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From: bob on 8 Sep 2006 22:17 I was playing around with a magnet on my CRT screen. Now my monitor has some dark patches. Any way to fix this?
From: Rod Speed on 8 Sep 2006 22:30 bob(a)coolgroups.com wrote: > I was playing around with a magnet on my CRT screen. > Now my monitor has some dark patches. Any way to fix this? Buy a new monitor.
From: paulmd@efn.org on 8 Sep 2006 22:32 bob(a)coolgroups.com wrote: > I was playing around with a magnet on my CRT screen. Now my monitor > has some dark patches. Any way to fix this? 1) Degauss button. If it's bad, it'll take a few tries. Sometimes the degauss is automatic on monitor power on, sometimes it's buried in the menu, sometimes there's a button. Just depends on your monitor. 2) manual degausser. If it's really bad, and the degaussing isn't helping. 3) stop screwing with magnents.
From: Paul on 9 Sep 2006 01:32 In article <1157768229.394842.146590(a)e3g2000cwe.googlegroups.com>, bob(a)coolgroups.com wrote: > I was playing around with a magnet on my CRT screen. Now my monitor > has some dark patches. Any way to fix this? A monitor has a built-in degaussing coil, and it applies an A.C. magnetic field, to try to erase residual magnetism in the monitor. That is enough to correct for small magnetic anomalies. Placing a magnet on a monitor, can magnetize the metal frame of the monitor. The built-in degaussing coil is neither powerful enough, nor positioned well enough, to correct magnetic vandalism of this kind. When I bought a new CRT 10 years ago, the brand new CRT had discoloration typical of a magnetization problem. I took the monitor to a TV repair shop at a larger TV/Stereo store, and they used a portable degaussing coil. The coil is about one foot in diameter. The service person waves the coil around the monitor and steps way back from the monitor before turning it off. Since the magnetic field lines point out of the hole in the middle of the coil, just before the service person turns off the coil, they turn it so the opening in the coil is no longer pointing at the CRT. That prevents the spike when the AC switch on the degaussing coil is turned off, from polluting the monitor again with magnetism. One treatment seemed to fix up my new monitor, so it had a nice white background when the picture was supposed to be white. Keep all magnets away from the CRT, if you expect to keep your color purity. The degaussing built into the monitor is enough to keep it clean, unless you stick a magnet on your screen or on the side where some framework metal is located. And since we know the magnet you used, came out of that disk drive you were playing with, that is about the strongest small magnet you could have selected for the job :-) The TV/Stereo store I used, did my degaussing for free, but I'm sure most businesses would charge for the service. Even though it only takes about 2 minutes to do. Note that there are no guarantees with the portable degausser - a determined vandal with a magnet can permanently ruin a monitor, if the applied field was strong enough. Even the portable degausser has a limited ability to erase magnetism in the frame of the monitor. If you were thinking of moving up to a 5 lb alnico magnet for your next experiment, think again :-) (some magnets to keep away from your monitor or TV set) http://scientificsonline.com/product.asp_Q_pn_E_3041946 Paul
From: Mike Walsh on 9 Sep 2006 11:24
"paulmd(a)efn.org" wrote: > > 2) manual degausser. If it's really bad, and the degaussing isn't > helping. A bulk tape eraser will work. -- Mike Walsh West Palm Beach, Florida, U.S.A. |