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Moved-Viewsonic VG2021m Blue flashing PLED no image

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    Moved-Viewsonic VG2021m Blue flashing PLED no image

    Thanks to Alexanna for showing me that I had posted incorrectly.....

    Hello and Greetings,

    I have a VG2021 monitor that was working fine until when coming out of standby (amber LED) it went to a dim flashing blue LED and no image. I have since replaced ALL Caps even though the 3x 220uf 25v 105's were only buldging, but have the same exact problem. I have used a DMM to check the +5 and +12 pins on the connector between the boards (power invert removed and benched) and Have 4.78 and 11.87 respectivly. I purchased the Cap kit from LCDalternatives and all are rubys. I have 21.2 volts across the main fuse (F200) of the DAC-12m033af REV 02a PCB. All connectors have been checked, No visable scorching. I have heard a 'chirping' coming from IEC? marked MP-1301 DCGM 0645 that coincides with the flashing LED. I have ordered a complete Power/inverter but was wondering in the meantime if you folks would have any other ideas.
    Thanks for your time
    Joe


    Update:

    Ok Folks This is where i really could use your help.
    After purchasing the cap kit from the above mentioned co., They did not solve my problem, the folks there suggested that you all were the people to contact if I needed experienced help in the matters of LCD monitors.

    Ok as you have read I replaced all the caps in the first power board and was left with the same problem. I purchased a complete board and the problem remains. The symptoms are as follows:

    With the first power board before replacing any caps
    Amber standby went to flashing dim blue power LED when coming out of standby.
    No OSD No image when connected to computer.

    After replacing all caps (except large 150uf 400v):
    Same flashing blue LED except it was brighter
    Blue LED is on IMMEDIATLY when power plug is inserted
    Chirping was heard at the component (coinsiding with flash of LED) marked
    2804793700
    E115982 MP-1301
    DCGM 0645
    No OSD No image when connected to computer.

    After inserting the new power board:
    Same Blue flashing bright LED Immediatly when plugging in power cord(sigh)
    Audible popping sound coming from internal speakers coinsiding with flash of LED (cannot hear the chirp)\No OSD No image.

    I did not have the protective metal cages that cover the boards on at this time. Just the boards mounted with all screws inserted and monitor supported by a wooden holder. -2 1x1's horizontal to surface of bench.
    Thats it guys, other than disconnecting all connectors and reinserting them and checking all PCB's for anything obvious thats all I can think of doing.

    Pictures can be submitted if need be, but I think they would be of little use at this point. Let me know if you would prefer to see them.

    power PCB Part # 12m033af rev 02a on both boards
    Chi Mei LCD Model A201P1
    Viewsonic VG2021m Bought 2005 Very light work as a Digital graphics and video editing computers monitor. Always off when not in use.

    Again Thanks for your time
    Joe

    Alexanna's reply:

    Unless you have two bad Inv/PS,There's three things left.
    I would start by removing the Ribbon cable from signal board to the LCD panel,Dose the behavior of the PLED change?
    Next unplug the Front panel switch from the signal board; you will not have a front PLED but do you get any indication that the back lights trying to come on.
    Or there may be a problem with the signal board.
    Pictures of the signal board will be needed, close up and in focus as close to 2000x2000 pixels as possible showing the entire board, using managed attachments.

    As a side note, this thread could easily be missed,for the members that concentrate mostly on the monitor section

    #2
    Re: Moved-Viewsonic VG2021m Blue flashing PLED no image

    I will get those pics here immediatly after trying the suggestions given to me from Alexaana.

    Comment


      #3
      Re: Moved-Viewsonic VG2021m Blue flashing PLED no image

      Ok
      No changes in symptoms after doing the suggestions by Alexanna.
      Pics as follows:













      Comment


        #4
        Re: Moved-Viewsonic VG2021m Blue flashing PLED no image

        Comment


          #5
          Re: Moved-Viewsonic VG2021m Blue flashing PLED no image

          Originally posted by Medlock View Post
          It probably would be a good idea to verify some voltages on the new power supply
          With everything hooked up and a signal going to the monitor, verify you have 12V and 5V at the 16 pin connector from the power supply to the signal card.
          Is fuse FP1 good? This is on the signal board next to the 16 pin connector
          Also measure the voltage on the pins of U4 it looks like it's a 3.3 voltage regulator.
          What numbers are stamped on U6? Upper right top of the signal card.
          Whatever I do, I consider it a success, if in the end I am breathing, seeing, feeling and hearing!

          Comment


            #6
            Re: Moved-Viewsonic VG2021m Blue flashing PLED no image

            Hi Alexanna thanks for your responce.


            Pins at the 18 pin for 5v and 12v are 4.9 and 11.8 respectivly.
            Fuse is good


            U6 is the same as U4



            U4----2.7
            --------I
            --I-----I-----I
            -G----2.7---4.6


            U6----3.2
            --------I
            --I-----I-----I
            -G----3.2---4.9


            Q8----1.4
            --------I
            --I-----I-----I
            -G----1.4---2.7


            note: on the top pins of U4 & U6 (pin4?) there was fluctuation of .1 volt coinsiding with flash of PLED.

            Thanks

            Comment


              #7
              Re: Moved-Viewsonic VG2021m Blue flashing PLED no image

              i was not aware of the 'manage attachments' at the bottom of reply page...i am working on a 14" monitor and didn't scroll far enough I guess.
              sorry about that.....if need be I can restart this whole thread, wow could I have messed this thread up any worse?

              Comment


                #8
                Re: Moved-Viewsonic VG2021m Blue flashing PLED no image

                I don't know either,after we get through this page it wont be that bad.

                The U components are low drop out voltage regulators with 1% tolerance, the tab and pin 2 are connected together internally.
                U4 has a lower input than U6,But the output 3.3 volts is way below the 1% tolerance.
                The data sheet I looked at listed the input minimum at 4.8 volts, and you are reading 4.6 volts on U4
                So the question becomes is the problem with the low voltage output of U4 caused by low input voltage to it, or a faulty U4 regulator. I honestly do not know. Whenever I have had a voltage regulator fail it has been noticeably hotter.
                I would check to make sure any of the ceramic smd caps around U4 don't show an extremely low resistance. If those check out OK,I would suspect the regulator as being the problem. The other option would be try to trace the input voltage of U4 and see if you can find where you're dropping the voltage.
                Whatever I do, I consider it a success, if in the end I am breathing, seeing, feeling and hearing!

                Comment


                  #9
                  Re: Moved-Viewsonic VG2021m Blue flashing PLED no image

                  I noticed on the back side of the signal boards PCB a discoloration in and around the regs, due to excessive heat I would think. Funny thing is that if you look at it through plain sight it is not as noticable. I will begin the trace back and see where the drop originates.

                  thanks

                  Comment


                    #10
                    Re: Moved-Viewsonic VG2021m Blue flashing PLED no image

                    Ok

                    The voltages leading from the 5v pin that feeds U4 and U6 are steady. The caps in and around problem area are of decent ohmage. Output of U6 is in spec and very steady. However U4's output as you said is out of spec and further is fluctuating irratic. +/- 1.2-.5 volts. This voltage feeds Q8 and therfore causes flucutation in its output also. This fluctuation is obviously persistent throughout all circuits supplied by these outputs. U4 does seem to be of higher temp than U6.

                    Question:
                    1. Will this low voltage and fluctuation cause the lack of anything working on this LCD? No back lights, no image, no steady PLED? I am guessing that the inverter is not seeing the 5V all is ok signal and not allowing a power up, yes?

                    2. How easily obtainable are these regulators and is Q8 a regulator also?

                    My experience with SMT and micro circuitry is minimal. Navy had me working on regulators the size of small cars compared to these...lol

                    Again Thanks for your time and patience,
                    Joe

                    Comment


                      #11
                      Re: Moved-Viewsonic VG2021m Blue flashing PLED no image

                      No I do not think the “Q” 8 is a voltage regulator.
                      http://search.digikey.com/scripts/Dk...ds=lm+1117+3.3
                      Check these regulators out you will need to verify they are the correct package.
                      You may also want to invest in some ChipQuik
                      http://search.digikey.com/scripts/Dk...l&name=SMD1-ND
                      Whatever I do, I consider it a success, if in the end I am breathing, seeing, feeling and hearing!

                      Comment


                        #12
                        Re: Moved-Viewsonic VG2021m Blue flashing PLED no image

                        Greetings Alexanna,

                        I have replaced the regulator and the voltages are now correct. 4.98 on the input 3.28 on the output. Voltages are steady. However nothing has changed. The PLED is still flashing has soon as the power plug in connected. No backlight, no OSD, and of course No image when hooked up to computer.

                        Should I not have at least back light as it seems they are powered from the invert/power board?

                        Is there, as in the instance of a motherboard, a signal to the power board that voltages are correct and it is OK to power up? I said 5v in my earlier post but could it be the 3.3v signal instead? If so which pin ID would that be on the 18pin connector and what voltage should I be looking for?

                        I am am going to 'fix' the images that I posted momentarily, as it seems I have offended the staff. Purely ignorance on my part as this media for instruction is new to me,or maybe its just because I'm ex-Navy?.ha!. I started a myspace page the day the network became passe',,lol

                        Thanks for your time,
                        Joe

                        Comment


                          #13
                          Re: Moved-Viewsonic VG2021m Blue flashing PLED no image

                          Pictures done correctly
                          Attached Files

                          Comment


                            #14
                            Re: Moved-Viewsonic VG2021m Blue flashing PLED no image

                            To try to answer your question, On the power supply at the 16 pin connector the voltages for the pins are noted on the board.There is 5v and 12v-some grounds- possibly some for audio, and a on/off pin this usually reads somewhere between 3 and 5 volts when the signal card is requesting backlights to be on. There will also be a pin to control the brightness of the back lamps it is usually just above 1 volt.
                            I don't remember if you have said, do you ever see a momentary flash of the backlights when you plug the monitor in?
                            The flashing of the PLED is a cause for concern. I would make sure your computer is set for a resolution the monitor can support. In fact try it at a really low resolution see if anything changes.
                            You have repaired a problem of low voltage at the regulator by replacing the LDO regulator.
                            Would you re check the voltages at the 16 pin connector, has the 12 volt rail come up any?
                            Any schematics are going to be hard to find for this PS/Inv,and signal card.
                            I am almost positive I have this monitor sitting on a shelf somewhere, so if no one has any ideas I will try to look at mine and try to do some comparison.
                            Whatever I do, I consider it a success, if in the end I am breathing, seeing, feeling and hearing!

                            Comment


                              #15
                              Re: Moved-Viewsonic VG2021m Blue flashing PLED no image

                              I have not been able to find a schematic for either board.

                              However the pins are marked clearly, but of course abbreiviated.
                              I will get a picture or write these tags down.

                              Comment


                                #16
                                Re: Moved-Viewsonic VG2021m Blue flashing PLED no image

                                Top Row- power plug at bottom left

                                - ADJ
                                - GND
                                - GND
                                - +5V
                                - +12V
                                - MUTE
                                - AOR -
                                - AOL-

                                BOTTOM ROW
                                - EVA
                                - GND
                                - DET
                                - +5V
                                - V_ADJ
                                - SHUT
                                - AOR+
                                - AOL+

                                I have figured that AOL-R +/- are audio

                                11.8 at the 12v pins are constant and are the same on both the new and repaired boards. With load and without.

                                No backlights what-so-ever, they do not flash or anything noticable.

                                The flashing light / resolution suggestion.
                                I cannot change resolution because if I set it at a certain res on this POS 14"
                                CRT it will change (i think/it always has during normal use) back upon
                                detection of plug n play LCD.
                                Keep in mind that I have no OSD or 'No Signal Detected' warning window after
                                powering up.(or should I say 'plugging in' as the PLED comes on immediatly
                                upon plugging in power.

                                (Keep in mind that I no longer have my old fluke (lent it out and surprise- surprise they ruined it.)

                                This POS however is 'pretty' acurate.
                                TFYT,
                                Joe
                                Last edited by Medlock; 09-13-2011, 12:24 PM.

                                Comment


                                  #17
                                  Re: Moved-Viewsonic VG2021m Blue flashing PLED no image

                                  What do you get on the 5v rail?
                                  My pc
                                  CPU : AMD PHENOM II x4 @ 3.5Ghz
                                  MB : ASUS M4A89TD PRO USB3
                                  RAM : Kingston ValueRAM 16gb DDR3
                                  PSU : Cooler Master 850W Silent Pro
                                  GPU : ATI Radeon HD 6850

                                  Comment


                                    #18
                                    Re: Moved-Viewsonic VG2021m Blue flashing PLED no image

                                    Hi Joshnz

                                    Top row 4.98
                                    Botom row 4.98

                                    note:

                                    the new regulator that i just put in U4 is showing signs of over heating.
                                    Granted that i am using a human digital thermometer.
                                    The U6 is at 90 and the U4 is approaching 110 and continues to climb.
                                    Last edited by Medlock; 09-13-2011, 12:51 PM. Reason: oops'd

                                    Comment


                                      #19
                                      Re: Moved-Viewsonic VG2021m Blue flashing PLED no image

                                      There are a number of reasons for the flashing power LED.

                                      One is when there is a shorted inverter driver, and this overloads the power supply when the inverter is switched on. That does not seem to be the case here.

                                      Another can be when the signal source is at too high a resolution for the LCD panel.

                                      A third is when the contents of the user eeprom is corrupted. That can sometiimes be resolved by resetting or reinitializing the eeprom. This usually involves holding down a combination of buttons when the monitor is plugged in.

                                      PlainBill
                                      For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.

                                      Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.

                                      Comment


                                        #20
                                        Re: Moved-Viewsonic VG2021m Blue flashing PLED no image

                                        Hi Bill

                                        Hmmm combo of buttons eh....
                                        There are 4 buttons and a settings reset
                                        I have tried the reset....now let me get out my abacus and determined how many combos might I need to try..ha!

                                        Just to repeat myself...the flashing PLED comes on immediatly when plugged in,
                                        if that makes a diff.

                                        Comment

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