I am looking for some help with my 6-year old ACD. It works for about 2-3 seconds when turned on, then flickers and dies. This happens regardless of whether it is plugged into my MacBook or Mac Mini.

Using a flashlight, I can still see my desktop on the screen, but it is extremely dark. The other features (MagSafe charger, speakers & iSight) are all working fine.

Going through the questions here, this seems like a pretty common problem, however the answers are conflicting and confusing - some people say the logic board is toast, others say the backlight is dead, and I've even read something about the backlight being part of the logic board (what??) which is faulty.

Can somebody please confirm exactly what is wrong, and the replacement part I'd need to buy? Your help would be greatly appreciated.

Regards

⟐ Commented June 01, 2025 at 11:05 MST

From here, I don't know how to proceed troubleshooting this problem. It's always evading my attempt to fix it. The best way to troubleshoot this problem would be to temporarily swap identical model components to isolate what is the source of the problem. But I'm living in an area where nobody has a ACD. I've tried bartering with ACD sellers on online marketplaces to no luck. There are six main physical components inside the monitor that are culprits, replacing each on the off-chance would cost a collective ~€300 if I was unlucky.

Images: http://imgur.com/a/09iOx

Dan,

I've read the service manual carefully several times but I can find no solution and I've read every answer to the backlight issue on fixit but find no solution.

I've taken apart and reassembled every component inside the monitor with the exception of the main driver cable leading directly into the monitor. It was covered with weird silver tape (electrical tape?) that had to be peeled back. But I haven't had the guts to attempt to remove the cable from the slot, as it doesn't seem to want to come out. Does anyone know how to remove this cable?

Images: http://imgur.com/a/i3JUs

I have an update 13 months since my last post. The brightness in my display eventually gave out entirely and just didn't boot up at all when I powered on the processor. But then to my surprise the processor also stopped booting! Which implies the problem was with the processor all along.

Anyway, I bought a replacement graphics card and PSU individually, and neither part solved the issue. I cleaned the inside thoroughly and made sure everything is connected and such.

I am not done with the problem. I have not yet found a solution. My current focus is on the backplane board as I have ruled out almost everything else.

Occasionally the processor boots after an attempt to power up, with the display flickering for a moment and then going black.

⟐ Answer edited January 22, 2025 at 7:37 MST

I have an LED cinema display 24" from 2009, I have excatly the problem that the screen blanks out after a 1 sec flash of the image (probably LED driver signal turns down). I was about to try the bypass solution above for the 3.3V drive input, but then wanted to ask first if the same backlight strip probem problem could be on my LED Display as well, because I would not want to loose the dispay dimming possibility.

update:

So I did take the LG LCD panel apart in search for the notorius LED Strip, see pictures:

Taking the LCD apart:

The LCD frame,

The Backlight panel,

The plastic frame,

The glass of the panel,

The back plate,

Finally getting down to the LED Strip

So I did resolder the LED connector (just added some solder to it and re-heated the 5 pins again thoroughly), but my problem still persists, the LED stripe only flashes quick at connection display port connection time. I am considering of doing some logic measurements tonight with my oscilloscope for the LED driver, but the willi fix for bypassing the 3.3V is starting to sound tempting (still trying to find out the real reason for this failure, and I have to admit that the LED stripe fault sounds more plausible to me due to the drive signal LED shutdown after one second flash.

@io nut

I made some advancements with the display but the reason for the fault is still unclear.

All of a sudden the LEDs decided to turn on again.

I am convinced that it has something to do with the horizontal positioning of my setup. While lit I quickly checked the LEDs and realised that Led nr. 27,30,40 and 60 are out. Next day when I started the display the background lighting did not lit again.

I figured it might have something to do with grounding and tried out connecting the displayport without the USB cable. No effect the LEDs turn on with or without the other USB connector and/or the Powerconnector. I realised that the LED cinema display brightness can not be adjusted without the USB cable connected to the my macbook pro.

LED illumination pattern 2/3 Leds.

LED illumination pattern every third LED

So after all the MODs my display is running again. Eventually I ended up only changing 9 capacitors (3 pcs of each of the black ones in the pic, the orange ones I still have originals) on the powersupply,

and resoldering the LED stripe connector,

in addition I assembled and reassembled the display several times (loose connectors).

So Im still not convinced about the source of the fault and Im now testing the display for a week, lets see if it actually stays on.

My Apple LED Cinema Display 24" is still up and running.

Unfortunately I have to report that my LED cinema display died again after one month of fluent usage. So Im back to square zero. :!

I decided to try out if my display runs and it seems to run again :). So lets see for how long, but I am suspecting some sort of capacitor voltages that are incorrect due to capacitor ageing.

⟐ Answer edited January 22, 2025 at 7:35 MST

⟐ Commented September 16, 2024 at 7:35 MST

⟐ Answered July 26, 2024 at 15:01 MST

I bought LED light checker , test result is each stripe 54V shown.

I found one of boost schottky diode ( STR0+ ) exploded. also mosfet has burned.

according to A1267's service manual I can find 24.5v and 15V from PSU into MLB.

I need to clarify "Power Source voltage firstly". please tell me some data if you have a exprience.

Question:

1. PSU Connector's Pin voltages: Can you tell me correct voltage each connect pin on MLB ?
   • now I measured pin#1 : 24.5 V , pin#2 : 24.5 v ( tied up pin#1 ) , pin#3: GND , pint#4 : GND ( tied up pin#3 ) , pin#5 : ? , pint#6 : ? , pint#7 : ?
2. Back Light LED test result
   • I can read about 54v each stripe by Back light Test. I guess back light well.

**

I am going to exchange 540N Boost MOSFET and B2100 schottky diode and HV9982 controller.

firstly I have to check power source of back light , locally I guess PSU provide 24.5V.

order to check TP11 --> TP12 --> TP81 and STR0+

anyone who know proper parts?

1. Mosfet part : Rds value ?
2. Schottky Diode part : Vd value ?

⟐ Edited July 07, 2024 at 7:58 MST

⟐ Answered April 06, 2024 at 3:48 MST

⟐ Answer unaccepted March 18, 2024 at 3:29 MST

Does not appear when the monitor is off. Only after it's turned on. Should I just chuck them?

⟐ Answer edited September 22, 2023 at 4:13 MST

I'm posting some pics. Any suggestions?

Thanks!

⟐ Answered September 21, 2023 at 12:44 MST

Hello everyone, i want to repair my minitor A1267, i removed the display and checked the power supply. I noticed that the 24V are working also the Fan is working and if i am plugging the usb to my Laptop the sound was only working for about 5 seconds, also the Display is not working but USB ports are ok. What can i do? Remove the logoc Board with a new one?

I also noticed that when plugging in the Display while the Monitor is powered, the Fan stoped spinning..

If someone could help me i would be glad.

Best regards

Marcel

⟐ Commented March 14, 2023 at 13:42 MST

This is my webcam connector https://drive.google.com/file/d/19FsGzWg...

⟐ Commented December 31, 2022 at 1:01 MST

It's almost 2022 and this monitor is till knocking around. I really is a nice display and design and would hate to throw it out. I tried Barkin Tunga's fix and tough it didn't solve the problem it did confirm that the monitor still has life in it.

Barkin Tunga's fix here: 24" LED Cinema Display flickers then dies (A1267)

Upon waking it up from sleep (connected to a 2013 MBP) the monitor did flicker and I could clearly see the desktop wallpaper on the display.

It seems to seems to me either something is loose, (cable?) or it could be a cold solder joint. Suggestions are welcome as to the real culprit.

Thanks folks!

~ EMJWAYLZ

⟐ Answer accepted November 08, 2022 at 4:52 MST

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!

⟐ Answer deleted September 01, 2022 at 12:46 MST

(which includes, late 2009 poly MacBook, early 2009 20inch iMac and a late 2009 27inch iMac ) someone please have a fix for this as I’ve been dealing with it for a long time now

⟐ Commented July 12, 2022 at 13:22 MST

⟐ Commented June 25, 2022 at 23:39 MST

When I connect my Apple Cinema Display 24" ... the flickering goes mental ...

Tried every configuration. still no luck

⟐ Commented May 30, 2022 at 20:40 MST

⟐ Answer deleted March 10, 2022 at 20:16 MST

I’m using without issues a Apple display 27 with my MBP 2017

But if I try an Apple cinema display 24: not seen, not detected, blank screen (same on my MB air) but… works fine on a MBP 2015!?

(I’m using the proper thunderbolt 2 to USB-C adapter).

Any idea ?

⟐ Commented February 10, 2022 at 15:52 MST