Wednesday, May 14, 2014

The best solution for dead Apple Cinema Display power adapter, detailed HowTo

I've got a hold on 23" Apple Cinema display recently, but with the faulty power supply. If you had the same problem, you probably now that it is a royal pain to get these today since Apple is not manufacturing those any more. If you look on the Ebay, you can find used ones with no guarantee.
Having seen this , i decided to take things into my own hands and use my high school electronics knowledge to fix this issue.
There is a workaround suggested on the web to use switching power supply, an external box with exposed wiring, which I did not like so I look at the available universal laptop power supplies that would be able to supply ~90W, 24V and 3.7-4A required for this project. I was lucky to find one that fits the description, made by Prudent Way with manually selectable voltage. Current was rate up to 6A and power was 90W. I just wanted to give it a bit of breathing room and I went with 145~150W version with the same other specs.
This method is the best since it does not involve invasive cutting of the monitor's proprietary video cable, but rather modification of the power supply cable. This ensures that not only power is working but USB is in sync as well. Other methods worked but USB was not usable.

DISCLAIMER: I am not responsible for any damage that this method may cause to you or your property, so there you have it, use at your own risk!

1. Cut carefully original dead power supply along seam line and expose PCB of the DC power connector, and cut all 3 wires. Leave them longer except the one leading to the resistor on the far left on the photo, that one we don't need. The PS was a tough nut to crack but it is possible with careful use of small saw.
See the DC power connector at the left side, the one monitor gets plugged in? Cut all 3 wires, black and red from the small PCB leading to the PS, and black one connected to ground on the AC connector. Now you have small board with the DC connector on it along with additional circuitry to sync the USB.

2. Look at the Prudent Way DC cable end, it is a female connector with 2 holes labelled + and -. Stick in red wire (after removing the insulation, approximately 0.5 cm) from the small PCB we took out front he dead Apple power supply to + and black to - respectively (red is + and black is -). Use electrical tape to secure the connections and isolate any static electricity that may cause issues. Make sure that all is well insulated.

3. Power on the power supply and adjust the voltage to 24V, the other settings are automatically selected for you. Make sure it is memorized by the PS (see Prudent Way documentation).

Plug in the power cable to the power supply and hope for the best. Power on your Mac beast. Again, I am not responsible for any damage you may cause using this method. It worked for me and since approved LCD PS was used it should be fine with everybody else.

4. Final look



The monitor works great, power supply is cooler than the original and USB ports work like charm.

Parts used:
- Prudent Way 150W power supply:
   http://www.prudentway.com/admin/uploadfile/PWI-AD150HC.jpg
   http://www.prudentway.com/products_showone.php?id=302#
-Electrical tape
-Small hacksaw
-Pliers
-Knife
-Dead 90W Apple Cinema Display power supply ;)

6 comments:

  1. Hi,

    I don't understand the thing about the USB ports.

    Why wouldn't USB ports work if you cut the cable from the monitor and connected the wires to the PSU?

    Thanks
    -J-

    ReplyDelete
  2. It's just because another method I saw had similar results without working USB hub on the monitor. That method involves using universal PSU and dealing with live 120V wiring that most users don't want to do and USB port do not work as with this method. That's all.

    ReplyDelete
  3. Can you please explain why the USB ports would not work with the other method? The one based on cutting the power cable from the monitor to the Apple Power adapter and then connecting the wires to a new power supply.

    The USB cable from the monitor would still be intact and can be plugged into the USB port of the motherboard, right?

    ReplyDelete
  4. "Inside there are 3 wires: black, red, and a tiny grey wire. The grey wire is a 5v wire presumably to give power to the USB and Firewire ports on the back of the monitor."

    If the grey wire is not connected to 5V -> no USB ports?

    ReplyDelete
  5. here:
    http://reismanitservices.blogspot.com/2012/01/replacement-power-adapter-for-23-apple.html
    They say that the USB ports work without the grey wire being connected.
    Maybe the grey wire is useless...

    ReplyDelete
  6. The fix detailed in this tutorial fixed my broken power adapter (90W).
    https://macs2u.blogspot.com/2013/10/fix-for-apple-cinema-display-power.html
    Everything is working well apparently.

    ReplyDelete