I just replaced a spindle motor in a Sony DVD player. Before I removed
the defective motor I was very careful to note the clearance between
the bottom of the plastic piece that the disc sits on when it rotates,
and the top of the housing that the motor is mounted to. I did this by
using a drill bit as a feeler guage before pulling this little disc off
the defective motor shaft when I removed it from the unit. Naturally I
reassembled everything in the reverse order maintaining the same
clearance with the new motor. The new motor spun up ok but would not
read the disc until (after some tweaking with the clearance) I
decreased it a bit more than it originally was. At that point the disc
read fine and the job it seems was finished. A couple of things disturb
me though. For one the final adjustment was done by pure guess work and
although it seems to work just fine, (I have watched through a complete
movie and listened to CD's on this unit), how do I know if the position
of the disc relative to the laser unit is dead center or marginal? Just
how critical is this clearance? Is there some room for a certain amount
of error here? And also what is the correct procedure for doing this
replacement? Thanks, Lenny Stein, Barlen Electronics.

wrote:
I just replaced a spindle motor in a Sony DVD player. Before I removed
the defective motor I was very careful to note the clearance between
the bottom of the plastic piece that the disc sits on when it rotates,
and the top of the housing that the motor is mounted to. I did this by
using a drill bit as a feeler guage before pulling this little disc off
the defective motor shaft when I removed it from the unit. Naturally I
reassembled everything in the reverse order maintaining the same
clearance with the new motor. The new motor spun up ok but would not
read the disc until (after some tweaking with the clearance) I
decreased it a bit more than it originally was. At that point the disc
read fine and the job it seems was finished. A couple of things disturb
me though. For one the final adjustment was done by pure guess work and
although it seems to work just fine, (I have watched through a complete
movie and listened to CD's on this unit), how do I know if the position
of the disc relative to the laser unit is dead center or marginal? Just
how critical is this clearance? Is there some room for a certain amount
of error here? And also what is the correct procedure for doing this
replacement? Thanks, Lenny Stein, Barlen Electronics.

Lenny,
I would think that although there is an exact position that it is
designed for, the margin of error can probably be something like the
distance the lens can move up and down to focus. For example if the
lens can move up or down 2mm while focusing then a 1mm difference should
not be too critical.
But... It usually seems a little more critical than that - to keep the
disc from scraping against the tray and allow it to eject properly, and
to keep the disc from getting caught on the spindle when ejecting.