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Samsung SyncMaster 213T again: good PS but no green LED

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    #1

    Samsung SyncMaster 213T again: good PS but no green LED

    Hey guys,

    I just inherited a non-working 213T. First, I thought it will be relatively easy to diagnose, since I was sure the issue is in bad capacitors. I disassembled the monitor and found out that capacitors look good, not bulging at all.
    Both fuses on P/S board are fine and read 0Ohm.
    When I turn the P/S on, I read about 160VDC on a big filter capacitor and I also get around 13V and 5V on the connector to the main board (with main board disconnected).
    Then I connected the main board to P/S and disconnected everything else (inverter and other connector but the buttons panel). Now, instead of 14V I read 17V, 5V are the same. However, nothing happens when I press a power button, no green LED. This makes me think the issue is in main board. Are there other tests I can perform to make sure it is the main board? Am I correct in assumption that it should lit green LED even with all other boards disconnected? I am attaching pics too.
    Attached Files
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    #2
    Re: Samsung SyncMaster 213T again: good PS but no green LED

    The main board controls the power LED. Check the voltage regulators on the main board and report them in the exact format as shown in the troubleshooting guide link below.
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      #3
      Re: Samsung SyncMaster 213T again: good PS but no green LED

      You need Power Supply, Logic and Button panel to get the LED to come on,The increase in voltage from 14v to 17v is normal, as you removed the Load.The 5v is regulated so that is why that does not change.You also need to plug in a computer with Power on to get a signal to the logic board,which normally would then change the Led colour when it sees that signal.

      Comment

        #4
        Re: Samsung SyncMaster 213T again: good PS but no green LED

        The 2 larger caps on the logic board in the top right corner (near the circled number 1) are they flat? Hard to tell from the top-down angle but the vents look a bit stressed.
        36 Monitors, 3 TVs, 4 Laptops, 1 motherboard, 1 Printer, 1 iMac, 2 hard drive docks and one IP Phone repaired so far....

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          #5
          Re: Samsung SyncMaster 213T again: good PS but no green LED

          Inv. board is bad. Replace complementary mosfet with IRF 7389 ( 8 pcs) not all bad, new capacitors 220uF/35V and FUSE 3A on inverter. On PS board reeplace old capacitors with new.

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            #6
            Re: Samsung SyncMaster 213T again: good PS but no green LED

            Try IC 202 on motherboard resoldering with SMD work station

            Comment

              #7
              Re: Samsung SyncMaster 213T again: good PS but no green LED

              Originally posted by retiredcaps View Post
              The main board controls the power LED. Check the voltage regulators on the main board and report them in the exact format as shown in the troubleshooting guide link below.

              Sorry, I don't see a link? I'll make better pics tonight and will post them, thanks!

              Comment

                #8
                Re: Samsung SyncMaster 213T again: good PS but no green LED

                Originally posted by Rtech View Post
                You need Power Supply, Logic and Button panel to get the LED to come on,The increase in voltage from 14v to 17v is normal, as you removed the Load.The 5v is regulated so that is why that does not change.You also need to plug in a computer with Power on to get a signal to the logic board,which normally would then change the Led colour when it sees that signal.
                I didn't think you need signal to make green LED to lit?

                Comment

                  #9
                  Re: Samsung SyncMaster 213T again: good PS but no green LED

                  Originally posted by WOTAN View Post
                  Inv. board is bad. Replace complementary mosfet with IRF 7389 ( 8 pcs) not all bad, new capacitors 220uF/35V and FUSE 3A on inverter. On PS board reeplace old capacitors with new.
                  As you can see I DISCONNECTED the inverter board completely: no green LED light.

                  Comment

                    #10
                    Re: Samsung SyncMaster 213T again: good PS but no green LED

                    Originally posted by smason View Post
                    The 2 larger caps on the logic board in the top right corner (near the circled number 1) are they flat? Hard to tell from the top-down angle but the vents look a bit stressed.
                    You know, you are right, they are not completely flat (as well as another one on the left side). So, you think this could be the problem?

                    Comment

                      #11
                      Re: Samsung SyncMaster 213T again: good PS but no green LED

                      Some better pics (I hope)
                      Attached Files

                      Comment

                        #12
                        Re: Samsung SyncMaster 213T again: good PS but no green LED

                        Originally posted by Nervous View Post
                        You know, you are right, they are not completely flat (as well as another one on the left side). So, you think this could be the problem?
                        I've seen those surface mount caps do that all the time and still be perfectly good. If I were attempting to repair that logic board, I would start with measuring the voltage regulators as retiredcaps mentioned. https://www.badcaps.net/forum/showthread.php?t=22231

                        Then go ahead and replace those 470uF 16v surface mount caps if you want. You can use regular caps for testing purposes. 470uF - 16v or 25v etc. Those caps have polarity so make sure the positive and negative sides are installed properly.

                        This could also be a problem PlainBill used to mention known as a "reset controller". I have never had to replace one, but the symptons are no power, no led, and the source of the problem was the logic board.

                        Maybe somebody more familiar than I could explain where to locate that reset controller and how to test it.

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