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Rotel 865Bx sounds super fast

Discussion in 'Electronic Repair' started by [email protected], Oct 2, 2007.

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  1. Guest

    Hi Gents,

    I have a rotel 865bx that has a problem. I have not worked on
    players, so any help would be appreciated.

    The problem is that after I insert a CD, and hit play, sometimes
    the counter speeds up and the music sounds super fast. If I tilt the
    player slightly, it sometimes stops. I have a couple of general ideas.

    1) Alignment problem?

    2) Intermittent that resolves when the pc board is flexed slightly?

    3) Other?

    Thanks.
    Steve
     
  2. Guest

    Is this skipping forward or it the pitch high like the chipmunks ?
    player. If it is skipping forward one of the sensors in the pickup may
    be partially occluded. If you can figure out how to set the tracking
    you might be able to compensate. Also, pickups are not all that
    expensive anymore, that is if you can get it.

    Is there anything special about this player that makes it worth
    fixing ? Even if it is an older unit and serves you well, that might
    make it worth it. If it has a metal to plastic ratio that can be
    detected, it may be worth it.

    If it is new junk just toss it.

    JURB
     
  3. James Sweet

    James Sweet Guest

    If the pitch has gone way up, I would look at the oscillator driving the
    DAC, that's about the only thing that can affect the playback speed.
     
  4. Arfa Daily

    Arfa Daily Guest

    That ain't quite exactly so, James. If the player is 'skipping'
    continuously, that can give the impression that it is going fast in the same
    way as when fast forward is pressed. Just about all 'standard' players fast
    forward by 'grab a block - skip five, grab a block - skip five etc '. If the
    player is really going fast as a result of clock trouble, the pitch of the
    playback sound will be altered, much as the pitch control alters things on
    disco CD decks. Otherwise, yes, I agree with you that it would have to be a
    clock issue.

    Perhaps the OP could confirm what he means exactly by "super fast". If it is
    a rapid skip, as I suspect it might be, the very first thing is to make sure
    that it is not something really simple like a button-push issue, and that
    the fast forward button is not being mechanically pushed somehow, in a way
    that gets resolved when the player is tipped / twisted. After that, it would
    be a case of removing the top, and observing the actions of the optical
    block and its drive gears when the problem is occuring. The drive for the
    sled should only be activated every 2 to 5 seconds or thereabouts. You
    should see the drive gear rotate a few teeth, and then stop. No overshoot,
    no shuffling about. Overshoot is often a sign of mechanical issues with the
    sled sticking. Erratic behaviour or shuffling is often a sign of a weak or
    dirty laser. You might try cleaning the lens just for sport.

    Other than that, it will be a case of just gently poking around the PCB with
    the butt end of a ballpoint pen, to see if you can locate an area which
    instigates or clears up the problem when disturbed. It could of course be an
    issue internal to the laser, in which case, poking the PCB is unlikely to
    yield a result.

    Finally, do not be tempted to make any adjustments - mechanical or
    electronic. Even if it has any adjustments - and many players don't now - it
    is unlikely that they would be the cause of the sort of problems that you
    are experiencing, and adjusting them without an intimate knowledge of what
    they do, is likely to compound the original problem, and in the case of the
    laser power pot, may cause irreversible damage to the laser.

    Arfa
     
  5. Guest

    Thanks gents. Sometimes it just sounds like Alvin for a whole song.
    Other times one just hears a blip for an instant, sounds ok for
    several seconds, and then blips again, randomly. Sometimes, I can lift
    the player on one side and it reverts back to normal. I have cleaned
    the optics, cleaned the CDs etc.

    Again, thanks for your replies. It is much appreciated.
    Steve
     
  6. James Sweet

    James Sweet Guest

    Open it up and poke around with a stick, ballpoint pen works well. Sounds
    like a bad connection somewhere is causing a clock issue, could be a cracked
    timing crystal as well.
     
  7. Guest

    Thanks James.

    I think I found the problem. I soldered alot of suspect
    connections, but still no luck. Then I worked around the basket and
    low and behold, touching the top that holds the Cd in place would
    cause the problem. I checked the springs and one seemed a little
    loose. One of the plastic 'retainers' the spring connects too was
    cracked and bent. I repaired it and reattached the spring and all
    seems ok, at least on the bench.
    I will check tonight at home and see if it still works ok.

    Thanks again James and others.
    Steve
     
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