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ARCHIVED FORUM -- April 2007 to March 2012
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This is the first Archived Forum which was active between 17th April 2007 and 1st March February 2012

 

Latest post 04-07-2008 3:27 PM by Keith Saunders. 4 replies.
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  • 02-26-2008 8:42 AM

    • majand
    • Not Ranked
    • Joined on 02-26-2008
    • Helsinki
    • Posts 72
    • Gold Member

    Avant missing red colour

    Hello,

    I bought a second hand Avant 28" VHS (type 81/11). When I saw it at the seller, the picture was fine. Also, when I brought it home and switched on, picture appeared fine, althoug I did not have any real picture, cause we do not have any analogue signal anymore. So, I was fidling to get the DVB decoder to work with one of the SCARTs in Avant, with no much of luck.

    Anyway, after about ten minutes, the red color  disappeared. Also there is a light grey haze behind everything with about eight horizontal white lines, which are connected to each other with diagonal lines. The background of menus is not black, but grey.

     When switching off, I see the curtains to close, but still there remains the grey background for a few moments.

    I then put in a video casette and I can get the picture from there, still missing red and the picture is flickering, or pumping, of about 1 sec frequency.

     
    I opened the back cover to see if something was visibly loosened in transportation, but did not see any obvious reason.

    Has anyone experienced similar problem? What might be the reason and how costly to repair?

     

    Also, should both SCARTs support normal RGB SCART? I did not get any life from there. But when the red disappeared, it was very hard to navigate in the menus, selection being in red.

    Thanks,

    Pekka
     

  • 02-26-2008 10:01 AM In reply to

    • Thomas
    • Top 500 Contributor
      Male
    • Joined on 04-16-2007
    • Norway
    • Posts 85
    • Founder

    Re: Avant missing red colour

    Hi,

    My guess is that the tube is failing.  I had the same gray haze and the lines on my 10 year old 28" Avant and I was told by the repairman it needed a new tube. (I scrapped mine and got an second hand Avant with DVD)

    I think I saw something about a proceidure i think was called "Burning off the Catodes" and that that might give your tube some renewed life, maybe some other member can give som more details ?

     

    Thomas

    7-40 Mk3, Beo5/Beo4, Avant32DVD, BS3K, PentaIII, BL4K, BL Active w/BL2500, Avant28CTV,Beoport, AppleTV, 2xBC6K

  • 02-26-2008 12:40 PM In reply to

    Re: Avant missing red colour

    Pekka,

    Thomas may well be correct about a problem with the tube, but I think a few other things need to be checked first.

    When you say "Anyway, after about ten minutes, the red color  disappeared. Also there is a light grey haze behind everything with about eight horizontal white lines, which are connected to each other with diagonal lines. The background of menus is not black, but grey."

    What you are actually seeing is the scan flyback lines which are only visable when there is a fault related to the tube or drive to it or the brightness is set very high. This also gives what you call the grey effect.

    I think you will need to get a TV engineer to do some voltage checks and also ensure there is dive to the red cathode of the tube. If there is RED drive signal to the cathode of the tube and the engineer determines that all other voltages are correct, then it will a faulty tube.

    Regards Keith....

  • 04-07-2008 3:22 PM In reply to

    • majand
    • Not Ranked
    • Joined on 02-26-2008
    • Helsinki
    • Posts 72
    • Gold Member

    Re: Avant missing red colour

    Just an update to this thread:

    The problem seems to gone away. Hooray!

    Couple weeks ago I was going to scope the signals, to find out if problem was tube or electronics. There I was, put power on to oscilloscope, removed the back cover from Avant and turned it on.

    I leaned over the set to see the picture and saw some red color on the side of the picture. Then there was some red all over the picture. Then a loud bang and the set went dark, only red led in the panel. Fortunately no smoke or anything.

    I collected some courage and pushed the TV button again, and voila!, out comes a perfect picture, with red and all. 

    My guess is that in transport some residue got into wrong pace in the tube and now, the shortcut was cleared with the bang. (where the olufsen is used then? :))

    Can't say much more than that the picture is really good, much better than any flats I've seen, not to even mention the sound.

    Regards, Pekka 

  • 04-07-2008 3:27 PM In reply to

    Re: Avant missing red colour

    Well Pekka,

    You may have been lucky. You can get tube flashovers which can clear faults like this, lets hope it stays that way.

    Regards Keith....

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