Apple Studio Display M7649 CCFL to LED conversion

[phunguss]

I have a few 17" Apple Studio Display M7649 on hand. I bought another one with a broken stand. When I got it home, it would power on, but not illuminate. I have another one that comes on but then powers off after 5-10 seconds. So with two bad ones, I was hoping to piece together one good working one. I started with some disassembly and swapped inverter boards to verify the boards and the CCFLs. The result is that one inverter is bad, one is half dead. One set of CCFLs is hanging on, and the other is completely dead.

Using the pinout on the main board, I used a multimeter to test voltages of both units while powered on and off so I had a good idea of what I was dealing with. I never got the real 28v as Apple specifies, only somewhere between 24-25v.

During the PPC Challenge 2025, I purchased some LED strips to put into a couple of older laptops, but never completed those tasks. The strips are about an inch short, but I thought I would give it a go and see if they would work in this display. I disassembled further with no guidance (iFixIt only has a reference to inverter exchange, nothing about the CCFL swap).

That was a little too far. I did not need to disassemble that much. Hindsight, I found the tiny Phillips screw to remove the CCFL.

But I also found the real LCD part number.

These are the LED "inverters" or drivers that came with the LED strips. The eBay sale said 9-24V, and the silkscreen on the back says 28V. I didn't want to get near the limit, so I included a voltage drop to 15V.

I created a new wiring harness to take the 24-28 to 15V, then to the drivers. (original for comparison)

This includes a simple two resistor voltage divider to get a 0.2V to the "inverter OK" line telling the control board that the drivers are working. 100-Ohm and 22k-Ohm.

Tuned the voltage to 15V when off, and when on, I get a small drop (expected).

First test of wiring and electronics, LEDs not installed yet.

The CCFLs had a small rubber stopper on each end of the illumination slides. I 3D printed in clear PTEG some replacements to hold the ends of the LED strips.

The face was slightly yellowed and dirty, so I cleaned slightly for dust but no de-yellowing action taken.

LED strips installed, just testing for power and light, verifying the Display controller board actually created an image (VGA monitor in the background to verify OS was running).

There is some light leakage, but once fully assembled, I am sure it won't be noticeable.

Full testing but not fully assembled. I am still 3D printing a 'tray' to hold the electronics. For now they are held in with double stick foam tape. Looks really cool with the back off.

And the brightness adjustment works!

The corners are a bit dimmer, but that is expected as my LED strips were a little short. I will order a longer pair for the other display.

 

[phunguss]

Since the previous post, I ordered some longer LED strips that were more appropriate. The previous post used two "laptop" kits which have an inverter that only drives one strip of LEDs. The new inverters came with dual strips, so each tiny inverter drives both strips. These inverters are also listed as 9-30V, so there is enough headroom with the 25-28V from the AGP slot, so no voltage limiter will be used as in the first post.

Here is an image of the new original lengths compared to an Apple 22" HD Cinema display.

After disassembling my 17" and trimming the LED lengths to match the CCFL tubes.

I 3D printed some mounts, and added some black hot glue to the wire ends to hold it in place and block any stray light. STL file added to end of the post.

Wiring. We are bypassing the logic in the controller board to tell it that the inverters are working normally. I made two sets of cables because I have two faulty displays (one replacing the dual from the first post, and a second with power but no image).

I have some other matching connectors, so I kept the original intact. Some randomly selected resistors to voltage divide the 5v to less than 1v but not zero. I added some shrink wrap to help identify wires of the wrong color.

And finally added some double stick foam tape to mount the board to the back of the metal.

I did not take any further pics of the completed assembly, but the corners are no longer darker. Both displays are bright and crisp!

I also have an Apple 23" Cinema Display but one side is severely yellowed. At first I thought maybe the acrylic was aged and sun yellowed. But upon disassembly, I discovered it was the internal back cover that was actually yellowed and the acrylic was clean and clear. Might be hard to see in this photo.

I sprayed the whole back with the same mailbox paint I used for my G5/Intel Classic Mac Pro cases.

And reassembled.

Again, bad lighting, but the yellow that I saw before is pretty much gone.

 

[mac27]

This is great. So what would you approximate as the cost to convert one of these displays over to LED? Would there be much difference between the size versions (15", 17", 20", 22", 23")?

 

[phunguss]

This is great. So what would you approximate as the cost to convert one of these displays over to LED? Would there be much difference between the size versions (15", 17", 20", 22", 23")?

Based on the long length of the originals (listed as 15-23"), they will fit any size of these displays. A set of five delivered is US$37 from eBay, you could probably find similar items on Amazon or AliExpress, depending on your global location. So US$7 for a set of LEDs and drivers, some misc resistors, shrink wrap, your time soldering, some 3D printed parts, double stick tape, and hot glue.

I would say you could do the conversion for about $10 total out of pocket, plus your time.

I have not dug into the inverter board on my 22 and 23 to see if the pinout is the same, but that may take a little discovery. I don't have a 20" to compare to.