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Focus after replacing Flyback Trans. JVC

Discussion in 'Electronic Repair' started by [email protected], Jul 19, 2005.

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  1. Guest

    I replaced the flyback tranformer on my 32" JVC, now I can's seem to
    get the sides and the center focused at the same time. I can get one or
    the other. Is there a trick to this??

  2. kip

    kip Guest

    Model is ????
    Flyback is Generic or ?
    Tell us more.

  3. Guest

  4. kip

    kip Guest

    Was it the QQH number or the other number. ?
    QQH is the real thing ...
  5. Guest

  6. Andy Cuffe

    Andy Cuffe Guest

    Are there two focus controls? If so, one of the will affect the sides
    more than the other. It's also possible that the old flyback damaged
    the dynamic focus circuit when it failed.
    Andy Cuffe

    <-- Use this address until 12/31/2005

    <-- Use this address after 12/31/2005
  7. Guest

    There are 2 focus knobs.
  8. kip

    kip Guest

    2 Focus knobs and a Screen control for a 32inch ???

  9. Guest

    Yes, 2 focus and a screen adjust on the FB trans
  10. Jason D.

    Jason D. Guest

    Apprently you have missed rare few old RCA TVs that had 2 H & V focus
    pots along with one screen. Even RCA does sell newer TVs with this
    but it is often found in high end type.

    JVC using them, Samsung does. Not just in monitors. Gives best
    overall focus. Some do have dynamic focus circuits as well which
    actively corrects for the focus error.

    Cheers, Wizard
  11. Guest

    So what should I try to fix this issue?
  12. kip

    kip Guest

    Yes I have seen a few of the older RCA,s with that added focus block (2
    and even Mits and like you say high end sets but to date I have not seen
    a JVC 32 with it.
    Just making sure he has the 2 Focus Pots and Screen as well...

  13. Ol' Duffer

    Ol' Duffer Guest

    Dynamic focus? (that extra ring of wire you thought didn't do
    anything and its associated circuitry)
  14. Guest

    The white wire, I soldered that back in place!?
  15. Andy Cuffe

    Andy Cuffe Guest

    I'm sure there is an official procedure, but this always works for me.

    First, figure out which control is which. One will appear affect the
    overall focus. This is the vertical focus control.

    The other will mostly affect the width of vertical lines and has the
    most effect at the left and right edges of the screen. This is the
    horizontal focus.

    Start with both controls near the middle of their range. You need to
    display something with sharp vertical lines at the edges and sharp
    horizontal lines in the center (a cross hatch is best).

    First, adjust the horizontal focus for the sharpest vertical lines at
    the edges. Ignore the thickness of the scan lines for now, just make
    the vertical lines are as thin as possible.

    Next, adjust the vertical focus for the thinnest horizontal scan lines
    in the dead center of the screen. Alternate between the two several
    times because they interact with each other heavily.

    If you don't have any way to display a cross hatch, you can use a
    computer if it has a TV output, or even the on screen menus of a VCR.
    Andy Cuffe

    <-- Use this address until 12/31/2005

    <-- Use this address after 12/31/2005
  16. RonKZ650

    RonKZ650 Guest

    The old Zeniths with dual focus had a procedure of putting a crosshatch
    pattern on the screen, adjust one focus for the thinnest vertical ine,
    the other for the thinnest horiz line. This works for me on all dual
    focus sets. Once you have a crosshatch pattern on the screen it is easy
    to see which control effects horiz and which effects vertical. From
    there you have to go back and forth between the two a few times to
    eventually get both at optimum. I don't like um, but part of the
  17. Guest

    Here is another thing, the tranformer has a black and red wire coming
    off it that connects to the board off the CRT, it is labled A and B - I
    did not see how those came off. I put them back as Black -A and Red B,
    would this effect anything?
  18. kip

    kip Guest

    Oh Boy !!!
  19. sofie

    sofie Guest

    Duh ! Obviously... yes.
  20. Guest

    So does anyone know if the red is A and the Black is B, or just the
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