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Large Widescreen TV's - Tilt Problems

Discussion in 'TVs' started by lonewaller, Jul 20, 2005.

  1. lonewaller

    lonewaller
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    Having complained to Toshiba about the tilt on my new 32ZP48 tv, I got the following back from them.

    "I am afraid that there is no adjustment for the slope of the picture as
    you described. An engineer would not be able to adjust it without
    disassembly. We have found that the large widescreen tubes are sensitive
    to changes in the Earth's magnetic field caused by the TV orientation (ie.
    which way the screen is facing compared to the way it was facing in the
    factory when it was set up). You should be able to see this yourself if
    you turn the TV through 90 degrees and then measure the slope again. In
    cases like this a threshold has to be set defining a fault condition, and
    up to 5mm is within this threshold. If the retailer were to replace the
    TV, it is possible that you might find that the replacement has a larger
    slope."

    Be advised, it you're thinking about buying a TV without a "tilt" adjustment feature, then you may end up very unhappy with the picture.

    Brian
     
  2. nig28

    nig28
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    Hi
    The TV engineer where I work has said that ""We have found that the large widescreen tubes are sensitive
    to changes in the Earth's magnetic field caused by the TV orientation"" is a load of tripe.
    Nigel
     
  3. martian1

    martian1
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    I think toshiba has let their standards drop over tv manufacture over the last few years, i had a 36" model 3 years ago which had the following additional features.
    Dirty screen [dark patches] :mad:
    Contrast flaring :mad:
    tilt :mad:
    crap geometry :mad:
    This tv cost over £1500 and had no tilt adjustment,the engineer came out and could not put anything right using the service menu, it went back!
    I got a rear pro tv instead which has now been changed for a projector. Last week our old 28" sony tv broke and i have replaced it with a £399 32" samsung with a lovely steel and glass stand. As you expect its features are limited..it has none of the above "apart" from the tilt feature :thumbsup: what a bargain.
    If you are not happy get your cash back.
     
  4. GaryB

    GaryB
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    Your engineer is wrong.

    TVs are aligned at the factory facing East/West to minimise the effects of the earth's magnetic field. This is to give as close to a "neutral" setting as possible. Any alignment required due to the effect of the earth's field when the set is used in its final location is then made using the tilt correction built into the set, if fitted.

    Most decent 32" sets have tilt adjustment built in for exactly this reason. It is not generally fitted to lower priced 28" models, partly because tilt is not such a problem on smaller tubes and partly for cost reasons.

    The TV factory of the manufacturer I work for has a special magnetic field simulator. This can simulate the effect of the Earth's magnetic field at any place on the planet so they can check that the tilt adjustment can indeed compensate for the Earth's magnetic fiels wherever the set will be sued.
     
  5. nig28

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    Hi
    As you probably gathered I am not a TV engineer myself, but I do like to try and understand the issues.
    Quote ""(ie.
    which way the screen is facing compared to the way it was facing in the
    factory when it was set up).""
    This quote from the OP sugests that if you turn your TV arroung 90 degrees you will solve the problem< this is not so
    you seem to be saying it is because the tvs are not made in the same area
    i think we need some input from other members to clarify the issue because i still think its a load of tripe
    nigel
     
  6. lonewaller

    lonewaller
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    Err - didn't actually mean to stir things up. Just thought I would post some info that may be of use to non-technical people.

    "nig28" - Toshiba didn't say that turning a TV round 90 degrees would solve the problem. What they said is that if you do so, you may notice a different level of tilt (or, if very lucky, and can turn your entire house - fix the problem).

    I was speaking to the friend who helped lift the thing out of its box and onto the stand who asked if I wanted to turn the tv to see what, if any, difference it made. Part of me said no bl**dy way while another part is very interested to see if it makes any difference.

    Brian
     
  7. GaryB

    GaryB
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  8. GaryB

    GaryB
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    Correct. The total difference turning a 32" through 90 degrees TV can be up to 4-5mm.

    It will (unless you live on the magnetic North Pole). Bear in mind that the Earth's magnetic field will also affect purity so you may notice some incorrect colour patches. Switch the set off for 10-15 minutes to get rid of them.
     
  9. nig28

    nig28
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    Hi
    I still do not understand how it works-therefore I still trust the person who has had 25+ years in the tv industry.
    If I raise my TV up 2"" at one side how come I dont need to adjust the picture, do YOU understand the principle of how it works?
    Nigel
     
  10. GaryB

    GaryB
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    I've had 26 years in the industry (which makes me feel really old) and am now Technical Manager for one of the major manufacturers (most of the regulars on here know which one) so hopefully I know what I'm doing, but even if I don't, a quick glance at some of the links I've given above will answer most of your questions. Basically, the vertical component of the earth magnetic field varies as a function of latitude and varies even more between the Northern and Southern hemispheres. Manufacturers even make CRTs optimised for each hemisphere. It's this tiny variation that causes the vertical shift on the TV as you turn it.
     
  11. red16v

    red16v
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    Hi, if I may as a broadcast engineer also with over 25 years experience, GaryB is absolutely correct with the points he makes. In very simple terms, a crt works by 'firing' a beam of electrons towards the front of the crt - the electron beam is deflected by a series of coils around the neck of the crt which generate a magnetic field to deflect the beam. it follows then that if the beam is influenced by a magnetic field it would also be affected by any other magnetic fields - including the earths magnetic field - which is static. High quality monitors have magnetic shields around them to shield the electron beams from the earths magentic field so that it does not affect the geometry of the picture (raster). Domestic monitors have no such shielding because they are built to a price and therefore are likely to a varying degree to be affected by the earths magnetic field. The bigger the crt the more the electrons beams inside the crt have to be deflected to fill the screen the more likely they are to be affected by the additional effects of the earth's magnetic field. The magnetic fields produced by the deflection yokes around the neck of the crt produce a dymnamic magnetic field to deflect the beams from left to right from top to bottom. The earths magnetic field at any given point on the earths surface is static and the effect of this is to cause the electron beam to twist - hence your picture may appear twisted. What Toshiba are saying is that you can see the effect of the earths magnetic field affecting a telly by moving the telly round by 90 degree - you MAY see the tilt of the picture alter. They are not saying it will cure the excessive tilt merely that you will see the effect although of course is may tilt the picture in such a way that the tilt is corrected in such a direction as to make the picture level. If the Telly is switched on when you turn it then you will also see the purity of the telly alter (ie, go out of adjustment) because the earths magnetic field in twisting the beams also causes them not to not land correctly on their individual phosphors - so the picture will appear with strange colours. Switch the telly off in this position and leaving it to cool down will cause the deguassing (de-magnetising) circuits to operate when you switch it back on to remove the affect of the earths magnetic field on the colour purity of the picture - it cannot correct the picture tilt which is due to a different affect. As has been well documented elsewhere on this thread this is why I personally never advise anyone to take a UK manufactured set abroad with them to the southern hemisphere since the crt will not have been set up to work in apart of the world with a diffrent magnetic orientation. There are plenty of www resources you can look up to see how the earths magnetic field varies across the planet. GaryB is spot on. Regards, yt.
     
  12. nig28

    nig28
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    Hi
    But again what your talking about makes no sense compared the telephone conversation of the op. What you are saying is if I take my TV to a different location (would that be 100 miles away or 10,000 miles away?) then the screen image would be tilted. But the op was talking about moving the TV 90 degrees within the same house.
    Which one is correct?
    Nigel
     
  13. LV426

    LV426
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    Both. It's as simple as this. Magnetism is a key factor in creating the shape of the image on your screen. Change the influence of magnetism on the screen by any means and you potentially change the shape of the image.

    Rotating or moving the set will change the influence of external magnetism. The joy of large domestic CRTs.
     
  14. nig28

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    Hi
    So what you are saying then, if the op,s faulty TV is replaced then the replacment TV will be exactly the same, if placed in that position in his house.

    Because it is not faulty, it is because the TV was made in a location with a different magnetic latitude! And it will be replaced with a TV made in the same place.
    Nigel
     
  15. GaryB

    GaryB
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    Subject to manufacturing tolerances, yes. That's why virtually all 32" TVs are fitted with a tilt adjustment. All of the 32" sets produced by the manufacturer I work for have always had tilt adjustment. I don't know the model mentioned earlier but I assume it must be a basic model and the circuitry and extra coil on the CRT have been eliminated to cut costs. Even so, IMHO, no manufacturer should sell a 32" or larger set without tilt adjustment for exactly this reason.
     
  16. nig28

    nig28
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    Hi
    Would the same effect be shown by a spirit level.
    Nigel
     
  17. GaryB

    GaryB
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    No. That uses gravity, not magnetism.
     
  18. nig28

    nig28
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    Hi

    The level of level picture is set in the factory, but when it gets into its final position in the customers house it is tilted, because of magnetism.

    The odd TV which gets past quality control and isnt level, maybe the person has been on the booze the night before.

    Lets assume that both of the above occures, the number of posters on this site complaining about quaality control I would say that poor workmanship would be responsible for most.

    Nigel
     
  19. lonewaller

    lonewaller
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    In Toshiba's defence, I perhaps should point out that I was aware there might a tilt problem, I just didn't realise it would bother me so much.

    I should also say that, generally, I'm happy with the TV and not too bothered about the tilt when in "normal " viewing (widescreen on RF channels). It's only when in 4:3 format, teletext (which uses 4:3), or when graphics or info boxes appear on screen which emphasize the "tilt" that it really bothers me.

    Toshiba also point out (btw it was by e-mail, so I've got it in writing) that a replacement set might have a worse tilt problem (conversely, a replacement could be better).

    This brings up the potential problems of buying (large items) over the internet. I'm in Aberdeen, the retailer is in Birmingham. It was bad enough getting the TV out of the box - I've none too keen at trying to re-pack it for return. Had I bought locally, I might well be more inclined to get the shop round to remove the TV and supply a different make (subject of course too any required financial adjustment). However, as I said, the retailer is not local. Incidently, I have no complaints over their service. The TV & DVD were delivered on the stated day. I have not yet asked for their comments regarding "tilt" problems (although I probably will do so, as I have a query regarding "noise" with the DVD player - must start another thread on the appropriate forum).

    After re-considering an earlier post of mine, I will try rotating the TV 90 degrees, as I have the option of locating the set in another corner of the living room. It could result in the tilt being worse or, with a bit of luck, if not totally curing the problem, at least result in less of a tilt. Slightly off thread, is there any problem in adding an extension to the Sky cable as it wouldn't reach the new location?

    Brian
     
  20. nig28

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    Quote "Slightly off thread, is there any problem in adding an extension to the Sky cable as it wouldn't reach the new location?"

    Hi
    If it is not a very long extention and you have a good signal to start with you should be ok, If in dought post another thread.
    Nigel
     
  21. red16v

    red16v
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    Hi, GaryB is spot on again - although I will say my Toshiba 32ZP48 does not have Geomagnetic (tilt) correction because Toshiba thought it wasn't necessary - as it happens my picture is perfectly level. Toshiba do fit this control to the 36ZP48. Regards, yt.
     
  22. lonewaller

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    Well, me mate finally had a chance to drop by, so we rotated the TV 90 degrees. Guess what, the tilt was more or less gone!!!

    Now all I have to do is decide if I'm going to re-arrange the living room to accommodate the TV is the other corner or leave things as they are and suffer the tilt - which is only really noticeable when there are graphics or info bars on the screen.

    Brian
     

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