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video noise on bg 800 and sony g70

Discussion in 'Projectors, Screens & Video Processors' started by gerni g., Mar 1, 2003.

  1. gerni g.

    gerni g.
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    hi,

    my name is gernot and i´m a newbie to this forum.
    started crt-ing 3 years ago with a vidikron 301 baseband baby.
    had the luck of a hv board fallout resulting in spot burn on all three tubes. instead of switching to the real thing, in came a vidikron 550.
    almost a year ago, bought myself a used barco g 800 for x-mas present. this machine is now enligtning our living room, most of the time watching tv. it´s running flawlessly about 4-5 hours a day.
    now here´s what i´ve noticed: on very bright scenes, some noise appears, looking like rolling scanlines. from my seatplace this is only in bright white parts visible but when standing in front of the screen, you could see it clearly.
    noiced that on a friends g70 as well, but looking like a light version compared to mine.
    some technical info: the barco has 5200 hours under the belt and i have a backup unit with 379 hours. swapped the following boards without remedy: input, quad decoder, vertical deflection, n-s correction, focus module, smps, power input and controller.

    maybe someone like roland or gordon knows the trick.

    thanx,

    gerni
     
  2. Roland @ B4

    Roland @ B4
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    Is this mostly on NTSC but region two or offair is ok?

    I have experienced this a few times with a bad earth. When the display was working with pal ie at the same 50hz frequecny as the mains it was fine. switch to NTSC 60Hz and in came the rolling bars.
    I ran a long earth lead from a water pipe to the projector chasis to prove it. (not as a permananet soloution)
     
  3. gerni g.

    gerni g.
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    hi roland,

    thanx for your reply.
    it´s visible in ntsc and pal.
    i´m feeding my barco with an extron lancia linedoubler.
    we tried a htpc with holo3d and mike parker mod, same result.
    also the complete av-system is fed by a dedicated spur with distribution block.
    all electronic stuff is connected to that distribution block only the antenna mast is connected to the same ground at a different point.
    the only thing left is to disconnect the fm antenna and the satellite dish and see whats happening.

    bye,

    g.
     
  4. jsydanma

    jsydanma
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    Old thread but I'm still curious if gerni g. found out what was the problem? I'm still having exactly the same problems with my D800. Really annoying and clearly visible to my seating position :-(
     
  5. Gordon @ Convergent AV

    Gordon @ Convergent AV
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    I have seen various variations of ths on various systems over the last few years. On one system changing the resolutions we sent to the PJ eliminated this background noise completely. Which surprised me somewhat. Worth trying.

    Generally though I'd be with Roland and would guess earth issue somewhere.

    In my previous job we were employed by a CRT PJ manufcturer to take down and transport a v expensive CRT PJ out of an expensive installation. It suffered scrolling bars. We took the thing down and tested it at our shop. NO fault. Sent it to the manufacturer...NO fault. Stuck it back up at the guys cinema. Fault appeared. So we got in our own electrician and he did a complete appraisal of all the house electrics (100YR OLD 3 STOREY Villa). The cause of the scrolling bars was eventually traced to a faulty earth cable in a second floor bedroom feed to a mains socket. It had taken months a replacement PJ and a trip from senior UK engineer from the projector manufacturers company to NOT be able to fix what was one suspect cable......these things are tricky.

    Gordon

    P.S. The cinema was in the baement.
     
  6. jsydanma

    jsydanma
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    Hmm, I tried yesterday extra grounding from the PJ chassis to waterpipe, no effect :-(
    I even borrowed a power filter (small metal box which has some capasitors and coils in it) from work and installed it to the mains supply of the PJ, the noise is still there :-(
    If I connent the PJ to non grounded power outlet it produces even more visible much wider scrolling bars to the picture. These wide bars are not present if grounded power outlet is used.
     

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