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Can anyone help with this repair? Thanks :)

Discussion in 'Electronic Repair' started by ljones, Oct 9, 2004.

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  1. ljones

    ljones Guest

    Hi,

    I have an old (I believe it was made around 1990/91ish) VCR. It's an
    SVHS model - a Sanyo VHR-S700E (Stereo, PAL; I'm in the UK). I'm trying
    to repair this vcr but I can't pinpoint exactly what the trouble is or
    where I should look.

    These are the problems:

    * The VU LEDs don't light up at all ( they should light up to show the
    volume levels; so far I've never seen them light up at all).

    * The tape refuses to rewind, forward wind or play - the video tries to
    but aborts the attempt.

    There is another problem which I will come to in a moment.

    First of all I thought that the second problem (regarding forward wind,
    etc) might have been the capstan and that it might have ceased up or
    needed oiling. I tried to do this with some sweing machine oil but it
    seems to have had no effect (though I did this with the capstan still in
    the machine).

    However the LED problem points to (I'm guessing) a possible power
    supply. Here is a picture of the inside of the VCR with the cable (I'm
    guessing) carries the power for the LEDs; there's a ribbon cable that
    connects nearby I guess this carries the signals to light up which LEDs
    need to be lit;

    http://img21.exs.cx/img21/9621/11142.jpg

    You can see another picture of the power supply section here - note the
    power supply is hard to get to and most of it inside a metal can:

    http://img21.exs.cx/img21/9408/11143.jpg

    There is a third problem though. I've noticed while I've had the video
    apart that any usage of the tape (eg trying to wind forward, back, etc)
    I have found one chip near the bottom of the capstan (on the underside
    of the video) seems to get very hot very quicky. Here's a picture:

    http://img21.exs.cx/img21/7159/3a4.jpg

    I'm guessing the big wheel in that picture with the belt on it is the
    underside of the capstan.

    Incidentally, here are some pictures of the capstan:
    http://img21.exs.cx/img21/8303/11144.jpg
    http://img4.exs.cx/img4/1299/13031.jpg

    And the left hand side of the VCR with the non-functioning VU meters:
    http://img4.exs.cx/img4/7922/13032.jpg

    Can anyone figure out what the problem is exactly? Are all these faults
    seperate or interlinked in some way? I'm guessing this might all be down
    to a power supply problem but where do I start looking? Does the fact
    the chip gets hot mean it is dead or just being fed bad voltages?

    :)

    Thanks for any help.

    ljones
     
  2. NSM

    NSM Guest

    |
    | Hi,
    |
    | I have an old (I believe it was made around 1990/91ish) VCR. It's an
    | SVHS model - a Sanyo VHR-S700E (Stereo, PAL; I'm in the UK). I'm trying
    | to repair this vcr but I can't pinpoint exactly what the trouble is or
    | where I should look.
    ....
    | First of all I thought that the second problem (regarding forward wind,
    | etc) might have been the capstan and that it might have ceased up or
    | needed oiling. I tried to do this with some sweing machine oil but it
    | seems to have had no effect (though I did this with the capstan still in
    | the machine).
    ....

    Sewing machine oil? Might as well shotgun it to death now.

    N
     
  3. ljones

    ljones Guest

    I found a FAQ on the internet which mentioned doing this and not to use
    something like WD40. It suggested (from memory) using a thicker oil or
    lubricant, not WD40 but sewing machine oil or machine oil.

    I do notice that with the brake disengaged the capstan moves quite
    freely by hand - but how free is free? I don't know if it moves enough.

     
  4. If you tried lubricating it and nothing much changed, that wasn't the problem
    (whether you made it better or worse doesn't matter for this conclusion!).

    Since I believe you had multiple symptoms, if they all happened at the same
    time one must search for a common problem. It could all be power supply
    related.

    If the machine was sitting around for a couple years and now has these
    problems, then they might be unrelated.

    First, do the cleaning and checking in the FAQ.

    Check the power supply voltages at standstill and while it's trying to
    move the tape.

    Sorry, I don't recall the other specific problems.

    --- sam | Sci.Electronics.Repair FAQ Mirror: http://repairfaq.ece.drexel.edu/
    Repair | Main Table of Contents: http://repairfaq.ece.drexel.edu/REPAIR/
    +Lasers | Sam's Laser FAQ: http://repairfaq.ece.drexel.edu/sam/lasersam.htm
    | Mirror Sites: http://repairfaq.ece.drexel.edu/REPAIR/F_mirror.html

    Note: These links are hopefully temporary until we can sort out the excessive
    traffic on Repairfaq.org.

    Important: Anything sent to the email address in the message header is ignored.
    To contact me, please use the feedback form on the S.E.R FAQ Web sites.
     
  5. NSM

    NSM Guest

    | NSM wrote:

    | > Sewing machine oil? Might as well shotgun it to death now.

    | I found a FAQ on the internet which mentioned doing this and not to use
    | something like WD40. It suggested (from memory) using a thicker oil or
    | lubricant, not WD40 but sewing machine oil or machine oil.

    WD-40 is not a lubricant - it's a rust penetrator. Sewing machine oil often
    contains solvents or kerosene. Lubricants for electro mechanical devices
    should be the ones recommended by the manufacturer, unless you are very
    skilled and experienced in which case the brave may substitute.

    | I do notice that with the brake disengaged the capstan moves quite
    | freely by hand - but how free is free? I don't know if it moves enough.

    Technicians use special equipment which can measure the torques etc. for
    these devices.

    Always fix the electrical problems first - the VU meters etc. It's possible
    that this indicates why the rest doesn't work. These things are a nightmare
    of motors, clutches, brakes etc., and if the power supply is faulty it's no
    surprise things don't work right.

    N
     
  6. ljones

    ljones Guest

    :) Thanks for that, but should I just take the entire power supply right
    out of the VCR to test it, or should I try to do it within the VCR
    first? The only problem is half of it seems to be mounted in a
    hard-to-get-to tin box x.x :(

    thanks

    ljones
     
  7. You'll want to test it under normal load. So, if you can get at its outputs,
    it should be left in the VCR. Of course, knowing WHAT the proper voltages
    should be may be more challenging. But if what are obviously DC outputs
    vary significantly as you attempt to run the various functions of the
    VCR, the power supply will be suspect.

    See the various FAQs on these topics.

    --- sam | Sci.Electronics.Repair FAQ Mirror: http://repairfaq.ece.drexel.edu/
    Repair | Main Table of Contents: http://repairfaq.ece.drexel.edu/REPAIR/
    +Lasers | Sam's Laser FAQ: http://repairfaq.ece.drexel.edu/sam/lasersam.htm
    | Mirror Sites: http://repairfaq.ece.drexel.edu/REPAIR/F_mirror.html

    Note: These links are hopefully temporary until we can sort out the excessive
    traffic on Repairfaq.org.

    Important: Anything sent to the email address in the message header is ignored.
    To contact me, please use the feedback form on the S.E.R FAQ Web sites.
     
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