Faint horizontal lines on external monitor when computer is on AC mode

My new external monitor, a Sceptre X240T, was working fine for the 4 days I tested it at home. Once I brought it to school it began to act oddly.

The monitor displays very faint horizontal lines as it refreshes, especially when displaying my black background. I tried resetting all settings and reinstalling my graphics driver, but the lines were still present. I hooked my laptop up to a hallmate's external monitor, and no faint horizontal lines were present.

When I went back to my monitor, I plugged in my monitor before I plugged in my laptop (to AC/power). No lines were present. When I plugged in my laptop, the lines began to appear. What I'm saying is that the lines don't appear when my laptop is on battery.

I've given all the information I could determine. Could anyone please help me?

 

That happens with my tecra P4 (sold), tecra A9 and a lot more notebooks.

It is because the notebook manufacturer didn't do a good job making the notebook, it has a grounding issue.

You can see that if you remove the GND pin of the power plug the problem will go away.

Toshiba offered a free 2-pin plug to some people.

I suggest just using it on battery or buying a screen with better shielding.

 

Can you plug in the notebook to a different plug than the monitor?

Try more than one combination - it is a grounding issue as stated above, but if you can find wall-plugs that are not on the same circuit, this will fix it.

 

Wow, thanks for that info

 

Does the screen have a DVI or HDMI input? And does your notebook has such a port? Guaranteed to solve the problem

 

Ice-Tea,

Not saying not to try your ideas, but if it really is a grounding issue as suggested (by working on the monitor across the hall), then this won't solve the problem. Or, more correctly it shouldn't.

If it does though, this points to his original notebook to monitor cable as being weak. As long as one of these suggestions solves the problem - it doesn't matter!

moral hazard, you're welcome!

 

Not sure where you get that idea. The grounding issue is likely to cause ground currents to run over the shielding of the VGA cable. No matter how good the cable is, it will cause distortions.

DVI, or rather the TDMS protocol is digital and should not be susceptible to moderate amounts of noise.

 

What exactly are we saying different then?

I get that idea because although there are standards for wiring codes and such, there is always some young journeyman who will switch the neutral and ground wires and this is what gives some of our electronics a fit.

Yeah, I know a thing or two about electrical.

 

You are saying that if it is a grounding issue it won't solve the problem. Chances are it will.

In addition, this will also solve issues related to badly designed notebooks; badly designed monitor AFEs, bad cables, EMI and probably a dozen other issues.

 

No, if it is a grounding issue, then bad wiring is the issue; to solve the problem you need to re-wire the receptacle or possibly even switch breakers back at the start of this electrical run.

Even if a DVI or HDMI cable masked the problem, it doesn't solve it.

The difference is that even if his visual problem (the faint horizontal lines on his monitor) seemed to be solved, the underlying issue (bad wiring) may still introduce random problems with his computer that would be impossible to solve as they would appear 'random' - (ie. 'but it worked just 10 minutes ago!').

Always better to solve than mask (a problem).

 

Ah, I see. Your assumption is that a grounding issue can only occur through bad wiring, which is not the case. Ground current can leak through bleeding resistors or a Y-cap in a PSU.

Not to mention that distortion in his image may have a gazillion causes besides grounding issues or bad wiring issues.

 

No. My assumption is based on the fact that it works in one location and not at another.

There can be many reasons for a ground leak, but in this instance, the electrical wiring is highly suspect.

Or, it may very well be a combination as it was here:

http://forum.notebookreview.com/showthread.php?t=438007

 

Djeez, man. Not easygoing, are you?

It could be the location, or maybe not. He plugged it in another monitor, not just another location.

But you know what? You are clearly clearvoyant and I'm not and you obviously clearly determined exactly what the issue is. So: you must be right, kudos for that.

 

Hey, I am very easy going.

You offered a solution that could potentially mask a problem that could be fixed as easily as switching which wall plug the OP uses.

Your other 'possibilities' indicate extensive electronics knowledge that would require an oscilloscope to diagnose or at the very least disassembling his notebook and/or monitor.

Seems to me that the OP should just try our suggestions and hopefully one will work for him/her.

No clairvoyance required - just some down to earth help - no egos involved.

 

I'm currently in class, but I will test some of these suggestions as soon as I can. Thanks for all the helpful discussion.

 

I used the AC outlet on the other side of the room and the monitor still had interference.

 

takua1, was that the only outlet you can try?

(It still may be on the same circuit).

 

The previous two outlets I tried were on the fourth floor of a dormitory. I just tried the monitor with an outlet on the first floor (in the lobby). The problem persisted.

If I need to try in a different building... it can be done, but these are the results I have thus far.

 

So it seems like there's an electrical issue with my laptop and there's no easy fix.

 

takua1,

just to be clear, are you plugging in your Monitor and your computer to the same wall outlet(s)? I hope you have been trying each on a different outlet.

What you may want to search for is an item I had found at a Sears store (large department store). This was sold in the electrical department and claimed to electrically isolate each component that was plugged into it - based on whether it was audio equipment, or, video equipment.

Sorry, I do not know what that was called, but this may help you with your video problems.

 

basically you have a ground loop. whilst plugging it in to a different socket might work the best solution would be to get a plug where there are only two pins going in to the power brick as i am assuming your current one has three

 

Yes, I've been using different plugs for testing the monitor.
tilleroftheearth, do you remember the price range of that product?

My charger does indeed have three pins. I've never looked into the market for power supplies, though. Where would I purchase such a plug? From my laptop's manufacturer?

 

My money is on dirty power, especially if your school building is somewhat old.

If you want a quick test, run to Best Buy / Office Depot, etc.. and buy a UPS (~$50-$100), and put that between your monitor and the wall plug. If that solves your issue, then it's an issue with the electrical wiring, and I would highly recommend keeping the UPS (and plugging anything valuable into it, not the wall).

If it doesn't, take the UPS back for a refund.

Make sure you get a UPS though, not a power strip / surge protector.

 

Your juice is dirty. Get a line cleaner.