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Sceptre X22WG-1080p monitor not staying backlit, Please Help!

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    #21
    Re: Sceptre X22WG-1080p monitor not staying backlit, Please Help!

    I too have the same problem - display comes on for a second and then no backlight. I took my PSU out and it is different than the ones pictured here. I did what plainbill suggested and tested A-B, C-D, E-F, and G-H for resistance and there is none. But this board is different, I have one transformer with leads on the corners. The resistance between the two left and the two right are almost exact. But nothing between the top two and bottom two.

    The caps look good, I can't see any discoloration or physical damage to any of the parts on the board. Should I just go a head and replace the caps to eliminate them as the problem?
    Attached Files

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      #22
      Re: Sceptre X22WG-1080p monitor not staying backlit, Please Help!

      Originally posted by trex66 View Post
      I took my PSU out and it is different than the ones pictured here.
      It is not uncommon for manufacturers to make revisions and complete board changes under the exact same model number. This is why we *always* ask for pictures of your boards.

      But this board is different, I have one transformer with leads on the corners. The resistance between the two left and the two right are almost exact.
      See the attached pic. What is the exact ohms reading between the two yellow points? What is the reading for the blue points? Please post the measurements. They should be within 3% of each other.

      The caps look good, I can't see any discoloration or physical damage to any of the parts on the board. Should I just go a head and replace the caps to eliminate them as the problem?
      They look like United Chemi-con caps?

      Bad caps can be a cause of 2 seconds to black. So can a bad inverter transformer. The other possibilities are bad ccfl lamp, bad ccfl wiring, and/or something wrong in the sense circuitry. See the guide (start with post #13)

      https://www.badcaps.net/forum/showthread.php?t=10419
      Attached Files
      Last edited by retiredcaps; 01-03-2011, 01:55 AM.
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        #23
        Re: Sceptre X22WG-1080p monitor not staying backlit, Please Help!

        Between the two yellow: 639.7
        between the two blue: 641.7

        They may be United Chemi-con caps, some are labeled KZE and others KZH

        that is quite a post, I will wrestle with that tomorrow, step, by step - thanks

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          #24
          Re: Sceptre X22WG-1080p monitor not staying backlit, Please Help!

          OK, I'm still pretty much a newb. I'm trying to follow the guide posted, I'm not sure I'm testing the right components. If I'm doing this right, I got two with a 0.00 reading. The kids woke up and I haven't had time to pull these off the board and re-test. But, to tell the truth, I'm looking for something else to test, seems odd that both of these would go bad at the same time.
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            #25
            Re: Sceptre X22WG-1080p monitor not staying backlit, Please Help!

            Originally posted by trex66 View Post
            Between the two yellow: 639.7
            between the two blue: 641.7

            They may be United Chemi-con caps, some are labeled KZE and others KZH
            1) Your inverter transformer measurements suggests it is good.

            2) The KZE and KZH are United Chemi-con caps. The little square crown is their symbol. Let's assume they are good for now and move below.

            3) Do you have a spare lcd monitor? I suggest testing the ccfls next.
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              #26
              Re: Sceptre X22WG-1080p monitor not staying backlit, Please Help!

              Originally posted by trex66 View Post
              If I'm doing this right, I got two with a 0.00 reading. The kids woke up and I haven't had time to pull these off the board and re-test.
              Don't pull those diodes off. Let's move onto the ccfl testing.
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                #27
                Re: Sceptre X22WG-1080p monitor not staying backlit, Please Help!

                OK, tested the ccfl's. In the picture I've posted previously, the top two left ones were 2 and out. The next one in line, next to the transformer. Lit up for a second then went dim, then out. The last one, far right - was 2 and out, then once it flashed on then went 2 and out. Does this tell you anything?

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                  #28
                  Re: Sceptre X22WG-1080p monitor not staying backlit, Please Help!

                  Originally posted by trex66 View Post
                  Does this tell you anything?
                  Most inverter IC chips are designed to shut off the backlight if one or more of the ccfls are bad. Think of it as "all or nothing".

                  The test that you did is "valid" if one of the ccfl is actually cracked/broken or the wiring is completely open.

                  As ccfls age, they draw more power. If one ccfl draws too much power, the inverter IC chip, it will shut down all ccfls.

                  The easiest way to determine this is by using another lcd monitor. Do you have another lcd monitor?
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                    #29
                    Re: Sceptre X22WG-1080p monitor not staying backlit, Please Help!

                    How I tested the four CCFL's was with a 12.5" CCFL lamp from another monitor. I just unplugged one lamp and plugged the spare into it. I did this with all four lamps. And I turned it on and off a few times ti verify the results. It's possible the lamp I used was too pulling too much power?

                    I have a few monitors around, but these only have one or two lamps, not a four lamp. Can I still use one to test the board?

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                      #30
                      Re: Sceptre X22WG-1080p monitor not staying backlit, Please Help!

                      Originally posted by trex66 View Post
                      How I tested the four CCFL's was with a 12.5" CCFL lamp from another monitor.
                      Going from a 22 inch ccfl lamp to 12.5 might be too much for a test? A 17 inch might be better, but let's assume the existing ccfls are good.

                      In post #1, you were ready to swap out the caps. If you have an ESR meter, measure the caps to see if they are within spec. If you don't have an ESR meter, you can try swapping out the caps to eliminate them.

                      What is the that multi pinned IC on the back side above point E/F?
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                        #31
                        Re: Sceptre X22WG-1080p monitor not staying backlit, Please Help!

                        Originally posted by trex66 View Post
                        How I tested the four CCFL's was with a 12.5" CCFL lamp from another monitor. I just unplugged one lamp and plugged the spare into it. I did this with all four lamps. And I turned it on and off a few times ti verify the results. It's possible the lamp I used was too pulling too much power?

                        I have a few monitors around, but these only have one or two lamps, not a four lamp. Can I still use one to test the board?
                        I am guessing when you say a 12.5”ccfl your talking about one from a 15” monitor.
                        You definitely noticed something different on one side of the inverter.
                        I am going to suggest you try one more thing. Position the panel so you’re able change the position of where the ccfls plug into the board [top ccfls plugged into where the bottom ones were]continue to use your test bulb repeat you testing,see if one second on and dim, stays with the same ccfls connector.
                        Al.
                        Last edited by alexanna; 01-03-2011, 04:04 PM.
                        Whatever I do, I consider it a success, if in the end I am breathing, seeing, feeling and hearing!

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                          #32
                          Re: Sceptre X22WG-1080p monitor not staying backlit, Please Help!

                          I didn't know if the CCFL's were full length or front to back behind the screen. I don't have a ESR meter, the DMM I have reads capacitance but I have to pull the caps off the board to get an accurate reading. the IC is very hard to see, from what I can make out is reads:
                          BIT 3713
                          F1FT7 CO652

                          Also didn't see this before, there is a small bubble on it, hard to see, but looks like a little damage.
                          Attached Files

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                            #33
                            Re: Sceptre X22WG-1080p monitor not staying backlit, Please Help!

                            Originally posted by trex66 View Post
                            I don't have a ESR meter, the DMM I have reads capacitance but I have to pull the caps off the board to get an accurate reading.
                            Hold off desoldering and measuring uF for now.

                            BIT 3713

                            Also didn't see this before, there is a small bubble on it, hard to see, but looks like a little damage.
                            Find the BIT 3713 datasheet and see if any of the pins are shorted. Post the link for the datasheet.

                            The datasheet usually has a functional block diagram that will help you determine which pins should not be shorted.

                            I agree that looks bubbled and that chip could be damaged.
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                              #34
                              Re: Sceptre X22WG-1080p monitor not staying backlit, Please Help!

                              Wow, talk about a hard to find datasheet... well never found it but there is a similar IC BIT3193 that I found. here is the link to the PDF. Again, thanks for all the help.

                              http://pdf1.alldatasheet.com/datashe...C/BIT3193.html
                              Attached Files

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                                #35
                                Re: Sceptre X22WG-1080p monitor not staying backlit, Please Help!

                                I found the exact one.

                                https://cdn.badcaps-static.com/pdfs/...3c7c387216.pdf

                                You want the exact one because there could be changes between chipsets over time.
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                                  #36
                                  Re: Sceptre X22WG-1080p monitor not staying backlit, Please Help!

                                  Nice, I searched for hours and came up with nothing. I don't know where you found it, but thanks.

                                  I don't have a clue where to start to test this IC... I can't read the block diagram, no idea what any of those initials stand for, or where they are on the board. I feel like the kid who jumped in the pool then realized he couldn't swim.
                                  Last edited by trex66; 01-03-2011, 11:14 PM.

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                                    #37
                                    Re: Sceptre X22WG-1080p monitor not staying backlit, Please Help!

                                    Originally posted by trex66 View Post
                                    I don't have a clue where to start to test this IC...
                                    Let's try this. It is brute force, but it gives all the readings possible. If you have a manual multimeter, set it to 200 ohms. If the multimeter reads "1" on the left hand side it is out of range. Just report the pin configurations that have resistance less than 200 ohms.

                                    With power off and lcd unplugged, measure the resistance between (I think you will see the pattern)

                                    a) pin 1-2, 1-3, 1-4, etc, etc, 1-15, 1-16
                                    b) pin 2-3, 2-4, 2-5, etc, etc, 2-15, 2-16
                                    c) pin 3-4, etc, pin 3-16
                                    ..
                                    ..
                                    ..
                                    y) pin 14-15, 14-16
                                    z) pin 15-16

                                    The members here can then help interpret the results.
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                                      #38
                                      Re: Sceptre X22WG-1080p monitor not staying backlit, Please Help!

                                      Please use the exact orientation and pinout as the datasheet otherwise there will be mass confusion.
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                                        #39
                                        Re: Sceptre X22WG-1080p monitor not staying backlit, Please Help!

                                        retiredcaps you're my seeing eye dog in this electronic world.

                                        it will be easier to list the readings I did get, most of the connections were 'OL'

                                        2-7 55.84 KΩ
                                        3-7 54.28 KΩ
                                        4-7 56.40 KΩ
                                        5-7 46.95 KΩ
                                        6-7 53.09 KΩ
                                        7-14 54.71 KΩ
                                        10-11 57.72 KΩ
                                        10-12 58.58 KΩ
                                        10-13 57.74 KΩ
                                        10-14 57.41 KΩ
                                        10-15 58.56 KΩ
                                        10-16 0.2 Ω

                                        I hope this can help shed some light on what is wrong here.

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                                          #40
                                          Re: Sceptre X22WG-1080p monitor not staying backlit, Please Help!

                                          Originally posted by trex66 View Post
                                          10-16 0.2 Ω
                                          There are a few possibilities.

                                          1) pin 10-16 is shorted by design (internally to the IC)
                                          2) pin 10-16 is shorted by damage to chip
                                          3) pin 10-16 reads shorted by other components on the board

                                          If you are good at soldering, try to lift pin 16 so that it is off the board. Then retest, pin 10-16. If it is still reading 0.2 ohms, we are left with #1 or #2.

                                          Looking at the datasheet, I'm not 100% sure, but I think pin 10-16 should not be shorted. That is, I believe the chip is damaged.

                                          edit: pin 10 is VDD (power supply pin of the device), and pin 16 is MODSEL.
                                          Last edited by retiredcaps; 01-04-2011, 02:47 PM.
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