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    Viewsonic VX910

    I am having a power problem with my VX910. The green light on the power button will light up however the screen remains blank. After a few seconds the screen will give an image for maybe 1 second. Once that image appears it quickly vanishes and the monitor power cycle through this process repeatedly.

    From what I've been reading online these monitors seem to have quite a few issues with bad caps and other power issues however I don't know which parts should be replaced.

    #2
    Re: Viewsonic VX910

    Originally posted by OSE
    I am having a power problem with my VX910. The green light on the power button will light up however the screen remains blank. After a few seconds the screen will give an image for maybe 1 second. Once that image appears it quickly vanishes and the monitor power cycle through this process repeatedly.

    From what I've been reading online these monitors seem to have quite a few issues with bad caps and other power issues however I don't know which parts should be replaced.
    All the bad ones.

    Open up the case, post pictures of the power supply board - top and bottom. (Note the link to the proper procedure for posting pictures in my signature.)

    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


      #3
      Re: Viewsonic VX910



      Attached Files

      Comment


        #4
        Re: Viewsonic VX910

        I'd like to beleive that all problems come from the power board however this is not true. There is a digital processing board that is in this monitor also. Whenever possible, post a pic of it (front/back) also.

        What type and values are the caps on the power board?
        The strong-minded rise to the challenge of their goals,the weak-minded BECOME HATERS

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          #5
          Re: Viewsonic VX910

          Not an exact match for the symptoms I am seeing, but check the transistors I have circled to see if they are shorted.

          PlainBill
          Attached Files
          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


            #6
            Re: Viewsonic VX910



            Attached Files

            Comment


              #7
              Re: Viewsonic VX910

              Originally posted by PlainBill
              Not an exact match for the symptoms I am seeing, but check the transistors I have circled to see if they are shorted.

              PlainBill

              Is it ok to test the transistors while still on the board? I had done some initial testing after getting your reply and the readings I was getting were rather odd. It seemed like however I placed the leads on my meter I always got a reading from it.

              Comment


                #8
                Re: Viewsonic VX910

                Originally posted by OSE
                Is it ok to test the transistors while still on the board? I had done some initial testing after getting your reply and the readings I was getting were rather odd. It seemed like however I placed the leads on my meter I always got a reading from it.
                OK, a newbie. We can handle that.

                Yes, you can test the transistors without removing them. Here is the procedure I use:

                Set the DMM to the lowest ohms ohms range - typically 200 ohms.

                There are three pins on these transistors (in the picture above, the pin at the left connects to the middle pin on the right). Numbering the pins on the right 1 - 3, measure the resistance 1 to 2, 1 to 3, and 2 to 3.

                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


                  #9
                  Re: Viewsonic VX910

                  I numbered the pins from the bottom to the top like I have below.

                  -3
                  -2
                  -1


                  For the transistor on the far left of the picture I got the following readings

                  1-2, 16.8
                  1-3, 8.9
                  2-3, 25.2

                  The next transistor ( second from the left) gave me these readings

                  1-2, 25.4
                  1-3, 9.1
                  2-3, 16.9

                  The two transistors on the right side of the picture do not produce a reading when connected from pins 1-2 and 1-3. They do however produce a reading of 168 Ohms when connected at pins 2-3.

                  I have attached a picture of my meter in case I may have a setting incorrect. Better to get something like that sorted out now rather than later.
                  Attached Files

                  Comment


                    #10
                    Re: Viewsonic VX910

                    Originally posted by OSE
                    I numbered the pins from the bottom to the top like I have below.

                    -3
                    -2
                    -1


                    For the transistor on the far left of the picture I got the following readings

                    1-2, 16.8
                    1-3, 8.9
                    2-3, 25.2

                    The next transistor ( second from the left) gave me these readings

                    1-2, 25.4
                    1-3, 9.1
                    2-3, 16.9

                    The two transistors on the right side of the picture do not produce a reading when connected from pins 1-2 and 1-3. They do however produce a reading of 168 Ohms when connected at pins 2-3.

                    I have attached a picture of my meter in case I may have a setting incorrect. Better to get something like that sorted out now rather than later.
                    Good idea posting the picture. You did the measurements properly. That 9 ohms sounds a little high, but the comparison to the other side indicates there is a problem.

                    If these transistors are the ones I expect, they should have the letters DK on one end, and Qx on the other (x can be any letter; on mine it was H). The actual part number is Rohm 2SC4672 and they are available from both Digikey and Mouser for about $.75 each.

                    Check the transformers, capacitors, etc. The service manual for a Belinea 101910 fits this monitor.

                    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


                      #11
                      Re: Viewsonic VX910

                      Originally posted by PlainBill
                      Check the transformers, capacitors, etc. The service manual for a Belinea 101910 fits this monitor.

                      PlainBill
                      now that you say it, i remember where i've seen those insides.. in my own Belinea 101910

                      caps are the primary suspect.

                      if you have an external 12V power supply with at least 1.5A, you could try to hook it up to the powersupplie's output pins while it's connected up.

                      sort of like this (notice the 2 wires going into the connector between the PSU and controller board)


                      that way the monitor should turn on.. easiest way to test if the inverter part of the powersupply and LCD controller board are OK.

                      i think the pins were labeled. if not, follow the traces from the pins to the cap right next to that pin header (on the power supply board!) which connects both boards. that's your "12V injection point"..
                      Last edited by Scenic; 05-26-2010, 03:40 PM.

                      Comment


                        #12
                        Re: Viewsonic VX910

                        Thanks for the help, ordered the transistors and hopefully will be able to report a successful repair.

                        Comment


                          #13
                          Re: Viewsonic VX910

                          as for the caps on the powersupply/inverter combo board, 16V caps will do just fine, as there's only 12V coming from the PSU..

                          they usually have 25V 470uF CapXons (crapxons) in there for some reason..
                          they get cooked to death in those monitors as they're pretty hot-running..

                          my own one is polymerized (16V 470uF nippon chemicon), allthough thats pretty much overkill..

                          good luck

                          Comment


                            #14
                            Re: Viewsonic VX910

                            Can I chime in on this thread? I have this same monitor, same issue, and my power supply board looks the same as well, with the same "burned" inverter on the right. If you look back at the very first picture he posted, the "white Box" on the right side has dark discoloration around it, and then the back picture on the left (where the white box now is) has a "circle" area of what appears to be a burned area. Mine looks just like that, and also on this forum somewhere I read that to test the ohms at the diodes on either side and you should get 750 ohms on boths sides, and if not, then one is probably failed. I did that test and I got 745ohms on one side, and 9 ohms on the other. The burned one, obviously game me the 9 ohm load. SO, none of my caps looked bulged at all, which I was disappointed to see, (hoping for an obvious quick fix) so, do the transisters sound like they would be the problem?

                            And OSE, did your repair work?

                            Comment


                              #15
                              Re: Viewsonic VX910

                              Originally posted by ajsemtb View Post
                              Mine looks just like that, and also on this forum somewhere I read that to test the ohms at the diodes on either side and you should get 750 ohms on boths sides, and if not, then one is probably failed. I did that test and I got 745ohms on one side, and 9 ohms on the other. The burned one, obviously game me the 9 ohm load.
                              For a diode test, turn your multimeter to the diode setting.

                              Put black probe on side and red on the other. Record the measurement. Then reverse the probes and record the measurement.

                              One should read around 0.5 to 0.7 and the other should be 0L.
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                                #16
                                Re: Viewsonic VX910

                                Originally posted by ppm007 View Post
                                Also check die Schottky Diode near those 2SC4672: D9 and D10

                                At a german board a guy with same problem wrote:
                                You can check both Inverters by R18,R22 and R20,23: if ok everyone should have 750 Ohm. If one Inverter is broken, the resistance should be lower
                                Technically, I wasn't doing a diode test. I was following this test that was on another thread in this forum. The thread was simply Viewsonic VX910 that was also discussing this problem. I haven't done the test on the transistors that was mentioned in this thread yet, as I went through a major cleaning upheaval in my office/shop/studio and my project was halfway reassembled to keep it together. I will hopefully get it back out this evening and test the points on the transistors and post the readings as well as pics later.

                                As for my experience, I'm a tinkerer, I have moderate soldering skills, but I am concerned about soldering those tiny little transisters... Any tips on soldering points that small? I have a 30 watt soldering iron and a 45 watt de-soldering iron, that I usually use to solder points on boards, because it makes pretty little points.. LOL and I can "cup" the molten solder in the nose instead of trying to feed wire solder into my iron tip.

                                Comment


                                  #17
                                  Re: Viewsonic VX910

                                  Originally posted by ajsemtb View Post
                                  As for my experience, I'm a tinkerer, I have moderate soldering skills, but I am concerned about soldering those tiny little transisters... Any tips on soldering points that small? I have a 30 watt soldering iron and a 45 watt de-soldering iron, that I usually use to solder points on boards, because it makes pretty little points.. LOL and I can "cup" the molten solder in the nose instead of trying to feed wire solder into my iron tip.
                                  I like the soldering videos by Curious Inventer on youtube.com. These are the 2 I suggest a lot to people, but he has much more on his channel.

                                  http://www.youtube.com/watch?v=3NN7UGWYmBY

                                  http://www.youtube.com/watch?v=I_NU2ruzyc4
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                                    #18
                                    Re: Viewsonic VX910

                                    WOw, those vids were great! Thank you for that. I got a lot of tips from those. Also, that's probably why my tips die so quickly, I don't tin them after I'm done, just clean them and boy do they get corroded!

                                    Back to my chip: OK well, I'm not going to add pics, because it looks exactly like the chip above in this thread, however, I did my own test for the transistors and heres what I got, again top to bottom 3-2-1.

                                    both on the right side were (closely enough to each other)
                                    1-2 745 ohms
                                    1-3 5.37k
                                    2-3 4.51k

                                    and the chips on the left

                                    1-2 9.8
                                    1-3 9.4
                                    2-3 .6 ohms

                                    SO, I would say those ones are definitely fried...

                                    Also, my caps are XICON. Haven't seen that name yet in these threads. Anyone? They do not seem to be bulged at all. :/ there are 2 470uf 35v and 2 330uf 35v. Oh, and a big one 1000uf 400v and a little one 10uf50v. Both those are CapXon.

                                    Are there any other components I should/can check that regularly fail with these power supplies? What's the final recommendation for chip repair? Thanks in advance for your help. If the monitor works again, great! If not, that sucks, but oh well. Already bought a replacement, but I don't throw anything away that I "might" be able to fix.

                                    Comment


                                      #19
                                      Re: Viewsonic VX910

                                      Originally posted by ajsemtb View Post
                                      Also, that's probably why my tips die so quickly, I don't tin them after I'm done, just clean them and boy do they get corroded!
                                      Yes, tin them after you are done. Tips are not cheap on quality irons.

                                      1-2 9.8
                                      1-3 9.4
                                      2-3 .6 ohms

                                      SO, I would say those ones are definitely fried...
                                      That is definitely shorted.

                                      Also, my caps are XICON. Haven't seen that name yet in these threads. Both those are CapXon.

                                      Are there any other components I should/can check that regularly fail with these power supplies? What's the final recommendation for chip repair? Thanks in advance for your help. If the monitor works again, great! If not, that sucks, but oh well. Already bought a replacement, but I don't throw anything away that I "might" be able to fix.
                                      I think any 19 inch LCD monitor is worth saving.

                                      Members here hate Capxon and recommend replacing all the Capxon.

                                      Caps do NOT have to bulge in order to be bad. They can out of uF tolerance and have ESR.

                                      You can also test our transistors and voltage regulators for shorts (with power OFF and monitor unplugged). Test to ensure all fuses are good. They should measure 0.3 ohms.

                                      I had zero soldering skills when I started, but I managed to install new transistors. The key to removing the old ones is to ADD a bit of fresh 60/40 solder. Then I use a solder sucker to remove all the solder. This is usually good enough so I can remove the old transistor.
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                                        #20
                                        Re: Viewsonic VX910

                                        Ok, now you can officially laugh at me... What are the fuses on this board? If they don't plug in somewhere, I wouldn't know they were fuses! LOL And to clarify, the transistors are are mounted to the heat sink? (other than the tiny ones on the bottom?)

                                        Also, looking at this board a little closer, I'm thinking these caps have already been replaced once. Well, the Xicon ones anyway. The reason why, is a couple aren't sitting flush and the solder jobs on the back are good, but not great, and appear to have some heat coloring around the points that are similar to not careful soldering, but I suppose could be from the Caps... Do caps get hot? ANywho, I've seen on these posts where to buy these parts, so I will order the tiny little transistors, and the caps and hopefully have a working lcd again.

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