Aiwa NSX-4000 Won't Play CD's Reliably 
Author Message
 Aiwa NSX-4000 Won't Play CD's Reliably

I have an Aiwa NSX-4000 mini-stereo system.  It has a 3 CD rotating
tray-drawer.  When you select a CD, the tray rotates to the correct
number, the mechanical (spinner) pickup picks up the CD, and SOMETIMES
spins it and registers the tracks on the display.  I noticed that very
often, the CD appears OFF-CENTER when on the spinner pickup grabs the
CD.  The unit has been opened and to a repair shop, and it is clear that
when the tray stops under the mechanical (spinner) pickup, the tray is
off-center.  But apparently even starting off-center, the CD aligns
itself on-center and spins without any wobble.

It IS the rotatating tray that does not stop EXACTLY under the spinner
pickup, and therefore the CD being grabbed is slightly off-center.  I
guess when the spin starts it "self-aligns" and spins ok.  But most of
the time, it won't spin the CD and not recognizing it, it responds as if
the CD is not there and no longer will even stop at that disk slot when
rotating the tray again.

Each time the tray stops, it is ALWAYS slightly off being right under
the spinner pickup, and when it drops the CD back into the round
depression in the tray, the CD is often resting on one edge of the round
depression.  The movement of the tray seems to jiggle it enough for it
to slide into the depression the way it normally should be.

Efforts to try to slip the gearing one notch to correct for this offset
don't work because when the sensor on the underside of the tray
registers that THIS is where the tray should stop, it is ALWAYS just
off-center from where it should be.  This unit is factory stock and has
had no modifications of any kind.  It did work when first bought about 4
years ago, but had virtually no use in the last 3 and 3/4 years.  It was
kept pulgged in, but turned off at the power button, demo mode
de-activated, and in a stereo equipment cabinet, behind a glass door,
like most stereo equipment is kept.  No overheating has ever been
noticed.

So with this "off-center" situation, and the possible off-center CD
being picked up by the spinner pickup and not willing to rotate it, it
makes for a CD player that doesn not work 90% of the time.

Each time you open the drawer and close the drawer or turn off the power
or un-plug the plug to reset the processor, it seems to "try" to get
back to normal, but inevitably, it stops playing future disks waiting to
be played.  When it plays a CD, it plays great, does not skip, goes to
each track ok, (on that disk only).  Whether it will play the next disk,
usually not, is a {*filter*}shoot.  Needless to say the laser pickup and
wiring has been cleaned and checked respectively.

Has anyone ever had this problem and found a specific soulution for it?
It would be a shame to trash what should be a good player.  No one seems
to know what to do.  This unit has had less than 20 hours of total CD
playing time on it, and has been kept in a clean and vented
environment..

Thanks in advance for any help and all help.  It would be greatly
appreciated.

Alan



Fri, 20 Jul 2001 03:00:00 GMT
 Aiwa NSX-4000 Won't Play CD's Reliably

Quote:

> I have an Aiwa NSX-4000 mini-stereo system.  It has a 3 CD rotating
> tray-drawer.  When you select a CD, the tray rotates to the correct
> number, the mechanical (spinner) pickup picks up the CD, and SOMETIMES
> spins it and registers the tracks on the display.  I noticed that very
> often, the CD appears OFF-CENTER when on the spinner pickup grabs the
> CD.  The unit has been opened and to a repair shop, and it is clear that
> when the tray stops under the mechanical (spinner) pickup, the tray is
> off-center.  But apparently even starting off-center, the CD aligns
> itself on-center and spins without any wobble.

> It IS the rotatating tray that does not stop EXACTLY under the spinner
> pickup, and therefore the CD being grabbed is slightly off-center.  I
> guess when the spin starts it "self-aligns" and spins ok.  But most of
> the time, it won't spin the CD and not recognizing it, it responds as if
> the CD is not there and no longer will even stop at that disk slot when
> rotating the tray again.

> Each time the tray stops, it is ALWAYS slightly off being right under
> the spinner pickup, and when it drops the CD back into the round
> depression in the tray, the CD is often resting on one edge of the round
> depression.  The movement of the tray seems to jiggle it enough for it
> to slide into the depression the way it normally should be.

> Efforts to try to slip the gearing one notch to correct for this offset
> don't work because when the sensor on the underside of the tray
> registers that THIS is where the tray should stop, it is ALWAYS just
> off-center from where it should be.  This unit is factory stock and has
> had no modifications of any kind.  It did work when first bought about 4
> years ago, but had virtually no use in the last 3 and 3/4 years.  It was
> kept pulgged in, but turned off at the power button, demo mode
> de-activated, and in a stereo equipment cabinet, behind a glass door,
> like most stereo equipment is kept.  No overheating has ever been
> noticed.

> So with this "off-center" situation, and the possible off-center CD
> being picked up by the spinner pickup and not willing to rotate it, it
> makes for a CD player that doesn not work 90% of the time.

> Each time you open the drawer and close the drawer or turn off the power
> or un-plug the plug to reset the processor, it seems to "try" to get
> back to normal, but inevitably, it stops playing future disks waiting to
> be played.  When it plays a CD, it plays great, does not skip, goes to
> each track ok, (on that disk only).  Whether it will play the next disk,
> usually not, is a {*filter*}shoot.  Needless to say the laser pickup and
> wiring has been cleaned and checked respectively.

> Has anyone ever had this problem and found a specific soulution for it?
> It would be a shame to trash what should be a good player.  No one seems
> to know what to do.  This unit has had less than 20 hours of total CD
> playing time on it, and has been kept in a clean and vented
> environment..

> Thanks in advance for any help and all help.  It would be greatly
> appreciated.

> Alan

Check the black ribbon cable that goes from under the drawer to the cd
board. This is a very common failure. It usually breaks right at the
connector on the cd board. This keeps the platter from finding the
proper position.
Good luck,
Rif



Fri, 20 Jul 2001 03:00:00 GMT
 Aiwa NSX-4000 Won't Play CD's Reliably
Alan:  

It could also be a slipping belt, if one is used to drive the tray.
Or it could be hardened grease at the tray hub, or along its perimeter
where some sets have little pads to support the tray.  After 3 or four
years, grease does tend to gum up, and this would make it difficult to
precisely stop the tray.  

However, there is a further possibility.   I had a Toshiba changer
that also would not line up the tray properly.  It turned out to be a
faulty tray motor.  If you can, check the voltage going to the tray
motor.  You might find that when the tray first stops there is still
voltage, albeit reduced, being applied. (This voltage will also go off
shortly thereafter.)

If your Aiwa is similar, there are notches in the bottom of the tray
corresponding to its rotational position, and an IR detector that
intercepts the notches.  There are sets of notches for each position.
I think there was a small notch then a large one, and then a small one
again, or something like that.  The large one is the "on target"
notch, at which point all drive to the motor is removed.  But before
reaching this one, the IR beam passes through one of the smaller
notches (i.e. from either direction).  This causes the drive to the
motor to be reduced.  I think it was from 5 Volts to about 1.5 or 2
Volts, in order to allow the tray to slowly come on target.  What
happened in the one I had was the motor was weak and could not develop
enough torque at the lower drive.  So rather than the tray completing
the last little bit of rotation and coming to a precise stop, it
would, instead, stop too early.  I noticed, also, that the problem was
more pronounced in one direction, i.e. in the other direction the tray
occasionally made it far enough for the disc to be lifted and play
properly.

After monitoring and recording the voltage to the motor under
operating conditions, I took it out and applied the same voltages,
forward and reverse, while holding the shaft.  Not very scientific,
but it was quite different when doing the same thing with a new one.
The new motor was inexpensive (about $15) and the set worked first
time and every time after, regardless of tray rotation direction.
Hope this helps.

Michael Caplan CET
---------------------------------------------------


Quote:
>I have an Aiwa NSX-4000 mini-stereo system.  It has a 3 CD rotating
>tray-drawer.  When you select a CD, the tray rotates to the correct
>number, the mechanical (spinner) pickup picks up the CD, and SOMETIMES
>spins it and registers the tracks on the display.  I noticed that very
>often, the CD appears OFF-CENTER when on the spinner pickup grabs the
>CD.  The unit has been opened and to a repair shop, and it is clear that
>when the tray stops under the mechanical (spinner) pickup, the tray is  
>[clipped . . . ]



Sat, 21 Jul 2001 03:00:00 GMT
 Aiwa NSX-4000 Won't Play CD's Reliably
Change the value of R406 on the 3CD PCB. It is either a 1K2 or 1K5 and you
need to either increase or decrease the value depending on whether the stop
error is clockwise or anti-clockwise. In 99% of cases I have seen the error
is anti-clockwise, and changing R406 to around 680R cures it.

I have seen this problem on MANY of these 3CD units from Aiwa. They are a
pretty badly designed pile of {*filter*}in my opinion, but the above should help.

Quote:

>I have an Aiwa NSX-4000 mini-stereo system.  It has a 3 CD rotating
>tray-drawer.  When you select a CD, the tray rotates to the correct
>number, the mechanical (spinner) pickup picks up the CD, and SOMETIMES
>spins it and registers the tracks on the display.  I noticed that very
>often, the CD appears OFF-CENTER when on the spinner pickup grabs the
>CD.  The unit has been opened and to a repair shop, and it is clear that
>when the tray stops under the mechanical (spinner) pickup, the tray is
>off-center.  But apparently even starting off-center, the CD aligns
>itself on-center and spins without any wobble.



Wed, 25 Jul 2001 03:00:00 GMT
 
 [ 4 post ] 

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