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Barco 800 Data, Red image slipping upwards

Discussion in 'Projectors, Screens & Video Processors' started by flibble, Apr 21, 2005.

  1. flibble

    flibble
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    Hello, I've recently moved house, including lugging the projector to it's new place. I did a setup up yesterday that I'm reasonably pleased with, but I ran into a problem when I sat down to watch a program on it.

    Over a period of about 5-10 minutes the whole image coming from the red tube moves up (in relation to the other two) by a few degrees, enough to cause it to be a couple of inchs higher on the screen, making the picture quite spectaculaly bad.

    I initially thought that it might be because I'd not tightened up the bolts that you use to physically aim the tubes at the green image. So I went into the 'Installation' menu to check that theory in the physical alignment pages. But it was correct on those pages :( and more importantly when I returned to the source image after using the menu it was *fixed*.

    But then, whilst I continued to watch the program it once again drifted up in the next few mintues. Again I used the genlock hash pattern to 'reset' it. I did this a few more times until the program was over. It seems completely repeatable :(

    Does anyone have any idea what this is?
    Is it a common problem?
    Have I managed to bang the projector too much in the move?

    Help! I can't watch a film whilst going into the menu every five minutes :(

    Peter
     
  2. flibble

    flibble
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    *Magnets* maybe.

    Some more info, it's not the Genlock hash pattern that resets the problem, it's just the bit at the start of the 'installation' menu where it turns off Red and Blue and displays a Green Hash pattern, is it performing a degauss here? (or something similar)

    I'm wondering if the magnetic field from the things it's stood on could be affecting it ? It's currently sat ontop of two old PCs, with the power supply (not turned on) of one of them roughly under the Red tube. Could a turned off PSU nearby have this affect?

    I guess I'll just have to take it off it's stand for a while and do some more tests.
     
  3. condor

    condor
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    My friend got himself a samsung Tv a few years ago, however he also got himself a subwoofer and put it next to the Tv. The Sub magnetic field completely destoyed the picture on one side. Try moving the pcs away from the PJ at least a meter, my HTPC is 2 meters away because of the EM field and the heat it generates will warm the components of the PJ. I am very new to this but at a guess I would assume its the psu that is mucking up the tube. Good luck.
     
  4. Roland @ B4

    Roland @ B4
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    You would be very unlucky for this to be the PC. There are very few stong magnets if any in a PC. It would need to be a very big magnet and it would need to be moving to make it drift.

    I think you may have a faulty vertical board (vertical because the image is working its way up)

    Table mounted standing behind the screen it is the third card in from the left. It should have two little potentiometers which are blue with BRASS tops. They will have a smadge of red and blue paint for their respective colours sometimes these get dirty. But more likey is that one of the components in that chain is loosing its magic powers and allowing too much or not enough current through.

    Get the projector nice and cold then quickly do a mid convergence to a gen locked pattern to make sure you have a starting point.
    Let it cool off again and see how long it takes for the pattern to shift.
    Let it cool off again, this time heat that board up with a hair drier if it goes much quicker at least you know where the issue is.
     
  5. flibble

    flibble
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    Yes, it looks like it's not the PC 'stand' causing it. I ran it off the stand yesterday and it was still moving upwards.

    I was a little confused, but it looks like the Pots on my board are Blue with white turning bits, but the picture in the service manual definitely says it's the 'SYNC + VERTICAL DEFLECTION' board.

    I haven't tried the hairdryer test yet (I wanted to check the service manual I got of the net to make sure I was hitting the right board (haven't got internet access at home yet)). But assuming it goes wrong/proves the issue, how difficult is it to fix? Is fixing something like this a service you provide Roland ?

    Peter
     
  6. Roland @ B4

    Roland @ B4
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    It could be so many things on that board. see if you can reproduce the problem first.
    I'm sure I have one around if yu need it
     
  7. flibble

    flibble
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    Well, I tried the 'hairdryer' test last night, blasted it for a good 15 mins (it seems so wrong to blow hot air at something that has fans on to keep it cool :) ). It seems to have no or only a negligible effect on the rate at which the picture moves up. Any more ideas for diagnostic tests ?
     
  8. supersub

    supersub
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    hi flibble
    i had a similar problem with the red image drifting up (ghosting) it seemed to be the BNC connectors not earthing correctly, the screws at the back of the BNC's had come loose some how, tightened them all up & have had no more problems.
     
  9. Roland @ B4

    Roland @ B4
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    Because the image shifts slowly as it heats up I was hoping the hair dryer may prove it was temperature related. More likely to be a capacitor not holding the charge properly.

    I'm still surpised that you have no adjusters with brass tops to control the vertical position. I thought these were there from day one on the 800's.

    I've sent you an Email asking for the part number (76****) to see if I have a spare
     
  10. flibble

    flibble
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    Supersub: Thanks for the suggestion, I'll give it a try when I get home, it seems a very plausable explanation given the PJ might have gotten knocked a bit in the move.

    Roland: I look this number up tonight, and I should be getting my camera back tonight too, so I'll take a photo of the card so you can see if this card really is a bit different, or if I'm just looking in the wrong place :)

    Peter
     
  11. flibble

    flibble
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    supersub: I had a quick check of the connections on the back and non seemed loose, I'll read up on earth testing and get a spanner out and make sure though.

    Roland: The number I could see was 780018-3, this was written on the top deck of the two boards in that card. I'll hopefully be able to attach some pictures to this message to show the card a bit better. The second close up photo does have a couple of blue boxes with brass screws on, I think I was was looking for something bigger :)
     

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  12. Roland @ B4

    Roland @ B4
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    pull the card out it will be on a sticker like this or one on a bright orange one.

    The number from my records will be 761738 or 762269

    It will be pretty unusual for it to be missing.

    Glad you found the pots. give the red a bit of a wiggle to see if the red has got dirty (do this with the projector on a grid)
     

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  13. flibble

    flibble
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    Arrgh, It appears the long and detailed reply I made to this post has disapeared, here's the quick overview.

    Success, I've tracked down the issue to my SVGA to 5BNC lead, I've bought another to test against and will report back tommorrow. (No red slipping up when using PC with SVGA to RGBS 'Interface' box).
     

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