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Apple Cinema Display 23" Troubleshooting - Another Case

8K views 37 replies 5 participants last post by  hexdiy 
#1 · (Edited)
Hello everyone!
I have a broken Apple Cinema Display 23"(Aluminium) A1082. Sumptoms Black screen and no led blinking
And wow, I have a plan to repair it ))))
If somebody can help i will be happy

First off all Great thanks to all guys from the links below for many helpfull tips
MAC CINEMA HD Display 23 Inch by Bud Martin | Photobucket
https://www.ifixit.com/Answers/View...ing+apart+a+23"+HD+Cinema+display#answer16092
https://discussions.apple.com/thread/2086442?start=30&tstart=0
Apple 23" Cinema Display possible fix for 'short-long-short' error | pixelchimp.net
http://www.ehmac.ca/mac-iphone-ipad...isplay-23-pcb-q49c-info-about-transistor.html
http://www.ehmac.ca/mac-iphone-ipad...311-cinema-display-troubleshooting-parts.html
Apple Cinema display 23" ... detection problem - Badcaps Forums
But ... monitor doesn't work yet



Next I will describe what I did, do and will do:

1. I have a 24.5V from power adapter to mainboard input and disconnected center pin. Only +24.5V and Gnd connected.

2. I checked input from DVI(pin14) +5V. Red wire (J6) at mainboard.

3. I changed LM1117DT- 33 (VR3) w/out success Vin= 5.06V Vout=3.24V

4. I check Q1 transistor(H7XZ1). If I right understand it's P-Channel 20-V (D-S) MOSFET Si2367DS
Gate 11.1V Drain 24.5V Source 24.5V I dont know this is good or bad voltage cause I dont know how it should be

5. 2672(VR1) have only one pin powered Vin=24.5V


I attached picture with voltage at main board with some points I checked



Investigation to be continued ... join this
 
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1
#36 ·
OK, after some more reading up, it seems that U8 most probably is the dedicated EDID EEPROM of the ACD.
As it seems, somehow, sometimes, the EDID info on this EEPROM gets corrupted. This may happen because of brownouts, by hot-plugging, or whatever.
SCL is not the system clock, only the clock of the EDID signal. DVI EDID is imparted via Philips I2C, a bi-wire protocol using SCA and SCL pin 6&7 on the 29 pin DVI connector.
What you've accomplished by cutting SCL is probably tricking your PC/Windows into believing the DVI monitor attached is Non-PnP, thus triggering a most basic resolution.
I've found a nice link explaining how to reflash corrupt EDID via Windows, maybe you can benefit from this:
http://www.komeil.com/blog/fix-edid-...-no-signal-dvi
Good luck!
 
#38 ·
Hi, Ixusss. Been a while, but I've stumbled on a way to trick a Mac or Hack, maybe even a PC to emulate EDID info from within your computer itself. This way, you could benefit from the full capabilities of your Cinema HD Display, even if EDID info is not exchanged properly due to a broken EDID rom chip, or even primitive adapter cables lacking DDC signal lines. It may take some study and stubbornness, but I think you're studious and stubborn enough...
Enjoy:
FixEDID V2.3.2, Application to generate overrides automatically for Apple Displays - Page 2 - Developers Corner - InsanelyMac Forum
 
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