John, Before he calls out the health squad, your friend might also check to see if a filter in the CRT power supply is failing. It's probably the most likely cause of the distortion and would be most noticable if the CRT is set at a 60Hz refresh rate.
Just move the monitor to a different location to rule out external fields and then dig in. Dick Shultz On 3/22/99 6:12 PM Rich Nute <[email protected]> said > > >Hi John: > > >> He sees the video distorted and was wondering >> about any health risks. > >The first thing you should do is ascertain that the >distortion is caused by an external source or an >internal (to the monitor) source. It is possible >that the degauss circuit has failed, in which case >you will get a distortion that remains constant with >position of the monitor. > >The cause of the distortion is likely to be the >magnetic interference from the transformer. You can >test for this by rotating the monitor (in which case >the shape and color should change), and by moving >the monitor further away from the transformer (in >which case the shape and color should change and >diminish). > >Note that a permanent magnet near the screen has a >similar effect, but over a limited area. > >A good web site that cites magnetic exposure >standards is: > > http://www.lessemf.com/standard.html > >60-Hertz magnetic exposure limits range from 2.5 >mG to 10 G, depending on the standard. There is >little agreement as to both the effect on the body >and the exposure limit. > >If you go to the home page, you will find some more >(highly pessimistic) info and some good (not >necessarily pessimistic) links. There is some data >describing possible health risks, but remember that >there is little substantial research in the effects >of magnetic fields upon the body. > > >Best regards, >Rich > > > >------------------------------------------------------------- > Richard Nute Product Safety Engineer > Hewlett-Packard Company Product Regulations Group > AiO Division Tel : +1 619 655 3329 > Effective 6/12/99: +1 858 655 3329 > 16399 West Bernardo Drive FAX : +1 619 655 4979 > Effective 6/12/99: +1 858 655 4979 > San Diego, California 92127 e-mail: [email protected] >------------------------------------------------------------- > > > > > >--------- >This message is coming from the emc-pstc discussion list. >To cancel your subscription, send mail to [email protected] >with the single line: "unsubscribe emc-pstc" (without the >quotes). For help, send mail to [email protected], >[email protected], [email protected], or >[email protected] (the list administrators). --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to [email protected] with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to [email protected], [email protected], [email protected], or [email protected] (the list administrators).
