Replacement power supply for Apple Cinema Display

LED PSU running an Apple Cinema Display
Close up of the supply & power switch

NB: Photos copyright Eroni De Oliveira

A reader sent me some information on replacing the Apple power supply for the Cinema Display. He realised that a 24V 'LED Strip' power supply should meet the power requirements for the display.

The power supplies sell for around $20 which is a considerable saving compared to the Apple version around $100 to $200 (depending on usage). He was in the process of testing 2 'dead' displays and was able to exchange parts between them to diagnose the problem for each display…

I ended up fixing one of the monitors by switching CCFLs between them, which confirms my belief that the most common problem among these older units, is related to the backlight bulbs. The other monitor has a cracked LCD display.

Like any fluorescent lamp, as they get old, and darkens it's extremities, their current consumption changes, triggering protection circuits in the ballast board and/or the logic board, as well as in the external power supply itself. Remember that these bulbs work with high voltage (around 420 Volts) and any small current variation at that level causes a much higher one at lower level, hence the need for protection circuits despite having a 3 Amp fuse at the ballast board. That explains why, sometimes, a more powerful power supply is able to correct it (temporarily nevertheless).

Another issue has to do with the high cost of the original power supplies been, most of times, twice the price of a defective monitor. I decided to use an alternative power supply that cost around $ 20.00 and are very stable and ripple free. They are designed to power LED strips, with an output of 24 Volts, 5 Amps (about 120 Watts). They have others with different specs also. The output voltage can be "fine tuned" to precisely 24.5 Volts; there is a control for that purpose.

The connection is simple: the shield (from the monitor) is grounded along with the ground from the AC line (green wire). The red, from the monitor, goes to the positive and the black to the negative. The "control/protection" from the monitor (center thin wire) I left disconnected. I trust that the 3 Amps. (on the ballast board) should blow, in case the bulbs get really bad. 

Ebay LED Power Supply and Alternative Ebay supplies

– Eroni De Oliveira.

The pictures are self explanatory, cut off the Apple power connector from the display and wire the correct outputs from the supply.
It certainly seems like a good solution. With a simple case added to the supply it should keep running for another few years just think about the heat dissipation if you do choose to put it in a case.
Thanks for the info Eroni, I envy your workshop :^)


Sorry you had a bad

Sorry you had a bad experience with the PSU. Eroni managed to get it working.

which power supply to use

I'd echo the comment about the PS specified in the link to be poor quality.   Mine died after a few months.

I built another with a Meanwell RS-150-24 (available from, among others) and it has been very reliable.  And only slightly more expensive than the eBay one.


Up and running

I finally got around to sorting this today, it was a bit daunting cutting the plug off a screen I'd bought on Ebay without being able to test but it works a treat. The first time I turned it on the screen wouldn't stay on without keeping my finger on the power button (nearly crapped my pants) but I knocked it off at the wall and tried again and it's perfect. I've used a well drilled sandwich/tupperware box as case for a bit of added peace of mind. Thanks for the guide!

Fixed my trusty old 23" Cinema Display

Thanks for this great post! I ordered the PSU from eBay for $18.95 including shipping and got it wired up in just a few minutes. My display now works perfectly. 

I broke open the old Mac power supply brick so that I could use the connectors. The AC power connector helpfully has "L" and "N" marked on the two power wires so you can just hook those to the new box. The proprietary display connector has a red and black wire and also a ground wire over to one side of the attached circuit board. I connected the ground wire from the AC connector and this ground wire to the ground post on the new PSU, hooked up red to V+ and black to V-, changed the input voltage on the new box to 110 and I was good to go.

USB ports seem to work fine.

You saved me from having to pay $100 to 175 for a new Apple PSU or, god forbid, having to buy a new non-apple display. 

That's great

Thanks for the info, recycling the PSU conectors seems like a good idea to me too :)

I would like to share.

Information perposes only etc…

This is NOT for the faint of heart. 

A source for a supply is the HP LaserJet 4 and probaly any in that family that uses the SanKen Model no. RG5-031, or similar variants. I found the 24v on pin 3 of the big connector. Ground or negative on pins 4,5 ,and 6. Pins 1 and 2 are 5v.

I think the important thing here is the presence fo the 24v fan under the grate that is above the controls and display. 

Bash the grate open, lift the metal tab and confirm the 24v mark on the fan. If it is there then rip off the right plastic panel. There it is at the bottom! This should confirm that you have a 24v sourse from the P/S. Question everything, grab your multi meter!


There is a HIGH voltage plug on ent side near the AC in plug!


Thank you for all the information here. I hope my contribution helps someone.

Mica P.F.

p.s. I know my spelling and grammer can be atrcious. :-)

Thanks for the info

I guess someone out there may have a dead Apple display & a HP printer to hack up. So long as the specs match up it should be OK I guess…


30" ACD - psu is now clicking


I hope there's still interest here and someone can point me in the right direction.

I acquired a 30" Apple Cinema Display that was missing a power adapter brick, and based mainly on the info in this thread, I bought a 24v 8.5A 150W power supply from ebay and wired it up. Everything worked fine for a few days, but now the psu makes a rapid clicking noise and the monitor won't power on. Did I fry something?

Did I need to adjust the voltage dial before hooking it up? 

I have a basic knowledge of electronics, but I thought I was in the clear, since everything was working fine. 


Sorry, that doesn't sound good

It would have been wise to check that the voltage was correct before running for an extended period.

Do you have a multimeter? 

I suspect you will need to measure the output of the PSU to see if it is now failing to provide 24.5v. 150W should have been enough for a 30" display but I guess it's possible that the display drew more current & maybe overloaded the supply? 

Turn the PSU off, disconnect everyting & let it cool. If you are lucky there may be a thermal fuse that resets. See if you can see the specification sheet for that model of supply, they are confusing, but eventually they can yeild useful info.

Thanks a bunch!

I really wanted to replace my mismatched 22" displays with a couple of Apple Cinema Displays, since I have a Mac Pro.

I was trying to understand why I saw all sorts of displays for sale with no power supplies, so I did some searching and came across your blog.

Being an electronics person, I had no problem locating a 10A 24VDC switching power supply which I am now using to power my two 23" ACDs purchased from a computer salvage vendor on eBay.

Total cost: $230.

Total satisfaction.


Thank you!


No problem. 

This was Eroni's idea, it's great to know it is working for you too.

Good luck with it & you are most welcome.


30" apple cinema display

hello for the people that have made this work on a 30" apple cinema display and its been continuously working with no problems please tell me the specific power supply and or laptop power supply if used you used please include full specs on power supply and and time in use with no problems and any thing that would be helpful to know while or before the operation in reference to the 30" apple cinema display this would be helpful to me and others as i have 2 that need power supplies and the information I've found online so far is for the 20" and 23" as far as giving conformation it worked on those size displays and continues to work i can not find this for the 30" with conformation of working continuously and specific specifications of adapters used so if you can please help by provide your experience and knowledge and it will be very helpful and appreciated by me and others thanks 

Please take a look at the

Please take a look at the links in the post.

There are LED power supplies listed, you will need to compare it to the original supply - e.g. you will need a supply capable of 150W (minimum) at 24V.

PS for 30" ACD

30" display internal power socket

I would like to try and do this with the 30" version of the display. I have already opened the display and rather than cutting off the end of the cable I would ideally like to connect the power supply to the internal socket of the board. From what I have read when you cut the cable you have a red, grey and black wire, however internally I can see 5 wires, 4 black and one thin greay wire in the middle. Does anybody know how I should connect these to the power supply? It might be worth noting that I am in the UK in case there are any differences. Thanks!

Alternative power supply for 30 inch cinema HD display – (150 wa

I purchase 24-volt DC 20 Amps power supply (china made), and I fixed it as you say.

It’s amazing, I save lot of money plus I put 20 Amps power supply with thermal sensor fan. I am really thank full to you.

Abul Faiz


Does the Voltage need to be 24.5V or is just 24V ok? Lots of people seem to just be using 24V PSUs, however the Apple website lists the supply requirement as 24.5V. Will running just 24V kill the screen?

Thanks in advance

Eroni's supply was tweaked to output 24.5V

Re read the original post, Eroni said that the supply was setup to output 24.5V. Others are apparently having sucess with 24V, but sticking to the original spec is the best thing you can do.

I suspect 24V may be close enough, however some power supplies can 'sag' and fail to output continously. I think you will be safer if the PSU can output 24.5V when under load, there is less chance of causing the display to stop working.

The voltages within the display are stepped up to be high voltage for the backlight, the input voltage & current needs to be within a range otherwise the inverter won't work, you'd get a different flashing error code for that.

If you are not sure seek out a replacement Apple supply, stay safe :)

High Pitched Sound from Converter

Thank you for this great tip. 

I bought the 24v 5a 120W converter ( to use with an Apple 23" Cinema Display, got it connected and working. However I hear a high pitched noise coming from the converter whenever I raise the brightness all the way on the display. What's the noise and is there a way to stop the noise? Thank you. 

Sorry I don't know what would

Sorry I don't know what would cause that high pitched sound. 

You should get up close to the monitor and to the power supply to be certain where the sound is coming from.

The power supply will use components that operate at a high frequency, sometimes a solder joint or collection of components can resonate making noise. If the power supply is making the noise I would contact the vendor & return it or enquire if it is considered 'normal'.

The display also has a high voltage inverter inside which powers the cathode backlights these can also squeal for similar reasons. The noise may be a sign that the cathodes or inverter are failing - the fact your older Apple PSU no longer works also points towards similar issues, as the lamps fail they require more current which the PSU was never made to supply.

p.s. I personally did not use this repair, it was another reader so my knowledge of these supplies is limited.

can't get supply for 30" ACD to work

I am trying to build a power supply for a 30" Apple Cinema Display.   I've actually tried one that I built (and worked well) for a 23" model, but it will not work with the 30" one; instead, the pilot light blinks in the repeating "short-long-short" error code which indicates the wrong supply.  I used a Meanwell LRS-150-24, which should supply (barely) the current required by the 30"; I've measured the output voltage of the PS and it is not sagging (below 24.5v) so I don't think that's the problem.  I wonder if it has something to do with the center wire (on the connector) ?  I have salvaged a connector from a dead 23" brick, and on it I connected the center wire to GND.  I tried disconnecting it completely, but still no luck.

I guess it's possible that

I guess it's possible that the same 3.3V regulator that causes the other models to show the 'short-long-short' error code could be causing your issue. See another page on this site

Another thing to consider is that the power supply needs to produce a sufficient current, not just sufficient voltage. An underpowered supply may cause the display to fail to work but I don't know if it would cause this error code.

The center pin on the supply is actually for telling the display what supply is connected, other people would use the 'center pin hack' to cover the pin to fool the display into thinking it was a more powerful supply. To me that suggests you should check that the center pin has infinite resistance, I think the 30" model uses the highest rated PSU.