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Question: Problem w/Mitsubishi 40" TV MITCS40505

Discussion in 'Electronic Repair' started by Rich, Jan 17, 2004.

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  1. Rich

    Rich Guest

    Hello all. I've never posted a question about a TV problem before so
    I'm not sure if I have the right newsgroup(s) or not but perhaps
    someone can help me. I'm a US serviceman (USAF) stationed overseas in
    Turkey right now and it's rather difficult to talk to an authorized
    repairman. I have a Mitsubishi 40" TV MITCS40505 ... it's about 7.5
    years old with a typical glass picture tube.

    Problems: (1) The upper-right and upper-left corners are discolored;
    when I have a no-input blue screen, the corners are a very bright
    pinkish purple. (2) Also, text is becoming somewhat difficult to read
    .... blurry. Note we've never played games on it.

    My questions: (1) Are these two problems repairable? (2) Is it
    something I can attempt myself? (I was an electronics technician for 6
    years working on communications/navigation systems ... but no TV
    repair experience). Regarding the blurry text problem, I was hoping I
    could just obtain a test pattern and align the colors/pixels with a
    plastic screwdriver ... ?

    Thanks for your patience and your assistance.

    Sincerely,
    Rich (Please don't reply via e-mail ... it's a dead address)
     
  2. Jerry G.

    Jerry G. Guest

    If this set was transported from North America, or another country, this
    effect can occur from the earth's magnetic declination at the new location.
    TV's and monitors have their CRT aligned to match the declination of the
    area where it is to be used. Naturally other magnetic field influences can
    throw the purity off as well. You can try doing a manual degaussing of the
    tube, with a manual TV degaussing coil. But, the internal one should be able
    to handle this.

    Other things that can throw the CRT alignment out or damage the CRT, is if
    the set was struck very hard during transport, or any adjustments moved from
    vibration.

    You would need the proper TV test generator that can put up a blank raster,
    the convergence grating pattern, and the full screen R, G, B raster for
    doing purity set-ups would be a plus. This is essential if you are going to
    touch the purity and convergence set-ups.

    As for doing the alignments, this is involved, and without the proper
    training and practice, you can wind up badly messing up the set! The
    set-ups require the combination of the positioning of the deflection yoke,
    fore or aft, yoke rotation, and using the ring magnets on the neck of the
    tube to achieve proper picture levelling, purity, and convergence. There
    are also some adhesive slip magnets that are inserted between the tube bell
    and deflection yoke for adjusting the corner convergence. These are also
    very critical to set up. I have seen people get in to these adjustments, and
    end up having to have a tech come over to their place for an hour or two to
    get it back again. Not all of them are very good at this type of set-up.

    The most inner ring magnets near to the yoke, are usually for the purity
    centering. The next two are usually the R/B align, and the next two are the
    B/G align. The combination of the spread of the rings, relative positions,
    and the total position of each group will determine the convergence
    relationship of the electron beams. These rings do interact on each other to
    some degree, and this is where it gets very hairy to adjust well. It takes a
    lot of practice to do it accurately.

    To describe a TV CRT alignment procedure would be a bit much to do over an
    email. Much of it is the skill and experience to do it.

    Another difficulty with these sets, is that most everything is glued or
    locked down with a type of lock-paint. You would have to use some solvent
    to thin this down in order to be able to move the adjustments. After
    adjusting, they have to be re-locked down again to prevent them from moving
    on their own.

    If you brought this set from another location, and are planning to bring it
    back, don't touch the adjustments. The set may most likely come back to its
    original alignment when returned, providing that nothing was damaged.

    The armed forces use many types of TV monitoring equipment. I am sure that
    they have some service people that are familiar with these types of set-ups.
    Or, do the ship everything out to another location for detailed servicing?



    --

    Greetings,

    Jerry Greenberg GLG Technologies GLG
    =========================================
    WebPage http://www.zoom-one.com
    Electronics http://www.zoom-one.com/electron.htm
    =========================================


    Hello all. I've never posted a question about a TV problem before so
    I'm not sure if I have the right newsgroup(s) or not but perhaps
    someone can help me. I'm a US serviceman (USAF) stationed overseas in
    Turkey right now and it's rather difficult to talk to an authorized
    repairman. I have a Mitsubishi 40" TV MITCS40505 ... it's about 7.5
    years old with a typical glass picture tube.

    Problems: (1) The upper-right and upper-left corners are discolored;
    when I have a no-input blue screen, the corners are a very bright
    pinkish purple. (2) Also, text is becoming somewhat difficult to read
    .... blurry. Note we've never played games on it.

    My questions: (1) Are these two problems repairable? (2) Is it
    something I can attempt myself? (I was an electronics technician for 6
    years working on communications/navigation systems ... but no TV
    repair experience). Regarding the blurry text problem, I was hoping I
    could just obtain a test pattern and align the colors/pixels with a
    plastic screwdriver ... ?

    Thanks for your patience and your assistance.

    Sincerely,
    Rich (Please don't reply via e-mail ... it's a dead address)
     
  3. BWL

    BWL Guest

    Adding to Jerry's reply, two other things; Mitsubishi has two small slide
    switches, either in front or back panel, labeled "Strength" and Polarity"; try
    different settings of these switches; in addition, make sure there are no large
    metal objects near the set, front or back. I had the hardest time trying to get
    pure screen on one of these in customer's house, until we figured out there was
    a metal pole buried in the wall behind the set.
     
  4. Rich

    Rich Guest

    Jerry, thanks kindly for your detailed post. You've given me hope
    that it's going to be okay. Thanks to the detail in your post, I
    won't be trying this myself. I thought it might be simple to get a
    test pattern DVD and tweak the alignment screws with an alignment tool
    myself, but your post helps me understand this wouldn't be wise. The
    problem only started when it left the U.S. ... never would have
    thought that magnetic declination could have been a factor. Very
    interesting! The idea of having a Turkish technician in there scares
    the hell out of me given all of our experiences with Turkish
    technicians over the past 6 months ... no ... we certainly won't be
    doing that. We'll have to wait until we come back to the states ...

    Thanks again!
    Rich
     
  5. Jerry G.

    Jerry G. Guest

    I forgot about these slide switches! This was for the orientation of the
    set in relation to the N - E and S - W, going from memory. This was
    somewhat effective. The system for this compensation is fairly complex.

    --

    Greetings,

    Jerry Greenberg GLG Technologies GLG
    =========================================
    WebPage http://www.zoom-one.com
    Electronics http://www.zoom-one.com/electron.htm
    =========================================


    Adding to Jerry's reply, two other things; Mitsubishi has two small slide
    switches, either in front or back panel, labeled "Strength" and Polarity";
    try
    different settings of these switches; in addition, make sure there are no
    large
    metal objects near the set, front or back. I had the hardest time trying to
    get
    pure screen on one of these in customer's house, until we figured out there
    was
    a metal pole buried in the wall behind the set.
     
  6. Jerry G.

    Jerry G. Guest

    When I was doing service work on these, we had so many people mess with
    their sets and always make them worse, thus increasing the cost to correct
    it. The newer sets mostly all have built in service set-ups. Many people
    are finding out how to get in to this mode, and really messing their sets
    up. Many of these internal set-ups require external instrumentation, and
    cannot be properly done by sight. The service set-ups are not user
    adjustments, and thus may not have a safe limit of range.

    I have seen people lock their sets out of operation so badly that the uPC
    and EPROM had to be changed for a new one that was factory cantered. Then
    the complete factory set-up had to be redone. This is costly for the parts
    and labour. If the tech is not very experienced at the particular model of
    set, the set-ups may not be as good as the one from the factory. Many of the
    smaller service centres don't have their instrumentation recalibrated and
    re-certified annually, and thus their accuracy for critical adjustments may
    also not be as good.

    I have seen sets that had problems due to part failures on them, and the
    customer went in to the service mode to try to fix it. They only compounded
    the problem. The tech has to then find a component fault on a mal adjusted
    set. This ends up costing a lot more in time.

    --

    Greetings,

    Jerry Greenberg GLG Technologies GLG
    =========================================
    WebPage http://www.zoom-one.com
    Electronics http://www.zoom-one.com/electron.htm
    =========================================


    Jerry, thanks kindly for your detailed post. You've given me hope
    that it's going to be okay. Thanks to the detail in your post, I
    won't be trying this myself. I thought it might be simple to get a
    test pattern DVD and tweak the alignment screws with an alignment tool
    myself, but your post helps me understand this wouldn't be wise. The
    problem only started when it left the U.S. ... never would have
    thought that magnetic declination could have been a factor. Very
    interesting! The idea of having a Turkish technician in there scares
    the hell out of me given all of our experiences with Turkish
    technicians over the past 6 months ... no ... we certainly won't be
    doing that. We'll have to wait until we come back to the states ...

    Thanks again!
    Rich
     
  7. Rich

    Rich Guest

    That was it! I switched the Polarity from "N" past "Neutral" to "S"
    and it fixed the pinkish-purple splotches! The colors are more bright
    and vivid too. Hopefully, when we return to the states, I'll be able
    to remember how to get rid of those pinkish-purple splotches that will
    be sure to reappear. ;-)

    Funny, I'm a bit of a techie, and I thought I knew my TV well, but I
    apparently didn't. I hadn't used those switches before and just
    learned to ignore them.

    Now I just need the alignment and I'll be good to go! Many thanks to
    all of you guys...

    Sincerely,
    Rich
     

  8. Magnets placed near the set can cause this. Many things could be
    magnetic, such as candlesticks, bookends, statues and loudspeakers.
    The effect sometimes remains after the magnetic objects are removed,
    so the use of a manual degaussing coil may be worth trying.

    One other thing, the magnetic variation thing: try rotating the set a
    quarter turn. If that clears it up, putting the set against another wall
    may be an option. Yes, I know the thing weighs a ton; my 35" is
    too much for me to lift alone.

    Blurry, too, eh? Can't figure that out.

    John
    USN (Ret.)
     
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