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    #1

    Samsung 225BW - 2 seconds to black

    I am having trouble repairing a samsung 225bw and I was hoping somebody on here might be able to lend a hand. I have accidentally become the monitor repair guy in my office and have fixed about 18 other samsung monitors (we bought tons of 203b, 204b, 930bf and other monitors known for having bad caps) with a 100% success rate so far, but I haven't had to do anything more complicated than replacing a transformer (1, the rest have been caps or fuses).

    This monitor was given to me to repair by a coworker of mine and it is not one that I am used to working on, although the power board does appear really similar to a 203b or 204b. When I was given the monitor it would take a long time to produce an image (5-10s) then blink on for about 0.25s then stay off, with the blue power light remaining on solid the entire time. I opened it up and found an obviously bad 330uF cap so I replaced the 330uF, 2x820uF and 2x680uF (inverter side of the board), however I did not have any 47uF 50V capacitors on hand to replace that one. In the last 18 I have repaired changing that capacitor made no difference (some I tried replacing one at a time to figure out what was really failing) so I don't keep any on hand.

    I measured the resistance of the secondary side of each transformer and got 1092 and 1083 ohms on them. F301 and F101 both measure out okay, and U302/U303 both measure the same: 0 ohms between pins 5-8, and using 5 as a ground I measure 6.15k to pin 1, infinite to pin 2, a slowly climbing number on pin 3 (~7k, but I think I am charging a cap measuring it..?) and infinite to pin 3.

    The large black IC on the back side of the board labelled U201 has something I just can't make out written on it, the first row ends with GN but it is almost impossible to read the rest of the letters/numbers.

    When powered up with the logic board and backlight connected I measure 13.0V on the 13V pins at connector CN2.

    What else should I be looking at? Can anybody offer some advice on what to try next? I found a couple threads through searching the forum but one of them is very long and I see no solution in it so far, although I am continuing to look. I have attached front and back pictures of the board, hopefully they are clear and legible enough
    Attached Files
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    #2
    Re: Samsung 225BW - 2 seconds to black

    If i missed it I am sorry ,but what symptoms are you experincing now?
    Whatever I do, I consider it a success, if in the end I am breathing, seeing, feeling and hearing!

    Comment

      #3
      Re: Samsung 225BW - 2 seconds to black

      You didn't miss it, I just didn't say things clearly Sorry

      I am currently experiencing exactly the same symptoms, takes 5-10s to light the backlight then after ~0.25s it turns back off.

      I was doing some further testing (instead of working, shame on me...) and I found that if I plug in one of my spare sets of backlights in place of the top set they light and stay on. I tried swapping backlight cables one at a time and it seems that if I plug in either of the top backlights the board shuts down after 0.25s, but if I leave my spare set plugged into the top it will stay on for several minutes. I guess that's a pretty conclusive indication it is the top set of backlights. I'll take it apart over lunch and see if anything is obviously wrong with them. If it was just the backlights I'm sorry for wasting everybody's time

      Comment

        #4
        Re: Samsung 225BW - 2 seconds to black

        It looks like you found the problem.
        Just go slow when you open up the panel,With all the monitors you are seeing you should be able to come up with a good used CCFL


        Look at he return wires where they are solderd to the CCFl,I always give them a tug to make sure the joint is good
        Last edited by alexanna; 11-01-2011, 07:29 AM. Reason: stressing the return wire
        Whatever I do, I consider it a success, if in the end I am breathing, seeing, feeling and hearing!

        Comment

          #5
          Re: Samsung 225BW - 2 seconds to black

          I don't really know what I am doing opening up this panel... The one I took apart had a physically damaged LCD so I scavenged the good parts that I could from it which were the backlights and the plastic sheet with the pattern printed on it. The sheet I edge drilled and installed 20 LEDs in then used as a lit side panel on my computer case, while the backlights are unfortunately from a 19" monitor and this is a 22" widescreen.... Also, since it is not one of the ones I normally see at work I cannot scavenge backlights from another monitor. I hope it is just the wiring! To be honest, I am a programmer not a hardware repair guy but I have a great deal of curiosity.

          Thanks for the help so far, do you have any specific advice for getting bits of the panel apart to access the backlights? It looks somewhat straight forward, just clips all over, but I worry there will be some minor details I am not familiar with.

          Comment

            #6
            Re: Samsung 225BW - 2 seconds to black

            Start with a large uncluttered,work area.Everything is self explanatory.
            Look for any small screws on the back of the LCD panel.
            As you disassemble stack every thing in order.
            Be very careful of the ribbons from the Tcon to the panel they can be fragile.Dust and stray hairs are my biggest problem!
            I think you would be surprised as to how many of the CCFLs are interchangeable,on most of the newer panels as long as the ccfls are the same Length they usually work.
            Whatever I do, I consider it a success, if in the end I am breathing, seeing, feeling and hearing!

            Comment

              #7
              Re: Samsung 225BW - 2 seconds to black

              The only CCFL's I have are about 10cm too short to fit this monitor... I'll take the panel apart over my lunch break. Looking at it now it is obvious the power wires to the top CCFLs are much darker than the bottom ones... Hopefully it is just a burned or bad solder joint at the close end.

              Comment

                #8
                Re: Samsung 225BW - 2 seconds to black

                Okay, I have disassembled the panel (and I don't even think I broke anything!) and I removed the backlights from the housing. Upon powering them up with them separated from the panel I can now hear a BZZT or squeal from the end of the one that has the darkened wires. I removed the tubes from the housing and separated them to make sure one wasn't shorting to the other, and now the backlight stays on for about 1 second, with each of these tubes lighting up less than halfway, while the other set of tubes (not burned wires) lights up completely. I think at this point it is safe to say the CCFL's are shot?

                I attached a picture of the burn marks going down the side of one tube from the top backlight assembly, the other tube from the same assembly bears an identical mark, the dark line is located where the 2 tubes are closest together, or on what I would call the side of the tube.

                Here is a quick youtube video of it trying to turn on:
                http://youtu.be/jgb9PRRJvCI

                Where is the best place to get some replacement CCFL's? Is it even a reasonable idea to try to replace the CCFL's or is it time to junk this monitor?

                I measured from the end of the white section on the ccfl to the other end of it and got a length of 470mm. How are CCFL's sized? should I have measured from the end of the glass?
                Attached Files

                Comment

                  #9
                  Re: Samsung 225BW - 2 seconds to black

                  Originally posted by zero10 View Post
                  Where is the best place to get some replacement CCFL's? Is it even a reasonable idea to try to replace the CCFL's or is it time to junk this monitor?
                  Members here have good experiences with ccflwarehouse.com. They sell "bare" lamps or "pre harnessed" lamps.

                  I have taken a shorter "pre harnessed" 19 inch 4:3 set of lamps out of an old monitor and put it into a 19 inch 16:10 monitor. The 4:3 was about 1 inch shorter, but it does work. Unforunately, I tore the tab bonds on the panel card somehow when either taking it apart or putting it back together and have a black vertical stripe. Otherwise, the "transplant" was successful.
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                  If you are new to this forum, we can help a lot more if you please post clear focused pictures (max resolution 2000x2000 and 2MB) of your boards using the manage attachments button so they are hosted here. Information and picture clarity compositions should look like this post.

                  We respectfully ask that you make some time and effort to read some of the guides available for basic troubleshooting. After you have read through them, then ask clarification questions or report your findings.

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                  Comment

                    #10
                    Re: Samsung 225BW - 2 seconds to black

                    Thanks for the site suggestion, it looks like they want about $10/lamp, but still it would be taking a gamble since I don't know for sure that I have not yet (or will not) damage the ribbons leading to the LCD itself.... perhaps it is time to cut my losses with this monitor and sell it for parts, there is far less risk in that route, but then I would be admitting defeat. This decision is tricky. I suppose I could test the LCD with it all apart and if it is undamaged so far I can go ahead with changing the lamps themselves.

                    Thanks again

                    Comment

                      #11
                      Re: Samsung 225BW - 2 seconds to black

                      Originally posted by zero10 View Post
                      but still it would be taking a gamble since I don't know for sure that I have not yet (or will not) damage the ribbons leading to the LCD itself....
                      On mine, it is obvious. I can actually see the tear, but at the time I didn't notice it. From what I understand, it is not user repairable as it requires some sort of ultrasonic welding (???).
                      --- begin sig file ---

                      If you are new to this forum, we can help a lot more if you please post clear focused pictures (max resolution 2000x2000 and 2MB) of your boards using the manage attachments button so they are hosted here. Information and picture clarity compositions should look like this post.

                      We respectfully ask that you make some time and effort to read some of the guides available for basic troubleshooting. After you have read through them, then ask clarification questions or report your findings.

                      Please do not post inline and offsite as they slow down the loading of pages.

                      --- end sig file ---

                      Comment

                        #12
                        Re: Samsung 225BW - 2 seconds to black

                        I don't see any visible tears in mine, but as I am repairing it for a coworker he doesn't want to take the $40 risk since the monitor was given to him for free. We have elected to part it out and sell the good bits on EBay.

                        Thanks for all the advice, I never would have gotten this far without this forum

                        Comment

                          #13
                          Re: Samsung 225BW - 2 seconds to black

                          Originally posted by zero10 View Post
                          Okay, I have disassembled the panel (and I don't even think I broke anything!) and I removed the backlights from the housing. Upon powering them up with them separated from the panel I can now hear a BZZT or squeal from the end of the one that has the darkened wires. I removed the tubes from the housing and separated them to make sure one wasn't shorting to the other, and now the backlight stays on for about 1 second, with each of these tubes lighting up less than halfway, while the other set of tubes (not burned wires) lights up completely. I think at this point it is safe to say the CCFL's are shot?

                          I attached a picture of the burn marks going down the side of one tube from the top backlight assembly, the other tube from the same assembly bears an identical mark, the dark line is located where the 2 tubes are closest together, or on what I would call the side of the tube.

                          Here is a quick youtube video of it trying to turn on:
                          http://youtu.be/jgb9PRRJvCI

                          Where is the best place to get some replacement CCFL's? Is it even a reasonable idea to try to replace the CCFL's or is it time to junk this monitor?

                          I measured from the end of the white section on the ccfl to the other end of it and got a length of 470mm. How are CCFL's sized? should I have measured from the end of the glass?
                          The next time you inspect the CCFLs ,if you are very careful and spray a little bit of lube on the silione ennd caps,
                          and take your time you can get them off without taring them
                          Whatever I do, I consider it a success, if in the end I am breathing, seeing, feeling and hearing!

                          Comment

                            #14
                            Re: Samsung 225BW - 2 seconds to black

                            Good to know, I have some high voltage tape I was going to use to re-wrap the ends if the CCFLs themselves were okay, or when I fit the new ones. It seemed like they should just slide off, but as they started to slide they tore in my hands under very little pressure, I was amazed how fragile those caps are.

                            Comment

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