Apple 23" cinema HD display PSU suddenly inadequate

Question

This has not happened to me, but a friend who is relatively new to apple products. 13 months after she got her 23" cinema display (which means one month out of warranty) the display suddenly would not turn on and was flashing short-long-short, or whatever the broken PSU signal is. Anyway, to verify that her PSU was indeed broken, I borrowed the 150W PSU from my 30", and the display turned on fine.
She went to the store and got a new 90W, but as it turns out the new 90W doesn't work either. It's still flashing the short-long-short code.
What this tells me is that the old power brick may not have been faulty, and that the display instead decided to suddenly require more power. Anyone else with this issue, or any suggestions what to do about it?
As for the old power brick, it's long gone and recycled in case you're wondering.

Answer 1

Similar Problem with our 2 year old Cinema Display in that it shows short-long-short flashing of Power LED and a blank screen. My wife said a thunderstorm was approaching, so she unplugged the computer and display power adapter. Next morning after plugging in the display stayed dead other than the flashing. Tried about everything including:
1) Connected a VGA montor to the display card using a DVI to VGA adapter - Card X1900XT seemed OK.
2) Reset PRAM
Like many I suspected Power Brick based on the Info from Apple. If the company is so environmentally friendly as they make out they would not seal their stuff, making it unrepairable - our throwaway society. The sealing only ages the electronics anyway because the heat transfer is restricted by the plastic case. I could not test the brick because it was difficult to get to the contacts in it without another proprietory Apple connector. So I thought what the heck and a sawed the brick open. The brick is outputting 24.7Vdc and also under load of 2.5A (my background is power electronics). The output connector has an identification resistor on one pin to ground that will incur a voltage across it when the display is connected. With the display connected and Brick open I measured 1V. This is how the displays identify the correct brick is attached. With the display connected, the 24Vdc was there and stable. So in my case I do not think it is the brick, but something in the display. One possibility is the Brick is not well designed and under some circumstances produces a surge when plugging the AC side in. A lightening induced surge is very unlikely, as it was very far off at that point and even so, an indirect strike should not get through to the load of a well designed power supply. You can be sure Apple do not design the Power Supplies, the Marketing only say how they should look. Must be a nightmare for the contracted design engineers.
We have no Apple Care, so repair will be likely unjustifiable. My wife has located a supplier with some 20" ACD's still in Stock (the 24" LED ACD has only a miniDVI so we cannot use that). Personally I would rather another brand. Our HP's at work have the same IPS type LCD display in side. They do not look as nice (our display is VESA mounted on the wall), and are bulkier, but at least you get 3 year warranty and they collect it for you on site if you have a problem.
I have used Apple products for 20 years, but this has got to be among the worst of their designed products from a reliabilty viewpoint.
Any one know how to open up a Cinema Display - I would like to look inside?