30’ Cinema Display > DVI to USB-C > M1: Erratic behaviour, need help!
First of all thanks everybody for the very helpful answers on this forum. I am experiencing very strange behaviour on a recently adquired 30' Cinema HD Display (a1083, 2007, HDCP not supported according to SwitchResX) and hoping somebody can help figure out the problem.
I have a 2021 14' Macbook Pro M1 Pro I am hooking up this monitor to via the Club 3D Dual Link to USB-C adapter everybody recommends. I bought both the HDCP version and the HDCP-Off version as part of my troubleshooting, but both exhibit the same behaviour:
When connected, the monitor LED light lits up for a second, the monitor is recognized by the computer, and it turns "on": the screen shows no image but there is backlight, so it is a faded black, as when you are watching a movie and a fully dark scene comes up. The usb ports work. The resolution is automatically set by my mac to 2560x1600 so it is not a problem with the resolution configuration. The computer acts as if the monitor is working perfectly.
So, the tests I've done so far:
- At first, I thought it was an internal problem: LCD, main board, t-con, all the issues that other people have had. But then I decided to try a SINGLE link DVI to Mini-Display port adapter that I had lying around, just for the sake of it, and plug it in to my older 2015 Macbook Pro. And to my surprise, the screen lit up with the image, and it works. The main issue, however, is that the resolution is capped at 1280x800 by the adapter's bandwith, naturally. But apart from the resolution, the monitor looks fine, so I think I can rule out logic board, t-con, backlight, etc...?
- I tested the Club 3D adapters with a 20' Cinema HD Display (a1081) I have and they work, delivering the right resolution on my M1 Mac. So I'm led to believe the adapters work fine and my M1 computer is also not the problem.
- I also tested the 30' Cinema HD Display with a Microsoft Surface with the Club 3D USB-C adapter and the behaviour kinda confirmed that I learned before: It works, if the resolution is left at 1280x800. As soon as I bump that up, the screen goes "black" as in, backlit but with no image. Notice that with my M1 for some reason I can't even get it to work at 1280x800, it remains black no matter what resolution I pick at Display settings.
- I did the flashlight test and when the monitor is black theres no image at all.
Additional info: The PSU is the 150w original one. I don't know how to use a multimeter to measure it, all I could do is try using it for the smaller 20' monitor and it works fine at all resolutions. But I also know that monitor has a much lower power consumption.
So the question is, what kind of issue could be making the monitor to go dark at 2560x1600 but to work fine at 1280x800 when using the Dual Link to USB-C adapter, which should have enough bandwith for full resolution?
Could it be that the power supply is not giving enough power for higher resolutions and I need to change it (is that even a thing?)? I don't have a 150w spare so couldn't try with a different one and I'm hesitant to go out and buy one ($$$) without confirming this. I have a multimeter but have no idea how to use it to measure my power supply.
Could it be that the logic board is faulty somehow and that makes it work only at lower resolutions?
Any ideas? I would love to get this one back to life! It looks so good on the desk and I can't afford a newer one right now.
Thank you so much!!