Subtle horizontal lines rippling down my computer screen.
March 26, 2021 7:46 AM   Subscribe

Lately, there are subtle horizontal lines that constantly ripple down my computer screen.

What might be causing this rippling? It is making me dizzy! The refresh rate is at 60Hz. Do I just need a new monitor or is the problem with my computer itself? Both my computer and my monitor are relatively old.
posted by SageTrail to Computers & Internet (11 answers total) 1 user marked this as a favorite
This sounds like interference from something else. Can you move the machine or move anything electric away from it to see if that helps? My second guess would be the monitor starting to go bad and that should not require a new computer, just a new monitor.
posted by soelo at 8:01 AM on March 26, 2021 [1 favorite]

Best answer: Does the interference change if you wiggle any of the cables? If this is a laptop, do they move when you change the hinge to a different angle?

Do the video cables cross or are entwined with any power cables?

Sometimes cables go bad, or their shielding wears out.
posted by nickggully at 8:03 AM on March 26, 2021 [3 favorites]

If your computer has different types of video outputs (VGA, DVI, HDMI, DisplayPort), and if your monitor has any of those inputs, try using a different type of cable to connect the computer to your monitor.
posted by alex1965 at 8:24 AM on March 26, 2021 [1 favorite]

Is this a flat LCD/LED monitor? Or an older/traditional monitor?

If your older/traditional monitor is using VGA or DVI cables and does not have a "bump" at one or both ends, you may need to add an "rf choke" to each end (or buy a new cable that comes with these).
posted by rozcakj at 9:11 AM on March 26, 2021 [1 favorite]

Have seen this failure mode on a number of LCD monitors (Dell). If the ripples are concentrated at one side of the screen, look to see if there are also afterimages of previous display when the picture changes (e.g. hazy shadows of your mailbox folders after the email is minimized). If you see that, the control board is dying and the monitor needs to be replaced. Otherwise yeah, I'd look at possible interference like others have said above - are there any other new (or old enough to be failing on their own) devices nearby?
posted by CyberSlug Labs at 9:54 AM on March 26, 2021 [2 favorites]

What's the make and model number of the monitor, and what kind of cable connects it to the computer? VGA? DVI? Something else?
posted by flabdablet at 1:40 PM on March 26, 2021 [1 favorite]

Response by poster: - Desktop computer.
- Flat screen monitor.
- Don't seem to be any electronics near it.
- Wiggling cables had no effect.
- Ripples are on entire screen.
- Connection is VGA. Monitor is AOC model # 195LM00003

I'm beginning to suspect I need a new monitor.
posted by SageTrail at 3:32 PM on March 26, 2021

Best answer: I saw this on occasion with a VGA connection on an older LCD screen I had. First thing I'd try is to switch to a digital connection like DVI, HDMI or DisplayPort, assuming both your monitor and computer supports one of those (which it should unless it is more than ~15 years old).

I can't find a manual for your monitor but if the ebay listing I saw for one is correct, it should support DVI; you may need to get a DVI cable if you don't have one. If you don't see a corresponding DVI port on your computer, you will need to get an adapter, depending on the type of connections you have on your computer. If you still see this effect when using a digital connection (or the monitor doesn't support digital connections) then it's likely time for a new monitor.
posted by Aleyn at 6:21 PM on March 26, 2021 [2 favorites]

Best answer: My old work monitor did this on VGA as well, fixed by switching to DVI.
posted by token-ring at 8:06 PM on March 26, 2021 [1 favorite]

Connection is VGA

OK, so there's some possibility you can fix this by fiddling with the monitor's on-screen menu.

VGA is an analog transmission standard designed to drive cathode-ray-tube monitors. CRT monitors don't have pixels in any way that relates to digitally generated source video; instead, the picture on a CRT screen is made from a single flying bright spot that scans out a stack of horizontal lines arranged like slats in a Venetian blind.

Analog video transmission signals likewise don't contain pixel information. Instead, the signal consists of regularly spaced bursts of line information, framed in a way that lets the signal control the brightness of the flying spot directly in real time.

LCD flat panels do have real physical pixels, which means that a CRT-compatible analog video signal like VGA needs to be sampled to work out how those should be lit. Various kinds of timing choices inside the monitor can conspire with various kinds of noise picked up by the signal cable to make that sampling go wrong in various ways, leading to visible artifacts on the display.

Any LCD monitor with a VGA input will have, somewhere in its the on-screen settings menus, controls that let you modify the sampling timing to get it as noise-resistant as it can possibly be. I couldn't find a manual for your specific model online but if you fiddle with the buttons that are usually somewhere near the bottom right corner of the bezel I'm sure you'll work out how to display and navigate those menus.

Here's a page that explains what the sample timing controls do and provides some test images you can use to help adjust them.
posted by flabdablet at 12:46 AM on March 27, 2021 [3 favorites]

And yes, switching to a digital video connection like DVI or HDMI will completely sidestep this issue. Digital signals are much more noise-resistant than analog signals, and if a digital signal gets overwhelmed by noise there won't be anything subtle about the resulting on-screen artifacts.
posted by flabdablet at 12:55 AM on March 27, 2021 [1 favorite]

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