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Philips picture adjustment?

Discussion in 'TVs' started by PeterL, Sep 21, 2003.

  1. PeterL

    PeterL Member

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    I bought a Philips 28PW9308 about 3 weeks ago and on the whole I have been very pleased with it. I have also been able to adjust some of the settings thanks to a few of you posting to this forum.

    One of the picture adjustments I have made has been via the service menu using a THX test on Star Wars II as the source. If you are familiar with these, they just provide a set of tests to ensure your video output is set correctly. Two of these tests show a grid matrix on the screen so you can make sure everything is squared up properly. There is one for 4:3 and another for 16:9.

    Anyway, the point I am getting too, is that having gone through and set and saved everything correctly, I have since noticed that the corners of the projected picture are slightly pulled in at the top and bottom at both ends.

    I say "since" because I didn't notice this before, but it could well have been there. By saying the picture is slightly pulled in at the top and bottom at both ends, I don't mean as you get when the horizontal and vertical THX grid matrix is not squared correctly. I ensured this was OK using the East/West set of adjustments in the service menu. It is not that the horizontals and verticals are not straight, but that the edge of the projected image is slightly pulled on top and bottom on both sides.

    Sorry to have been so long-winded in my explanation (I hope you are still with me :zonked: ), but it is this last thing that I need to adjust. Does anyone know how?

    Thanks in advance...
  2. rct

    rct Member

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    Try Upper East/West corner and Lower East/West corner adjustments (these settings are available on my 9617 but I don't know whether or not the 9308 has these). Do this in both 16:9 and 4:3 modes ;)

    edit: Just had a thought after re-reading your post... do you mean that say a uniform grid was on the screen with equal height rectangles from top to bottom, and on your set the rectangles in the middle are shorter that those at the top and bottom edges? If so you need to adjust "V S-Correction"

    Hope this helps :)
  3. PeterL

    PeterL Member

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    Thanks RCT for taking the time to reply.

    It isn't the upper and lower east/west corner adjustments, as I changed these to correct bends top and bottom in the vertical lines on the THX test cards. The effect I am seeing is that the verticals on the test are OK as are the horizontals, but the top and bottom corners (on the vertical) are pulled in slightly on the projection, so in effect the matrix is OK, but the outer projection is not squared at the corners.

    Something like the following (not a very good drawing). NB. the outer vertical lines are the edge of the projected screen, not part of the THX matrix):

    / | | | | | \
    | | | | | | |
    | | | | | | |
    \ | | | | | /

    Would the "V S-Correction" setting correct this, or would it be something else?

    Thanks again.
  4. rct

    rct Member

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    It is the E/W corners in combination with E/W parabola which need to be looked at again. Reduce your E/W corner correction to 0 and get straight lines in the middle portion of the screen using E/W parabola and possibly the (incorrectly named) horizontal bow, then use the corner correction. You'll need a matrix from another test disc with lines to the edges of the screen to do this properly e.g. Ultimate DVD, Home cinema Essentials or Avia. The V S-correction will not have an effect on your problem although it is often wrongly calibrated, so do take a look at it ;)

    Good luck :)
  5. PeterL

    PeterL Member

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    Thanks RCT for the further information.

    I made the adjustments as you suggested last night and it seems the settings I did have were way out. Having said that, I have still not been able to correct the effect I described.

    All of the verticals and horizontals are straight as far as I can see, although as you suggested the THX test card is not the ideal medium to do this with. Studying the output close up, it looks like the left and right corners on the verticals of the projection are being clipped rather than as I described before, being pulled in.

    Could this be because of problems similar to what you described on another thread concerning the use of totally flat screens as with my Philips 28PW9308, in that it is difficult to get the edges and the corners set correctly because of the curvature from the CRT source? Alternatively, could it be a physical mask around the perimeter of the visible part of the tube that is causing this clipping? I don't know, I am not experienced with this sort of thing, just raising a question.

    You mentioned in your last post about other test discs you can get which are much better for doing these sort of adjustments: e.g. Ultimate DVD, Home cinema Essentials or Avia. Where can I get one of these from as if I make any more adjustments I am reluctant to rely on the THX card which as you said is not ideal.
  6. rct

    rct Member

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    Whilst flat screens pose some problems with focus and geometry, the issue you descibe shouldn't really be present to a large degree.

    You will almost certainly get good results if you note down the original settings (in case something goes wrong) and then recalibrate from scratch after resetting all values to zero. Carry out adjustments in the order they appear in the menu. Once roughly calibrated, go back to make fine adjustments. The Trapezoid and Parallelogram correction facilities may prove useful in your situation.

    If it was the physical mask causing the clipping you would clearly see the lack of phosphor coating is those regions with the TV off, I doubt sincerely if this is the cause.

    With any luck, you should be able to get reasonable (not perfect) results. Manufacturers have decided (in their own interests) that the vast majority of consumers don't notice even huge discrepancies in the picture (look around Dixons or similar) and so get away with selling products with poor quality control and factory calibration.

    Ultimate DVD Platinum can be bought from EzyDVD
    Avia was available from these forums as a powerbuy although I don't know if this is still running. You could always place a "Wanted" ad in the classifieds forum.

    Good luck! :smashin:
  7. PeterL

    PeterL Member

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    Thanks RCT for all your help with this.

    I checked out the Avia powerbuy and it is still available from here, although it is £27.

    Ultimate DVD Platinum bought from EzyDVD comes out as around £15 including delivery from Australia.

    Just one more question? Which is the best - Ultimate looks good value for 2 disks, but if Avia, is it worth the extra £12 or so for what I want to do? (OK, I know that's 2 questions! :zonked: )

    Thanks!
  8. rct

    rct Member

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    Avia is meant to be better although I make do just fine with ultimate DVD ;)
  9. PeterL

    PeterL Member

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    Thanks RCT. Ordered Ultimate DVD Platinum from EzyDVD for £13.42 including delivery from Oz - bargain! :smashin:
  10. blindlemon

    blindlemon Guest

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    PeterL,

    It could be that what you're seeing is the fact that the parabola and corner adjustments simply can't create a perfectly straight edge to the image! It'll be pretty good to a centimetre or so from the edge - then it goes awry, whatever settings you use. You may have to increase the H-Size setting to "push" the errors off the edge of the visible screen. A bogus compromise, I know, but the only one I found that worked :(

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