On Sat, Jul 21, 2001 4:49 PM, [EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]> wrote:
>A friend with a degree in electrical engineering
>thinks there might be a
>problem with ground loops here ...
>>>
Hi Peter,
Thanks very much for your reply!
>CRTs are magnetically deflected.
>
>Most CRTs are exceptionally well designed as to line
>cord radiation
>(so-called "conducted emissions"), and as a
>consequence these devices are
>well designed as to susceptibility to external
>emissions through the line
>cord.
>
>You need improved magnetic shielding, as others
>have suggested.
I wondered about this. . . But what would I be shielding it from? My
computer is farther away from the monitor--31"-- than what I'd suppose most
people have. (I do have an older second monitor, but it's not plugged in or
connected to anything.) My SCSI peripherals' cables aren't usually
connected to the computer, and when they are, they're operating maybe 40"
away from the monitor. (No difference in operation when the perhipherals
are connected, either.)
I had the problem prior to getting the external speakers.
There's a radio 19" away from the monitor, though I don't see any
operational difference when it is turned on vs. off. (It's still plugged in
when it's off, though.)
One of the thing I suspect: that the dimmer switch in the room needs
replacing with an ordinary switch. Also the dimmer switch in the room next
to this one. And I sometimes suspect that the flourescent strip under the
overhead cabinet directly over the monitor makes it a little worse, while
I'm less suspicious of the flourescent strip under the cabinet a little
farther down the wall.
The one thing I'm very sure of: if the vacuum cleaner is operating on the
downstairs circuit it gives this monitor (upstairs) fits.
Of course, there's the keyboard right in front of the monitor, but what
monitor would have been designed that needs a shield between it and the
keyboard??? (Plus, I can just picture leaning way up and over a shield to
see the monitor... Hah! Well, the keyboard is probably not the problem.)
>(Yup, I've got an EE degree, too).
Extraordinarily handy training, Peter!
How I envy people who know something about electrical stuff with all the
little--what is it?--electrons and charges? On the positive side, though,
when equipment doesn't operate, in no time at all I'll remember to plug it
in. (Plus, I know what you are supposed to do about impedence. I guess Bob
Dole deserves some credit there, though.) Next, to find out about magnetic
deflection...
--
Best wishes,
Mary
<http://www.2mbit.com/~mgrimsley/computerstuff/index.html>
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