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    Asus VW246H will not power on

    Hi,
    I have been reading quite a few posts in the past couple of days and I am amazed at the level of help offered on this forum.
    So many people, giving so much time to help others is outstanding.
    Some of the content is waaay above my head, as I am a complete novice when it comes to electrical components, so please be gentle.

    Anyway if you could help me to diagnose the issue with my monitor - Asus VW246H it would be greatly appreciated!

    The monitor will no longer power on, no power LED - nothing.
    It has been playing up for a couple of months. Would power on & off using the power button OK. Unless the mains plug was switched off.
    If this was switched off the monitor would not come back on unless I disconnected all of the cables overnight. Then the next day it would power on again.
    Now it has stopped altogether.

    I have taken it apart and cannot see any obvious signs of the caps being faulty. None of them have 'blown' and although parts of the board do look slightly brown, nothing obvious appears to have blown.

    I have seen a replacement power board here: http://parts-lcd.com/asus-parts-c-2/...01-p-1025.html which if it comes to it, I am prepared to buy.
    However, I would like some further diagnosis this is at fault before spending the cash.

    I only have a multi meter available to test components, which I understand is not enough to test the caps properly.

    I hope the attached photos are good enough quality to help, if not or others needed please let me know.

    Please help! Where do I start??
    Attached Files

    #2
    Re: Asus VW246H will not power on

    Ok do you have a Digital Multimeter at hand?

    Comment


      #3
      Re: Asus VW246H will not power on

      Ok, excellent first post. That helps a lot. I'll start with some basic tests since you admit you are a novice (we all were too once). From your symptoms it sounds like it could be that startup cap on the lower right (C606?). That big cap should show some very high voltage. Around 230v * 1.414 = 325 or so. Notice that thick white line to the left of the plugin? That is the "hot" section of the power board. If any of the components in that area are out then you won't get 325v to the main (big brown) cap. Here's the way I would start out...with power board unplugged..
      1. Test the white F601 fuse (use lowest ohm setting and look for low ohms)
      If the fuse is good.....
      Now you have to plug in the power board and be cautious...
      2. Check for voltage on the main cap leads. There should be a marking for the + or - on the board. You'll need to set the multimeter to DC, high voltage.

      You could also order a startup cap (lower right -- C606?) if it passes both of those tests.
      If it passes both of those tests then let us know and we can move on from there.
      Just be real careful on the main cap test. I usually put my elbows on the bench to give me steadiness with the probes. Good luck mate!

      Comment


        #4
        Re: Asus VW246H will not power on

        Thanks for the replies. I am at work now, so will try those 2 tests tonight, and post back with the results.

        For testing the fuse, what results should I expect? I am right in thinking that if the ohms level doesn't change the fuse is blown?

        Comment


          #5
          Re: Asus VW246H will not power on

          Right I have tested both of those.
          The fuse read 0.6 once it settle down. The readings were all over the place initially.

          The main cap read 333v.
          So I presume both of these are OK.

          The cap at C606 reads '50v 47uF' down the side. I guess that is the capacity I need to search for.
          Does anyone know of any where in the UK to buy quality caps?
          I don't want to try anything of poor quality, if I can help it.

          Look forward to your replies
          Last edited by UKRobster; 11-27-2013, 02:09 PM. Reason: typo

          Comment


            #6
            Re: Asus VW246H will not power on

            Fuse and main cap are ok...

            Lets check voltages at the connector from the PSU to the Main board.

            DMM set to 20VDC black probe to chassis (screw hole is good) and red probe to each pin and post results.... Also check for any markings near the connector that would indicate the correct value for each pin... Take a photo of it for us too

            Comment


              #7
              Re: Asus VW246H will not power on

              Asus had a lot of bad solder joints on there ccfls causing shorts and burn out ends check your ccfls that might be the problem.

              Comment


                #8
                Re: Asus VW246H will not power on

                Originally posted by newtothis View Post
                Fuse and main cap are ok...

                Lets check voltages at the connector from the PSU to the Main board.

                DMM set to 20VDC black probe to chassis (screw hole is good) and red probe to each pin and post results.... Also check for any markings near the connector that would indicate the correct value for each pin... Take a photo of it for us too
                Sorry to be so green and ask what could be a simple answer. But where do you mean for me to check?
                Could you outline it from one of my photos?

                swgaspidey: How would I check my CCFLS - again sorry to ask, but I am very new to the inner workings of monitors.

                Comment


                  #9
                  Re: Asus VW246H will not power on

                  Hi - Iam just on my way out but another quick test would be on the yellow/orange torpedo fuse at the top of your first picture designator is F851.
                  NO power to boards meter on ohms 200 should read the same as holding the probes together.
                  Please upload pictures using attachment function when ask for help on the repair
                  http://www.badcaps.net/forum/showthread.php?t=39740

                  Comment


                    #10
                    Re: Asus VW246H will not power on

                    Ok Robster. Let me translate; since I remember what it was like to be a novice.

                    Selldoor - is asking you to check the fuse F851 just like you checked the white one earlier. Should show very low ohms if its good.

                    Newtothis - is asking you to see if you have any voltages going to the main board. The connector is CN701 and it's the white plastic thingy with the wires coming out. Set to 20 volts dc and put the red probe into the holes where the wires are. The black probe goes to a screw on the main board (cold ground). You should see voltages like 5v, 12v. Any voltage at all. I doubt you will, because I don't believe your power transformer is starting up at all.
                    You can disregard the comment about the ccfl's because they won't cause a no power/led problem.

                    Also you UK guys. He needs to be able to get a low esr 47uF 50v capacitor in the UK. Just in case it does turn out to be that little startup capacitor.

                    Comment


                      #11
                      Re: Asus VW246H will not power on

                      Originally posted by Lumberjack777 View Post
                      Ok Robster. Let me translate; since I remember what it was like to be a novice.
                      Thanks for your patience, it is appreciated.

                      I will check those things and let you know.

                      Thanks guys!

                      Comment


                        #12
                        Re: Asus VW246H will not power on

                        I have looked but dont have a new cap to send.

                        Suggest this one http://cpc.farnell.com/rubycon/50yxf...nce/dp/CA05111

                        They seem to have a no postage offer on at the moment even for small orders.

                        They are in packs of 5 so you order 1 - should be 89p inc vat

                        If you struggle to get the no handling and no postage let me know.
                        Please upload pictures using attachment function when ask for help on the repair
                        http://www.badcaps.net/forum/showthread.php?t=39740

                        Comment


                          #13
                          Re: Asus VW246H will not power on

                          I checked the fuse at F851 and it eventually settled at 0.6 - as before.
                          Then checked each connection in the connector CN701, with the mains plugged in.
                          Nothing - well not actually true I got -0.03 on most of them. Certainly no volts through!
                          So I didn't bother to take a picture at this point as it seems the power is not getting that far.

                          selldoor: thanks for the link for the start-up cap. I had been looking this afternoon and had seen a couple of another site http://uk.rs-online.com/web/ but they had different ripple current ratings.
                          The one you have recommended has yet another different rating! Geez there is a lot to learn about all this stuff!

                          I have ordered the cap you pointed out, will change it and let you know the outcome!

                          Comment


                            #14
                            Re: Asus VW246H will not power on

                            OK - Not sure about the connector test.
                            When doing this you usually need to have all the boards connected. It doesnt make it easy as you have to try to get the probes to the pins with the socket in place and if you dont have thin probes its a problem. Some people have had success by inserting a sewing needle into each hole on the socket one at a time then putting the probe to the needle.
                            It has to be connected up as when you switch on there are signals go back and forth between the boards and it does a self test before it starts the power supply fully.

                            Something else to try whilst waiting for your cap is to set it all up, and if you have not yet removed the start up cap, warm it gently with a hairdryer then
                            try and power up the monitor.
                            Please upload pictures using attachment function when ask for help on the repair
                            http://www.badcaps.net/forum/showthread.php?t=39740

                            Comment


                              #15
                              Re: Asus VW246H will not power on

                              Oh OK, I didn't realize the boards needed connecting while testing - D'oh!
                              I will see if I can get it hooked up and read them again, properly!
                              Thanks for the tip about the sewing needle!

                              If I did use a hairdryer on the start-up cap and it powered on. What would that prove?
                              Does that indicate the cap is at fault?

                              Comment


                                #16
                                Re: Asus VW246H will not power on

                                Originally posted by UKRobster View Post
                                Oh OK, I didn't realize the boards needed connecting while testing - D'oh!
                                I will see if I can get it hooked up and read them again, properly!
                                Thanks for the tip about the sewing needle!

                                If I did use a hairdryer on the start-up cap and it powered on. What would that prove?
                                Does that indicate the cap is at fault?
                                Yeah, the probes on my DMM are so thick I soldered needles to them. It really helps if you are checking little legs from an IC chip.

                                But you should have at least had standby voltage of 5V from one of the wires to the main board. Even if everything wasn't connected. But connect them all and see if you have a difference eh.

                                The hairdryer is a great tip. As an aluminum capacitor heats up the ESR gets lower and lower (good). That's why people can turn off a perfectly good monitor. But it won't start up the next time. BUT....if the little capacitor is completely dried up on the inside, it won't make any difference. Worth a shot though.

                                Comment


                                  #17
                                  Re: Asus VW246H will not power on

                                  Hi guys,
                                  Sorry for not posting back sooner, but I am in the middle of decorating and that took all of my time over the weekend!

                                  Anyway I have some good news.
                                  I replaced the start-up cap last night and tested the monitor.
                                  It powered on! Great!

                                  Then (not so great) I started putting it all back together, just finished clipping the case together again, and thought I would just test it again before assembling the stand.
                                  It would not power on! It was late, and I although I was tempted to tinker some more I went to bed.
                                  Today I started thinking that I could be having the same issue as before:
                                  As in, after switching off the wall outlet I would have to leave it unplugged overnight for it to power on again. So this evening I have tested it again & it powered on first time. So I switched off the wall outlet and unplugged the power cord. Plugged it all back in and tried again. It works!
                                  I have performed this procedure several times and it seems to power on every time (so far!)

                                  A massive Thank You! to Lumberjack777 & selldoor for your help.
                                  I cannot express how grateful I am, that fixing my screen so close to xmas only cost me 89p!

                                  I do however have my fingers crossed that the wall socket/leave overnight scenario doesn't occur again.
                                  But if it does you know the first place I will be posting

                                  Thanks again,
                                  Rob

                                  Comment


                                    #18
                                    Re: Asus VW246H will not power on

                                    Great to hear! Thanks for the feedback. I love it when it's just that little cap

                                    And thanks to Selldoor for the place to buy the right cap in the UK

                                    Comment


                                      #19
                                      Re: Asus VW246H will not power on

                                      I don't understand ukrobster, you have assembled back together and it not working (sorry for my english), then you have done several test where all the times you switchoff the monitor and unplug the power from the wall? But the real test was also to switch on and off without unplug it..

                                      Comment


                                        #20
                                        Re: Asus VW246H will not power on

                                        Hey everyone, Same monitor and same issue.
                                        I've been following the troubleshooting suggestions above and here's my finding.
                                        The problem it appears to be in fuse FD851... I'm getting a reading of 126ohm.

                                        Also while plugged in, the Big brown cap reads 160V (I'm in the US).

                                        Any ideas? does the fuse need replacement, or do I need to do further tests?>

                                        Comment

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