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JVC HR-J837MS no power??

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    #1

    JVC HR-J837MS no power??

    Hello Everyone,

    One of my friends bought in a faulty JVC HR-837MS VCR today. It has a strange problem. It doesn't seem to receive any power. Sometimes when I plug it in, it buzzes for a second and stops.
    I think that the power supply unit is most likely dead but the only problem is that I can't open it up! The Power supply unit is covered by a metal casing and is welded to the PCB.

    Through naked eye inspection, nothing seems to be burnt on the PCB. The caps seem fine. The 250V cap isn't bulged. All the low voltage caps are Elna, Sanyo and Tosin brand. The 250V fuse is still intact and isn't blown. My friend told me that it was working the day before and decided to die the next day.

    Does anyone know whats probably wrong so I can I have some idea of where to start.
    I fix computer components, not VCR so I only have a vague understanding of the whole concept.

    I'll get photos soon. I just has to wait for the trusty Sony Cybershot to finish charging.

    Thanks.
    Don't find love, let love find you. That's why its called falling in love, because you don't force yourself to fall, you just fall. - Anonymous
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    #2
    Re: JVC HR-J837MS no power??

    maybe power surge?
    some info here https://www.badcaps.net/forum/showthread.php?t=245&
    capacitor lab yachtmati techmati

    Comment

      #3
      Re: JVC HR-J837MS no power??

      Hello Everyone,

      My Camera finished charging, so here are some pictures of the internals.

      Originally posted by willawake
      maybe power surge?
      It could be a power surge, but I'm not very sure. This unit hasn't been used in months after it gave up on its owner.

      If i am lucky, the unit will give off a short buzzing noise, but thats all it can do for now, intermittently buzz....

      The mechanic of the VCR look very clean except for a few dust particles. I wonder if we can have widescreen tapes?? I highly doubt it but.... there's a "Wide Quality" button on the front of this unit.... I wonder what that button does??

      Anyway, I don't know whats wrong with it apart from the unit not powering up. Any advice would be great.

      Thanks.
      Attached Files
      Last edited by stevo1210; 04-28-2007, 09:06 AM.
      Don't find love, let love find you. That's why its called falling in love, because you don't force yourself to fall, you just fall. - Anonymous

      Comment

        #4
        Re: JVC HR-J837MS no power??

        post a pic of the psu.
        iirc that one uses a switcher and had a 1@50 that would dry out.

        Comment

          #5
          Re: JVC HR-J837MS no power??

          The Power supply unit is covered by a metal casing and is welded to the PCB.
          PCBs are made out of not conductive material, they don't weld very well!

          JK! The sheild is probably soldered on the board with very large joints. Flip the board over and get an iron on the big solder lugs. Sucking the solder away when it melts usually helps, too.

          Comment

            #6
            Re: JVC HR-J837MS no power??

            Originally posted by Spacedye69
            PCBs are made out of not conductive material, they don't weld very well!

            JK! The sheild is probably soldered on the board with very large joints. Flip the board over and get an iron on the big solder lugs. Sucking the solder away when it melts usually helps, too.
            Spacedaye69, I think you are correct. I guess it is welded onto some big solder lugs undernaeath. I'm not sure because I cant look from underneath the PCB yet since I cant take the mechanics off the board.

            I dont know which screws to take off first to release the mechanics from the PCB without making everything fall apart.... I can't put it back together if I take off the wrong screws and the whole tape drive section fall apart.

            Does anyone know how to take off the Mechanical tape drive section off the PCB?? e.g. which screws to take off etc.

            I can provide more pictures if anyone wants if that helps at all. I just need to somehow take off the mechanical section without making it all fall apart and i'll be fine the rest of the way.... hopefully....

            Thanks.
            Don't find love, let love find you. That's why its called falling in love, because you don't force yourself to fall, you just fall. - Anonymous

            Comment

              #7
              Re: JVC HR-J837MS no power??

              Pull the front plate off(the section with the door and controls) and remove the outer srews that hold the pcb down. The board should lift out with the mechanics still attached. Others I've seen, the assembly is held to the board with plastic clips.

              Comment

                #8
                Re: JVC HR-J837MS no power??

                Hi everyone,might be something here http://www.e-repair.co.uk .I found it pretty intresting.

                RegR

                Comment

                  #9
                  Re: JVC HR-J837MS no power??

                  Originally posted by kc8adu
                  post a pic of the psu.
                  iirc that one uses a switcher and had a 1@50 that would dry out.
                  I finally got around to taking the whole board and video machanism out (turned out quite easy to remove) and I measured at Elna cap right next to a Nippon chemicon 250V cap.

                  The Elna cap is a 2.2uf 50V cap and it has no continuity on my ohm meter. I think that cap is the culprit in the no power issue, all other caps had continuity.

                  Thanks.
                  Don't find love, let love find you. That's why its called falling in love, because you don't force yourself to fall, you just fall. - Anonymous

                  Comment

                    #10
                    Re: JVC HR-J837MS no power??

                    Oh great.... I measured every 50V cap in that VCR and they all have the same reading of no continuity. I must have done something wrong. I know that all the caps can't be bad at once.... How do I know if a cap is dry??
                    Don't find love, let love find you. That's why its called falling in love, because you don't force yourself to fall, you just fall. - Anonymous

                    Comment

                      #11
                      Re: JVC HR-J837MS no power??

                      you need an esr meter to test caps.the ones you are testing wont move the meter much as they charge like larger ones will.

                      Comment

                        #12
                        Re: JVC HR-J837MS no power??

                        sounds like the psu is your problem
                        sounds like it might be trying to start but cant
                        (granted something on the other boards maybe causing this but not likely)

                        As KC8 has said, unless a cap of that size had gone short circuit A multimeter is not very useful for checking them.

                        Larger values you can get an idea by the fact its changing...but this is still not a definitive test.
                        ESR meter is best for trouble shooting large caps in psu's smaller ones are cheap so if you suspect them best just replace them.
                        (a lot of the time not the fault but can be if around the controller)

                        Sounds like its a fault in the psu but probably may not be a cap fault.
                        Trouble shooting procedures for SMPSU's found here and else were is what you are going to have to follow to resolve this one.

                        like is the fuse blown is the chopper transistor dead are the rectifier diodes ok, then look into possible causes of why they died.

                        the other alternative is to search the net for possible common failure faults for this model.

                        Heres a link on troubleshooting SMPSU's

                        Be careful all disclaimers apply here...they can kill U

                        HTH cheers
                        Last edited by starfury1; 08-24-2007, 10:20 AM.
                        You step into the Road, and if you don't keep your feet, there is no knowing where you may be swept off to." Bilbo Baggins ...

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