• Greetings to one and all from rainy Yorkshire UK.

    I have been directed to dual-board by a very helpful gentleman called Klaus aka Dualcan from vinyl engine.

    I.recently bought a CS503-1 as a means of playing my old vinyl and find I have a slight problem.

    The records play but as soon as the stylus touches the record the platter slows down quite a lot.

    It is more noticeable at the outer edge and improves as it gets nearer the centre.

    I have cleaned the motor spindle and drive belt but it is still the same.

    Is it possible there is something else I can try?

    Many thanks, Kevin.

  • Maybe you need a new belt? Just guessing. Is it still the old belt from 30 years ago? Then this should be the first thing you try.

    Gruß,
    Helge


    Im Betrieb: 1219
    In den Fingern gehabt: 1019 - 1209/14/16/18/19/20/28/29/37/41/46/49 - 415/35/50/55/91 - 502/04/05/10/21/40 - 601/04/06/20/21/22/26/50 - 701/04/14/21/31

  • Hi, yes it is probably the original belt. I'll try a new belt and see if that helps. Do you think it is worth oiling the motor bearings and cleaning the PCB or should I leave them alone as the motor is working.

    Is there any kind of test I can do to check if it's the motor speed that's fluctuating?

    Kevin.

  • Hi Kevin !

    Do you think it is worth oiling the motor bearings and cleaning the PCB or should I leave them alone as the motor is working.

    As far as I know the 503-2 uses a DC-Motor, which is a "one box design" and isn't intended to be opened or serviced.

    Those - driven by AC from internal or external transformer - will have a power supply circuit, which consists of a few diodes and a larger capacitor at least. There is a slight chance that aging has taken its toll from the main capacitor, so that the driving voltage drops when the motor gets under load - but that's pretty vage to be honest. The motor has an integrated speed regulator and should catch up with that resistance when the needle drops onto the record.


    I would also recommend to replace the drive belt in first place and would clean out and re-oil the main platter bearing. Old dried out oil there could significantly affect the load to the motor and cause an issue. I would check that before starting to dig in the electric part of it and / or replace the motor.


    The 503 came in 1987 and was considered "a new generation model" already with its smaller (and cheaper) DC-motor.

    It wasn't one of the old style units that use an AC-mains powered synchronous motor as the 505 - which can be taken apart and serviced.


    :)


    Is there any kind of test I can do to check if it's the motor speed that's fluctuating?

    Unfortunately not, if you don't own a tachometric measuring device (laser operated using a marking on the pulley).

    You just can check the system as a whole including motor, belt, platter bearing with a smartphone app*. But that just tell you that the speed is deviating and flutters this and that percentage.


    :)


    *) That the RPM Speed and Wow App

    Peter aus dem Lipperland


    Solo mio, vendro unscrupuloso, custombres sansaclu.

    Einmal editiert, zuletzt von wacholder () aus folgendem Grund: Ein Beitrag von wacholder mit diesem Beitrag zusammengefügt.

  • I think a new belt will cure it as turning the old belt inside out so the slightly rougher surface was against the pulley definitely helped.

    I have a question about the headshell as the cartridge is not square to the record surface. There is no adjustment possible on the headshell to twist it slightly.

    Will i have to shim the cartridge on one side to make it square to the record surface.

    2 Mal editiert, zuletzt von phattanglo ()

  • Hi Kevin !

    I think a new belt will cure it as turning the old belt inside out so the slightly rougher surface was against the pulley definitely helped.

    Well ... the original belt has two different surfaces: a rougher one for more grip that belongs to the inside and a smoother one that reduces the drag between belt and detecting arm and speed-changing fork. The Dual belt-drive speed mechanism is a preselector: the belt is not thrown over to the other speed when the motor is off (to prevent damage on the belt). It has a detection arm that is released when the motor starts turning and enables the changing fork to switch position - and throw over the belt consequently with it.


    It is also noted in the user manual on belt change that the rougher surface belongs to the inside.


    Modern replacement and aftermarket belts - unfortunately - in most cases have no smoothed outer side. That may or may not affect the operation, but theoretically it causes more drag on the belt control parts and *may* affect the speed.


    :)

    Peter aus dem Lipperland


    Solo mio, vendro unscrupuloso, custombres sansaclu.

  • Hi Peter, I don't think the belt texture will be a problem as the speed change is electronic rather than mechanical.

    I'm just trying to figure out a way to align the cartridge, perhaps there is an adjustment screw at the pivot end of the tonearm as there is nothing at the head shell end.

  • Hi Kevin !


    Ah well .. that's the 503 not the 505. I'm more in the older stuff as it seems.


    ?

    Peter aus dem Lipperland


    Solo mio, vendro unscrupuloso, custombres sansaclu.

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