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Mitsubishi TV PIP question

Discussion in 'Electronic Repair' started by Alan Clayson, Jun 12, 2004.

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  1. Alan Clayson

    Alan Clayson Guest

    I have a Mitsu CK-35702...probably 10-12 years old. In the last two
    weeks the set has started showing signs of what appears to be the
    classic PIP failure (vertical flicker that subsides after running the
    set a couple of hours and a darkening screen).

    My question is whether this set would have the 930B522 PIP
    board....and secondly, if so, is it particularly difficult to get it
    out?

    Living in the woods of southern Vermont, I guess it would be possible
    to ship the board somewhere for repair (while doing a temporary
    bypass), but the chance of getting a qualified tech in this area would
    be quite slim. The size of the TV precludes my sending it out for
    repair.

    If, in fact, the PIP board is a 930B522, I'd prefer to order parts
    prior to pulling things apart.

    Thanks for any insights.

    Alan
     
  2. RonKZ650

    RonKZ650 Guest

    My question is whether this set would have the 930B522 PIP
    It's got the 930B552 PIP board which is the same used on the smaller models and
    is the one that causes trouble. It unplugs easily from the main board. If you
    want to replace the surface mount caps it takes about 13 and a good amount of
    soldering skill to avoid damaging the board.
    Good luck.
    Ron
     
  3. Alan Clayson

    Alan Clayson Guest

    Thanks alot for the info, Ron.

    My main efforts will be to construct a temporary bypass while I decide
    whether to find someplace outside to rebuild the board or tackle it
    myself. There used to be places that did this sort of thing.

    As long as I know the board type, I'm sure I can handle the bypass OK.

    I appreciate your help.

    Alan
     
  4. JURB6006

    JURB6006 Guest

    If you intend to contruct the bypass yourself, why not just fix it instead.
    While I'd do it for you I would have to charge you.

    If you can solder it's an option, and anyhting is better than what they charge
    for a new one.If you think you want to do it, I'll give ya a couple pointers.

    Twist or cut the old caps off, do not attempt to unsolder them, do them value
    by value. Just in case "shit happens" I'd recommend you scan it if you have a
    flatbed before removing any caps. If you get interrupted and lose track, or if
    the polarity markings are gone or obscured on the board, having am image, even
    on the computer screen can save your butt.

    Once a cap is out, remove all solder and the old leads with solder wick, then
    let the wick and your iron land for a second on the board, it'll heat it up and
    you'll smell that crap evaporating out of it. This stuff is corrosive so the
    less of it in there the better. Don't stay there too long or you'll damage the
    board.

    Wipe it off with a Qtip dipped in acetone.

    Then apply new solder to the pads. Don't bother using surface mount
    replacements, it's simply not nessecary nor is it a good idea.

    If you wanted me to do it I'd have to charge you about $60. If there is
    something that makes the board unrepairable I'd probably send you a good one
    for $100, but if you wanted yours rebuilt with SMD caps I'd have to charge
    about twice the $60. SMDs are simply not worth it when you have that much room,
    also they are pretty crappy caps to start with, regular lytics out perform
    them, and if you really wanted to get fancy you could use tantalums.

    I wonder if anyone out there has done this and maybe can actually say there is
    a picture improvement of any kind with tantalums.

    No matter what kind you want you should take inventory and order them all in
    advance. Just put the module back in (tape up the ground wire), put all but
    four of the screws in a baggie and you won't need the bypass. Wait until you
    have everything you need right there, until then watch it the way it is. Put
    the back on for now. Don't run a TV in your home with the back off.

    Anyway, I know you didn't really say you wanted to do it yourself, but you did
    say that you would do the bypass, that leads me to believe you can at least
    solder. That's why I figured I'd throw this at you.

    Basically you could "bypass" it with a fixed module.

    JURB
     
  5. Art

    Art Guest

    Also, when inspecting the PIP PCB make sure that the material from the caps
    did not eat thru some of the very thin traces on the surface of the board.
    This is a very common occurrence and can be aggravating to repair. Also,
    while in the set you may want to ESR the rest of the caps in the set and
    replace any that are questionable.
     
  6. James Sweet

    James Sweet Guest


    I used to always repair these boards, though lately I've come across a
    couple which had much worse trace rot, those I just bypassed, too much work
    when there's electrolyte under SMD IC's and such.
     
  7. We repair lots of these sets. The rule of thumb we use is if any of the
    electrolyte has reached the IC, ditch the board. If it is limited to just
    around the caps, clean the traces completely, tin the areas that you have to
    scrape clean, and replace all of the SM caps with radials.

    Keep in mind that not all of the boards can be easily bypassed. The later
    versions of that board had a higher input level on the luma line and it has
    to be adjusted for. The NESDA Ohio site has some useful notes that include
    the numbers of the boards.

    FWIW, recently in Florida, most of the boards that we have been seeing
    recently have been so badly corroded that they are not worth attempting
    repair.

    Leonard
     
  8. Alan Clayson

    Alan Clayson Guest

    I want to thank everyone that offered help on this query. There is
    certainly a large group of talent here, and what's better, a real
    willingness to share hard-earned knowledge. I appreciate all the help
    and advice.

    As for resolving the issue, I'm still trying to evaluate options.
    Sounds like repairing the PIP board is the smart alternative (and the
    one I'd prefer....as opposed to a bypass).

    JURB, your soldering lesson is right on the mark. I'm trying to decide
    whether with my capabilities, it's a good idea to undertake this or
    not. I've done alot of plumbing and a few PC cables, but no PCB work.
    The walk through is much appreciated.

    Do I understand correctly that once the old caps are removed from the
    board, it can be inserted and used as a temporary bypass?

    Thanks once again for the excellent help.

    Alan
     
  9. RonKZ650

    RonKZ650 Guest

    Do I understand correctly that once the old caps are removed from the
    The set won't get a picture at all if you remove the caps and reinstall the
    board. You either need to repair the board or do the bypass of the board.
    Mitubishi at one time I believe had a plug in bypass board available to
    eliminate the entire PIP board. I always just repair the board. At least in
    your case, since you still have a picture, the chances of electrolyte out of
    the caps doing major damage to the board is slim.
    Ron
     
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