External monitor flicker, laptop ground loop problem solved
Are you having problems with a flickering external monitor on your laptop?
Does the flicker go away if you remove the laptop charger?
If you answered yes to the above questions, you probably have a ground loop. Slimplified this is because the monitor is grounded (using a 3 prong coord) and the laptop is not grounded.
What you need to do is disable the ground for the monitor. If you are using a european 240V connector just put some scotch tape over the sides of the connector, that is the ground. Check that the tape does not break when the connector is inserted. You might have to put several layers of tape on the connector.
If you have other connector types you can take a spare power cable and remove the ground prong for the monitor, or you could just use an adapter that only has 2 prongs but accepts three, like this one:
After this the flickering should go away.
BEWARE your monitor is now ungrounded, so don’t use it in the bath-tub.
Good luck!
thanks for your bewareness..
You’re welcome
I had the same problem with this laptop ext. monitor grounding and i think i have better way to solve this…i used continuous cable or u can use socket that doesn’t have grounding (those two pins) cos i think that putting that scotch tape is a lil bit risky cos it can caught fire. . .
Okay, so you connected to an ungrounded socket using an extension cable. Ok yes that will work too. However, there is no way the tape can catch fire. It just isolates a grounding point, and its not in contact with any live wires.
But thank you for your comment!
Thank you so much. I was able to fix a truly long-standing problem of mine. I bought alll kinds of different supposedly helpful gadgets to plug in between my monitor and the power source, my laptop and the power source, the adapter and whatever else and I had almost given up on this issue which was really really annoying. Your entry just sorted the whole issue in 2 minutes. Thank you so much.
Ingo, glad to help
thanx for commenting!
I broke the ground pin of my laptop powerbar and now it works perfectly! thank you!
Hi,
Nice post and very helpful in identifying the problem I had with an external LCD monitor.
However I have something you might find interesting,
I don’t know a great deal about electrical circuits nor ground loops,
Though I’ve just realized that my laptop charger that was causing the flicker used
a grounded (three prong) plug. My Monitor also uses the three prong plug.
When I removed the laptop power it would stop.
So my problem was:
MONITOR – grounded power supply
LAPTOP – grounded power supply
My laptop came with two power supplies/cords which have different sets of prongs.
The grounded power supply, which has a higher Watt value, is needed when you need to power a Docking station.
So I tried using my two-prong (lower Wattage) power supply for the laptop and the problem has vanished.
So solution is:
MONITOR – grounded power supply
LAPTOP – two-prong power supply
My solution arrangement seems to be the problem arrangement that you have described in the post!
In saying that, It could very well be my problem has vanished because I am now using a power supply with a lower Watt value.
65W compared to 90W. I’m not sure how Wattage effects the flickering of monitors.
This would would mean that the “ground loop” problem was never the cause of my monitor flicker?
Either way my monitor now works with no flicker at 60Hz refresh rate so all is good
though interested
to hear your opinion.
Cheers.
PS. Using the grounded, higher Watt, power supply on my laptop also caused My
External Amplifier to output a lot of static ‘noise’, very noticeable after some music has stopped for example. Actually noticeable whenever no sound is being output from the laptop …
Removing the laptop power supply would stop this noise.
The amplifier is also powered through a grounded (three-prong) power cord.
SOLUTION: Using the smaller Watt (two-prong) power supply for my laptop also got rid of this problem.
Though the amplifier still gives out some static noise which you can hear when there is no music or sound output from the laptop. Though I think this is normal and has always happened?
This problem “doesn’t” go away when I disconnect the laptop charger.
NOTE: My Laptop is connected to My amplifier via the headphone jack on my laptop -> RCA lead input on my Amp.
Cheers again.
Chris.
Chris,
Cool! To me it sounds like both problems are ground loop problems. I’m gonna read your post again at a slower pace when i have time
But thanx for posting and glad you got it sorted out!