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Samsung LCD monitor repair question

Discussion in 'Electronic Design' started by Jan Panteltje, Jul 2, 2008.

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  1. I have a Samsung syncmaster 206 BW LCD.
    All of the sudden the blue gain seems almost double the normal on analog in.
    Cannot seem to be able to correct for it (other then cutting the VGA cable and
    placing an attenuator in blue ;-) ).
    I do measure nice 75 Ohm terminations, so it is not an open termination.
    Has anybody ever opened up one of those, is it one big LSI?
    Or is there a chance for human repair?
    Else I will have to send it away..... with unknown results.
    Googled for an hour, could not even get a service manual, or picture of the inside.
  2. Joerg

    Joerg Guest

    Tried another monitor on the same PC, or this LCD on another computer,
    just to make sure?
  3. Jup, same monitor on other PC, same problem.
    It happened during a resolution mode switch, and it is very very hot here
    (for the Netherlands), so temperature may have been a bit too high for it.

  4. Joerg

    Joerg Guest

    Do you have a breakout VGA plug or can you get in the PC and probe?
    Maybe the termination ain't there when it clicks into the selected mode
    because some CMOS switch blew?
  5. Nico Coesel

    Nico Coesel Guest

    Yup and it depends. Some monitors have a seperate ADC others use one
    big chip. You could open it and do some measurements with an
    oscilloscope to see where the problem is.
  6. On a sunny day (Wed, 02 Jul 2008 11:46:26 -0700) it happened Joerg

    Jup, same monitor on other PC, same problem.
    I have not yet figured out how to open the thing.
    I thas a 3 year guarantee, it is now exactly 1 year (minus 12 days).
    So I want to be sure that I can actually fix it, before I break some seals.
    The connector is hidden, perhaps one separate board, within the plastic case.
  7. Have to avoid voiding the guarantee.
    It is from
    Their service department was gona send me a new IDE cable 7 years ago,
    still waiting..
    Last few times I ordered something there, nothing happened until I made a follow up phone
  8. Joerg

    Joerg Guest

    Then why not send it in? You can also measure an open terminator at the
    PC side. Run it in VGA basic mode which it usually does for the first
    10sec during boot and look at the levels. If the blue level suddenly
    jumps a little when going to a similar blue-level screen in your regular
    viewing mode then the terminator most likely goes open. If that happens
    only on blue then it looks like a warranty repair case.
  9. Because their service department sucked, and no idea how long it
    will take them to repair it, even if they repair it.

    I have fed it some nice test signals, also looked for a defectibe blue clamp,
    that seems all OK.
    I ran ntest.exe on it too (Nokia monitor test, recommended, do a google for it).

    Well... I will think about this for a while..... what to do with it.
    Why am I so reluctant with service departments? Because I worked in one myself.
    I will save you the stories.
  10. Adrian C

    Adrian C Guest

    I worked in one too. Since you are effectively admitting you are
    resigned that way to waste time and patience, and time is money (or
    whatever) - I'd just stuff it in the trash* and buy another. They are
    cheap enough compared to hourly rates...

    * i.e. sell it on eBay as a non-worker.
  11. Adrian, that thought of putting it at the street, and driving over to
    Mediamarkt and picking up a new one, did occur to me, and is
    very tempting.
    But then I may as well open it up with a can opener and have a look.
    If I have to ship it back and forwards 3 times before it works OK
    (and for how long), that gets close to new value.
    But if anyone had a look inside it might help me make a decision :)
    That is why the question.
  12. Joerg

    Joerg Guest

    A brief Google peek seems to indicate blue is sometiems a problem with
    this monitor series:

    Chances are, it's one of those RoHS solder joint issues. So if it's easy
    to open you could take a look.

    Done it, too, in Rotterdam. But it was medical and actually fun. Our
    subsidiary lost their service tech and since I was in the area they used
    me as a "tech" for a week. Some repairs were literally pit stop style.
    Truck arrived, unloaded, trucker had lunch, returned, loaded the unit
    and brought it back. It was also a good experience to brush up on my
    Dutch. Although they spoke a weird accent there up north. A velo is a
    fiets and so on, and the beer was better in Belgium :)
  13. Guest

    I've a samsung 940 syncmaster that died due to bad caps in the voltage
    supply board after about a year. To open it up press along the seam
    (parallel to the screen) at a bottom corner with a butter knife and
    start prying the halves apart. Remember to remove the stand first then
    carefully dissect the innards.

  14. Nico Coesel

    Nico Coesel Guest

    You can drop it at my place anytime :)
    Maybe they'll just send you a new one. I doubt they will attempt to
    repair a TFT monitor at component level. It may take a long while
    though because someone has to decide you can get a new one.
  15. Joerg

    Joerg Guest

    Are those guys over there at all worried about customer retention?

    <shaking head>
  16. mpm

    mpm Guest

    In the days of old, the RGB settings were just different value
    resistors in the negative feedback of op-amps.
    Blue required the most attenuation (least gain). Sorry, I forget the
    values, but there actually is a IEEE standard out there for broadcast
    video... I can dig it up Monday if you need it.

    My total GUESS is that the monitor stores the value somewhere for a
    digital pot, and either the pot or the communication to it has a
    problem. If a surface mount resistor opened, that could explain it...

    I concur that if it's under warranty, you should try to get it fixed
    that way.
    Newer electronic stuff sometimes just isn't worth the headaches you'll
    encounter trying to decipher the circuits, find the parts, and/or get
    them soldered up correctly. Best of luck. I don't envy you having to
    send something that's barely a year old in for service. If it's any
    consolation, I have a Samsung Syncmaster at work (probably not your
    exact model) but it's been very reliable. I'm sure they depot these
  17. That is the 245BW, not the 206BW.
    If mine looked like that I would already have trashed it :)

    I did have the impression for a moment that I smelled burned resistor.

    When we stopped the TV shop, I needed some income, went to an agency, and they
    placed me with the service department of a big Dutch company that starts
    with 'P', ends with 's', and they make light bulbs too.

    The way things (video recorders) were repaired there, was: replace board, not fixed?
    replace next board, not fixed? replace third board, fixed?
    Charge for 3 boards + time.
    Some of those guys had no training, likely did not even know what a chip was.

    Ja, zelfs in a klein land zoals Nederland zijn veel talen te vinden.
  18. Thank you, sounds doable :)
  19. Joerg

    Joerg Guest

    I know, but often the basic design of the electronics in them didn't
    change much.
    Not good. There is usually a reason why it fried.
    That was all the rage in the early 80's in Europe, "modular design".
    Turned out a module swap repair was a lot more expensive so the whole
    concept fizzled. They thought they could get a recycling chain going
    where refurb modules would cycle through. Saba, and other companies.
    Very true. The topper was when I rented a house with three others in
    Hengelo for an electronics gig. One was from Terschelling, one from
    Friesland (they have a completely non-Germanic language up there ...),
    one from Heerlen and me from Vaals but with lots of Vlaams because I was
    a member of a Belgian sports club. When the guy from Heerlen and I
    talked too fast the other two could no longer follow the conversation.
    When we listened to an Urbanus tape and had major ROFL episodes they did
    not laugh. They didn't understand a thing, often not even what he was
    joking about.

    Out here at a company they had the regular auditors there and one was
    born in South Africa. When docs from the Dutch subsidiary came up they
    sometimes called me in to explain stuff, mostly about what the legal
    importance of something was or what an invoice could have been for.
    Sometimes I read stuff aloud, mumbling to myself. Then she would fall
    back into Afrikaans and all the other guys became totally confused.
  20. Nico Coesel

    Nico Coesel Guest

    Probably not. A country wide pizza delivery service calls their pizzas
    'double fucking tasty' in their TV commercials over here.
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