Acer XG270HU - replaced panel, won't do 144Hz now

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djdjukic
Posts: 3
Joined: 25 Nov 2019, 13:14

Acer XG270HU - replaced panel, won't do 144Hz now

Post by djdjukic » 25 Nov 2019, 13:44

Hello,

I have an Acer XG270HU that has worked brilliantly until the screen was broken by accident. I then bought and installed a new M270DTN01.3 panel, which seemed identical to the old one at first glance.

However, the monitor will no longer sync at 144Hz. Additionally, when booted into Windows, my RX580 can't drive the monitor over DisplayPort at all.

DP does work in Linux (up to 120Hz) or in Windows using a different GPU (I tried an HD 7750 and a GTX 760), also up to 120Hz. I think this has something to do with DP 1.2 support. Changing DP 1.2 to 1.1 in the monitor's menu doesn't help anything. The same goes for disabling FreeSync.

I tried making custom 144Hz modelines to no avail; the best I've gotten is 141Hz (CVT - reduced blanking) over HDMI, which runs stably.

The failure mode at 144Hz is rather interesting - only the top active line works, and i can see the top pixel of the mouse pointer when I move it across. This is the case for all resolutions at 144Hz, with GPU scaling off, of course.

I suspect that the scaler in my monitor can't drive the panel properly. The monitor was built in 2016 and the old panel has a date code of 15/27, while the new one is 18/11. When I peeled back the black tape on the new panel and compared the PCB to the old one, I noticed that the new one has 2 additional chips and associated passive circuitry, but is otherwise the same.

Does anyone have a better idea of what could have caused this? I've tried to find new firmware for the scaler to no avail. There's nothing to change in the service menu, it looks exactly like the one from Acer's website (pic attached). Also attached are pics of the labels of both panels.
Attachments
xg270hu_monitor_factoryosd.jpg
xg270hu_monitor_factoryosd.jpg (161.39 KiB) Viewed 418 times
new panel label.jpg
new panel label.jpg (103.61 KiB) Viewed 418 times
old panel label.jpg
old panel label.jpg (124.2 KiB) Viewed 418 times

djdjukic
Posts: 3
Joined: 25 Nov 2019, 13:14

Re: Acer XG270HU - replaced panel, won't do 144Hz now

Post by djdjukic » 21 May 2020, 13:51

If anyone with the same problem stumbles upon this - I have managed to find a newer scaler PCB, manufactured in 2019, and the new panel works brilliantly with it. It has a different, more "gamer" looking OSD menu, but that seems to be the only distinguishing feature apart from the date code sticker from the back of the monitor.

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