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From: firstname.lastname@example.org (email@example.com)
Subject: Re: CDRW does not read cds
Date: 27 Sep 2002 15:03:49 -0700
References: <3D926F44.A8786603@webaccess.net> <3D93A9C1.8F29D7EC@webaccess.net>
NNTP-Posting-Date: 27 Sep 2002 22:03:49 GMT
Chuck Simmons wrote in message news:<3D93A9C1.8F29D7EC@webaccess.net>...
> "firstname.lastname@example.org" wrote:
> > Chuck Simmons wrote in message news:<3D926F44.A8786603@webaccess.net>...
> > > "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.
> > > >
> > > >
> > >
> > > > 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.
> > If I got this well, this poster is suggesting that the fault is at the
> > focus mechanism? If so, what are the possible (SAFE) solutions to it?
> > I suspect that I'm better off buying a new CDRW.
> There are a number of possible faults. A drive can detect that it can't
> spin. It can detect focus failure and it can detect tracking failure
> once focus is established.
> However, some simple things to check. There are usually two switches
> (often in the same plastic housing) to sense tray open/closed. If the
> drive cannot get a tray closed signal due to a faulty switch, it won't
> try to do anything. The circuit board sometimes has maked teat points.
> Verify that +5, +12 and +3.3 (if used) are OK on the board itself.
> Sometimes there is a focus drive test point marked in various ways. It
> will typically go to a chip made by Rohm which has power tabs on it
> (there may be up to three Rohm power IC's. If the input signal to the
> Rohm chip focus pin is ramping up and down but the lens does not move,
> the Rohm chip is bad or the focus VCM is burned out. Focus and tracking
> VCM resistances can be measured with the power off. These should be
> about 4 to 10 ohms (usually close to 7 ohms in units I see). An open
> focus VCM is fatal.
> Anyway, look for the tray open/closed switch if your drive is so equiped
> (most are). If this has failed, the problem is simple to correct.
> Problems on the optical unit you cannot correct. Note that the optical
> unit may be VERY ESD sensitive. Do not disconnect the flex from the main
> board unless you are very well practiced with ESD procedures.
I appreciate your help. However, being a novice, I did not quite
understand your tips. Maybe real **detailed** instructions, (if anyone
has the time for it) would help.
By the way, I have some more info on the subject: I managed to see a
red spot on the lens (appearing after closing the tray). So that maybe
an indication that the laser may work ok.
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