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24" display; Built-in iSight Camera, Microphone, and Speakers; 1920x1200 resolution. Released October 2008, identified by model number A1267.

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Backlight not working. Camera, Sound, USB, and LCD are functional.

Hi everyone,

I have a 24” LED Cinema Display that stopped working properly. The monitor is able to power my laptop, utilize the USB ports with data, sound works, and the iSight camera works. I isolated the issue to the backlight as I shined a light on the screen and I can see my desktop mirrored.

Interestingly, when I first plug in the display while connected to my Macbook Air, the screen will flicker for a split second so I assume that the backlight still works and that is NOT the issue but I am not entirely sure. When the display is on, I do not see a dim glow at the bottom even at the highest brightness.

I opened up the display to make sure the the cables were not pinched or anything and fully connected but I am at a loss right now. I unscrewed the power supply and logic board and didn’t notice any bulging capacitors after doing a very quick glance. I noticed on the power supply board there was a white chalk like substance covered on the left portion of the board and I cleaned it with isopropyl alcohol but didn’t notice anything else.

I was trying to follow a similar guide on this website but I am not sure where to start. Wondering if it could be a capacitor issue, or voltage issue?

Should I just cut my losses and recycle the machine?

Thank you!

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What do you see when you shine a flashlight into the display, place it on the glass at a sharp angle do you see the faint image of your desktop and its icons? You may want to do this in a darkened room.

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There is an image on the screen but no backlight. I've isolated the issue to the backlight and I am not sure if its a capacitor, backlight function cable, or backlights themselves. When I first plug in the display, it will flicker. I opened up the display and did not see any bulging capacitors but I did a very quick glance. I have highlighted all my steps I have taken in my original post but I am not sure where to proceed next.

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@johnnyn - At this point you'll need to measure the voltage of the backlight power feet to the display. Do you have access to a DVM?

You'll find the service manual here: Apple LED Cinema Display 24" Repair

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I have access to a DVM and was planning on testing the voltages as my next step. However, when reviewing the repair guide and other forum posts on here, I can't seem to locate where the GND (ground) test point is.

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@johnnyn - The best place is one of the six screws which hold the logic board.

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I’ve been trying to solve this same issue for several years. I can’t recall where I found the info, but one possible problem is that the LEDs have worn out and there is a circuit that turns them off when they run too long. You’ll know this is the issue of it works intermittently. After turning the monitor off for several minutes/hours/days, the backlight will work again for a while, but eventually die again. It gets worse over time till it just won’t light up anymore.

The problem I’ve had is finding replacement LEDs. Every few months, I do a search on Alibaba hoping they’ll turn up. (I once bought a set, but it was mislabeled and was actually LEDs for the larger display. If anyone wants them, please contact me!)

I believe there was a solution to circumvent the circuit also, but you lose the capability to adjust illumination.

If you learn anything more or find a source, please share! Good luck!

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Johnny será eternamente grato(a).
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