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Pioneer CLD-92 not reading laser disks

Discussion in 'Electronic Repair' started by Andy Cuffe, May 21, 2007.

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  1. Andy Cuffe

    Andy Cuffe Guest

    This high end laser disk player from 1990 plays CDs fine, but when a
    LD is inserted, it only spins for a few revolutions before it ejects
    it. My first instinct would be to say the optical pickup is bad, but
    other LD players I've seen with problems try a lot harder to play
    before giving up. I don't think it's the spindle motor because when
    it's playing a CD it has plenty of torque (I actually can't slow down
    the disc by holding the spindle). The pickup moves freely and the
    tilt motor is working. Since I don't have a service manual, I'd like
    to hear any ideas before I really dive into it.
    Andy Cuffe

     
  2. So the spindle motor on this one is used for both LDs and CDs?

    With only a few revolutions and I assume never getting up to speed, it
    can't even know if the LD is valid so sounds like it may be shutting
    down due to another problem.

    There is also the newsgruop alt.video.laserdisc though they don't do
    much in the way of repair there.

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

    Important: Anything sent to the email address in the message header above is
    ignored unless my full name AND either lasers or electronics is included in the
    subject line. Or, you can contact me via the Feedback Form in the FAQs.
     
  3. Andy Cuffe

    Andy Cuffe Guest

    Yes, it uses the same motor for both which is obviously massive
    overkill for CD playback. Since it has lots of torque when playing a
    CD, I would think it could spin a LD faster than it does.

    It never gets faster than about 10 RPM when loading a LD. I can see
    some RF at the test point (although way below its normal frequency due
    to the low speed), so it must be more or less focusing.

    It seems strange that it gives up so fast. Other LD players will
    grind away for a couple of minutes when they have trouble playing a
    disc. It's also odd that it ejects the disc when it fails. I'm
    hoping someone can tell me what this model normally does when it can't
    play a LD.

    I've already checked for obvious problems such as power supply
    voltages and gross mechanical problems. I'll double check for sensor
    problems that might be causing it to reject the disc.
    Andy Cuffe

     
  4. It does realize it's an LD in there and not a CD, right? :)

    With any RF, it's focusing. I assume you mean 10 rps. I doubt there is
    any way it can conclude the LD is bad at 10 rps. I assume you've tried
    more than one LD.

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

    Important: Anything sent to the email address in the message header above is
    ignored unless my full name AND either lasers or electronics is included in the
    subject line. Or, you can contact me via the Feedback Form in the FAQs.
     
  5. Andy Cuffe

    Andy Cuffe Guest

    It does correctly say LD in the display. I actually do mean 10 RPM!
    It's a stretch to call it RF at that speed, but there's a definite
    signal at the test point. I compared it to a different LD player and
    it spins up the disc as soon as it detects it.

    It's definitely a problem with the LD spindle servo which is separate
    from the CD servo. There's virtually no voltage on the LD spindle
    error line (which is labeled on the board). I tried applying an
    external voltage to it through a 10 k resistor and the spindle motor
    immediately came up to speed (of course, not in sync). I traced the
    error signal back through an amplifier circuit and everything seems
    fine there. It then goes back to a large custom IC.

    By this time, the player was working better than before. It was
    actually spinning the disc at almost the right speed and produced
    intermittent video. After allowing it to cool down it was exactly as
    it was before. Leaving it turned on in stop mode for about 30 minutes
    is enough to get it to start partially working again.

    Clearly there's a thermal problem. Hopefully just an electrolytic
    somewhere. A couple of times it has suddenly turned itself off
    without warning (as if I had pulled the plug). I'm going to pull the
    power supply and also check the various regulator circuits scattered
    around the other boards. Fortunately, unlike most Pioneer LD players,
    most of the boards are accessible while the player is assembled.
    Andy Cuffe

     
  6. Freeze spray time!

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

    Important: Anything sent to the email address in the message header above is
    ignored unless my full name AND either lasers or electronics is included in the
    subject line. Or, you can contact me via the Feedback Form in the FAQs.
     
  7. 1ziggi1

    1ziggi1 Guest


    How much voltage? I have the exact same problem on a CLD95. 0 voltage
    and no signal on the error line but when I applied 2 volts to the
    error line the spindle motor starts to spin up for a few seconds.
     
  8. Andy Cuffe

    Andy Cuffe Guest

    I've set this project aside for a while. I will post back if I make
    any progress. It's not a high priority at the moment.
    Andy Cuffe

     
  9. Andy Cuffe

    Andy Cuffe Guest


    I found a beat up, but working low end model with the same transport.
    To cut a long story short, it was the pickup. Swapping the pickup
    from the parts machine into the CLD-92 got it working. It didn't even
    need any alignment.

    Andy Cuffe

     
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