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Samsung Syncmaster 2243swx - 2 seconds to black

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    #1

    Samsung Syncmaster 2243swx - 2 seconds to black

    Hello guys,
    I have another 2 seconds to black problem I could really use some help troubleshooting.

    The monitor in question is a samsung 2243swx, which is a series I had never heard of before and it belongs to my boss (apparently I am becoming well known around the office as the monitor repair guy now). He brought the monitor to me and I confirmed the 2 seconds to black issue. One of my first tests was to connect a set of known good CCFLs, one of them lights completely right away, the other one starts with about 10mm of very dim light and extends out to about 25-30mm within the 0.5-1 seconds it takes for the protection circuit to kick in and the inverters to shut down. After a few seconds it tries again and this time it can light 50-70mm of the one set of CCFLs (the other set still lights perfectly) before it shuts down.

    The caps on the board are "SAM YOUNG" brand, and none of them are bulged however I have not yet built an ESR meter to test their ESR. I will try swapping them today for new ones but I do not expect it to fix the problem at this point.

    I checked the resistance on the secondary coils of the transformer and got the following:
    Good side: 891
    Bad side: 961

    If I test them after trying to get the board to light CCFL's for 10-15 minutes the numbers are closer together
    Good side: 928
    Bad side: 958

    The transformer is labelled TM-0815 and from what I can tell the secondary side should have a resistance of 875 ohms (as determined from one product page, so maybe this is not trustworthy information).

    I thought perhaps it was a set of bad capacitors on the high voltage side so I swapped the caps from one side to the other, there was no change in which side would not light.

    I also desoldered the transformer to check it for burning (as the board looked darkened near it) and found no evidence that it has been overheated.

    I measured the resistance between all sets of pins on the 2 ICs on the bottom side of the board and found no shorts.

    Am I looking at a bad transformer here? What else could it be? The monitor belongs to my boss and he is willing to pay the ~$26 for a replacement power board but I feel like it should be possible to fix the problem with this one. I hate to buy a transformer on a guess, but I already have a spare one of these coming (as I bought a pair):
    http://www.ebay.ca/itm/250773133702?...84.m1439.l2649

    Can I replace the transformer with one of these, then connect it to smaller CCFL's (as this transformer is only rated 650V instead of the 700V the board for the 2243swx specifies) to rule out whether the transformer is at fault???

    Thanks for any input you guys can provide!
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    #2
    Re: Samsung Syncmaster 2243swx - 2 seconds to black

    One more thing, the writing on the board, most of the scribbles are just marks so I knew where to put the caps back when I swapped the sides, however the B beside the one connector (top left corner of the image) marks the bad side.

    Comment

      #3
      Re: Samsung Syncmaster 2243swx - 2 seconds to black

      I replaced the low voltage caps over lunch and it is not working any better.

      Comment

        #4
        Re: Samsung Syncmaster 2243swx - 2 seconds to black

        Originally posted by zero10 View Post
        Am I looking at a bad transformer here?
        The two transformer readings should be with 3% of each other. On the bad transformer, you may have a very fine break in the winding which leads to the increased resistance.

        The monitor belongs to my boss and he is willing to pay the ~$26 for a replacement power board but I feel like it should be possible to fix the problem with this one.
        $26 for a replacement power board is fairly reasonable seeing how a replacement transformer from lcdparts.net will cost $21.90 + shipping. Ebay has a TM-0815 for about $14 (total).
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          #5
          Re: Samsung Syncmaster 2243swx - 2 seconds to black

          Yeah EBay has a TM-0815 for a pretty reasonable price, but the power board price itself is also tempting. The tinkerer in me really wants to know if the transformer is indeed the only problem here, but spending somebody else's money comes with consequences if it is spent badly...

          Do you think the replacement transformer I bought for a Samsung 932B will work (for testing purposes) on this board? I suppose if it doesn't I would have to replace the power board anyway, and my boss is already willing to go that route I am just trying to save him a few bucks. Should I just try it? I would test it with shorter CCFL's (from a 19" or 20" monitor) then replace it with the proper transformer if they work.

          Comment

            #6
            Re: Samsung Syncmaster 2243swx - 2 seconds to black

            Originally posted by zero10 View Post
            Should I just try it? I would test it with shorter CCFL's (from a 19" or 20" monitor) then replace it with the proper transformer if they work.
            I have never tried it myself and don't know all the ramifications if it doesn't work. I'll let others with more experience in this area to comment.
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              #7
              Re: Samsung Syncmaster 2243swx - 2 seconds to black

              You shoud only 'try' the other transformer if you know for certain that it is the same resistance as the original,and is mechanically the same, ie the pins are wired exactly the same.I supect the fault is caused by the faulty transformer,and replacement would be adequate,but as you seem to be unsure,as to what to do,the decision can only be yours.

              Comment

                #8
                Re: Samsung Syncmaster 2243swx - 2 seconds to black

                Originally posted by zero10 View Post
                Yeah EBay has a TM-0815 for a pretty reasonable price, but the power board price itself is also tempting. The tinkerer in me really wants to know if the transformer is indeed the only problem here, but spending somebody else's money comes with consequences if it is spent badly.
                If you REALLY want to be a tinkerer, and you think the pcb will stand the wear-and-tear, try swapping the transformers. That should provide a pretty sure indication whether the suspect one is indeed the problem.

                Even though I have about 40 years' experience in soldering , I personally wouldn't as I have too much respect for the board. But YMMV.
                Friends don't let friends buy Samsung ....

                Comment

                  #9
                  Re: Samsung Syncmaster 2243swx - 2 seconds to black

                  I am sure that the transformers are mechanically the same (aside from one detail mentioned below), they have very similar primary winding resistance and slightly different secondary winding resistance (I expect this is because one board specifies 650V and the other says 700V), the biggest worry I have is the 2 pins located on the low voltage side of the transformer out on the corners. I think these pins provide the feedback for the driver board, telling it how much current is being drawn on each side? If so, I wonder if the transformer I swap in might provide too high of a voltage on these pins and damage the sensing circuitry. How can I figure out whether this will be a problem? I can't find any data sheets on either transformer and I show no continuity from these pins to any others on either transformer. Also, looking closely at the one burned transformer I have from another monitor (identical to the replacement one I want to swap in for testing) I see no wires at all leading to those pins, is it possible they are not connected? Am I misunderstanding how the feedback circuitry works?

                  Aside from that I am pretty confident it will work as I am swapping in a lower voltage transformer than the one that was in there so I shouldn't damage anything on the high voltage side unless there is something I am not considering here?

                  Comment

                    #10
                    Re: Samsung Syncmaster 2243swx - 2 seconds to black

                    I did some destructive testing of my burned transformer from another board (the burned version of the one I want to swap in) and those corner pins have no connection to them, they are not involved in any way with the feedback / sense circuitry.

                    Comment

                      #11
                      Re: Samsung Syncmaster 2243swx - 2 seconds to black

                      The new Samsung 932B transformer arrived today. I was wrong about it being physically compatible, the pins are about 5mm closer together on the 2243's transformer. I checked the low voltage side whore the monitor was trying to power up and it showed 2.4vac on my meter, and checking the Samsung 932B i had on my desk showed 2.1vac when running which i thought was close enough so i made up some small jumper wires and soldered in the new (incorrect) transformer. Much to my surprise it was able to light a full set of ccfls from a 19" monitor i keep on my test bench and stayed running for the 30 seconds i allowed it to. I am pretty confident that this confirms the transformer as the problem and i am ordering a new one tonight. Hopefully this means i can save my boss the difference in cost between the transformer and the whole board, which is over $15.

                      Comment

                        #12
                        Re: Samsung Syncmaster 2243swx - 2 seconds to black

                        Originally posted by zero10 View Post
                        so i made up some small jumper wires and soldered in the new (incorrect) transformer.
                        Congrats. I don't think anyone since I have been participating here has ever tried that.

                        Good to know for future. Bookmarking this page.
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                        Comment

                          #13
                          Re: Samsung Syncmaster 2243swx - 2 seconds to black

                          It was a bit of a reach but I figured:
                          1) I have a spare known good transformer (I tested it in the correct monitor first)
                          2) I have a power board that I would otherwise have to replace in its entirety

                          Given those things there was just about nothing to lose by trying it. It was a bit of a pain to make up little 5mm high x 6mm wide z shaped jumper wires and solder them to the transformer, then mount the transformer at an angle and solder the wires to the board without heating them enough to melt the solder at the other end (<10mm away), but some quick hands and blowing on everything to flash cool it seemed to be the trick.

                          My spare set of 19" monitor CCFLs were lit more brightly than usual with this setup but I figure 30 seconds of running on my desk wouldn't harm them, plus they were my spare set anyway. I wouldn't do this as a permanent repair but it is enough to convince me to take the chance and buy the correct transformer.

                          Nobody at my work would believe that it functioned so I showed it off (tested it...) a couple more times today for 30 seconds each time and it does not exhibit the 2 seconds to black problem any longer so I'd say this one is solved, I just need to wait for the right transformer to arrive in the mail.

                          Thanks for the advice!

                          Comment

                            #14
                            Re: Samsung Syncmaster 2243swx - 2 seconds to black

                            The new transformer showed up today and I swapped it in. After 30 minutes the monitor is still working great so I am giving it back to my boss and calling it repaired. Another one saved from the scrap heap!

                            Comment

                              #15
                              Re: Samsung Syncmaster 2243swx - 2 seconds to black

                              I am having the exact same problem with my boss, I need to start fixing dead monitors we have in the back, and this is the same exact monitor with the same exact problem, so I suspect. I opened it up, and swapped out the 3 capacitors, but it still suffers from the 2 sec to black issue. I really appreciate you going through this yourself, I am a novice when it comes to electronic assembly, my main knowledge focus lies in other it areas. Was the TM-0815 transformer compatible with the pins for the monitor? I noticed you mentioned jimmy-rigging an old transformer, was that only on your test set up? not the new transformer from ebay?
                              http://www.ebay.com/itm/100-NEW-TRAN...-/251131824462
                              did you run into any problems installing the new transformer?
                              i'd appreciate the help, thanks

                              Comment

                                #16
                                Re: Samsung Syncmaster 2243swx - 2 seconds to black

                                just realized that last thread was dated 2011...

                                Comment

                                  #17
                                  Re: Samsung Syncmaster 2243swx - 2 seconds to black

                                  hello what is a ccfl connection order? i disassembly a monitor but forget the connections order,sorry my poor english

                                  Comment

                                    #18
                                    Re: Samsung Syncmaster 2243swx - 2 seconds to black

                                    Generally it doesn't matter, but usually there will only be a few combinations that do fit.
                                    Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
                                    For service manual, schematic, boardview (board view), datasheet, cad - use our search.

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