Staring at a flawless computer monitor for eight hours a day or more can give you a headache. Now imagine staring at a wavy, undulating image that's impossible to focus on. It's enough to make you seasick. In my article "Five tips to fix a screen flicker," I highlighted specific techniques for eliminating a screen flicker and asked TechRepublic members to submit their suggestions for dealing with this irritating problem.
You responded with a multitude of potential screen flicker culprits, from power lines to copy machines. Because of the volume of feedback, I can’t publish every response. However, I believe the following is a fair representation of your suggestions.
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Wiring and power line problems
Until monitors come with their own internal generators, there's no escaping the power grid's influence. From faulty wiring to power surges and EMFs, nothing seems to affect monitors more than electricity.
Member Clarkmk experienced a power-related screen flicker and advises IT pros to check their building's wiring when diagnosing a persistent display problem. "We had a flicker problem that disappeared when the room lights were turned off," Clarkmk writes. "Also, the monitors flickered in one half of the room but not the other.
"The room has two doorways, with a two-way light switch at each door. After tracing the wiring, we determined that the power wires between the two light switches ran through the walls, but the wire to the lights ran overhead through the ceiling. In effect, the room wiring acted as a one-turn transformer’s primary winding, and the monitor acted as the secondary.
"The wiring was fixed so that the cable between the light switches ran through the same conduit as the wire to the lights. This fix eliminated both the current loop and the problem."
Member Yugraj's organization also suffered power-related problems, but this time it was the supply coming into the building. "Our office is in an industrial area and, due to the use of heavy machinery in nearby units, the power factor value is quite low," Yugraj writes. "We had monitor flickering problems on almost all of our systems." To resolve this problem, Yugraj says they have installed a capacitor bank on the main supply that improves the power factor, eliminating the flicker.
Ryk wrote that his monitor developed a flicker upon moving to a new house. The problem turned out to be the high-tension power lines running over his backyard. "Anything producing a strong electromagnetic field will cause flicker," Ryk writes.
Watch the copy machines
Both Jwbham and Jdaggon warn techs of the copy machine's potential to cause display problems. "I had a client that complained for several months about sporadic ‘quivering’ in her monitor," Jwbham writes. "I was on site one day and noticed that it happened every time someone made a copy—two rooms over. We plugged the copier into another outlet, and the problem went away (or at least it moved)."
Jdaggon writes that the problem can occur even when no copies are being made. "Some larger copiers ‘pulse’ their heaters even when no copies are being made," writes Jdaggon. "One copier actually put a 42-volt pulse on the neutral line of the AC wiring for two seconds every minute. It seems that this was a faulty copier, but the repair technician said it was operating fine and that it should be plugged into its own circuit!"
Hunt down those dust bunnies
"Older monitors can accumulate dust in the housing that will produce loud pops and cause the screen to flicker, due to static electricity," Car_net_tech writes. To resolve such a dusty situation, Car_net_tech suggests spending a few bucks and buying a new monitor, while Hawkmoon believes a little spring-cleaning will do, with adequate safety precautions of course.
"Just have the case removed and the dust evicted with compressed air, a vacuum cleaner, and/or plastic-handle dust brush," Hawkmoon writes. "Take care to avoid the 35,000-volt anode connection and flyback transformer, but using canned air should avoid the shock hazard. Reinstall the case before applying power to monitor."
Cell phones banned while driving—and typing?
While the jury is still out on whether mobile phones cause brain tumors, there's no doubt they can cause display problems. Member Cyjohnson was suffering from a screen flicker that had no apparent cause. Cyjohnson's monitor was flickering, and the cell phone didn't appear to be the culprit because the ringer was turned off. Then one day when the phone was ringing, Cyjohnson noticed the monitor flickering. After a little further testing, Cyjohnson concluded that the cell was definitely causing the screen flicker.
Member A.fielding confirms that such interference can occur even when the cell phone is not on a call. Some cell phones periodically communicate with the cell when powered on but not in use. This can also cause a screen flicker. "Sometimes the simplest things we might overlook are the culprits," Cyjohnson writes.
You get what you pay for
Until now we've focused on factors outside the monitor that can cause display problems. But sometimes the monitor itself is just not delivering the image quality you need. Kichigai believes monitor grade plays a significant role in image quality. "Keep in mind that sometimes the monitor itself just isn't up to par," Kichigai writes. Many times end users report monitor problems with low-end monitors regardless of environmental factors or display settings. "I've bought my share of ’cheap‘ monitors," Kichigai admits, "and had to return them and upgrade." Kichigai recommends considering support and replacement costs before purchasing low-grade monitors.
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Bill Detwiler has nothing to disclose. He doesn't hold investments in the technology companies he covers.
Bill Detwiler is Managing Editor of TechRepublic and Tech Pro Research and the host of Cracking Open, CNET and TechRepublic's popular online show. Prior to joining TechRepublic in 2000, Bill was an IT manager, database administrator, and desktop support specialist in the social research and energy industries. He has bachelor's and master's degrees from the University of Louisville, where he has also lectured on computer crime and crime prevention.