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I have a 27 inch panasonic and have about 19 real thin lines across the top of the screen. It is in the top 4 inches of the picture tube.Model CT-2701G Built 9/03

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  • Barry Wolf Jul 15, 2008

    Thanks for the fast response.

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This fault is located in the vertical section of your TV. It has leaky capacitors nearby the vertical output IC # 401 thai is mounted on a heatsink. Check C414, C417 and C427 with a capacitance meter, if you do not own one just replace them all.
Let me know if you need further assistance.

Posted on Jul 14, 2008

  • Jaime Hernandez Jul 14, 2008

    Find the location of the IC# 401 with the following markings:
    LA78041

  • Jaime Hernandez Jul 14, 2008

    The mention lines of your TV can't no be adjusted using the remote or any other adjustments will work until the defective parts have been replace.

    This might not be a DIY due to the danger of working with high voltage device such as TVs. High voltages are in excess of 32KV.

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Scan coils (field) measure about 5 to 15 Ohms from the plug where they connect to the main PCB
Look for the cables that come down from the scan coils (deflection yoke) to the main pcb
its either two cables and two plugs or a 4way cable with one plug to the main pcb
2 of the wires goto the vertical(height) and 2 to the width
try to work it out which (the fattest wire is width)
The width ones go towards the loptx(line output/flyback transformer),
and the height ones go to the field output chip (or transistor pair) Follow the printed circuit from the plug and look for a 7 or 9 pin chip on a cooling plate(heat sink for the posh),
it should have a diode connected to it and about 25v on both ends of the diode.
I have a 27 inch - d80c7d6.gif

Posted on Jul 14, 2008

  • Kleanthis Mavropoulos
    Kleanthis Mavropoulos Jul 14, 2008

    If the 25v is missing there is usually a fault in the chip, which blows the protecting resistor which takes the power from the loptx.
    so follow the print back from the chip/diode to the loptx pins, and test all the small fusible resistors on the way, and replace as required.
    If the 25v is ok its usually just the chip or no drive from timebase chip.
    if the 25v is low and the chip is warm/hot then the chip is duff
    whilst doing all this pcb track following check for bad joints.
    If the 25v is ok then we need to look at the field_timebase_chip supplies (usually +12v)
    Finding this chip can be fun, I usually guess, and test all the pins and find none have power, so then I go back to power supply or line derived power, and look for regulators

    After repair leave it run for a few minutes and switch off and see if its getting hot,
    if it is, there is something else wrong.
    check/replace the electrolytic caps nearby and make sure the supply voltage is not too high (25v is usual)

    if the line across is wavy then check the field scan coils for open circuit (right back to the plug)

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Dos the lines go and travel watery??

or do they remain still??

and are the lines like solid bars?

Posted on Jul 14, 2008

  • dewan nafees ahmed Jul 14, 2008

    Take out the comb filter and
    replace the surface mount electrolytic capacitors (I think there were
    around 4 of them) on the comb filter and put it back in the
    motherboard.

    Replace the electrolytic capacitors
    in the power supply section.

    start with replacing (2) 860uf
    180v caps just after the bridge rectifier and continue along the
    circuit.
    Some (15) or so capacitors later, it will finally clear the the
    horizontal bars and lines

    thank you sir

    dont forget to rate the solution

    have a great day


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How long hav u been havin this kinda problem

Posted on Jul 14, 2008

  • 1 more comment 
  • Yaz  S
    Yaz S Jul 14, 2008

    does the thin strip change size?

  • Yaz  S
    Yaz S Jul 14, 2008

    it shud be a convergence problem..ie.if the strip does not change size

  • Yaz  S
    Yaz S Jul 14, 2008

    or the horizontal line is a "collapse of field" and is usually caused by a dry solder joint, be very careful if you attempt a repair yourself (if you can find the suspect solder joint) because extremely high voltages are in certain areas of the circuit, especially in the line output stage. i suggest u get the help of a professional



    Thanks for using Fixya

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