A1267 Cinema Display 24" no backlight

[Alan.L]

anyone has fixed one of this?

i get backlight for split second soon as i connected to a mac. yes i still get a image after no backlight.

i've measured the test points and i get all these voltages.

 

[Alan.L]

found this,

https://imgur.com/a/O0Vqo

 

[Alan.L]

i've removed the solder blobs and surprise both fuses is still there and has continuity.

so now not sure if i have a panel problem or psu or logic board..

 

[dukefawks]

Usually it's the LEDs inside the LCD. See if you can light up the LEDs with external power supply. There are 4 pins and thus 2 strings of LEDs. I believe they need 45V or something. Just start at 30V and go up from there.

 

[Alan.L]

it has 6pins. i've took the led strips out and have tested individuals LEDs and all are working. i also have manage to chip a small corner of the LCD (inside) while trying to remove the frame. i've put all back together. lcd is still seems fine. should i leave it as it beyond our skills ?

 

[Alan.L]

was going to dismantle for parts. then it decide to turn on permanently(hope it stays) . why?...maybe its a intermittent issue.

 

[Alan.L]

ok after 10min, the backlight goes out. any idea Duke?

 

[dukefawks]

As I said it is in the LED strips. You need to reflow every single LED on the strip and also the connectors.

 

[Alan.L]

i've reflowed the connector and LEDs on the strips with hot air from the bottom. the display's backlight has been running all night
i'am now more confident to get more in to fix.

i often can hear small ticking/buzz noise, is this from PSU?

 

[dukefawks]

I hope you used flux and nudged each LED to verify it actually reflowed. With the aluminium heat sink strip just using bottom heat I doubt you can get a proper reflow.

 

[Alan.L]

Yes i’ve used flux and have nudged each leds, and they moved back into place when i over nudged them due to surface tension . I did tried using soldering irons, but these solder joints are too small for any tips i owns. Do you have to repair these screen often? This solution isnt even available on google and youtube. Thanks Duke. The screen has been running for a whole day today. Will test for few more days then pack..