Ghostly horizontal flickering on external monitor?

[zwaldowski]

I have an HP Pavilion dv6654us Notebook PC, which has an Intel GM965 chipset with X3100 integrated graphics.  Connection to an external monitor yields horizontal flickering.  It's barely noticeable on white, but very noticeable everywhere else.  It also seems to degrade the color of my images.  I have checked the VGA port on the side of my laptop, and it is clear and free of obstructions.

I currently use Windows 7 Ultimate, but this very same issue has occurred on every operating system I have used this monitor on this laptop with, including Windows Vista and multiple Linux distributions.  I currently have the latest BIOS, however, it has occurred on every version I have tried.  All operating systems have the latest Intel video drivers available.

The monitor is an Acer X223W.    This monitor is not the issue, as I have amid-range business Dell laptop with an Intel GM945 that does not cause this problem at all.  On my HP, the problem occurs on the external monitor at all resolutions.  Changing the mode on my Intel video also has no effect, this issue occurs both in extended mode and when only showing on the external monitor.  It does not, however, effect my laptop's LCD screen or any non-LCD external monitors such as projectors.

I want to check on what people think of this on the forums before I get involved in the - what you must admit - horrible process of support HP offers.

Message Edited by zwaldowski on 04-13-2009 02:24 PM

[jmnielsen · Accepted solution]

I suspect you have a ground loop issue. Ive seen this on several laptops over the years and not isolated to just HP. Your monitor likely has a three prong plug and hence a ground. Your laptops AC adapter likely has a three prong as well and itself is grounded. Yet your laptop likely (as you can see from the cable going from the ac adapter to the laptop) does NOT have a ground. You end up with a ground loop back into the monitor and hence noise.

The only solution I have found is I took a spare power cable and removed the ground prong for the monitor. You could just use an adapter that only has 2 prongs but accepts three. The later Id suggest trying. Worse case your out 50 cents.

Now keep in mind that ground is there to in effect protect you. Id never suggest doing this but I can almost garauntee this is your issue. I suppose engineers dont design laptops with a ground as they are such low voltage. Regardless its a bad idea and IMHO bad engineering. They should have a ground for scenerios just like this.

Id like to note its not the monitors fault. Ive seen this with dozens of lcd and crt monitors. Its the fact the laptop has no ground.

[zwaldowski]

Wow, that's amazing!  I can't thank you enough!  Just grabbed a pair of needlenose pliers and twisted the ground right off my monitor's power cable (which is connected to a power stripp, if that makes things any safer).  Better than ever before, I can use my laptop again!

[darkhorse192]

Wow I was just recently having the exact same problem with my zt3000 and a samsung syncmaster 2443bwx I tried everything to fix the problem and figured I just had a sucky graphics card for external monitors until searching the forums led to this post.  As soon as I got home from work I tried the no ground trick with my monitors cable and it was instantly perfect.  Thanks again for the helpful advice.

[krisvinu]

Thank you so much. I was searching a solution for the same problem.

[bethm34]

I just received my HP 2159 monitor and noticed the same flickering once it was hooked up. Came to the HP support site to see if I could figure out the problem. Thanks for this post/solution. The 3- to 2-pronged adapter seems to have worked and saved me hours of fidgeting with setting or calls to HP!

[petrollm]

Hi The horizontal flickering is really hard on the eyes!!!  I am prepared to try the removal of the ground on the adapter - but why would the problem occur when I am running the laptop on battery without the adapter plugged in? Please make any suggestions

[CanoeBoard]

HUGE thank YOU

I bought a NEC EA232 monitor last week and had exactly this problem. Contacted NEC immediately, they suggested it was a faulty monitor and sent out a new one the next day. Same problem! Changed cables, no change. Then tested it on 2 other laptops, a 2011 LG 13" and a 2008 Samsung 13", neither caused the problem!

Anyway I will let NEC Germany know of this solution, and see what they say.

thanks, Ben

[basebalwmn]

I am getting the same kind of issue when i connect my hp g71 laptop to my hd tv using an hdmi cable. AM i having the same issue??? Although i would be hesitant to remove the ground on it and operate it.