-
All replies
-
Helpful answers
-
Apr 3, 2014 2:42 PM in response to Bruce Thomson1by Bruce Thomson1,A little searching and I found the description of the problem in an Apple document (link below). The repeating short-long-short pattern action reads:
Make sure you are using the correct power adapter with the display. This alert will only appear on displays built in 2004 or later which require an external power adapter.
Other information implies that this is insufficient power from either a power supply failure OR excessive current draw by the back lights with age (in which case the power supply is now effectively inadequate) OR a spurious detection of that condition by the monitor. Seven years old, I'm thinking it's not worth any effort.
http://support.apple.com/kb/ht2811
There is a YouTube video about a "repair" that insulates the center pin on the power supply to Cinema Display to fool the display into thinking everything is OK. One comment on that video:
To the people using this tape method to fix your Cinema Display. Keep in mind that the problem is caused by a failing 3.3v regulator on the logic board inside the screen case. Taping it will force the screen to keep working, and given time, will probably kill the logic board. The proper repair is to remove the logic board, and replace the 3.3 volt regulator. This regulator is connected to the PSU sense signal pins, so when it fails, it causes the display to think you have a defective power brick connected.