Thanks for the idea.

I tested the "home" switch for the sled with my multimeter, dialed in
to the 200K ohm setting. It's just an ordinary (tiny) spring-loaded
two-position pin switch.

With the switch pressed in (ie. sled is at center of CD hub), I get no
resistance (00.0 on the multimeter display). But with the switch
released (ie. sled is anywhere *except* right at the center), I get a
reading of 47.8 on the multimeter display. These results are both
using the 200K scale setting on the ohmmeter.

I would have expected infinite resistance, not 47.8, with the switch
released. So that's a bit surprising. The switch isn't perfectly
open when the pin is released, although there's obviously much more
resistance than when the pin is pressed in.

Do you think there is inadequate resistance with the switch released,
or would 47.8 a normal result for this kind of switch?

I'd love the problem to be a bad switch, but Murphy's Law says I can't
get off this easily.

Thanks.


On Apr 12, 12:10 pm, Jumpster Jiver wrote:
wrote:
I have an Alpine CHM-S630 6-disk CD changer that is giving me grief.

The unit selects each CD properly from the magazine, but as soon as it
loads it into place, the optical sled slams out to the full extent of
the limits of the track, out to the extreme edge of the CD diameter.
It never appears to go to the center of the CD, and it never takes a
read from the disk.

After the sled hits the track limit, then for about 2 seconds, the
worm & roller mechanism keeps trying to push the sled out through the
side of the case, resulting in a horrible grinding noise as the
plastic block on the sled strips itself against the "worm" screw,
since the sled can't move any farther.

After about 2 seconds elapse, the unit gives up and stops trying to
push the sled past the limit of the track. Another 2 seconds after
that, the unit gives up on spinning the CD, and the CD comes to a
halt.

This happens every time the unit loads a CD.

I've tried cleaning the lens on the sled, but it doesn't seem to be an
optical problem. It doesn't seem to be a mechanical problem, either.
The worm & roller for sled movement works just fine - the problem is
that for some reason, the unit is telling the sled to slam out past
the limits of its track. I'm stumped.

Can anyone point me in the right direction for a fix?

Thanks.

It sounds like the "home" switch or sensor is stuck or damaged, making
the unit think the sled is stuck at the center of the disc and making it
constantly try to move the laser away from the center.
I would look for a broken switch or the tab that activates it.
Good luck.