From: Chuck Simmons
Organization: You jest.
X-Mailer: Mozilla 4.61 [en] (X11; U; Linux 2.0.33 i586)
Subject: Re: CDRW does not read cds
Date: Thu, 26 Sep 2002 02:22:00 GMT
NNTP-Posting-Date: Wed, 25 Sep 2002 19:22:00 PDT
"N. Thornton" wrote:
> email@example.com (firstname.lastname@example.org) wrote in message news:...
> > Hello,
> > I have a panasonic (matshita/matsushita) CDRW , model CW-7585, that
> > was working fine on winXP Pro and Roxio Easy cd creator 5 platinum.
> > Since yesterday it won't regognize cd's blanks or not. I opened it to
> > see if I could fix it using the extremely helpful instructions at
> > http://www.repairfaq.org/REPAIR/F_cdfaq.html. This is what I found:
> > Whenever I close the tray, (with/without a cd in it), the pickup moves
> > back and forth on the rack, positions at a specific location and then
> > stops. Then nothing happens. (Normally, the cd should start spinning).
> > About the laser, I could not see any red spots in a dark room,
> > whenever I closed the tray (with/without a cd in). Maybe the absence
> > of a cd did not power on the laser, and its appearance covered the
> > laser beam.
> Stop. You will permanently damage your eyesight like this. Do not play
> like this with cdrom lasers, nor cdrw lasers. Read up on it if you
> doubt me. It doesn't sound like youre taking the necessary precautions
> while working with a dangerous laser.
Don't blow this completely out of proportion. The CD read power we use
in my lab is between 500 microwatts and one milliwatt. It is best not to
look directly into the lens but there is no particular problem with
scattered light. I have to operate CD and DVD devices open in order to
make measurements including optical power output. Write power is more
problematic and eye protection should be used when measuring write
> If the pickup moves but the spindle doesnt turn, the laser focus is
> not the issue. Possibles are the sensor not detecting the CD is
> present, or spindle motor is dead, or its drive cct. There are many
> other possibles of course.
Many CD and DVD devices use focus to decide if there is a disk inserted.
There is no other sensor in most. If a focus region cannot be found, the
drive assumes there is no disk. A CD drive can actually focus and track
without spinning the disk. Focusing on a stopped disk is useful but
tracking vibrations at one spot is a little futile. DVDROM can focus on
a stopped disk but cannot track. Anyway, if the lens does not do a
couple of "pushups" when the drive is turned on, it is probably not
bothering to look for a disk. The sledge moving to the ID at power up
and "tray open" is a feature. If the sledge is not at the ID, in many
units the tray interferes with the sledge when it opens or closes.
Moreover, the spiral on CDs and on the first layer of a DVD is always
outward so the drive must start at the ID.
> Before even opening a cd drive, test it in DOS using a Win startup
> disc. 19 times out of 20 the CD works fine while it won't in windows,
> thus showing the problem to be software.
> Regards, NT
... The times have been,
That, when the brains were out,
the man would die. ... Macbeth
Chuck Simmons email@example.com