24" Apple Cinema Display Lcd A1267 [backlight Broken]

You are looking at a 24" Apple Cinema Display that is being sold AS IS for PARTS/ NOT WORKING!

When you plug it in to a laptop, nothing shows up. The screen of the laptop flashes like it normally would but then no display on external screen. I feel a little air flow from the bottom of the external display so I know it's running. So basically I don't think that the power supply of screen has an issue.

The screen and the glass are in good physical condition.

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Clarecastle, Clare
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3 months ago

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7 months
@Haru-tan: Alright I'll see if I can go alone from here using your information. If you have the means to sell a functional LED panel please consider me. Thanks.
7 months
The image linked below features a pair of backlight assemblies with LED modules. One of the substrates is bare, as it was damaged and therefore used as source of donor modules for another assembly. The LED modules themselves are Lumileds LXML-PWC1-0100 units and can be purchased from Mouser or similar distributors.

Image: https://i.imgur.com/4SqJLV8.jpg
Modules: https://www.mouser.ie/ProductDetail/Lumileds/LXML-PWC1-0100?qs=7Vwje68bFtOUOQDlxXphMw%3D%3D

My repair procedure entails desoldering and testing each individual LED module with a bench power supply in constant current mode, in order to determine which modules are usable and which have deteriorated and need to be replaced.

I'm afraid you are unlikely to find any online guides dealing specifically with the repair process, as knowledge of this design flaw is not particularly common. Rossmann's forums may be of help, as well as EEVBlog's videos dealing with SMD soldering. I can't help but feel as though I am breaking the unwritten code of engineers by sharing this! :P
7 months
@Haru-tan: Thank you for the response. The monitor failed around the same time as my Mac Pro 4,1 did (for unknown reasons). I disassembled the monitor to look inside and re-seat the cables and all that. Swapped out the Logic board as that what some people in online forums suggested, to no change. I've been trying to contact a German seller on eBay the previous two weeks about a faulty 24" ACD he has for sale, but has not read his messages. Both the monitor and the Mac Pro I'm desperate to fix. I have tried much to repair both of them to no success.

I would like to learn more about the LED modules you speak of. I have taken out the LED panel before, but not deconstructed the panel itself to show the modules. What do they look like? I can not find a tutorial online guiding through the process of replacing them. Are they just regular 1W white LEDs? I am willing to perform the repair if I knew exactly what I was doing. I did notice when I bought the monitor in 2009 that at certain occasions (such as leaving the monitor powered off for a few days), the top left-hand side of the screen would have a visible damp patch.

If you are able to sell me a replacement LED panel whole, I am in the market for that. Or if it would be helpful to swap and replace working LED modules from a partially broken LED panel, I would also be interested in that. Thanks for the information regardless.
7 months
Greetings. Clare is a three hour drive for me, so while I can't purchase this from you, I thought I would offer some advice. I have repaired many of these 24" ACDs and almost all of them fail in exactly the same manner due to a design flaw.

The backlight assembly in these monitors consists of 60x1W LED modules soldered to an aluminium substrate, which is mounted to the frame of the LCD panel. This provides inadequate heat dissipation for the modules, resulting in a premature current draw falloff at a given forward voltage. The LED driver is constant current, which means that over the lifetime of the monitor, it is gradually ramping up the supply voltage in order to keep pace with the deterioration of the LED modules. Eventually, the voltage required to maintain the required current exceeds the upper limit of the boost converter and trips the over voltage protection, giving the impression of a dead backlight.

The solution is to replace some or all of the backlight LED modules. Hope this helps!