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Sony turntable runs too fast, too slow

Discussion in 'Electronic Repair' started by [email protected], Jul 14, 2006.

  1. Guest

    Most of the time, my Sony PS-LX430 turntable runs too slow. On the
    occasion when it'll run at the correct speed, it will sometimes
    suddenly speed way up for a few seconds then go back to normal. Other
    times, it'll play OK then suddently slow down, where , as I said, it
    remains most of the time.

    When it's too fast or too slow, it's at neither 33 RPM nor 45 RPM.

    Because it occasionally runs too fast, it doesn't seem likely it's a
    stretched-out belt. Any suggestions on what the problem can be?

    Thanks.

    -- Jeff
     
  2. Some turntables have a dc motor that has a built in speed control.
    If you can take it apart and look over the motor and find a small hole on
    the bottom of it, that may be the adjustment control. Maybe try a little
    contact cleaner there and see what it does.
    Just my 2 cents in. JTT
     
  3. Guest

    Hi James

    As i was once a prefered sony repairer my memory evades me as to
    weather or not it is a direct drive or belt drive t/table. if it is a
    direct drive then as the previous reply suggests try that one out
    otherwise replace the actual motor itself.

    There are several cheap non orgional brands out there such as the
    generic dai ichi brand ccw or cw (counter clockwise or clockwise this
    is normaly noted on the back of the motor along with voltage ratings
    etc) If there is a small hole also in the back then it is surely a
    speed controlled type.

    If it is a belt drive type the belt may not be stretching as such but
    maybe stickey or gooey. I know this is usally consistant with old
    stretching belts but i have in the past found the belt to be fine is
    size but still gooey. In that case replace it and clean the turntable
    plate where the belt runs and also the brass speed adjuster, this
    sticky stuff builds up on both places and can cause all kinds of wierd
    faults.

    Just a few hints, you may have alread explored them.

    Phill
     
  4. n cook

    n cook Guest

    If like the PS LX520 then crystal controlled servo operation of speed
    control so no pots.
    Does it use a TC9142 servo controller ?
     
  5. Arfa Daily

    Arfa Daily Guest

    I think you are getting confused about what constitutes a " direct drive "
    turntable. A directly driven turntable is one where the centre bearing of
    the platter is also the shaft / bearing of the motor - ie the motor *itself*
    runs at either 33 or 45 RPM, and is an integral part of the speed control
    servo loop. It usually employs a multi-magnet rotor, which is often part of
    the platter itself, and is driven by an electronically generated and
    controlled rotating field that is applied to the stator coils. This is not
    the case where a small DC motor with an internal governor, is fitted, such
    as has been described. These invariably run at a couple of thousand RPM, and
    drive the platter via a belt. The other drive scheme, now obsolete for many
    years, is idler drive, where a high speed motor with a stepped shaft, drives
    the inside rim of the platter, via a spring-loaded rubber jockey wheel.

    I'm pretty sure that these Sonys use a belt-drive from a small DC motor, but
    I have a dim recollection of them having an external control board, with a
    difficult to obtain 4 pin regulator IC, which had a habit of failing. I
    could be completely wrong there, it's been a long time since I saw one, but
    there's definitely some bells ringing somewhere ...

    It's probably worth the OP just checking the joints on the regulator, and
    any speed-set pots and selector switches, but I think it likely that he will
    be up for at least a replacement regulator IC, and probably motor as well,
    if they are still available. It may be possible to sub a cassette motor with
    an internal governor, but bear in mind that one of the dual speed ones would
    have to be used, which always use external speed-set pots, and it may be
    difficult to get the required shaft speeds and torque, to match the pulley
    size fitted to the original.

    Arfa
     
  6. Is there some connection between being a preferred Sony repairer and
    memory loss then? Also, apparently, dyslexia? :)
     
  7. A stretched belt can cause a TT to run too fast by riding up on the edge of
    the pulley.

    Leonard
     
  8. Swampy

    Swampy Guest

    It usually employs a multi-magnet rotor, which is often part of
    the platter itself, and is driven by an electronically generated and
    controlled rotating field that is applied to the stator coils. This is
    not
    the case where a small DC motor with an internal governor, is fitted,
    such as has been described.

    This is quite true indeed as i did not suggest anything about that i
    simply asked the question. It too has been awhile since i looked at one
    as well.

    As for the reply from Mr Payne in the ass.

    You sir are the reason why a lot of ppl simply read and do not reply to
    posts. It is with comments like yours that drive ppl away from these
    sites. I did not see your input either. So instead of adding remarks
    like that, why not use the quick wit you have displayed and vist the
    quick wit groups and save us all the from your unwanted BS comments
     
  9. Chuck

    Chuck Guest

    Try spraying the speed switch with deoxid 5 and working it back and
    forth a few times and if you can reach them, the speed pots. If this
    takes care of the speed drift, then set the pots for accurate speeds.
    Chuck
     
  10. Franc Zabkar

    Franc Zabkar Guest

    There are a few service manuals here:
    http://www.vinylengine.com/library.php?make=Sony

    The cheapies (LX-40/43/44) appear to use a cheap 2-speed DC motor and
    a belt drive. I don't see the LX-430, though.
    A free service manual is available from this site:
    http://www.user-service-manuals.com

    Sony PS-LX430 Service Manual (includes extraction from Instruction
    Manual (User Manual)) in English PS-LX430 / PS-LX430C / PS-LX431 /
    PS-LX431N / PS-LX433 9-952-171-11

    BTW, I have obtained one manual from this site in the past. The site
    owner asks that you donate to a particular human rights organisation
    but will still allow you to download a manual if you have already
    donated to other charitable organisations of your choosing.

    - Franc Zabkar
     
  11. Eiron

    Eiron Guest

    Garrard 501.
     
  12. Arfa Daily

    Arfa Daily Guest

    This, however, is NOT your bog standard motor and jockey wheel drive. It is
    instead, a precision motor and specially made drive wheel assembly, fitted
    to a phono deck that costs 10,500 ( That's ten THOUSAND ) quid. I would
    expect to get a very superior drive system for that. I'm not sure that I can
    accept all the blurb that's published on this deck, in an effort to justify
    its ridiculous cost. I think most people, including those who profess to be
    able to hear the difference between interconnects, would struggle to hear
    the few dB extra 'quietness' in the drive system over a belt drive, that the
    makers claim. I notice that they do not quote any figures over a genuine
    direct drive system. As far as the claims about wow and flutter go, again, I
    would dispute that this can be genuinely 'heard' without the use of
    sophisticated test equipment, if comparing the 501 to a good quality belt or
    direct drive deck, with a heavy platter. The laws of physics dictate that
    due to the inertial mass of the platter, you simply can't make rapid changes
    to its rotational speed. It would be interesting to know what type of motor
    is actually used in the 501, and how exactly its apparent speed stability is
    achieved. There are people, I know, who will always claim that things like
    this are definitely better, and worth every penny of the price, but I rather
    suspect that many of them, are still combing e-Bay to find a bottle of snake
    oil to lube their tonearm bearings with ...

    Arfa
     
  13. Franc Zabkar

    Franc Zabkar Guest

    Sorry, I just had to check:
    http://tinyurl.com/o6vfp

    :)

    - Franc Zabkar
     
  14. Arfa Daily

    Arfa Daily Guest

    Ha!! I'll post on one of the HiFi groups immediately !!

    Arfa d;~}
     
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