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    #41
    Re: Viewsonic VX910

    OK, quick question. Should I be using Lead or Silver or lead free solder? I had another question, but it escapes me.. Sorry if I post again a short question in a few minutes...

    Comment


      #42
      Re: Viewsonic VX910

      Ok, just to update, I resoldered the pins to the transformer that is on the failing side of the inverter board. I believe 1 side works, and the other doesn't because of values I've found on other threads match up. I desoldered 1 leg of each resistor that has heat shrink tube around it to test its value, and they are both in tolerance, (which was disappointing because the really big Cap was holding voltage for like 10 minutes and I read on another thread about that happening and a resistor being faulted and that solving that problem... )

      I have also desoldered the MOSFET to test. When my DMM probes are not touching in OHM mode, it reads (blinking) 1 (not blinking)0.00M ohm. Closed (probes touching) it reads .1 ohms. With the continuity tester it has a blinking 1 followed by .000K when open, .001k OHMs when closed. And on diode mode 1.470 V open and 000 V closed. Just point of reference for the following tests.

      ohms:
      1-2 Blinking 10.00M
      1-3 blinking 10.00M
      2-3 17.68m counting down

      1-2 no continuity
      1-3 "
      2-3 "
      Diode
      1-2 1.470
      1-3 1.469
      2-3 .489V

      Can anyone tell me if I have successfully tested this MOSFET? I don't know if I even tested it right or not, and if I did what the results mean. Also, I tested with the black probe on the left, then went back with black on right, and that way they all failed...
      Attached Files

      Comment


        #43
        Re: Viewsonic VX910

        Oh, and the other question was, can I test capacitors with a DMM without capacitance test? There was no ohm readings, continuity, or voltage (with diode test) on their respective function on the meter...

        Comment


          #44
          Re: Viewsonic VX910

          Originally posted by ajsemtb View Post
          Can anyone tell me if I have successfully tested this MOSFET?
          Those results look okay.
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            #45
            Re: Viewsonic VX910

            Originally posted by ajsemtb View Post
            can I test capacitors with a DMM without capacitance test?
            To test a cap properly, you need to test 2 things.

            The uF itself. A multimeter with a capacitance check is required. For example, a 1000uF cap should measure roughly 1000uF. If it reads 88uF, it is obviously bad.

            The second parameter to test is the ESR. A cap used in a SMPS environment should test around 0.3. An ESR tester is required to measure this.
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              #46
              Re: Viewsonic VX910

              Originally posted by ajsemtb View Post
              Retired, I did that test on the transformer still installed, the best I could, and the one transformer T2 tests with 745 ohms, which I've read somewhere is supposed to be right. This one is testing 55.9 ohms.
              Okay, let's run this test again as per post #36 and post the actual results of all your readings. I would like to see the actual pin to pin readings (the raw data) with the exact ohms reading for each one.

              Just so we are clear, we are testing the two transformers in the upper corners near the connectors to the CCFL. I can't make out the designation because we don't have a decent picture (hint).
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                #47
                Re: Viewsonic VX910

                Here are some good pics. (hint taken) Now keep in mind that this board has been recapped before with blue Xicon's and there is no way to know how much of the burn marks (dark areas) are from previous repairs and my repairs. In this pic, all the aluminum caps have been replaced with Panasonics (including the start up cap now) except for the big Kahuna. I have enough ceramic caps on order to replace the 2 little blue ones right by the littler transformers as well as the poly cap thats red on the other side of the transformer.

                I can't perform that test right now because I have taken off the little transistors on the bottom to replace and I haven't reinstalled them yet. However, after removing them and testing them via ohm and diode test, it actually tested good, but I destroyed the other on removing it (they are tiny little suckers...). So I may not have popped them as I had thought before. No way to know now... OH I just remembered I actually did that test again, and no I don't have the exact number but it was around 55 ohms before I removed the transitors.

                I'll do the test again once I have them back in place. Also, I should have the rest of my parts tomorrow for the other repairs.

                Also, I tested the resistors in R18 and R22 and they are in tolerance to about 10%.

                And also in these pics, the MOSFET is out. you say it sounds like its working?
                Attached Files

                Comment


                  #48
                  Re: Viewsonic VX910

                  Originally posted by ajsemtb View Post
                  I can't perform that test right now because I have taken off the little transistors on the bottom to replace and I haven't reinstalled them yet.
                  To test the transformers, you don't need any of those transistors installed.

                  You just need to measure the resistance (with power off and unplugged) of the legs of those EPC-19 transformers. Ideally, they should be measured out of circuit, but let's measure them in circuit once more. If the readings look funny, we can remove the transformer and remeasure out of circuit.
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                    #49
                    Re: Viewsonic VX910

                    Originally posted by retiredcaps View Post
                    To test the transformers, you don't need any of those transistors installed.

                    You just need to measure the resistance (with power off and unplugged) of the legs of those EPC-19 transformers. Ideally, they should be measured out of circuit, but let's measure them in circuit once more. If the readings look funny, we can remove the transformer and remeasure out of circuit.

                    I have another question about that. I know you will probably want a picture but on the bottom there is some white glue substance over some of the pins. How do I remove it to remove the transformer if I Need to?

                    Comment


                      #50
                      Re: Viewsonic VX910

                      Originally posted by ajsemtb View Post
                      I have another question about that. I know you will probably want a picture but on the bottom there is some white glue substance over some of the pins. How do I remove it to remove the transformer if I Need to?
                      That glue was probably used during the assembly process to hold some component in place until it is finally soldered in.

                      I usually just use my fingers to pry apart the glue. Others use an exacto knife.
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                        #51
                        Re: Viewsonic VX910

                        Sure, take the easy way out...

                        Comment


                          #52
                          Re: Viewsonic VX910

                          Originally posted by ajsemtb View Post
                          Sure, take the easy way out...
                          Actually, I don't have an exacto knife at home. Plus some of the older monitors I have fixed have hardened glue so it comes off pretty easily with just the fingers.
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                            #53
                            Re: Viewsonic VX910

                            I pulled the transformer, because with all this tinkering, and the fact I have a desoldering tool helps, its becoming easier to start pulling parts... I think this may be a problem. I attached a picture of it, and I'm not getting ohms readings and barely any continuity between pins. If looking at the picture, lets call the top 4 pins T1-T4 then Bottom 6 B1-B6. To simplify, I only get ohms readings between pins T2 and T4 429 ohms, B1 and B6 .2ohms B2 and B4 .2ohms B3 and B5 .2 ohms. Continuity tests agree with those pairs. Nothing else connects... Sound good or bad? I can't find a data sheet other than dimensions anywhere. On the parts list it says X'FMR, EPC-19H (12P), D=0.05, 1700Ts, FSP035-1PI01, 150mH Anyone want to decode that please? I know its a transformer, and the model is EPC-19 H Beyond that... It is also 10 pin. The letters on the side of it are
                            SPI STJ00029
                            0505 1 FC
                            Attached Files

                            Comment


                              #54
                              Re: Viewsonic VX910

                              Originally posted by ajsemtb View Post
                              I pulled the transformer, because with all this tinkering, and the fact I have a desoldering tool helps, its becoming easier to start pulling parts... I think this may be a problem. I attached a picture of it, and I'm not getting ohms readings and barely any continuity between pins. If looking at the picture, lets call the top 4 pins T1-T4 then Bottom 6 B1-B6. To simplify, I only get ohms readings between pins T2 and T4 429 ohms, B1 and B6 .2ohms B2 and B4 .2ohms B3 and B5 .2 ohms. Continuity tests agree with those pairs. Nothing else connects... Sound good or bad? I can't find a data sheet other than dimensions anywhere. On the parts list it says X'FMR, EPC-19H (12P), D=0.05, 1700Ts, FSP035-1PI01, 150mH Anyone want to decode that please? I know its a transformer, and the model is EPC-19 H Beyond that... It is also 10 pin. The letters on the side of it are
                              SPI STJ00029
                              0505 1 FC
                              The continuity readings would be normal. Remember, this is a Royer oscillator. Look at Figure 2 in this application note.

                              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


                                #55
                                Re: Viewsonic VX910

                                Yeah, so I FIXED IT!!!!! With all y'alls help of course. I got my parts in and I don't know exactly what part fixed it, because I just decided to replace EVERYTHING, and didn't do tests in between... SO on this board, I replaced all the Aluminum Capacitors, the 2 ceramic blue caps by the transformer on the right side of the board, the 2 little transistors on the bottom of the board, the red poly cap on the top of the board (with one that was the same amounts, but it was bigger 15mm leads instead of 10mm leads, but I bent them to look like spongebob Square pants and legs and it fit fine... , resoldered the transformer, tested the MOSFET, tested the resistors at R112 and R320 by desoldering 1 leg and doing an ohm reading, all in tolerance. And now it works!!! All in all, less than $20 in parts and shipping, still cheaper than a new power supply!

                                SO my suggestion to anyone who has this board and will come on this thread in the future, change your caps (including the tiny startup cap, but not necessarily the huge one unless its bulging) replace the little blue caps right by the transformers, the red cap in front of the transformers marked 154, and replace the tiny transistors on the bottom of the board. Not really hard, just be careful with your soldering iron that you don't miss and hit something else... :/ And watch the videos on this thread about surface mount soldering. Thanks to RetiredCaps, PlainBill and everyone else that helped me with this repair!!!

                                Someday I'll get a capacitance meter and be able to figure out which of these caps actually failed... Yes, I will keep them until I can check them so I know... LOL

                                Attached is a pic of my "array" with it back in its place in the middle..
                                Attached Files

                                Comment


                                  #56
                                  Re: Viewsonic VX910

                                  Originally posted by ajsemtb View Post
                                  Yeah, so I FIXED IT!!!!! With all y'alls help of course. I got my parts in and I don't know exactly what part fixed it, because I just decided to replace EVERYTHING, and didn't do tests in between... SO on this board, I replaced all the Aluminum Capacitors, the 2 ceramic blue caps by the transformer on the right side of the board, the 2 little transistors on the bottom of the board, the red poly cap on the top of the board (with one that was the same amounts, but it was bigger 15mm leads instead of 10mm leads, but I bent them to look like spongebob Square pants and legs and it fit fine... , resoldered the transformer, tested the MOSFET, tested the resistors at R112 and R320 by desoldering 1 leg and doing an ohm reading, all in tolerance. And now it works!!! All in all, less than $20 in parts and shipping, still cheaper than a new power supply!

                                  SO my suggestion to anyone who has this board and will come on this thread in the future, change your caps (including the tiny startup cap, but not necessarily the huge one unless its bulging) replace the little blue caps right by the transformers, the red cap in front of the transformers marked 154, and replace the tiny transistors on the bottom of the board. Not really hard, just be careful with your soldering iron that you don't miss and hit something else... :/ And watch the videos on this thread about surface mount soldering. Thanks to RetiredCaps, PlainBill and everyone else that helped me with this repair!!!

                                  Someday I'll get a capacitance meter and be able to figure out which of these caps actually failed... Yes, I will keep them until I can check them so I know... LOL

                                  Attached is a pic of my "array" with it back in its place in the middle..
                                  All you need is two more and Halle Berry reading a book.

                                  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


                                    #57
                                    Re: Viewsonic VX910

                                    Good job on fixing your monitor. I have a Viewsonic VX710 that has the same power supply and it also had bad electrolytic caps. I've seen some debate on the forums about whether the big primary-side filter cap should be replaced. They do fail. The 100uF, 400V filter cap on my VX710 did fail. When I desoldered it from the board, I found that one of the legs was broken or burned off inside the capacitor case. That seemed extreme.

                                    I also found the power supply controller chip had failed, probably because the main filter cap failed. The controller chip was a SG6841 surface mounted to the bottom of the board.

                                    I think this design from Viewsonic has bad cooling. The heatsinks are too small and the case ventilation is poor. Bad solder joints develop, the circuit board gets discolored. I guess we've seen that in your pics.

                                    Comment


                                      #58
                                      Re: Viewsonic VX910

                                      Originally posted by ajsemtb View Post
                                      Yeah, so I FIXED IT!!!!! With all y'alls help of course. I got my parts in and I don't know exactly what part fixed it, because I just decided to replace EVERYTHING, and didn't do tests in between... SO on this board, I replaced all the Aluminum Capacitors, the 2 ceramic blue caps by the transformer on the right side of the board, the 2 little transistors on the bottom of the board, the red poly cap on the top of the board (with one that was the same amounts, but it was bigger 15mm leads instead of 10mm leads, but I bent them to look like spongebob Square pants and legs and it fit fine... , resoldered the transformer, tested the MOSFET, tested the resistors at R112 and R320 by desoldering 1 leg and doing an ohm reading, all in tolerance. And now it works!!! All in all, less than $20 in parts and shipping, still cheaper than a new power supply!

                                      SO my suggestion to anyone who has this board and will come on this thread in the future, change your caps (including the tiny startup cap, but not necessarily the huge one unless its bulging) replace the little blue caps right by the transformers, the red cap in front of the transformers marked 154, and replace the tiny transistors on the bottom of the board. Not really hard, just be careful with your soldering iron that you don't miss and hit something else... :/ And watch the videos on this thread about surface mount soldering. Thanks to RetiredCaps, PlainBill and everyone else that helped me with this repair!!!

                                      Someday I'll get a capacitance meter and be able to figure out which of these caps actually failed... Yes, I will keep them until I can check them so I know... LOL

                                      Attached is a pic of my "array" with it back in its place in the middle..
                                      I am happy to your success and I am motivated to fix my 2 monitors now…
                                      Is it possible that you can provide the part numbers and where you ordered them from?

                                      I have replaced some caps already but still didn’t work. (See img)

                                      Thanks for you help…
                                      Attached Files

                                      Comment


                                        #59
                                        Re: Viewsonic VX910

                                        Originally posted by nasjatt View Post
                                        I have replaced some caps already but still didn't work.
                                        What is wrong with the monitor?

                                        For example, do you get a green power LED? Do you see the monitor flash on briefly?

                                        The more info you give, the better help you will get.
                                        --- begin sig file ---

                                        If you are new to this forum, we can help a lot more if you please post clear focused pictures (max resolution 2000x2000 and 2MB) of your boards using the manage attachments button so they are hosted here. Information and picture clarity compositions should look like this post.

                                        We respectfully ask that you make some time and effort to read some of the guides available for basic troubleshooting. After you have read through them, then ask clarification questions or report your findings.

                                        Please do not post inline and offsite as they slow down the loading of pages.

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                                        Comment


                                          #60
                                          Re: Viewsonic VX910

                                          Originally posted by retiredcaps View Post
                                          What is wrong with the monitor?

                                          For example, do you get a green power LED? Do you see the monitor flash on briefly?

                                          The more info you give, the better help you will get.
                                          The power light goes on/off fast and screen flashes with it
                                          < little slower then this

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