| Author |
Message |
Gary DeWitt
Guest
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 Posted:
Fri Nov 12, 2004 7:01 pm Post subject:
electron gun(s) and magnetic fields |
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I have a 54" RCA rear projection. I had a new hardwood floor installed
with an electric heating grid underneath. The grid consists of heavy
screen mesh, similar to window screen but 2-3 times heavier wire, laid
in one continuous circuit back and forth across the room. There is a
high voltage, low amperage current running through it. Here's the
problem - when the heater is on, the guns in my tv misalign, looks
like 3-d image viewed without the correct glasses. Soon as I turn off
the heat, the tv returns to normal. How can I shield the tv from the
floor induced field? Faraday cage? (I don't really want to view thru
wire mesh!) Grounded sheet of steel under the set? Raise the set a
foot or two off the floor? Both? Any suggestions, particularly from
those who have solved this problem or engineers, would be greatly
appreciated!
Real E-mail: gpdewitt at earth link dot net (no space in earthlink)
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Jamie
Guest
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| Posted:
Fri Nov 12, 2004 7:01 pm Post subject:
Re: electron gun(s) and magnetic fields |
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sorry, i don't think you can.
you would have to align the TV
with the heat on and then align
it again after.
the only thing i can think of is
that the electric heaters are
not properly laid out over
laying each other to cancel each
other out which in this case
can be hard to do..
you could try elivating the
tv on a stand or get your
self a DLP projection.
Gary DeWitt wrote:
| Quote: | I have a 54" RCA rear projection. I had a new hardwood floor installed
with an electric heating grid underneath. The grid consists of heavy
screen mesh, similar to window screen but 2-3 times heavier wire, laid
in one continuous circuit back and forth across the room. There is a
high voltage, low amperage current running through it. Here's the
problem - when the heater is on, the guns in my tv misalign, looks
like 3-d image viewed without the correct glasses. Soon as I turn off
the heat, the tv returns to normal. How can I shield the tv from the
floor induced field? Faraday cage? (I don't really want to view thru
wire mesh!) Grounded sheet of steel under the set? Raise the set a
foot or two off the floor? Both? Any suggestions, particularly from
those who have solved this problem or engineers, would be greatly
appreciated!
Real E-mail: gpdewitt at earth link dot net (no space in earthlink) |
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NSM
Guest
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| Posted:
Fri Nov 12, 2004 7:01 pm Post subject:
Re: electron gun(s) and magnetic fields |
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|
"Gary DeWitt" <gpdewitt@yahoo.com> wrote in message
news:7bb05e8f.0411120930.6d6b2d1c@posting.google.com...
| I have a 54" RCA rear projection. I had a new hardwood floor installed
| with an electric heating grid underneath. The grid consists of heavy
| screen mesh, similar to window screen but 2-3 times heavier wire, laid
| in one continuous circuit back and forth across the room. There is a
| high voltage, low amperage current running through it. Here's the
| problem - when the heater is on, the guns in my tv misalign, looks
| like 3-d image viewed without the correct glasses. Soon as I turn off
| the heat, the tv returns to normal. How can I shield the tv from the
| floor induced field? Faraday cage? (I don't really want to view thru
| wire mesh!) Grounded sheet of steel under the set? Raise the set a
| foot or two off the floor? Both? Any suggestions, particularly from
| those who have solved this problem or engineers, would be greatly
| appreciated!
Interesting!
1. The higher off the floor the TV is, the lesser the effect.
2. Alternate layers of sheet steel and aluminium under the TV, insulated
from each other by paper, might diminish the effect.
3. Use a separate heater when you want to watch TV.
N |
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N Cook
Guest
|
| Posted:
Fri Nov 12, 2004 9:02 pm Post subject:
Re: electron gun(s) and magnetic fields |
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|
"Gary DeWitt" <gpdewitt@yahoo.com> wrote in message
news:7bb05e8f.0411120930.6d6b2d1c@posting.google.com...
| Quote: | I have a 54" RCA rear projection. I had a new hardwood floor installed
with an electric heating grid underneath. The grid consists of heavy
screen mesh, similar to window screen but 2-3 times heavier wire, laid
in one continuous circuit back and forth across the room. There is a
high voltage, low amperage current running through it. Here's the
problem - when the heater is on, the guns in my tv misalign, looks
like 3-d image viewed without the correct glasses. Soon as I turn off
the heat, the tv returns to normal. How can I shield the tv from the
floor induced field? Faraday cage? (I don't really want to view thru
wire mesh!) Grounded sheet of steel under the set? Raise the set a
foot or two off the floor? Both? Any suggestions, particularly from
those who have solved this problem or engineers, would be greatly
appreciated!
Real E-mail: gpdewitt at earth link dot net (no space in earthlink)
|
2 ideas
Find someone who has a heap of mu-metal sheets and lay under TV
or trace with sniffer or pipe/metal detector the exact run of heater wires
at a point away from TV. Excavate down and cut and bypass the few loops
that go under the TV
electronic hints and repair briefs , schematics/manuals list on
http://homepages.tcp.co.uk/~diverse |
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Charles Schuler
Guest
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| Posted:
Fri Nov 12, 2004 9:02 pm Post subject:
Re: electron gun(s) and magnetic fields |
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|
Any iron or steel (but not stainless steel) shield (such as sheet metal)
that you can place between the heater and the TV will help. Iron has much
lower reluctance than air, so the magnetic field from the heater will be
concentrated in the shield. Stainless steel is weird in this regard and
usually won't help even though it can be made up of mostly iron. |
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Sam Goldwasser
Guest
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| Posted:
Fri Nov 12, 2004 11:00 pm Post subject:
Re: electron gun(s) and magnetic fields |
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gpdewitt@yahoo.com (Gary DeWitt) writes:
| Quote: | I have a 54" RCA rear projection. I had a new hardwood floor installed
with an electric heating grid underneath. The grid consists of heavy
screen mesh, similar to window screen but 2-3 times heavier wire, laid
in one continuous circuit back and forth across the room. There is a
high voltage, low amperage current running through it. Here's the
problem - when the heater is on, the guns in my tv misalign, looks
like 3-d image viewed without the correct glasses. Soon as I turn off
the heat, the tv returns to normal. How can I shield the tv from the
floor induced field? Faraday cage? (I don't really want to view thru
wire mesh!) Grounded sheet of steel under the set? Raise the set a
foot or two off the floor? Both? Any suggestions, particularly from
those who have solved this problem or engineers, would be greatly
appreciated!
|
A Faraday cage won't help. It's magnetic interference and magnetic
fields are difficult to block.
--- sam | Sci.Electronics.Repair FAQ Mirror: http://repairfaq.ece.drexel.edu/
Repair | Main Table of Contents: http://repairfaq.ece.drexel.edu/REPAIR/
+Lasers | Sam's Laser FAQ: http://repairfaq.ece.drexel.edu/sam/lasersam.htm
| Mirror Sites: http://repairfaq.ece.drexel.edu/REPAIR/F_mirror.html
Note: These links are hopefully temporary until we can sort out the excessive
traffic on Repairfaq.org.
Important: Anything sent to the email address in the message header is ignored.
To contact me, please use the feedback form on the S.E.R FAQ Web sites. |
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Sam Goldwasser
Guest
|
| Posted:
Fri Nov 12, 2004 11:00 pm Post subject:
Re: electron gun(s) and magnetic fields |
|
|
Jamie <jamie_5_not_valid_after_5_Please@charter.net> writes:
| Quote: | sorry, i don't think you can.
you would have to align the TV with the heat on and then align it
again after.
|
That won't help if the heating grid is powered from AC.
--- sam | Sci.Electronics.Repair FAQ Mirror: http://repairfaq.ece.drexel.edu/
Repair | Main Table of Contents: http://repairfaq.ece.drexel.edu/REPAIR/
+Lasers | Sam's Laser FAQ: http://repairfaq.ece.drexel.edu/sam/lasersam.htm
| Mirror Sites: http://repairfaq.ece.drexel.edu/REPAIR/F_mirror.html
Note: These links are hopefully temporary until we can sort out the excessive
traffic on Repairfaq.org.
Important: Anything sent to the email address in the message header is ignored.
To contact me, please use the feedback form on the S.E.R FAQ Web sites. |
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Art
Guest
|
| Posted:
Fri Nov 12, 2004 11:00 pm Post subject:
Re: electron gun(s) and magnetic fields |
|
|
Also the Manufacturer will be absolutely no assistance regarding this since
the symptom is being induced by it's environment. As noted, you may want to
consider a DLP, MMD, or Plasma television reciever. Or, move the curent
television to a room that is not heated in such a manner to resolve that
particular problem.
"Sam Goldwasser" <sam@saul.cis.upenn.edu> wrote in message
news:6wmzxmeq0d.fsf@saul.cis.upenn.edu...
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Graham
Guest
|
| Posted:
Fri Nov 12, 2004 11:00 pm Post subject:
Re: electron gun(s) and magnetic fields |
|
|
| Quote: | I have a 54" RCA rear projection. I had a new hardwood floor installed
with an electric heating grid underneath. The grid consists of heavy
screen mesh, similar to window screen but 2-3 times heavier wire, laid
in one continuous circuit back and forth across the room. There is a
high voltage, low amperage current running through it. Here's the
problem - when the heater is on, the guns in my tv misalign, looks
like 3-d image viewed without the correct glasses. Soon as I turn off
the heat, the tv returns to normal. How can I shield the tv from the
floor induced field? Faraday cage? (I don't really want to view thru
wire mesh!) Grounded sheet of steel under the set? Raise the set a
foot or two off the floor? Both? Any suggestions, particularly from
those who have solved this problem or engineers, would be greatly
appreciated!
|
Swap your rear-projection TV for a Plasma or LCD.
Or use an alternative heat source.
I am not trying to be flippant, if the convergence shift is as bad as you
say, I don't think you will ever shield it.
--
Graham.
%profound_observation% |
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WEBPA
Guest
|
| Posted:
Sat Nov 13, 2004 1:00 am Post subject:
Re: electron gun(s) and magnetic fields |
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|
Modify your heater circuit to run on DC. Then, your picture will "glitch" only
when the heater system turns on and turns off. This modification may be easier
than you think.
Also: I suspect your heater runs on HIGH current, LOW voltage...not the other
way 'round.
webpa |
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Gary DeWitt
Guest
|
| Posted:
Sat Nov 13, 2004 6:03 pm Post subject:
Re: electron gun(s) and magnetic fields |
|
|
| Quote: | 2 ideas
Find someone who has a heap of mu-metal sheets and lay under TV
|
What is mu-metal, and is there a source where it can be salvaged from?
I saw something like this on the web, poorly described and priced at
hundreds per square foot! |
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Sam Goldwasser
Guest
|
| Posted:
Sat Nov 13, 2004 6:03 pm Post subject:
Re: electron gun(s) and magnetic fields |
|
|
gpdewitt@yahoo.com (Gary DeWitt) writes:
| Quote: | 2 ideas
Find someone who has a heap of mu-metal sheets and lay under TV
What is mu-metal, and is there a source where it can be salvaged from?
I saw something like this on the web, poorly described and priced at
hundreds per square foot!
|
Mumetal is a highly magnetically permiable material. However, it's expensive
as you note, and difficult to work (you can't bend it without reannealing for
maximum effectiveness).
And, since you can't see through it, at least the front of your TV
will be exposed. If it is simply put under the TV but the magnetic field
will still come in from the beyond.
You will end up spending much more on bandaids than on an LCD TV.
--- sam | Sci.Electronics.Repair FAQ Mirror: http://repairfaq.ece.drexel.edu/
Repair | Main Table of Contents: http://repairfaq.ece.drexel.edu/REPAIR/
+Lasers | Sam's Laser FAQ: http://repairfaq.ece.drexel.edu/sam/lasersam.htm
| Mirror Sites: http://repairfaq.ece.drexel.edu/REPAIR/F_mirror.html
Note: These links are hopefully temporary until we can sort out the excessive
traffic on Repairfaq.org.
Important: Anything sent to the email address in the message header is ignored.
To contact me, please use the feedback form on the S.E.R FAQ Web sites. |
|
| Back to top |
|
|
Charles Schuler
Guest
|
| Posted:
Sat Nov 13, 2004 6:03 pm Post subject:
Re: electron gun(s) and magnetic fields |
|
|
"Charles Schuler" <charleschuler@comcast.net> wrote in message
news:zK2dnewA7b8xvgjcRVn-ow@comcast.com...
| Quote: | Any iron or steel (but not stainless steel) shield (such as sheet metal)
that you can place between the heater and the TV will help. Iron has much
lower reluctance than air, so the magnetic field from the heater will be
concentrated in the shield. Stainless steel is weird in this regard and
usually won't help even though it can be made up of mostly iron.
|
Additional information:
"So, in our example of placing a steel plate between the magnet and the area
we desire to shield from the magnetic field, the ends of the steel plate
will have all the flux lines possible trying to get into it, traveling down
to where they must exit to get back to the magnet (the flux channel) and
exiting in a big bunch. Remembering that the more flux lines, the stronger
the field, what we have accomplished with our actions is to make the
magnetic field near the ends of the steel plate stronger (collected flux
lines) and more inhomogeneous (bent more). Both of these points make the
stray magnetic field more of a problem near the ends of the steel plate. One
way to overcome this problem is to make the steel plate much larger that the
desired area to shield. As the dimensions of the steel plate get larger, the
larger the area of the lowest magnetic field behind the steel plate."
It would seem that if the steel plate was large enough, the flux lines at
its edges should be far enough away from the electron guns and the problem
will be solved or at least greatly reduced.
Source: http://www.acornnmr.com/appnotes/shielding.htm |
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NSM
Guest
|
| Posted:
Sat Nov 13, 2004 11:13 pm Post subject:
Re: electron gun(s) and magnetic fields |
|
|
"Sam Goldwasser" <sam@saul.cis.upenn.edu> wrote in message
news:6wzn1lvmug.fsf@saul.cis.upenn.edu...
| Mumetal is a highly magnetically permiable material. However, it's
expensive
| as you note, and difficult to work (you can't bend it without reannealing
for
| maximum effectiveness).
And a cheaper alternative is alternate layers of steel and aluminium,
insulated with paper.
NM |
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Jim Adney
Guest
|
| Posted:
Mon Nov 15, 2004 6:02 am Post subject:
Re: electron gun(s) and magnetic fields |
|
|
On Fri, 12 Nov 2004 13:30:27 -0800 Jamie
<jamie_5_not_valid_after_5_Please@charter.net> wrote:
| Quote: | the only thing i can think of is
that the electric heaters are
not properly laid out over
laying each other to cancel each
other out which in this case
can be hard to do..
|
I agree with this. I don't know if the makers of this kind of heater
have thought of this problem, but they should have. It should be
possible to lay the heating material in such a way that the external
field is minimized, but it sounds like this was not done in your case.
It might be worthwhile to check with the maker of your heater to see
if they have guidelines in installing it. I have no idea how hard it
might be to get it corrected.
I agree with Sam, that trying to shield it is likely to be futile.
-
-----------------------------------------------
Jim Adney jadney@vwtype3.org
Madison, WI 53711 USA
----------------------------------------------- |
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