# Samsung 24" screen strange DVI behaviour



## Pred77 (Jul 18, 2013)

Hi.

I'm coming with a technical question that seems to be quite easy to answer.

I have Samsung SM2443BW 24" 1920x1200 screen. The problem is that since I bought it on the net one day, DVI port is not working, almost at all (VGA is OK). What is the problem? When you power up your PC while monitor is connected with DVI cable, system is starting and on the screen nothing happens.

I have also one ASUS monitor and it's working good on these DVI ports and cables, so my PC or wires failures are totally excluded.

You may think: "you have destroyed DVI input in your screen", but I have excluded that too! How? When I disconnected ASUS' DVI from an GPU input and connected Samsung's DVI cable the same place, desktop was displayed correctly, but was stretched with 1280x1024 ASUS' resolution.


There is the question: is it somehow possible to load fresh screen firmware without changing any parts? 
Can you predict based on your experience, could that be only screen software problem?

Computer specification:
GPU: AMD Radeon HD5850
CPU: AMD Phenom X4 955
Mainboard: Gigabyte GA-790XTA-UD4.
RAM memory: Patriot DDR3 2x2GB.

Tested on Windows 7 and Windows Server 2012.

Thank you for all opinions about that.


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## itsakjt (Jul 18, 2013)

There may be a problem with the monitor PCB. Also make sure the DVI cable is compatible. DVI can be of various types. DVI-I, DVI-D, Dual DVI-D and the list goes. Google those and make sure you have the required cable.


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## Flibolito (Jul 18, 2013)

Is there a input/source button on the monitor that you have to use to switch to digital. I have used to Samsung monitors in the past that would not auto select. At first I thought something went wrong during the build but once manually switched over no problem. Just a thought.


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## Pred77 (Jul 18, 2013)

Thank you for responses.

As default, monitor was selecting source automatically. I've changed that in preferences to manual mode to avoid auto-redirecting from blank DVI to fully working VGA.

Unfortunately it looks like some signal processing isssue. I hope it is only digital firmware problem, but well, we don't know. 

Do you know any program able to force signal via chosen graphic output port? That sounds like a quick solution - force rightly prepared signal to the screen without any system recognition and use it in standard way.


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## SaltyFish (Jul 19, 2013)

Are you using a single link DVI cable? 1920x1200 is the upper limit of single link DVI. A damaged or poorly made cable will make that limit lower. This shouldn't be a problem if you're using dual link.

Use the ASUS to get 1280x1024. Then plug it into the Samsung 2443BW. Change the resolutions one by one to see how far you can go.

For reference, can you tell us what your cable connector looks like?


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## Pred77 (Jul 20, 2013)

I am using DVI-D single link cable, which was attached to the monitor. Unfortunately I don't have any dual link cable, but I suppose that would not help here.

When I tried to switch monitors on the same DVI output, I was not able to change display resolution when Samsung was connected. But I think resolution is not a problem here, because 640x480 BIOS does also not appear on the screen.


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## Mussels (Jul 20, 2013)

i'm starting to wonder if your problem isnt completely unrelated here, and you've just skipped a step.


have you turned the computer off, unplugged the VGA cable, connected the DVI cable and then powered on the machine. did you then set the correct resolution in windows, and made sure all drivers (video card + monitor) are installed?

so to be extra clear: the DVI cable is the only one connected, and its connected to the correct video card (not an onboard GPU)


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## Pred77 (Jul 20, 2013)

Yes, I did it. I was trying to make it working the way you described and many other I don't remember. To be sure I followed your steps now and nothing happened after powering on computer. I also tried pass VGA and DVI signals at once. VGA source showed BIOS, DVI didn't.


When the cable is totally unplugged from PC and I switch screen to DVI source, I can see there typical moving box "Check input signal". But when I plug connector into graphic card (even if computer is totally unplugged from power), monitor turns into sleep mode, without showing anything on the screen. Then if I unplug DVI cable, "Check input signal" appears again.

After some testing using small screw I realised, that screen goes sleep only when I connect such pairs of pins:
3 - 15
11 - 15
19 - 15
22 - 15
looking on this scheme: https://upload.wikimedia.org/wikipedia/commons/0/03/DVI_pinout.png

So that happens when I connect shielding with ground. I cannot find any conclusion based on that information, but I am sure my DVI cables I are not damaged or broken.

In my opinion it looks like Samsung is not able to communicate with computer using some startup signals (I don't know how it works so I may be wrong). Maybe that's why it showed something when I switched quickly it's plugin to already initialized graphic port.


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## Mussels (Jul 20, 2013)

i wonder if the 5850 has some weird BIOS problem, or your motherboard does.


whats your primary graphics card set to in the BIOS?


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## SaltyFish (Jul 20, 2013)

The shielding pins are electromagnetic shields for the signals of adjacent pins. The screen blanks when those pins are connected because the monitor thinks there is valid video signal being sent. But since there's obviously no actual video data being sent on the nearby pins, the monitor outputs a black screen (black is the result of all three RGB values being 0). You should get the same result on your ASUS monitor.

You may be right that the Samsung monitor has trouble relaying display information to your computer. I'm guessing it's the EDID information and likely has to do with pin #7. It would explain why you could display a signal on the Samsung monitor only when it was first displayed on the ASUS monitor. And it would also explain why the Samsung monitor doesn't display (you get the moving "check signal input" box and not a blank screen, right?) at start-up and when you try to change the resolution. If this is correct, then it's either a problem anywhere between the contact on pin #7 and where the EDID is stored on the Samsung's circuit board.


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## Mussels (Jul 20, 2013)

i suppose the next test would be to connect the monitor to another PC and see what happens. it seriously could be just partially damaged.


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## Pred77 (Jul 20, 2013)

@Mussels: My motherboard does not have integrated graphic card, so there's no possibility to choose card.

@SaltyFish: I checked out of curiosity connecting shield pins with ground pin on ASUS screen and it does not wake up from sleep mode (but it also doesn't show any "No signal" in IDLE, that's normal for this model).

I think my informations are a little chaotic, so I sum them:

1. Samsung connected with DVI to computer is always in sleep mode. The same thing take place when I connect shield pins with ground pin.

2. When I connect pins on DVI input, "check input signal" box dissapears, but also display's backlight go out.

I think there must be something wrong in digital Samsung's digital component, because monitor works perfectly with analog (VGA) input.

Edit: @Mussels: I will try, unfortunately now I don't have any other PC with DVI output nearby to tell you about result.


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## Mussels (Jul 20, 2013)

Pred77 said:


> I think there must be something wrong in digital Samsung's digital component, because monitor works perfectly with analog (VGA) input.



can you try it on another PC, with DVI? even if you have to transport it to someone elses house, or a PC store. that really is the only way to narrow it down further.


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