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Viewsonic VX2235WM - blank screen on/off

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    #21
    Re: Viewsonic VX2235WM - blank screen on/off

    One thing to note that even if the capacitance values measure within 20%, the ESR value is more important. Therefore, if the cap value measures okay, but the impedance (ESR) value is too high, it can cause the cap not to perform correctly causing the problems you see. You need an ESR meter to measure the ESR value for each cap.

    Comment


      #22
      Re: Viewsonic VX2235WM - blank screen on/off

      Yeah, I know. I wish I had an ESR meter, but I don't, and last I checked, they cost way more then I can afford. Well, looking on Ebay now, I see there are some cheapish ones. If I get $60 to blow I'll see what I can do about it.

      In the meantime all I have to go by is capacitance and looking for bulging tops. The filter cap may not have been the problem, but it was bulging slightly, and I'm sure enough it was or would become a problem soon.

      Comment


        #23
        Re: Viewsonic VX2235WM - blank screen on/off

        Since the Blue LED is still on, it can be that the Inverter on signal from the main board had dropped out or the inverter circuits had shutdown, or the B+ for the inverter section dropped out. You will need to monitor those signals first to find out what is not present when the backlights go out.
        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


          #24
          Re: Viewsonic VX2235WM - blank screen on/off

          What would cause either of those two symptoms?

          Comment


            #25
            Re: Viewsonic VX2235WM - blank screen on/off

            Failed components, unstable power supply voltage, etc. Cannot tell until you can narrow down what section is bad first. Slightly bulging is not good at all, it means it is failing already. I would replace the set of caps since some already went bad, unstable voltages can cause lots of inconsistent operation.
            Last edited by budm; 07-15-2013, 09:59 PM.
            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


              #26
              Re: Viewsonic VX2235WM - blank screen on/off

              All right. Where would I test for these voltages? Should I nab pics of the power supply for you, or can you point out the areas I need to check?

              Comment


                #27
                Re: Viewsonic VX2235WM - blank screen on/off

                So right now you do not have any more slightly bulging top caps on the board, right? If you do, then replace them first.
                I will need the good clear pictures of the power supply/inverter board, top and bottom sides.
                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


                  #28
                  Re: Viewsonic VX2235WM - blank screen on/off

                  Okay. Tomorrow I'll take out the power supply and grab pics.

                  No, there are no more bulging caps, and I've pulled out half the caps and tested them, best I could. Replaced a few already even though the ones I pulled out tested fine.

                  Comment


                    #29
                    Re: Viewsonic VX2235WM - blank screen on/off

                    Attached is a shot of the power supply hooked up, and a picture of the underside of the power supply.

                    Most of the capacitors have been tested using my capacitance meter, and a few were replaced just because I had known good replacements on hand, and wanted to rule them out as a problem. It's gonna be a bit tricky, but where should I connect the multimeter leads, and what voltages should I look for?
                    Attached Files

                    Comment


                      #30
                      Re: Viewsonic VX2235WM - blank screen on/off

                      OK, on the multi-pin connector, the pins are labeled, on my pictures I did not take good pictures that show all the label of the pins. Can you write down what they are?
                      Here are some of my pictures:
                      http://s807.photobucket.com/user/bud...tml?sort=3&o=6
                      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


                        #31
                        Re: Viewsonic VX2235WM - blank screen on/off

                        If the Led is still Blue then the monitor can see the input PC signal.So you need to check that the Backlight on Signal is sent from the logic Board to the Psu/inverter.This will be in the region of 3-4 volts DC, and if you have that then it looks like '2 secs to Black' symptoms and follows the sticky.Not all Monitors show a dark image when the Backlights fail so you cannot assume that they are OK.

                        Comment


                          #32
                          Re: Viewsonic VX2235WM - blank screen on/off

                          Originally posted by budm View Post
                          OK, on the multi-pin connector, the pins are labeled, on my pictures I did not take good pictures that show all the label of the pins. Can you write down what they are?
                          Here are some of my pictures:
                          http://s807.photobucket.com/user/bud...tml?sort=3&o=6
                          Starting from the row of pins closest to the 1000uf 25v capacitor:

                          EUA
                          GND
                          DET
                          +5V
                          V_adj
                          SHUT (I think, it's hard to read.)
                          ACR+
                          AOL+

                          Comment


                            #33
                            Re: Viewsonic VX2235WM - blank screen on/off

                            Hmm, what is the full model number of this monitor? It should have -1, 2, ect. after the WM. there are at least 9 versions of this VX2235WM.
                            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


                              #34
                              Re: Viewsonic VX2235WM - blank screen on/off

                              Nope, no number after the WM. See for yourself.
                              Attached Files

                              Comment


                                #35
                                Re: Viewsonic VX2235WM - blank screen on/off

                                OK, pin 15 on the main board is the INverter on/off pin, it should change state when the monitor is on and when it is off, black probe on the chassis, red probe on pin 15.
                                I believe this should match your main board.
                                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


                                  #36
                                  Re: Viewsonic VX2235WM - blank screen on/off

                                  Ah. Embarrassingly, I'm not that good with schematics. Could you point out pin 15, say in the picture I took?

                                  Comment


                                    #37
                                    Re: Viewsonic VX2235WM - blank screen on/off

                                    See picture of PIN 15 on the POWER SUPPLY BOARD.
                                    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


                                      #38
                                      Re: Viewsonic VX2235WM - blank screen on/off

                                      The plot thickens.

                                      I rigged up a jumper wire to pin 15 on the power supply so I could connect my multimeter, and plugged it in. The connector is slightly off kilter now but all pins still make contact. I read 3.01 volts from pin 15 when the display is lit.

                                      Now here's where it gets interesting. I held the monitor on its side for 10 minutes waiting for it to fail and it didn't. Finally my arm got tired and I shut it down.

                                      I'm gonna check the solder joints for the pins on the power supply and logic board.
                                      Last edited by Mrx3750; 07-16-2013, 01:18 PM.

                                      Comment


                                        #39
                                        Re: Viewsonic VX2235WM - blank screen on/off

                                        I looked more at the pin out, not sure if it is using pin to pin between main board and the power supply board or not, if it is not pin 15 on the main board may be connected to pin 16 on the power supply board, not 15 to 15, you can get to pin 16 on the top side of the board and check the voltage on that pin also.
                                        Re-flow the solder on those pins is a good idea.
                                        Last edited by budm; 07-16-2013, 01:47 PM.
                                        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


                                          #40
                                          Re: Viewsonic VX2235WM - blank screen on/off

                                          Just got done resoldering every pin on both boards, plugged in the monitor for a quick test and it came up fine. The connection for pin 15 on the logic board looked a little iffy. I'm gonna try running the monitor and see if it fails again. If it does, I'll look at pin 16. If it runs for an hour with no problem, then I might have fixed it.

                                          Edit: Ahhhh nope! Just went out again!
                                          Last edited by Mrx3750; 07-16-2013, 02:04 PM.

                                          Comment

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