CRT Spot burn

Discussion in 'Projectors, Screens & Video Processors' started by thelaw, Sep 5, 2002.

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  1. thelaw

    thelaw
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    Hi,

    Just got my Barco Graphics 800, took the lenses off on the blue today ( i didnt have a wrench with me when I went to buy it stupidly enough ) it has slight 16:9 burn but nothing that I didn't expect from these damn blue tubes. Whats with that anyway? is there some kind of scientific reason why blue burns first? something to do with UV wavelengths id imagine.

    My main question which I know I mentioned before but Im still not sure of. If the G2 spot kill circuit was not working properly, would the projector burn spots in the tubes the first time it was not killed properly? or would it take a lot of on then off cycles for a spot to appear?

    I'm very paranoid to power this thing up unless I know this at least, I have powered it up and down about 5 times since I have got it, and I do get a fraction of a second on turnoff where the CRTs static will show as a spot (not very bright though) as I've never used a CRT projector before I wasnt sure if this was normal. Barco released a kill board addon to this model, Im not sure whether mine has it. Where abouts is the focus module?

    Cheers,
    Jon
     
  2. Roland @ B4

    Roland @ B4
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    The Blue tube goes first because it is the most common colour for powerpoint backgrounds. It is the most difficult colour to repoduce. I'm surpised to hear that it is a 16x9 wear.

    So long as it is just an aging then display a white screen and pull the projector back utill it just disapears off the edge of the screen and install the peojector there.

    Focus board is the one with the four small red leads comming from it. I has the G2 and focus adjusters on the side. It's attached to the diagnostics board will all the lights one. I know the little sub board you mean but I'm blowed if I can remeber seeing one.

    Momentary spotting at switch off is normal so long as it is not bright.

    Spot burns are easy to see with the naked eye with the lens on just need a bright torch.
     
  3. thelaw

    thelaw
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    Thats what I wanted to hear :)

    It isnt bright at all, I dont think it does it every time either.

    I think that it must have been fixed when the new green and blue were installed because there is not a spot burn in sight on them two. Maybe the projector spot burned the previous green and blue, so it was fixed and given new tubes, the red spot burn isnt too bad, maybe they left it.

    Are sony still manufacturing new 07MPs? i know they would be prohibitively expensive, just out of interest though are they still being made? red tubes seem to be pretty cheap, when I can afford it I will probably try and retube it, and maybe find someone whos parting out their pj for a blue tube.

    Green seems to be in best condition out of the lot.

    One other thing, are these HD8 deltas expensive? they look quite high quality and well built.

    Cheers Roland,
    Jon
     
  4. thelaw

    thelaw
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    Ahh sorry, just another question, i apologise for bombarding you with so many, I appreciate your help a lot

    What input numbers are the s-video ports, and to I have to change the '75ohm' switch next to them?

    Cheers,
    Jon
     
  5. bxd

    bxd
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    Hi Jon,

    The s-video input is no 2.

    The switches are termination switches and should be on (i.e. terminated). If you are sending the signal back out of the projector and onto a monitor then you would have the switch in the off position.

    Brian.
     
  6. thelaw

    thelaw
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    Started it up again, and turned it off. The spotting is only happenning on the blue CRT, its not bright at all, not half as bright as when its displaying an image.

    Is this something to worry about or not?

    Cheers and excuse my paranoia once more :),
    Jon
     
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