[PLUG] OT: EM-Damaged Display

[Mike De La Mater]

I'm sure you've already checked, but is there a degauss button on the monitor, 
and does it change anything?

Mike

2/13/03 9:01:45 PM, Dylan Reinhardt <plug at dylanreinhardt.com> wrote:

>Hi all,
>
>This is a bit off-topic, being a hardware / physics question... but it's 
>something I thought y'all might enjoy chewing on anyway.
>
>About 18 months ago, some friends of mine got a new PC from a local vendor 
>I recommended.  The display was a good quality 17" CRT (AOC Spectrum 7GLR).
>
>After 8-9 months of unblemished operation, the display started showing huge 
>amounts of distortion in large, wavy, occasionally-changing horizontal 
>bands.  It looked for all the world like some kind of electromagnetic 
>interference.
>
>I poked my head out the window and sure enough, their satellite dish was 
>mounted on the outside of the house, maybe 2-3' from the back of the 
>display.  I had taken a different display over for testing purposes and 
>when I plugged that one in, everything worked fine.  I decided I was wrong 
>to suspect the satellite dish.  The problem -- whatever it was -- must have 
>been the display.  That opinion was supported by the fact that the problem 
>persisted when I plugged the first display into a PC back at my office.  I 
>sent it back to the manufacturer and received a replacement, but no 
>explanation.
>
>Fast forward another 8-9 months and now the replacement display (also a 
>CRT, but different model) is showing very similar problems and I'm thinking 
>I might have been right about the satellite dish in the first place.  I 
>have installed dozens of these displays around Portland and have never seen 
>anything like this anywhere else.
>
>At this point I have to admit I'm way out of my league.  Some questions 
>come to mind:
>
>1. Can there possibly be any such thing as cumulative damage from EM 
>interference?
>2. Could the satellite dish be a red herring?
>3. Will a gaussmeter help me diagnose the problem or find a better spot for 
>the computer?
>4. Might an LCD display survive any better than a CRT?
>5. Is there any kind of low-cost shielding I could be using here?
>
>Since I never got that EE degree, I'm at a bit of a loss... any thoughts or 
>help would be greatly appreciated.
>
>Thanks in advance for anything offered,
>
>Dylan
>
>
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Mike De La Mater
Small business networks and technology consulting
503-702-6749
mikedela at ipns.com