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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 01-06-2008 3:06 PM by deaddruid. 4 replies.
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  • 01-06-2008 9:52 AM

    • deaddruid
    • Top 500 Contributor
    • Joined on 05-24-2007
    • Malvern, Worcestershire
    • Posts 247
    • Founder

    MX power-up and retrace lines

    My MX3500 has a strange behaviour on power-up. Is it normal?

    On all my previous (non B&O) TVs, the picture faded up, a few seconds after power-on. However, on my MX3500, about two seconds after power-on, I get an all grey raster, with vertical retrace lines visible. A second or so later, this fades away, to leave a good picture, with no retrace lines visible.

    To me, this suggests that the set is feeding extra current somewhere on power-up (most likely grid G2, or cathodes) and then backing off to a normal level. Do these TVs do this to get faster start-up? If so, are the visible effects meant to be suppressed somehow, or is the behaviour normally visible?

    Of course, it could be a faulty TV! 

    Mark


    p.s., If I've used the wrong forum please tell me - it was hard to decide between "Workbench" and "Vintage".

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  • 01-06-2008 10:08 AM In reply to

    Re: MX power-up and retrace lines

    Hi Mark,

    the Workbench is the right place :)

     This behaviour is a beginning fault, defect capacitors in the power supply and mainboard.

     Maybe next week there is a workshop power supply MX3500/5500.

     Martin

  • 01-06-2008 12:01 PM In reply to

    • deaddruid
    • Top 500 Contributor
    • Joined on 05-24-2007
    • Malvern, Worcestershire
    • Posts 247
    • Founder

    Re: MX power-up and retrace lines

    Thank you, Martin. I'll have to work out how to unwrap the boards from around the CRT! The MX2000 was easy, but the MX3500 seems to have everything crammed into too small a space. I don't understand what you mean by "Maybe next week there is a workshop power supply MX3500/5500", though. Has anyone made a list of electroytic capacitors inside an MX3500, so I can order then prior to dismantling? Thank you, Mark
  • 01-06-2008 12:56 PM In reply to

    Re: MX power-up and retrace lines

    Just have a look at the VX workshop Wink

    Probably next week i have an old MX5500 for repair here in my hobbyshop... i'll take some pictures and partlists.

    Martin

  • 01-06-2008 3:06 PM In reply to

    • deaddruid
    • Top 500 Contributor
    • Joined on 05-24-2007
    • Malvern, Worcestershire
    • Posts 247
    • Founder

    Re: MX power-up and retrace lines

    Ah! Now I understand. Looking forward to it! Mark
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