part of the LCD panel) has any signs of pinched or shorted wires. Verify that the no backlight issue is fixed.Defective function cable prevented backlight from being enabled by logic board.12. Replace function cable and retest. Go to step 11.No 24 V DC present for LED backlight power.
I turned the display off and on and then it was dark.With the help of a torch light I saw a faint image of the desktop. First the backlight was very low or was flickering while trying to dim the display via the system panel. Hope this helps, good luck.After four years of using the backlight of the LED Cinema Display 27" was turned off. Replace logic board and verify that the no backlight issue is fixed.Defective logic board LED backlight driver output.Before you go and replace anything let us know what you found.
I found out that the microntroller is connected to the pin 10 (enabled) and the pwm pins (17,18,19). It can be used for driving either RGB LEDs or multiple channels of white LEDs.With the multimeter you can track the connections from pin to pin. The data sheet of the HV9982 you can find some basic information about the driver and this function:HV9982 is a three-channel, closed loop, peak-current mode PWM controller designed to drive a constant out- put current. It cares about the right current, because LEDs require more precise current management. the mosfets and coils of the driver (producing 80 voltage for the led stripes)The led driver (called HV9982) is responsible to drive the leds stripes with current. So the display is working without the backlight.First of all I teardowned the display like it shown in Teardown Apple Display
We just connect the PWM pins to logical one and that is 3.3 volt. (see for PWM)But we have some luck! We can bridge the signal to 100%. And you think the display is broken. In this case the backlight stays dark without any light. He turns the led driver on but "forget" the create the PWM signal. With the help of an oscilloscope I found out that the microcontroller does not send a PWM signal.
In the following image you can see how the microntroller is connected to the pwm pins of the led driver:I don't know what 800 ? is but new ones are avail. This would cause a short circuit. You cannot just put 3.3 volt to the pwm pins because they are connected with the microcontroller.
If Apple were to plan a failure like that and some disgruntled employee or reverse engineering tech were to discover or disclose it, it would be financial and marketing SUICIDE. Yes, there are always firmware revisions along the dev path but not ones that effect a failure years later. Also, with the monitors that are available now, repairs are becoming non-economical. It would not help you anyway. I paid about $99 retail for the last one I bought.
Risking their entire company just to sell a few more monitors. Placing a kill code in the monitor is much more devious and Apple consumers would recognize that. There were a small group of people desperate from their failure to solve a design problem.
Apple Cinema Display 27 Mac LG Failure
Decided to bite the bullet and took the LCD panel apart. Backlight still had a mind of its own (working whenever it felt like it) and eventually it stopped working altogether.2- tried Michael's mod -> backlight wouldn't still kick in at all, but the image on the lcd flickered4- remembered the iMac LG failure and took Aussie John's advice.
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