[Mark Zacharias]

"David Platt" wrote in message
news
In article ,
wrote:

In both circumstances, will occasionally just stop playing disc
entirely, sometimes midway through a song.

Steps I've taken so far:

1. Made sure any CD I put in there is mint clean.

2. Used a brush-style CD player lens cleaner disc according to lens
cleaner instructions.

Both steps have reduced behaviors in A & B, but not elminated them.

What else can I do to eliminate these problems, even under hood?

Also: Are these symptoms of read-head laser alignment, or of logic
control?

These could be symptoms of a read-head "wear-out". The laser diodes
do suffer with age - the laser output decreases, and the reflected
signal seen by the photodiode has a lower and lower signal level.
This causes both an increase in the error rate of the signal, and
problems in tracking (the track-following servo doesn't have enough
signal to work correctly).

A *very* short-term fix which sometimes helps (or at least can help
diagnose that this is the problem) is to tweak a trimpot in the laser
circuit which boosts its output. It's short-term because the
increased current though the laser accelerates its aging... you're on
a "slippery slope" to laser failure. The only long-term fix is to
replace the laser (which is commonly part of a larger optical assembly
that must be replaced as a unit) and then realign.

These could be symptoms of dust or dirt or tar in the optical path
(e.g. lens) which your "cleaning disc" hasn't removed... these discs
often don't work very well, and (depending on how the brush works) can
knock the lens out of alignment and make matters worse. A careful
manual cleaning of the lens (and, in some players, of a small mirror
located between the lens and the laser/photodiode) with a soft-bristle
brush sometimes does better. Some people report good results using a
very small amount of a liquid cleaner (either electronics-grade
isopropyl alcohol, or the sort of liquid cleaner used for
polycarbonate eyeglass lenses) - moisten a brush, wipe the lens
gently, then wipe equally gently with soft lint-free eyeclass-lens
cleaning tissue.

If you or anyone else smokes around your CD player, it's likely that
some tobacco-smoke "tar" has built up on the lens (and/or mirror if
one is present). This stuff is very difficult to remove, and if the
lens is impaired by it you may have no choice other than to replace
the whole optical assembly.

These could also be symptoms of tracking problems due to gunked-up
"rails". CD players have two different mechanisms for tracking the
groove - the lens itself is moved (within the optical sled) to track
small positional changes, and the whole sled is moved on linear or
semicircular "rails" to make larger adjustments. If dust builds up on
the rails, or if the lubrication dries out or turns gummy, the sled
won't move smoothly and the CD player can lose its ability to track
the disc. This can often be remedied by cleaning the rails (wiping
them with a Q-tip moistened in electronics-grade isopropanol) and then
relubricating with a small amount of the right lubricant. Sewing-
machine oil, watchmaker's oil, instrumentation oil are all good
choices - they're light, low-viscosity, non-drying oils which have no
solvents. Tri-Flo is a Teflon-bearing oil which also can work well.
Don't use WD-40 or Liquid Wrench.




Pickup flat wire.

part number 1-575-001-11.

Common problem with models using the the KSS-240 pickup.

Mark Z.