Syncmaster 2493 - LED not lit, monitor won't power up

Collapse
X
 
  • Time
  • Show
Clear All
new posts
  • johnwartjr
    New Member
    • May 2013
    • 9
    • USA

    #1

    Syncmaster 2493 - LED not lit, monitor won't power up

    I am working on a Syncmaster 2493.

    The screen is black. The power LED never illuminates.

    I have tried another power cord.

    It belongs to a friend of mine who said it made a loud quacking noise before it failed.

    I have a DMM, an ESR meter, and good rework equipment. I tested all the caps on the power supply with the ESR meter and all are within 10% of their rated values.

    Any suggestions where I might start?

    Thanks!
  • Pentium4
    CapXon Be Gone
    • Sep 2011
    • 3741
    • USA

    #2
    Re: Syncmaster 2493 - LED not lit, monitor won't power up

    Can you see a picture if you shine a flash light on the screen?

    Comment

    • selldoor
      Slow Learner
      • Dec 2010
      • 7870

      #3
      Re: Syncmaster 2493 - LED not lit, monitor won't power up

      Tested the fuses?
      Please upload pictures using attachment function when ask for help on the repair
      http://www.badcaps.net/forum/showthread.php?t=39740

      Comment

      • johnwartjr
        New Member
        • May 2013
        • 9
        • USA

        #4
        Re: Syncmaster 2493 - LED not lit, monitor won't power up

        Fuses test good.

        I plugged it into a PC, and the PC detects the monitor, but the picture never comes up. With or without a flashlight shining on it. Turn the power switch to 'off' and it goes away on the PC, turn it on, it comes back on the PC, but the screen never illuminates and the power LED never lights.

        The power LED does not light on the front of the monitor.

        I attached some PCB photos.
        Attached Files
        Last edited by johnwartjr; 05-05-2013, 08:25 PM.

        Comment

        • budm
          Badcaps Legend
          • Feb 2010
          • 40746
          • USA

          #5
          Re: Syncmaster 2493 - LED not lit, monitor won't power up

          Check to see if you have 160vdc on that large filter cap (82uf/450v), and see if you have 5V at the SB PIN.
          More pictures here:
          http://s807.photobucket.com/user/bud...?sort=3&page=1
          Attached Files
          Never stop learning
          Basic LCD TV and Monitor troubleshooting guides.
          http://www.badcaps.net/forum/showthr...956#post305956

          Voltage Regulator (LDO) testing:
          http://www.badcaps.net/forum/showthr...999#post300999

          Inverter testing using old CFL:
          http://www.badcaps.net/forum/showthr...er+testing+cfl

          Tear down pictures : Hit the ">" Show Albums and stories" on the left side
          http://s807.photobucket.com/user/budm/library/

          TV Factory reset codes listing:
          http://www.badcaps.net/forum/showthread.php?t=24809

          Comment

          • johnwartjr
            New Member
            • May 2013
            • 9
            • USA

            #6
            Re: Syncmaster 2493 - LED not lit, monitor won't power up

            5.25 at the SB pin, 176 VDC across the cap.

            Comment

            • budm
              Badcaps Legend
              • Feb 2010
              • 40746
              • USA

              #7
              Re: Syncmaster 2493 - LED not lit, monitor won't power up

              If you do have 5V standby voltage which is used for running the main/logic board, that means the main board is not working if you do not see any indicator on the front of the unit. Do you also get >3V at the PS_ON pin which is generated by the main board?
              Never stop learning
              Basic LCD TV and Monitor troubleshooting guides.
              http://www.badcaps.net/forum/showthr...956#post305956

              Voltage Regulator (LDO) testing:
              http://www.badcaps.net/forum/showthr...999#post300999

              Inverter testing using old CFL:
              http://www.badcaps.net/forum/showthr...er+testing+cfl

              Tear down pictures : Hit the ">" Show Albums and stories" on the left side
              http://s807.photobucket.com/user/budm/library/

              TV Factory reset codes listing:
              http://www.badcaps.net/forum/showthread.php?t=24809

              Comment

              • johnwartjr
                New Member
                • May 2013
                • 9
                • USA

                #8
                Re: Syncmaster 2493 - LED not lit, monitor won't power up

                I get 0 VDC, but 7.9 VAC when measured against the ground pin on the same connector. Not sure if this is a DC or an AC reading.

                These readings are with only the PS sitting on my workbench.. do I need to connect the other boards back to it to check the PS_ON pin properly?

                Comment

                • budm
                  Badcaps Legend
                  • Feb 2010
                  • 40746
                  • USA

                  #9
                  Re: Syncmaster 2493 - LED not lit, monitor won't power up

                  PS_ON signal is DC, in the cold side of the circuits, the chassis is the ground ref point for the cold side. The negative leg of the large filter cap is the ground ref point of the hot (primary side) side of the circuit, not the chassis.
                  You have to have all the board connected since the main board needs the 5V STBY and the power supply needs the PS_ON from the main board to turn on the PFC and the 12v/24v power supply section.
                  Please read my guide below to understand how it works.
                  Never stop learning
                  Basic LCD TV and Monitor troubleshooting guides.
                  http://www.badcaps.net/forum/showthr...956#post305956

                  Voltage Regulator (LDO) testing:
                  http://www.badcaps.net/forum/showthr...999#post300999

                  Inverter testing using old CFL:
                  http://www.badcaps.net/forum/showthr...er+testing+cfl

                  Tear down pictures : Hit the ">" Show Albums and stories" on the left side
                  http://s807.photobucket.com/user/budm/library/

                  TV Factory reset codes listing:
                  http://www.badcaps.net/forum/showthread.php?t=24809

                  Comment

                  • johnwartjr
                    New Member
                    • May 2013
                    • 9
                    • USA

                    #10
                    Re: Syncmaster 2493 - LED not lit, monitor won't power up

                    Thanks. I'll get back to this tomorrow and post back with the results.

                    Comment

                    • johnwartjr
                      New Member
                      • May 2013
                      • 9
                      • USA

                      #11
                      Re: Syncmaster 2493 - LED not lit, monitor won't power up

                      Sorry for the delay, life got in the way

                      PS_on is 3.1 volts
                      I checked the 24 volt supply, and it's a solid 24 volts
                      I also checked the pins marked 5.3 volts - they measure 5.4 volts

                      Comment

                      • budm
                        Badcaps Legend
                        • Feb 2010
                        • 40746
                        • USA

                        #12
                        Re: Syncmaster 2493 - LED not lit, monitor won't power up

                        OK, PS_ON is OK otherwise you will not be getting the 24V for the inverter board.
                        So now I will need good clear pictures of the inverter board as a whole and also in 1/4 section so I can easily see the components and traces.
                        Same for the main/logic board.
                        Never stop learning
                        Basic LCD TV and Monitor troubleshooting guides.
                        http://www.badcaps.net/forum/showthr...956#post305956

                        Voltage Regulator (LDO) testing:
                        http://www.badcaps.net/forum/showthr...999#post300999

                        Inverter testing using old CFL:
                        http://www.badcaps.net/forum/showthr...er+testing+cfl

                        Tear down pictures : Hit the ">" Show Albums and stories" on the left side
                        http://s807.photobucket.com/user/budm/library/

                        TV Factory reset codes listing:
                        http://www.badcaps.net/forum/showthread.php?t=24809

                        Comment

                        • johnwartjr
                          New Member
                          • May 2013
                          • 9
                          • USA

                          #13
                          Re: Syncmaster 2493 - LED not lit, monitor won't power up

                          More pics
                          Attached Files

                          Comment

                          Related Topics

                          Collapse

                          • PantherDave
                            Microsoft Surface Pro (5th gen) model 1796 - no power
                            by PantherDave
                            Hi all!

                            I'm trying to troubleshoot a Microsoft Surface Pro (5th gen) model 1796 that won't power on. Motherboard model is M1007506-015. My priority is retrieving data, but the SSD is integrated so it looks like if I can't repair it it'll need to go to a data recovery company. I've done a little basic board repair before, but nothing this advanced until now. So please forgive my ignorance in advance. 😅

                            I found the boardview for this laptop in the forums here, and am able to open it on my PC with FlexBV.
                            https://www.badcaps.net/forum/troubl...-hardware-devi...
                            05-29-2024, 02:01 PM
                          • GLISIT
                            Asus Probook P5440UF-XB74 power issue
                            by GLISIT
                            Hi all,

                            TL;DR - this laptop is driving me nuts with the oddball power-related behaviors. Appreciate any insight you can provide!


                            I'm experiencing a power issue on an Asus Probook P5440UF-XB74. Although I've worked with electronics and computers for decades, this is my first attempt at getting into motherboard-level component troubleshooting. Any help the community can provide is greatly appreciated!

                            A few weeks ago I was using the laptop (on battery power) for a Zoom meeting. The battery was running very low (long meeting) but I wasn't worried about...
                            01-16-2025, 02:29 PM
                          • sam_sam_sam
                            Desoldering gun station modified to use a 18 volt @ 20 amp switching power supply
                            by sam_sam_sam
                            I have wanting to do this project for quite sometime now and I finally found a switching power supply that will work on this desoldering gun station ZD-915 that the original switching power supply took a shit and just was not worth trying to fix it because this switching power is not quite big enough to handle the heater element and the vacuum pump

                            One note when I tested the switching power supply and the voltage control board I noticed that this desoldering gun heat up much faster than the original switching power supply which I was really surprised by to the point that I might buy...
                            03-31-2024, 02:12 PM
                          • mikey5791
                            Philips 196V3L monitor power led off
                            by mikey5791
                            Hi, i was given this lcd monitor last week with the issue of power led blinking. Upon checking the power board, i found 2 pieces electrolytic caps bulged and replaced them.
                            Later, when i switched on ac power and detected 5v and 15v dc at output pins. But as soon as i pressed on the front power button, the led on power button lights for 1 second and it turns off.

                            So, i tried disconnect the flex ribbon cable from t con board. But all i got is a white screen with nothing on. I suspect there is something short somewhere that prevent the display being turned on. Can someone with...
                            01-25-2024, 07:52 PM
                          • sam_sam_sam
                            Using a 5 volt @ 12 amp switching power supply and two USB doctor volt / amp meter to three IPads on one power supply
                            by sam_sam_sam
                            I have been wanting to do this project for some time using a Mean-well switching power supply that I bought at least ten of them that were originally in a device that was abandoned for some reason they were listed new but removed from equipment that was never used

                            I do not understand Mean-well the capacitor next to the voltage reference ic chip was a brand that is known for failure over time the other capacitors are brand name needless to say it got replaced before I even powered it on for the first time

                            I used a four USB outlet and electrical plate that is made for...
                            08-03-2024, 07:54 PM
                          • Loading...
                          • No more items.
                          Working...