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Marantz Cassette Deck motor replacement... possible ?

Discussion in 'Electronic Repair' started by Adrian Brentnall, Feb 23, 2005.

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  1. Hi All
    My old (1980's) Marantz SD230 cassette deck 'died',,,,, suddenly !.
    Symptoms - lights on - but no reponse to the 'play' button.

    A quick check of the voltages shows that 'something' appears to be
    pulling more current than it should, puling the main DC rail down from
    19V to about 6V.

    Disconnecting the multi-way connector that drives connects to the
    drive motor and the play / record / pause switches restores the DC
    rail to nominal.

    12V dc applied direct to the motor results in a current of about 400mA
    - but no rotation. Is it a fair assumption that the motor's at fault ?

    If so - anybody know where I could find a replacement - motor is
    marked MMI-6A2LK - or is it one of those things that won't be
    economical to source / repair ?

    Thanks in advance
    Adrian
    Suffolk UK
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  2. Guest

    Hi Adrian,

    I dont know who would supply them in the UK - they're not a difficult
    item to obtain here and i expect the same would apply over there.

    Get a copy of a magazine called "Television" - it's a UK publication
    with plenty of parts suppliers advertisements.

    Cheers,
    Sam T
     
  3. HI Sam

    Thanks for the comments.
    Last night, in a 'well it doesn't work at the moment so it can't get
    any worse' mood, I did a bit of 'open heart surgery' on the offending
    motor.

    It's in a little tin can - and by carefull levering with a small
    screwdriver I was able to get the 'lid' off the can - after which the
    motor and the control pcb could be winkled out of the can.

    Further dismantling separated the motor itself from the pcb - and
    showed that the motor was reading short-circuit.

    Having reached the point of no return <g> - I dismantled the motor,
    and found that there was an amount of something or other between the
    segments of the armature. Careful cleaning, followed by a tiny drop of
    contact cleaner - reassembled the whole thing - and, lo and behold,
    the motor spins !!

    Put it all back together and everything works......

    I'm not sure about long-term reliability <g> - and it would probably
    be a better job long-term with a replacement motor - but I only need
    the deck for a quick recording project (taping hymns for our local
    Church) - so provided it lasts long enough for that I'm happy....

    Thanks again for your help
    Adrian
    Suffolk UK

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  4. Jerry G.

    Jerry G. Guest

    Many of the electronic suppliers can have a universal type cassette tape
    machine motor. You need to tell them the operating voltage of the motor, if
    the servo control is built in to the motor or not, and if the motor is CCW,
    or CW. If the motor is non standard, they need to have the model of the
    machine. You will have to transfer the pulley from the old motor to the new
    one.

    --

    Jerry G.
    ======


    message Hi All
    My old (1980's) Marantz SD230 cassette deck 'died',,,,, suddenly !.
    Symptoms - lights on - but no reponse to the 'play' button.

    A quick check of the voltages shows that 'something' appears to be
    pulling more current than it should, puling the main DC rail down from
    19V to about 6V.

    Disconnecting the multi-way connector that drives connects to the
    drive motor and the play / record / pause switches restores the DC
    rail to nominal.

    12V dc applied direct to the motor results in a current of about 400mA
    - but no rotation. Is it a fair assumption that the motor's at fault ?

    If so - anybody know where I could find a replacement - motor is
    marked MMI-6A2LK - or is it one of those things that won't be
    economical to source / repair ?

    Thanks in advance
    Adrian
    Suffolk UK
    ======return email munged=================
    take out the papers and the trash to reply
     
  5. Tim Schwartz

    Tim Schwartz Guest

    Adrian,

    Your were quite ambitious to take apart the motor and fix it, and what
    you did was clean out the brush dust that was shorting the segments of
    the commutator. Hopefully you also lubricated the bearings with a drop
    of good quality (synthetic) oil. While the motor may now work for
    years, you'll probably have to check the speed, as its likely to be off
    after all of that. The standard way to check speed is with a reference
    tape (usually 3KHz) and a frequency counter. Simply play the tape and
    connect the output of the deck to the counter, and adjust the pot for a
    reading that is the same as the frequency of the tape.

    I think the motor is a Panasonic (Matsushita), and can be replaced by a
    Mabuchi, which is a common brand of replacement motors. They are
    nominally 2200 RPM, you already know its 12V, and you can see if it
    rotates Clockwise or Counter-clockwise (anti-clockwise). Here in the US
    a motor like that costs around 3-6 pounds. The new motor is likely to
    be quite a bit smaller overall, but should mount right up. You'll have
    to transfer the pulley from the old motor to the new one. Don't forget
    to measure the height of the pulley from the motor top before removing
    it.

    As you are doing recording, I'd suggest that the speed be checked as
    soon as possible, so that the recording can be played on other machines.

    Regards,
    Tim Schwartz
    Bristol Electronics
     
  6. JR NORTH

    JR NORTH Guest

    Be careful to check if the motor is shielded, or chassis grounded.
    Failure to do this caused me to blow a Technics M205 decks board when I
    replaced the motor with an otherwise correct replacement.
    JR
     
  7. HI JR

    Thanks for the comment

    It seems as if the motor is electrically isolated from chassis. Inside
    the nice metal screening can is a plastic-bodied motor, which connects
    to the regulator pcb - both terminals of which are wired but not
    directly connected to ground.

    Anyway - (at the moment) it would appear to be working (after the
    disassembly, clean - reassembly process described in this thread - so
    - fingers crossed - I shall not need to go looking for a replacement
    just yet...

    Thanks for the warning !

    Adrian
    Suffolk UK


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