TV in Northern Hemisphere
Philip J Jones
I have a problem. I have just relocated to Ohio, USA from Australia, and
have brought my PAL TV and VCR with me so the kids can watch their
favourite videos. Of course, I know that the NTSC system will not work with
it, but it's just for our PAL videos.
I rigged up a 120V to 240V transformer (Australia uses 240V, 50Hz), to run
the thing, and all works fine EXCEPT the colors are upset, with everything
basically being purple and green. This apparently is because the earth's
magnetic field is different in the Northern Hemisphere, compared to the
Southern Hemisphere. Furthermore, BELIEVE IT OR NOT the colors are correct
if I turn the TV upside down!! However, this is none too good for watching.
Apparently, there is some sort of adjustment I can make inside the set, to
rectify this. Of course, the same set (a Sharp 21" set) is probably sold in
both hemispheres so there must be some adjustment, and furthermore, I would
have thought it would be an analog adjustment, as the set would be used in
many different latitudes. So it seems to me that if I knew what to adjust,
I could twiddle it and see.
Can someone help, please. This is a serious, genuine request, even though
to many of you it will sound like your leg is being pulled!
Phil Jones
Phil Witt
On 3 Jan 1998 22:17:29 GMT, "Philip J Jones"
<PHIL.LOU...@stratos.net> wrote:
>Furthermore, BELIEVE IT OR NOT the colors are correct
>if I turn the TV upside down!! However, this is none too good for watching.
You may have moved to a part of Ohio where they are still
using reverse gauss in the power generation equipment which
results in a color-complement phenomenon, also known as
R+Y B+Y / M minus IQ. A few years back one of the major
paint companies used to sell an evaporative filter coating
which, when sprayed on the CRT, resulted in the restoration
of the proper colors. You might check with some of the
local paint stores. Most people with this problem, however,
just broke down and bought new TVs.
HTH.
Jeroen Stessen
> have brought my PAL TV and VCR with me so the kids can watch their
> favourite videos. Of course, I know that the NTSC system will not work with
> it, but it's just for our PAL videos.
>
> I rigged up a 120V to 240V transformer (Australia uses 240V, 50Hz), to run
> the thing, and all works fine EXCEPT the colors are upset, with everything
> basically being purple and green. This apparently is because the earth's
> magnetic field is different in the Northern Hemisphere, compared to the
> if I turn the TV upside down!! However, this is none too good for watching.
>
> rectify this. Of course, the same set (a Sharp 21" set) is probably sold in
> both hemispheres so there must be some adjustment, and furthermore, I would
> have thought it would be an analog adjustment, as the set would be used in
> many different latitudes. So it seems to me that if I knew what to adjust,
> I could twiddle it and see.
>
> Can someone help, please. This is a serious, genuine request, even though
> to many of you it will sound like your leg is being pulled!
Hello Philip,
No, not at all, this is a well-known fact, which is in
fact mentioned in the FAQ for news:sci.electronics.repair .
Actually, I provided this information, via Sam Goldwasser.
Facts:
- the vertical component of the earth magnetic field varies
as a function of latitude, particularly between hemispheres
- a vertical magnetic field will influence the color purity
of a CRT
- the magnetic shielding of a CRT will, after degaussing,
not provide complete compensation for the vertical field,
especially for the space between shadow mask and screen
- that's why manufacturers produce different displays for
different hemispheres: northern, southern and neutral,
they do this by adjusting for optimum purity in a
simulated magnetic field.
Your options (apart from tossing the TV) are:
- Re-adjust the purity, this involves moving the deflection
coil, adjustment magnets, adding more magnets, etcetera.
This is a big job and success would not be guaranteed.
- Simulate a southern hemisphere location by creating a
vertical magnetic field around the TV, put two big multi-
turn wire loops (Helmholtz coils) above and below the TV
and run a DC current through them. Might be expensive ...
- Replace the picture tube with a northern hemispere type,
this is very expensive.
- Mount the picture tube upside-down inside the TV cabinet.
Then reverse the wires for the line- and raster-deflection
to put the picture correct side up again.
In the latter case, you might have some problems with:
- the mounting nuts for the tube are hard to reach and may
have left thread (look carefully before turning !)
- the wires to the inverted picture tube panel being too
short, they can probably be easily extended
- the distance between high-voltage anode connection and
the chassis (circuits) being too short (safety !)
- condensation dripping into the anode contact.
Bang & Olufsen once made a compact style television where
they wanted the anode contact to be away from the top of
the cabinet, so the back cover could fit tighter. So they
mounted the tube upside-down. Consequently they had to
order southern hemisphere tubes for a northern hemisphere
TV set. That works, of course.
A final tip (from similar experience for the reversed case
and some lost hours): put your mains transformer far away
from the set, because the 60 Hz stray field will interfere
with the 50 Hz raster and shake the picture with 10 Hz.
Hope this helps, cheers, happy new year,
Jeroen.
-------------------------------------------
From: Jeroen Stessen, Eindhoven, Nederland
mailto:Jeroen....@iaehv.nl
-------------------------------------------
You don't have to like Windows 95 to use it
Tech Guy
You may have answered your own question in your post (Australia uses 240V, *50Hz*)
You can down-convert the voltage though the frequency of the AC is still out of sync.
Philip J Jones wrote in message <01bd1894$cabf4100$2f9a...@phil.louise.jones.stratos.net>...
|I have a problem. I have just relocated to Ohio, USA from Australia, and
|have brought my PAL TV and VCR with me so the kids can watch their
|favourite videos. Of course, I know that the NTSC system will not work with
|it, but it's just for our PAL videos.
|
|I rigged up a 120V to 240V transformer (Australia uses 240V, 50Hz), to run
|the thing, and all works fine EXCEPT the colors are upset, with everything
|basically being purple and green. This apparently is because the earth's
|magnetic field is different in the Northern Hemisphere, compared to the
|Southern Hemisphere. Furthermore, BELIEVE IT OR NOT the colors are correct
|if I turn the TV upside down!! However, this is none too good for watching.
|
|Apparently, there is some sort of adjustment I can make inside the set, to
|rectify this. Of course, the same set (a Sharp 21" set) is probably sold in
|both hemispheres so there must be some adjustment, and furthermore, I would
|have thought it would be an analog adjustment, as the set would be used in
|many different latitudes. So it seems to me that if I knew what to adjust,
|I could twiddle it and see.
|
|Can someone help, please. This is a serious, genuine request, even though
|to many of you it will sound like your leg is being pulled!
|
|Phil Jones
Laurence Taylor
In article <01bd1894$cabf4100$2f9a...@phil.louise.jones.stratos.net>
PHIL.LOU...@stratos.net "Philip J Jones" writes:
-> I rigged up a 120V to 240V transformer (Australia uses 240V, 50Hz), to run
-> the thing, and all works fine EXCEPT the colors are upset, with everything
-> basically being purple and green. This apparently is because the earth's
-> magnetic field is different in the Northern Hemisphere, compared to the
-> Southern Hemisphere. Furthermore, BELIEVE IT OR NOT the colors are correct
-> if I turn the TV upside down!! However, this is none too good for watching.
Variations in the Earth's magnetic field between locations often cause
this sort of effect; I have seen similar, though nkot so severe,
problems, when moving the set across the room!
You have to give the set a GOOD degaussing - the normal degauss at
switch-on isn't really sufficient (although it will probably improve
slowly over time). Get you local repair shop to degauss the set with a
degaussing coil - I doubt if you'd be able to get him to do anything
else with it, most repair merchants don't know what to do with anything
"unusual".
As a last resort, remove the tube and invert it, but only do this if you
are used to doing things to the insides of TV sets - very high voltages
can remain for many weeks after the set is switched off.
Oh yes. regarding the 120/240V transformer - one, make sure it is
suitably rated, and two, put it as far away as you can from the set, or
the picture will be affected.
rgds
LAurence
Laurence Taylor
In article <68oqc1$1h8$1...@newsfep2.sprintmail.com>
NOSPAMpatr...@sprintmail.com "Tech Guy" writes:
-> You may have answered your own question in your post (Australia uses =
-> 240V, *50Hz*)
->
-> You can down-convert the voltage though the frequency of the AC is still =
-> out of sync.
Since TV transmissions are no longer locked to the mains supply, it
matters not what the frequency is as long as the voltage is corrct.
rgds
LAurence
Cyril Williams
In article <883956...@iapetus.demon.co.uk>, laur...@iapetus.demon.co.uk
(Laurence Taylor) wrote:
>
> In article <01bd1894$cabf4100$2f9a...@phil.louise.jones.stratos.net>
> PHIL.LOU...@stratos.net "Philip J Jones" writes:
> >
> > I rigged up a 120V to 240V transformer (Australia uses 240V, 50Hz), to
everything basically being purple and green. This apparently is because the
earth's magnetic field is different in the Northern Hemisphere, compared to
the Southern Hemisphere. Furthermore, BELIEVE IT OR NOT the colors are
correct if I turn the TV upside down!! However, this is none too good for
watching.
> >
> Variations in the Earth's magnetic field between locations often cause
> this sort of effect; I have seen similar, though not so severe,
> problems, when moving the set across the room!
> rgds
> LAurence
>
>
>
Could the reason be that colour is different in the US?
Joking apart, I was amazed by the original posting and thought that the
whole thing was a leg-pull - - until I tried turning my 14" portable upside
down. Bingo!
Now, can someone explain to me why the angle of magnetic dip has so much
greater an effect than the earth's horizontal field component? I can't say
that I have ever noticed a problem if the set is turned around - and,
believe me, I am a very critical person!
--
_ ___
/ ' ,/ ____________|____________
(_\//^// U e-mail: willi...@argonet.co.uk
/
Jeroen Stessen
Cyril Williams <willi...@argonet.co.uk> wrote:
> Joking apart, I was amazed by the original posting and thought that the
> whole thing was a leg-pull - - until I tried turning my 14" portable upside
> down. Bingo!
> Now, can someone explain to me why the angle of magnetic dip has so much
> greater an effect than the earth's horizontal field component? I can't say
> that I have ever noticed a problem if the set is turned around - and,
> believe me, I am a very critical person!
Hello Cyril,
(You did degauss the set after turning it around, yes ?)
The explanation is in basic electromagnetism:
The electron speed is mainly axial, a vertical magnetic field then
causes a horizontal ("east-west") deflection. Colour selection is
in that same horizontal direction, so purity is compromised.
The other 2 components of the magnetic field cause minor problems
too. Notably the axial component is hard to shield and causes a
rotation of the picture and minor purity errors in the corners.
For this, some (widescreen) TVs have a compensation coil around
the neck of the tube. Expensive high-resolution computer monitors
may have compensation coils for all 3 directions (with automatic
adjustment from 3 magnetic field sensors).
Think of the implications of building projection TVs in Belgium
for the Australian market... With 3 CRTs there is obviously no
purity problem, so degaussing is not incorporated. But there is
a problem with convergence, and with geometry. Just think...
Think of the implications for HDTV... High-resolution picture
tubes are more sensitive to magnetic field. Luckily, plasma
display panels and LCDs (and PALCs) are insensitive.
Isn't it fascinating to be living on a big magnet ?
Regards,
Jeroen.
-----------------------------------------------------------------------
| From: Jeroen H. Stessen | PHILIPS Consumer Electronics B.V. |
| Building: SFJ-3.38 Eindhoven | Advanced Systems & Applications Lab. |
| Phone: ++31.40.27.32739 | P.O. Box 80002, NL 5600 JB Eindhoven |
-----------------------------------------------------------------------
| mailto:Jeroen....@ehv.ce.philips.com | Let's make things better |
-----------------------------------------------------------------------
The Duck
In article <34BB14...@ehv.ce.philips.com>, Jeroen....@ehv.ce.philips.com
says...
~Cyril Williams <willi...@argonet.co.uk> wrote:
<snip>
~Hello Cyril,
~
~
~The explanation is in basic electromagnetism:
<snip>
~Think of the implications for HDTV... High-resolution picture
~tubes are more sensitive to magnetic field. Luckily, plasma
~display panels and LCDs (and PALCs) are insensitive.
~
~Isn't it fascinating to be living on a big magnet ?
~Regards,
~Jeroen.
~
Could you please enlighten me, "PALC's" is a term that I am unfamiliar with.
Thanks
Huey
Jeroen Stessen
The Duck <av...@comcen.com.au> wrote:
> Could you please enlighten me, "PALC's" is a term that I am unfamiliar with.
Plasma Addressed Liquid Crystal display. Invented by Tektronix,
the inventors then founded their own company (the name escapes
me right now). The patents remained with Tektronix which is now
owned by Sony. Sony now sells 28" 16:9 "Plasmatron" TV. Sony
now has a joint venture with Sharp and Philips to develop better
PALC displays together.
Basically it is an LCD, with colour filters and backlighting and
all, but the active matrix transistors have been replaced by
plasma channels which act as switches to address individual lines.
Because the glass panel is now entirely passive, it is easier to
up-scale to larger sizes than TFT-LCD (yield problem).
This is much different from a real plasma display panel where
plasma generates UV light which is converted to visible light by
3 colours of phosphor. Then there is no backlight involved.
Got it ?
Regards,
Jeroen.
--
Jim Phillip
Jeroen Stessen wrote:
>
The patents remained with Tektronix which is now
> owned by Sony.
Totally untrue. Tektronix is not owned by Sony although they do have
some sort of joint venture in Japan only.
Jim Phillip
Louis A. Carliner
Jeroen Stessen <Jeroen....@ehv.ce.philips.com> wrote:
>The Duck <av...@comcen.com.au> wrote:
>> Could you please enlighten me, "PALC's" is a term that I am unfamiliar with.
>
>Plasma Addressed Liquid Crystal display. Invented by Tektronix,
>the inventors then founded their own company (the name escapes
>me right now). The patents remained with Tektronix which is now
>owned by Sony. Sony now sells 28" 16:9 "Plasmatron" TV. Sony
>now has a joint venture with Sharp and Philips to develop better
>PALC displays together.
>
>Basically it is an LCD, with colour filters and backlighting and
>all, but the active matrix transistors have been replaced by
>plasma channels which act as switches to address individual lines.
>Because the glass panel is now entirely passive, it is easier to
>up-scale to larger sizes than TFT-LCD (yield problem).
>This is much different from a real plasma display panel where
>plasma generates UV light which is converted to visible light by
>3 colours of phosphor. Then there is no backlight involved.
>
>Got it ?
>Regards,
Let's hope that these do not have that yuckky diswatery gray rendition of
blacks that plague current LCD projectors and to a lesser extent DLP's that
still render dark scenes very much like that of a slightly overexposed
Kodachrome transparency slide!
Louis. . . .
>Jeroen.
>--
>-----------------------------------------------------------------------
>| From: Jeroen H. Stessen | PHILIPS Consumer Electronics B.V. |
>| Building: SFJ-3.38 Eindhoven | Advanced Systems & Applications Lab. |
>| Phone: ++31.40.27.32739 | P.O. Box 80002, NL 5600 JB Eindhoven |
>-----------------------------------------------------------------------
>| mailto:Jeroen....@ehv.ce.philips.com | Let's make things better |
>-----------------------------------------------------------------------
Louis A. Carliner
Your source for video calibration expertise for
Washington, D.C., Maryland, Virginia and West Virgina
as well as Southern Delaware UNTIL SOMETIME THE LATE
FIRST QUARTER OR EARLY SECOND QUARTER 1998
in transistion to West Central Florida
by an ISF/Joe Kane trained specialist equipped with both
the Philips color analyser and ISF optical comparator.
WILL TRAVEL ELSEWHERE! JUST PAY MY WAY!!
Phone: (301) 340-6120
email: lcar...@idsonline.com