Problem with my TV at home

Discussion in 'General Electronics Chat' started by circuitashes, Jun 25, 2008.

  1. circuitashes

    Thread Starter Active Member

    May 13, 2008
    37
    0
    My Samsung TV set has developed a problem and i need some help fixing it.

    When i switch it on some vertical colour bars fill the screen and don't go away until i hit the sides of the set. Its driving me crazy.

    What could be the cause/problem and possible solution? Are there any good links to schematic diagrams of TV circuits?
     
  2. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    Its better and safer for you to take the TV to a professional because inside the TV very high voltages are developed which may be lethal.
     
  3. Wendy

    Moderator

    Mar 24, 2008
    20,764
    2,535
    Can't argue with that. The other side of the same coin is I'd rather take it to someone who has already made all their mistakes on someone elses TV, as opposed to mine.
     
  4. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    If you really want a schematic for your TV, try here:
    http://www.samswebsite.com/photofacts.html
    They are not free.

    But unless you are an experienced technician, I reaffirm the suggestions that have already been made to take it to a TV repairman. CRT-type sets have very high (and lethal) voltage levels on the picture tube for long periods of time even after it's been unplugged from the mains. Even LCD flat screen sets use high voltage (300v-700v) to power the CCFL backlight.

    As Bill suggests, it is all too easy to cause far more damage to your set. Giving it a thwack to get rid of the test pattern will reduce the expected life of the set due to the physical stress on the components.

    If your TV set is over 6 years old, I strongly suggest you skip the repair and opt for a new replacement set. A 7-year old TV is generally near the end of it's useful life.
     
  5. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
  6. loosewire

    AAC Fanatic!

    Apr 25, 2008
    1,584
    435
    Have you ever had the back off of a t.v. any t.v.-WAS THE T.V.
    DROPPED,OR FALL STAND OR TABLE.We have to determine your
    knowledge,once you let us know your experience.Do you have
    a soldering gun,have you ever soldered a curcuit board.Anwser's
    to these question,s can help us advise you better,who know's
    you may have fund's to go out buy a new one.
    Read my post about being shocked with electricity I'm lucky
    to be alive.Step by step let us know , do you have
    electonic tool's.There are member's that could repair a t.v.,
    as these guy's say time is money,and they work with low voltage.
    There computer knowledge is worth more than any t.v.
    If you are going to school to become a engineer,buy a new t.v.
    Reply before you do anything,Don't touch the t.v. until you are
    qualified.Let us know what equipment and tool,s you have.
    Guy's I know you work with high voltage-within 2-feet use that
    arc stick.The real bad stuff.
     
    Last edited: Jun 26, 2008
  7. acebodge1

    Member

    Jun 18, 2008
    13
    0
    Hiya,if someone here could advise a safe way of discharging the juice stored in the set,i would clear the dust/cobwebs,in the back of the tv,with hoover and soft clean dry paintbrush.It stopped my tv from misbehaving[sparks jumping around HT lead on tube].Also i would try another scart lead,or waggle the existing one about a little,to see if the scart lead connection is at fault,thats if a scart is used to connect your tv to a vcr,or sat/cable box
    WARNING,the charge stored in the back of a tv can last for days,,,,it will easily kill you.
    regards bodger
     
  8. circuitashes

    Thread Starter Active Member

    May 13, 2008
    37
    0
    Its about 3 yrs old.
     
  9. circuitashes

    Thread Starter Active Member

    May 13, 2008
    37
    0
    Thanks to all of you for the safety concerns. However, i'm not so much interested in repairing my CRT TV as in understanding (from an electronics point of view) the reasons it is misbehaving.

    All i'm asking for is an electronics explanation.
     
  10. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    It could be as simple as an accumulation of dust inside the set, coupled with humidity, creating an electrical short somewhere on the main board. If someone in the household smokes, that causes such malfunctions to occur much more quickly, as the sticky tar accumulates rapidly, and attracts dust.

    Your set appears to have a bar test pattern generator built in that's used for aligning the CRT at the factory or TV repairman's bench. That might have a pushbutton or "flying lead" jumper to enable the alignment circuit. Or, it could be just bad solder joints.

    If Howard Sams publishing (the link I posted above) doesn't list a schematic, it usually means that the manufacturer of the set published a version.
     
  11. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    Use a 25" shorting probe under the aquadag connection. If you don't know what that means, you probably should not be doing it. Paying for a service tech is a lot less expensive than paying for emergency room copay, or for a funeral.
     
  12. loosewire

    AAC Fanatic!

    Apr 25, 2008
    1,584
    435
    Do you have the equipment to do the repair,have you ever had the back off of a t.v. . Can you reply so we can communicate. This could a learning
    experience. LOOSEWIRE

    p.s. I need to find out how to edit my post, Look at some of them.
     
    Last edited: Jun 26, 2008
  13. circuitashes

    Thread Starter Active Member

    May 13, 2008
    37
    0
    No i do not have the repair equipment. Moreso, after the safety warnings from the other posts, i do not think i would want to do any repairs right now. I think i would be OK with some more explanations, like the one from SgtWookie.
     
  14. Gadget

    Distinguished Member

    Jan 10, 2006
    613
    0
    Probably dry joints.... components..(especially heavier components, or those mounted on heatsinks) that have bad solder connections.
     
  15. theamber

    Active Member

    Jun 13, 2008
    318
    0
    You do not need a schematic diagram to fix this problem. I am 99.9% sure is a cold solder joint causing you this problem and is very easy to fix, I have done it many of times.
    You will have to open the TV discharge the Flyback transformer, CRT and any large Capacitors or just do not touch any metalics parts.
    With the main board backward you can take a visual look to see if you can spot the cold solder joint usually arround the vertical driver IC for this particular problem if you do not see it take the back part of a screw driver (plastic) and hit softly inch by inch until the problem goes away(the TV has to be on for the hitting test) then turn it off and resolder all the parts within that area if you still did not see the cold solder. Sometimes it is extremely hard to see the cold solder and you just solder all the parts around the area where the lose contact was found.
     
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