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TV shows stripes/lines at the top of the screen

Discussion in 'Electronic Repair' started by Tech Data, Jun 11, 2006.

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  1. Tech Data

    Tech Data Guest

    "What should I check for?" The nearest servicer in the Yellow Pages and
    ask them what they'd charge to correct this. If the first and only
    thing you try is to turn things that move to repair this, then guiding
    you to the probable circuit would most likely turn the tv into dumpster
    fodder. That's a nice product. Spend a little and get it fixed right.
  2. -Almazick-

    -Almazick- Guest

    I have Panasonic TV about 1 year old. It was working great til a few weeks
    ago, now it shows stripes/lines at the top of the screen that used to get
    better after tv was getting warm. Now I got more stripes/lines at the top of
    the screen and they don't dissapear even when tv gets warm. I removed the tv
    rear cover and found only 2 knobs for Focus and Screen and they won't solve
    the problem. I tried to adjust Var Resistor and again nothing. What can I
    do? What should I check for? Please help.


  3. -Almazick-

    -Almazick- Guest

    Thanks for your response but it's not what I'm looking for. I'm looking for
    help and to point me to the right direction. If I wanted to give it to
    service I would done it a long time ago but that's no fun at all. That's
    the idea to learn it and do it yourself. Also If I had no idea what I was
    doing I wouldn't even touch it but I've done in the past couple of projects
    creating PCB and making IC to work. It's all about fun and enjoying what
    you are doing. This is diy electronics repair forum and people expect to
    get help to solve the problem not to create another one just like you
    advised it and please next time stay on the subject and don't create another
  4. Arfa Daily

    Arfa Daily Guest

    It is a nice idea that you would like to fix it yourself, but I have to say
    that the advice that you were given by Tech Data, in this case, was valid
    for your own safety, if nothing else. Modern TV sets are DANGEROUS items -
    probably more so than their predecessors. They all utilise switch mode power
    supplies, and if you do not understand these, or work with them on a regular
    basis, and have a proper transformer-isolated safety supply to run them
    from, then they can be lethal - and I mean that by the most death-causing
    literal definition that you can find.

    Creating PCBs, and making ICs work do not, unfortunately, qualify you to be
    poking around safely in the back of a TV. Even twiddling the screen pot,
    without knowing what it does, or how to readjust it correctly so that you
    don't have a useless CRT on your hands in a couple of months, to add further
    to your woes, indicates that you should not be attempting this.

    Whilst this is a DIY repair group, for some types of repair, a degree of
    expertise is still required, and in our opinion, you simply don't have the
    necessary expertise to be attempting a repair such as this. Those of us who
    do, would be irresponsible to advise you to try, for your own safety. The
    advice you were given was good, and I think the same as most of us would
    have given - take it to a reputable repair shop. If you really don't want to
    spend the money on it, and it really is just a year old, then pick up the
    phone and bleat long and hard to Panasonic's customer liason - you might
    just get a result, and live long enough to enjoy it ...

    Also, if you wouldn't mind, please don't top-post. It makes threads
    difficult to follow once they get above a couple long.

  5. Tech Data

    Tech Data Guest

    Wow, thanks for putting me in my place. Did you realize that you posted
    twice and, by omission, indicate that you think Panasonic made only one
    television, ever, and you own it? If you expect someone to lead you to
    a magic fix, you might want to post a model number or, at the very
    least, a color.
  6. The problem is likely a bad capacitor in the vertical deflection output.

    But I agree - get it fixed by a professional and DON'T touch any of the
    internal adjustments! This is a circuit failure.

    --- sam | Sci.Electronics.Repair FAQ:
    Repair | Main Table of Contents:
    +Lasers | Sam's Laser FAQ:
    | Mirror Sites:

    Important: Anything sent to the email address in the message header above is
    ignored unless my full name AND either lasers or electronics is included in the
    subject line. Or, you can contact me via the Feedback Form in the FAQs.
  7. Dave D

    Dave D Guest

    If you'd provided a model number and resisted the temptation to indulge in
    dangerous buffoonery, then maybe the *group* (this is *not* a forum!) would
    have considered you had enough credibility to undertake a repair. However,
    by your actions you have demonstrated that the only successful undertaking
    will be your subsequent funeral.

    You clearly do not understand televisions or their circuits and adjustments,
    and I'm certain few people would recommend you learn the craft with a good,
    newish TV when they know full well you may injure/kill yourself or wreck the
    TV. Seriously- anyone who thinks the 'focus' control will cure lines at the
    top of the screen has no business inside a TV set- even my 13 year old
    daughter knows what 'focus' means ;-)

    Furthermore, a basic rule of repair is that adjusting things when a fault
    arises is a no-no. Apart from the simple fact that it rarely helps to effect
    a good repair, it will at best mask the fault, and at worst make a simple
    repair into a realignment job which increases the total repair cost. Worse
    still you randomly adjusted settings you didn't understand- what did you
    hope to achieve? Would you randomly adjust things on your car's carburettor
    if the tail light developed a fault?

    If you want to learn TV repair, I recommend you get a good book and
    understand how they work before you go inside and practice, you and the TV
    will live longer.

    The answer to your question is electrolytic capacitors in the vertical
    deflection circuit as Sam stated- about 99% certainty. It's not an expensive
    job and straightforward enough for a half decent tech, so I recommend you
    pay to get it done.

    As for wanting to fix it yourself as part of a learning process, learning
    what exactly? You had to come here to ask where the fault was, so the hard
    part has been answered for you. The remainder of the job is soldering in
    replacements, far better you practice soldering on a scrap PCB than a year
    old TV.

    Good luck with your TV, and stay alive!

  8. -Almazick-

    -Almazick- Guest

    Thanks a lot for the answer. Sorry for not posting the model because I did
    not think it was very important just because it is a general problem. I
    spent all night reading tv problems and found similar problem with the same
    answer. I was wondering where can I get Service Manual for Panasonic
    CT-24SL14J or just a schematic to find bad capacitor in the vertical
    deflection? I checked IC yesterday but I couldn't find a bad capacitor by
    an eye. Regarding safety I do understand it is very dangerous to put your
    fingers inside of the tv because of the High Voltage unless your discharge
    capacitors or follow safety code. I learned my lesson a long time ago. I
    do know what I'm doing and it is not the first time. I also understand that
    I don't have enough experience but again it is all about learning.
  9. Franc Zabkar

    Franc Zabkar Guest

    Look for an IC on a heatsink, possibly an LAxxxx type. Then download
    its datasheet and study the application circuit therein. You will see
    several electrolytic capacitors. You may as well change all of them -
    they are cheap enough.

    BTW, in Australia you would be entitled to a free warranty repair on
    the grounds that your one year old (?) TV is not of merchantable
    quality. This is despite the fact that the manufacturer's voluntary
    warranty is only 1 year.

    - Franc Zabkar
  10. Dave D

    Dave D Guest

    By eye? No good in this case. Testing with an ESR meter or substitution is
    the way to do it. If in doubt, just change all the electrolytic capacitors
    in the vertical deflection area, they aren't expensive parts and it could
    prevent further trouble.

  11. -Almazick-

    -Almazick- Guest

    Great I found everything already. Instead of LA4845 it is using AN15525 IC.
    In datasheet it shows 3 caps in example schematic. I'll try to replace on
    tuesday some of my caps in my tv. Really bad that I don't have ESR meter
    should make my job a lot easier :) again thanks a lot.
  12. JANA

    JANA Guest

    Troubleshoot the set for defective components in the vertical deflection
    area. It is impossible to guess to the exact components. There are many
    involved. You will require at the very least, a DVM, ESR meter, and the
    service manuals for your set. If the problem gets complicated, you will need
    a scope. Also, it is an asset to have the proper training in electronics,
    and in TV servicing.

    Your best solution is to bring the set to a service centre and have them
    service it for you. There are also serious safety issues when servicing TV
    sets and electrical appliances.



    "What should I check for?" The nearest servicer in the Yellow Pages and
    ask them what they'd charge to correct this. If the first and only
    thing you try is to turn things that move to repair this, then guiding
    you to the probable circuit would most likely turn the tv into dumpster
    fodder. That's a nice product. Spend a little and get it fixed right.
  13. JW

    JW Guest

    Then stop touching it already.
  14. Okay if the rest of you all are done with your immature flame war,
    can say through all my experience that is is definitely a ba
    capacitor either in the vertical or power supply area. No cap shoul
    be getting too hot, so this may be a symptom of the main voiltag
    bias being out of range. Look inwside the back cover for test-point
    and check that main B+ voltage is within 5% of spec (if given)

    So the guy wants to learn, noone becomes an expert from a book alone
    If any of you people flaming were experts, you should already kno
    that. While I agree that diagnosis comes before adjustments, and tha
    some skill is required, he IS NOT FIXING YOUR EQUIPMENT, so get ove
    it. If they do something wrong, it's on them, not you, in case yo

    Sheesh, seems people here are a bit too uppity about things that the
    have made into their own personal problem. Quit shutting out someon
    with an idea, everyone has to make mistakes to learn. You could al
    suggest politely that the focus control will not fix it. For thos
    who want to know, I am self-taught on many a different area that yo
    will never understand, and know more in many than all the book-smart
    in the world

    8 years of college cannot teach what I have learned in as little a
    five seconds..
  15. Arfa Daily

    Arfa Daily Guest

    There is a difference between helping someone to learn safely, and being
    irresponsible. By saying that he had attempted to 'repair' his faulty
    television set, by twiddling controls whose function he understood nothing
    about, the OP demonstrated that he was not competent to be inside a
    television set with safety. Now you may think that is ok, but I think that
    if those of us who are properly qualified, and whose collective wisdom
    exceeds yours by many times, were to recommend that he continued to poke
    around inside an item of equipment that REALLY COULD KILL OR SERIOUSLY
    INJURE him, this would be irresponsible, rather than helpful.

    For sure, we all learn by making mistakes, but you're not gonna learn a lot,
    if your first bad one puts you in the mortuary. In order to learn repair of
    TV sets, and similar equipment, safely, you need at least a mentor, who is
    fully qualified, and standing by your side watching your every move. You
    absolutely MUST understand the safety angles of what you are doing,
    otherwise, with a couple of repair successes under your belt, you will start
    to become a self-proclaimed self-taught *expert* who then goes on to carry
    out dangerous work on other people's equipment.

    Whilst it is possible for qualified people to learn new techniques and hints
    and tips from groups such as this, it is not possible for total amateurs to
    learn arts such as TV repair, safely. Would you seriously suggest that
    someone should try SCUBA diving, or sky diving, or mountain climbing or
    racecar driving, without having been practically taught by someone who knows
    how to do it safely ? No, of course not, and anyone who believes seriously
    that electricity is not equally dangerous, is a fool.

    No one has been *flamed* on here. Perhaps one or two of the comments were a
    little less than polite, but if you think that is flaming, then you have
    lived a sheltered internet life. Everyone from amateurs to professionals are
    welcome on here, and will normally recive good and valid advice, but don't
    expect those of us who take a responsible attitude to safety, to encourage
    either those who don't, or those who have no knowledge of such matters.

  16. Dave D

    Dave D Guest

    Now now, Arfa! 'Electromotive Guru' is obviously someone the group should
    look up to. After all, he advises someone who knows so little about basic
    physics that he doesn't know what a focus adjustment does, to, and I quote:

    "Look inwside the back cover for test-points and check that main B+ voltage
    is within 5% of spec" (because) "this may be a symptom of the main voiltage
    bias being out of range"

    Obviously good advice ;-) He also thinks it's good advice for a non-savvy
    consumer to take the back off his set and poke around inside so he can
    'learn', without having even the most basic knowledge of electronics.

    By his reasoning- my 13 year old daughter knows what focus means, and it's
    not just a car made by Ford, so she must be even more qualified than the OP
    to poke around inside a TV! Next time the TV breaks I might give her a
    service manual and a soldering iron and let her fix it for me. It's a nice
    RPTV so plenty of room for her to crawl inside and measure the 'main bias
    voltage'. I wouldn't want to deprive her of a learning experience after all!

  17. -Almazick-

    -Almazick- Guest

    Hello Dave D,
    I see your point regarding your 13 year old daughter knows what focus means
    and that's good but you need to learn how to read first before you flame
    anyone. If you read my original post you can find "I removed the tv rear
    cover and found only 2 knobs for Focus and Screen and they won't solve the
    problem." I do know what focus and screen means too but I did not say that
    I was tweaking them or did not know what it was. What I meant that I found
    only 2 knobs and it won't solve the problem because they have nothing to do
    with the problem I had (vertical deflection output). In older tv's used to
    be knobs behind the cover or small holes for vertical and horizontal
    adjustments. You assumed that I did not know what focus is and made
    something out of nothing. Anyway let's just stop arguing and stop putting
    people down. If people ask for advice, let's just give them because you
    don't know what they know and their experiences. Just like Electromotive
    Guru said, him and me are self-taught on many a different area that you
    won't have any idea how to fix it. In some areas I'm more stronger and some
    weaker and when I ask people for advice who knows more than me I don't
    really want to listen flames because I can bet you ask questions in other
    boards and you don't want people flaming you. I used to be on boards a long
    time ago helping people with cars, satellite dishes, operating systems,
    computer hardware and web designers because I'm good at it but I never made
    any flames. Don't like the question just go to the next one, simply ignore
    them. People always make a mistake with a bad description just like I did
    but it doesn't mean you are better than me because you really don't know me.
    On the other hand I fixed the tv and it only took me about 30 minutes. As
    you can see people it takes less time to fix something with a proper answer
    than reading all that flaming and your bad opinions which makes me sick. If
    you don't like something it doesn't mean you have to start flaming people
    just ignore and go to the next post. It makes our life's a lot easier. A
    big thanks to people who pointed me to the right direction: Sam Goldwasser,
    Franc Zabkar, Jana and Electromotive Guru.
  18. Dave D

    Dave D Guest


    OK, I accept I have misunderstood you, but please understand that "and they
    won't solve the problem." can also mean you tried them to no avail. Damn
    the English language, ambiguity is too common!

    I am sorry you didn't consider my advice to be helpful, and indeed
    considered it to be flaming. However, we are not mind readers. How was I to
    know you were techinically minded? You certainly didn't give that impression
    from your OP which was vague and admitted lack of knowledge of the working
    of TVs, and clearly I'm not the only one who thought that.

    Generally, if people come here with intelligent questions and can provide
    troubleshooting info, they will get intelligent answers. If they come here
    and give the impression that they know nothing (as you did- you said you
    wanted to learn) and ask questions like 'my TV went funny, which part do I
    change?' (extreme example) then they will often be disappointed.

    If you read back over my posts you'll find that in actual fact I did give an
    answer, despite what you think. Furthermore, though it wasn't what you
    wanted to hear, my advice to stay away from TVs until you get up to speed on
    LV equipment was sound and I had your interests at heart. I could have said
    'dive in with both hands while it's on, and make sure you're a bit damp',
    but no- I was simply concerned for your safety. The advice was given based
    on the impression of your abilities *you* created here, and I stand by it.

    Anyhoo, no offence intended- it was just banter. Good luck with the repair.

  19. Papa_J

    Papa_J Guest

    Bottom Line: Did you get the set repaired as a result of the information you
    collected or is it still broken.
    PLEASE!! Forget or forgive the flack and debris??
    Many of the folk here in this N/G have been around for a fairly long period
    of time doing these repairs, inclusive of Sam, and many others.
    Their main concern is for the SAFETY of the technicians, even SAM posts that
    information plainly, at the beginning of his very good instructional web
    After that fact then the appropriate data is attempted to be transferred via
    this means, some if it is miss-interpreted, some if it is
    miss-representative of the actual symptom(s). However all of it is normally
    meant as trying to assist another technician to do their actual, hands on
    Ocassionally we all share our "Opinions", and we all acknowledge what the
    average one's worth (IMHO).
    Again: My specific question is: Do you have the set repaired? If so than you
    have received assistance appropiat to your quest. If not, then more through
    diagnostics may be required.
    Good Luck!
  20. -Almazick-

    -Almazick- Guest

    I fixed the tv by the information I received from Franc Zabkar. I found
    datasheet then found similar schematic for my tv. Changed 1 capacitor
    turned on the tv and everything was working.
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