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808 grief

Discussion in 'Projectors, Screens & Video Processors' started by Tim Cooper, Apr 20, 2002.

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  1. Tim Cooper

    Tim Cooper
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    I seem to be having problem after problem with the PQ on my Barco 808s....I recently carried out a 5bnc mod upon my Radeon 7200 in my HCPC ( details with piccys in the HCPC forum), initial findings on PQ are very good with increased definition better colours etc, BUT (isn't there always) when i pause a dvd on a dark scene the picture "shimmers" it's also noticeable on the desktop too, the shimmer is random no discernable pattern, the only way i can describe it is like increasing & decreasing the contrast control very quickly the shimmer is more noticeable if you leave brightness & turn the contast down/off the shimmer looks to me; a problem with the luminence portion of the picture signal.
    I have reconnected another lead to the graphics card using port 3 on the 808, shimmer still there!
    I've checked the leads for impedence mismatch all the way through the signal path, all read 76-77 ohms.
    Now it could just be coincidence that this problem now manifests itself (i've also got grief with the colour temp) so i can't help but think the two are somehow connected?????
    Curious thing i can bypass the graphics card altogether by using the PJ's genlocked pattern at the resolutions i use, turn down the contast almost to zero & the shimmer is there so do i take it maybe the PJ has a fault?????
    Faults aside though the picture really is good
    Roland: please PM me or contact me tj.cooper@blueyonder.co.uk
    Any help app'd
    Tim
     
  2. Tim Cooper

    Tim Cooper
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    I've now determined that the shimmer/flicker is from the PJ.
    I disconnected ALL leads going to the PJ selected internal test pattern turned down the contrast & yes it's still there :-(
    Any other Barco owners experience this?
    Cheers
    Tim
     
  3. Roland @ B4

    Roland @ B4
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    Sorry Tim been away abit

    Probably power supply me thinks.

    Activate the warm up screen in the service menu.That gives you a white screen which will allow you to see the flicker worse.

    Is it a very fast flicker like film probably at 50Hz?

    When you use the internal pattern try a few different frequencies does the speed of the flicker change? If not, it's the P supply.
     
  4. Tim Cooper

    Tim Cooper
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    Hi Roland,
    Been having kittens over the weekend looks as if no one has heard of this problem before.
    You can see the problem better when the contrast is off, like the PJ has a problem maintaining contrast/brightness levels, but then again i might be talking a load of male dangely bits :D
    I have the warm up screen & yes the flicker is there, tried also different internal test patterns & the flicker is there the frequency has NOT changed & yes it's fast flicker like you get at 50hz more like a shimmer on the desktop from my HCPC & flicker when i turn the contrast down.... i think we may onto something here although another tech from the erm other forum reckons it might be my quad &/or the rgb board ????
    I was going to call you anyway to get my PJ calibrated Jenz convinced me :D
    I think we may be onto something here hopefully fingers crossed if you need my details email me.
    Thanks Roland i think i can sleep better tonight :D
    Tim
     
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