Announcement

Collapse
No announcement yet.

Viewsonic VX912 on/off/fizz/quiet

Collapse
X
Collapse
 
  • Page of 1
  • Filter
  • Time
  • Show
Clear All
new posts
Previous template Next
    #1

    Viewsonic VX912 on/off/fizz/quiet

    Hello, googled the problem, i think the forum might already have a smiliar answer, i have attached a ropey pic


    upon turn on now with just mains connected, there is a fizz/quiet/fizz quiet. the power light split-second flashes on green, then off 1 second, repeat, and co incides with the fizz. monitor is about 5 years old

    http://pic0.picsorlinks.com/ph_or_61085_adfc46f.jpg

    The only noticeable damage is the transformer, which appears to have signs of toasting (brown crisp residue - maybe should be light yellow?). caps and components appear intact, altho the 3 top-right caps are bulging slightly.


    the smell of the toasty transformer does seem to match a very faint smell, upon the computer initially crashing

    the monitor has taken out 2 motherboards with it so far - had image on 0.5 secs, off 1 sec, repeat for a few seconds, then (i believe) motherboard went.

    obv i think when the monitor is turned on and nothing attached, the power LED shouldn't give split second flashes, and shouldnt get the fizz. so possibly can test without the motherboard/vga card connected

    Just wondering if anyone knows if this problem, (main control cct board, or power board). altho of course couldnt rule out a fault with the main cct board, which might cause the power board (transformer) to pop. Thanks
    Last edited by quartz; 11-22-2010, 07:01 AM.
    Tags: None
    #2
    Re: Viewsonic VX912 on/off/fizz/quiet

    Clearer pictures please. Then maybe we can be of help.
    Originally posted by PeteS in CA
    Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
    A working TV? How boring!

    Comment

      #3
      Re: Viewsonic VX912 on/off/fizz/quiet

      1) Post clear focused pictures AFTER reading

      https://www.badcaps.net/forum/showthread.php?t=1868

      2) Please do not post pictures inline as they slow down the loading of pages.

      3) For best picture quality and clarity take your boards to a window on a sunny day, turn flash off, and use macro mode. Take a top down view of all your boards (front and back). Make sure the photo is legible so that we can read the PCB printing clearly. A shutter speed of 1/125 or faster will produce nice clear focused pictures. Try to get a photo that is 2000x2000 resolution or as close as possible.

      4) Here is an example of the pictures we want.

      https://www.badcaps.net/forum/showpo...94&postcount=1
      --- 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.

      --- end sig file ---

      Comment

        #4
        Re: Viewsonic VX912 on/off/fizz/quiet

        have just repaired one,and the problem was the Large filter cap thatyou cannot miss....100uF 400v..would not even move my ESR meter,and the same transformer was burning up.

        Comment

          #5
          Re: Viewsonic VX912 on/off/fizz/quiet

          thanks will put those in & check pics

          you wouldnt know what the burn-up L111 transformer is at all ? I've made out

          sp18le00081 5p7

          hi-pot 0503 og

          Comment

            #6
            Re: Viewsonic VX912 on/off/fizz/quiet

            Located a good picture

            (this is a stock photo, not my actual board)

            I'm not sure if I inserted the image wrongly
            Attached Files
            Last edited by quartz; 11-22-2010, 02:52 PM.

            Comment

              #7
              Re: Viewsonic VX912 on/off/fizz/quiet

              Good job on the picture!

              That is not a transformer, rather a coil. If that is burnt, something failed just beyond it and I agree with Rtech that the mains cap is likely the primary suspect. If you have a known good cap from another piece of equipment that is (a) close in capacitance (80-150uF) and (b) greater than or equal to in voltage, you could remove the original and substitute it for a temporary test.

              An old computer PSU is a good source for these.

              Toast
              veritas odium parit

              Comment

                #8
                Re: Viewsonic VX912 on/off/fizz/quiet

                thanks, yep, i dont mind buying the caps needed, small enough money if its not a fix, just trying to find out if i can buy that coil component

                (in case anyone can verify) I have actually found this board with a 'Z' on the end of the model number, not expensive, but tbh I want to try and replace some components.

                Comment

                  #9
                  Re: Viewsonic VX912 on/off/fizz/quiet

                  Not likely to find that coil. Again, finding one from another unit may be the only choice. I would remove the coil and do a resistance check on each side. If they match, then I don't think it will be a concern once the caps are done.

                  A good way to localize the noise is to use a paper towel tube held to your ear. (Poor man's stethoscope) It should get you very close to the source.

                  Toast
                  veritas odium parit

                  Comment

                    #10
                    Re: Viewsonic VX912 on/off/fizz/quiet

                    Have you checked the underside of board see whats burnt?

                    Comment

                      #11
                      Re: Viewsonic VX912 on/off/fizz/quiet

                      thanks. continuity on the coil beeps for both of them, both wires seem intact ? just the plastic coating on the wires may have heated up a bit. pcb itself is intact, just a slight haze which might have been the plastic giving off some smoke or something ?

                      actually i just removed the coil component from the pcb again and 1 corner of the black plastic wall broke off. must have been weakened or something. is the coil just a lump of wire or does it have insulation from each winding ? might be best just to get a new board anyway..

                      Comment

                        #12
                        Re: Viewsonic VX912 on/off/fizz/quiet

                        Basically yes, a lump of wire. Resistance should match and will be less than 1 ohm.

                        It's actually 2 coils on one core that the mains power travels through to the board. Hot (Line) on one side and Neutral on the other. It's an EMI filter coil/choke to keep the switching "noise" off the mains.

                        Toast
                        veritas odium parit

                        Comment

                        Previous template Next
                        Working...