Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

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Adrian Brentnall
 
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Default Marantz Cassette Deck motor replacement... possible ?

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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Adrian Brentnall
 
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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

On Thu, 24 Feb 2005 09:16:55 +1100, wrote:

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

On Wed, 23 Feb 2005 17:56:52 +0000, Adrian Brentnall
adrianthepapersand the
wrote:

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=================
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Tim Schwartz
 
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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 (Matsu****a), 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


Adrian Brentnall wrote:

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=================
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JR NORTH
 
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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

Adrian Brentnall wrote:

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



--
--------------------------------------------------------------
Home Page: http://www.seanet.com/~jasonrnorth
  #7   Report Post  
Adrian Brentnall
 
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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


On Thu, 24 Feb 2005 22:20:21 -0800, JR NORTH
wrote:

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

Adrian Brentnall wrote:

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


======return email munged=================
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