Sceptre X24WG Blinks on and off

Question

Sceptre X24WG Blinks on and off

Hi there,

I just bought a Sceptre 24" widescreen monitor (X24WG) that is supposed to have native resolution of 1920x1200 @ 60hz. I've plugged it into the Mac Mini (G4 w/1.42 and 1 GB RAM) via the DVI input and tried to get the 1920x1200 resolution to work. But once selected in the Control Panel, the display goes black for a few seconds, comes back on for a second, then goes black for a few more seconds. It just keeps performing this cycle until I select 1920x1080 at which point it stabilizes.

1280x1024 seems stable as does 1360x768. The rest are just like the 1920x1200, constant blinking in and out.

I have tried the VGA input, at which point more resolutions become stable, but the clarity versus the DVI is horrible!

Am I out of luck with the Mini when trying to reach the 1920x1200 resolution on DVI? Or is it the cheap monitor? Or a combination of the two?

Mac Mini 1.42 (1GB RAM), iBook 700mhz, iBook 800mhz, Apple TV, Mac OS X (10.4.10)

Posted on Nov 17, 2007 3:39 AM

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Answer 1

BSteely

Level 5

7,643 points

Nov 20, 2007 6:41 PM in response to Christopher Stutheit

Although that symptom sounds strange, it is possibly related to non-coherency of the TMDS receiver in the Sceptre and the fact that the pixel clock will be above 135 MHz for 1920 x 1200 timing. See this note and search on the word "coherent" for details:

http://developer.apple.com/documentation/Hardware/Conceptual/HWTechVideo/Articles/Video_implementation.html#//apple_ref/doc/uid/TP40003994-DontLink ElementID65

If you are stuck with that monitor and can't return it, you might have success using a program like DisplayConfigX or SwitchRes X to build a custom timing with a lowered pixel clock. I don't think you can get as low as 135MHz at that resolution, but getting closer to 135 MHz might make all the difference.

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Answer 2

Nov 28, 2007 9:59 AM in response to Christopher Stutheit

ive just purchased this monitor as well and am having similar problems with my G4 DP (mirror doors). i got it from costco, so returning it isnt a problem, but would like to fix it if possible.

did you try running any of those progs?

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Answer 3

Nov 28, 2007 11:43 AM in response to BSteely

Thank you so much for the insight. I tried what you recommended and, indeed, I can get the monitor to hold steady at 1920x1200 using DisplayConfigX set to 135 MHz on the pixel clock. It runs at 53 MHz refresh rate by doing so, which seems awfully low to me, but the monitor seems to tolerate it.

However, I still cannot get rid of the red and green dots that appear periodically after waking the display from power saving mode. The only cure is to switch to a new supported resolution and then back to the 1920x1200. This clears the red and green dots for some reason.

I saw another post about buying the same monitor and having the same problems... unfortunately I am working overseas right now and had the monitor shipped to my UK location from Newegg.com. Returns and/or exchanges through them for LCD's, ESPECIALLY to those of us overseas, are hardly worth it. I'm looking to sell the monitor on eBay here since there seems to be nothing wrong with the monitor itself. It just doesn't play nice with my Mac Mini... 😟

BSteely: Thanks again for your response! You definitely diagnosed the root of what is going on here. Thank you!!!

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Answer 4

BSteely

Level 5

7,643 points

Nov 28, 2007 10:09 PM in response to Christopher Stutheit

Glad to hear it worked out. You might try setting the Vertical scan rate to an even 50 Hz in SwitchRes X. This will drop the pixel clock even a little more. That might be enough to get rid of the green and red dots. There's not much downside to running at 50Hz. That's the same as PAL TV sets over on your side of the pond and also the frequency of AC house current, if I'm not mistaken.

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