I was wondering why a CD player that previously used to play CD-Rs now isn't able to read them?

It will still play normal pressed CDs.

The normal CDs have a silver coloured surface whereas the CD-Rs have a green coloured surface.

I was wondering why a CD player that previously used to play CD-Rs now
isn't able to read them?

It will still play normal pressed CDs.

The normal CDs have a silver coloured surface whereas the CD-Rs have a
green coloured surface.

If it's now failing to play specific CD-Rs that it used to play, then
this could indicate that the player's laser diode is getting near the
end of its life. Its output is dropping, resulting in a weaker signal
reflected from the disc's data layer, and the photodiode in the reader
assembly isn't getting a strong enough reflection to track the data
spiral and/or decode the data bitstream.

The same effect could result if you've got a buildup of dust or
tobacco-smoke tar on the laser diode or the photodiode. The more
light is blocked or scattered by these materials, the weaker the
detected signal.

CD-R discs already produce a weaker reflected data signal than an
"pressed" CD. CD-RW discs are (usually) even weaker. So, a CD player
which is "dying" will usually being to reject CD-RW discs first, then
CD-R, and then finally "pressed" CDs.

If it's a CD player of particularly high value, it may be possible to
have the optical assembly, or even the entire "loader" mechanism
replaced. For cheap CD players, alas, the cost of servicing them is
usually more than the cost of buying a new one (if the service parts
are even available).

If the problem affects newly-burned CD-R discs, more than older CD-R
discs you made years ago, then the newer CD-R blanks may be to blame.
Some brands and types of CD-R disc have poor reflectivity, and the
"80-minute" CD-R discs (which are pretty much the only kind you can
find these days) are inherently harder to track than the "72-minute"
variety which used to be the standard.

David Platt wrote:

The same effect could result if you've got a buildup of dust or
tobacco-smoke tar on the laser diode or the photodiode. The more
light is blocked or scattered by these materials, the weaker the
detected signal.

Arfa and I have had a running discussion about this over the years on this
group.

I live 3,000 feet up in the desert, the air is dry and dusty. There is
plenty of wind all the time so there is no hydrocarbon buildup from
automobile exhaust.

The cleaning disks with the brushes work fine for me, I have never had
one scratch a lens, and they brush the dust off.

Arfa lives in England and has very different weather and the dust is more
of a sluge than dry dust. He always cleans his lenses differently.

(Arfa, want to chime in here?)

Geoff.



--
Geoffrey S. Mendelson, N3OWJ/4X1GM/KBUH7245/KBUW5379

"Geoffrey S. Mendelson" wrote in message
...
David Platt wrote:

The same effect could result if you've got a buildup of dust or
tobacco-smoke tar on the laser diode or the photodiode. The more
light is blocked or scattered by these materials, the weaker the
detected signal.

Arfa and I have had a running discussion about this over the years on this
group.

I live 3,000 feet up in the desert, the air is dry and dusty. There is
plenty of wind all the time so there is no hydrocarbon buildup from
automobile exhaust.

The cleaning disks with the brushes work fine for me, I have never had
one scratch a lens, and they brush the dust off.

Arfa lives in England and has very different weather and the dust is more
of a sluge than dry dust. He always cleans his lenses differently.

(Arfa, want to chime in here?)

Geoff.



--
Geoffrey S. Mendelson, N3OWJ/4X1GM/KBUH7245/KBUW5379



The laser must be focused sufficiently well to start with or the cleaning
disc will never spin.

The brush glued to the disc does a crappy job at best. Manual cleaning is
really the way to go.

I routinely measure the HF pattern from the laser before and after cleaning.
I have never seen a detectable increase in the peak-to-peak level of the HF
pattern after using a cleaning disc.

An increase of 25% to 50% after a proper manual cleaning is not unusual.

Mark Z.

Thanks for all the replies so far, I have a few more questions:

Why does the laser degrade? Does using CD-Rs degrade the laser faster?

We don't live in a very dusty area!

I have only tried a disc cleaner which has small brushes stuck to it. How would I manually clean the laser - using IPA and a cotton swab?

Is it possible to increase the laser output or adjust it easily?

Thanks.

M.Joshi wrote:

Why does the laser degrade? Does using CD-Rs degrade the laser faster?

It's a tiny LED that burns up as you use it. Eventually it "goes dark",
but inbetween that and full brightness is a lot of time.


I have only tried a disc cleaner which has small brushes stuck to it.
How would I manually clean the laser - using IPA and a cotton swab?


That's the usual plan. It has never worked for me because the IPA will
make a sludge out of the dust. It probably will work for you.


Is it possible to increase the laser output or adjust it easily?

Most CD players, DVD players, and computer drives have a "brightness"
control to adjust the output of the laser.

The problem with that is unless you can measure the output, you are guessing,
and if you guess too high, the laser will be dead in seconds. If you guess
right, or measure it, the diode will produce more output, but it will also
burn up faster.

So you may be able to get more time out of it, but in the end, this is a
signal to either replace the diode, or the player.

On the other hand, you may be experiencing reduced output due to capacitor
failure, so the first thing to do after cleaning it, is to poke around with
a voltmeter and a voltage chart if you have one and the necessary skills.

Geoff.


--
Geoffrey S. Mendelson, N3OWJ/4X1GM/KBUH7245/KBUW5379

"Geoffrey S. Mendelson" wrote in message
...
M.Joshi wrote:

Why does the laser degrade? Does using CD-Rs degrade the laser faster?

It's a tiny LED that burns up as you use it. Eventually it "goes dark",
but inbetween that and full brightness is a lot of time.


I have only tried a disc cleaner which has small brushes stuck to it.
How would I manually clean the laser - using IPA and a cotton swab?


That's the usual plan. It has never worked for me because the IPA will
make a sludge out of the dust. It probably will work for you.


Is it possible to increase the laser output or adjust it easily?

Most CD players, DVD players, and computer drives have a "brightness"
control to adjust the output of the laser.

The problem with that is unless you can measure the output, you are
guessing,
and if you guess too high, the laser will be dead in seconds. If you guess
right, or measure it, the diode will produce more output, but it will also
burn up faster.

So you may be able to get more time out of it, but in the end, this is a
signal to either replace the diode, or the player.

On the other hand, you may be experiencing reduced output due to capacitor
failure, so the first thing to do after cleaning it, is to poke around
with
a voltmeter and a voltage chart if you have one and the necessary skills.

Geoff.


--
Geoffrey S. Mendelson, N3OWJ/4X1GM/KBUH7245/KBUW5379



Pretty much everything that everyone has already said. Some players were
always a bit marginal with home-burns, and the slightest degradation of the
laser is enough to stop them working. The reason for this is as David says.
The process for producing the reflective layer is different between a
commercial pressed disc, and a home burnt one, and a home burn is a lot less
reflective.

Over the years, I have cleaned probably thousands of laser lenses using IPA
and a cotton bud. Irrespective of the nature of the contaminant, I don't
think that I have ever had it turn to anything that I would describe as
"sludge". IPA has always got the surface back to a sparkly clean for me.
After cleaning with the alcohol-moistened swab, it is necessary to polish
with a dry one. Sometimes, the actual plastic of the lens seems to degrade,
and it drops from optically clear to a sort of 'cloudiness'. There is, of
course, no recovering that. Also, if a lens is *very* dusty, there's a good
chance that there is a layer of dust on the optical block's internal mirror,
and possibly the surfaces of the pickup diode array window, and the window
on the laser diode, depending on how they are arranged physically. These
days on most lasers, there is an open 'tunnel' into the optical cavity under
the lens. I have had some success with carefully holding the lens to one
side with a scalpel tip, and blowing some compressed air down the side into
the tunnel.

Cleaner discs with brushes are, for the most part, a useless gimmick. Most
lenses, if examined in profile, have a sort of 'wall' around their edge.
This serves at best to stop the bristles touching anything other than the
very highest part of the lens, and at worst, deflecting them so that they
touch no part of the lens. In the case of DVD players, the rotational speed
of the disc is much higher than that of a CD, and the lens is often smaller
and more exposed. On several occasions over the years, I have had players
cross my bench - notably Panasonic ones - where the bristles of the cleaner
disc brush have caught in the lens suspension, and torn it apart. I would
never recommend anyone to use such a disc, because at best, it's unlikely to
do any good (although Geoff obviously does appear to have had some success
in his climate in Israel) and at worst *can* do damage to the 'wrong' type
of player.

On adjusting the laser, generally this is not a good idea other than for
proving a point. Some lasers are intended to be adjusted as part of a
setting up procedure. Notable among these are Pioneer ones. There is a
specific level of eye pattern that you adjust for, and having it correct
significantly affects the laser's ability to read a disc, and the
performance of the servos - particularly the tracking servo. Too much level
is just as bad, performance-wise, as not enough. With typical Sony lasers
from the KSSxxx series, or Sanyo types, the pot is usually sealed. I have
found that deviation from this setting rarely does any long term good. It
can be useful for proving the point when an observed eye pattern is low, but
even if you get the pattern and performance back to where it should be by
turning it up, generally, the item will be back in a few weeks with the
laser either failed or in much poorer condition than it was. I guess this is
because the laser diode was at the end of its service life in the first
place, and the increase in current through it in order to get its output
back up, is enough to accelerate its already advanced state of demise ...

This is not the case, however, with Pioneer lasers which, compared to other
makes, seem to live for ever.

Arfa

In the old days I read somewhere about the relative power used in the lasers in CD players. I noted that Pioneer used about the lowest power and yet after replacing one and adjusting the tracking gain etc., I got the thing to track while rapping a screwdriver handle HARD on front of the unit.

On the other hand Sanyo (and I assume Fisher) models were reported to use the highest power lasers and I didn't see any better tracking out of them.

It is possible that the cleanliness of the disk was more of an issue with the lower laser power but I am not sure of that - it must depend greatly on the detector array of course.

I'm not sure how much power Yamahas used but I had two that went out thermal, I mean a shot of coolant and they would work again. One actually responded favorably to lowering the laser power. (I think I lowered it....)

I really do wonder how much of this is actually laser degradation versus a coating of dust on the optics. Enough times I had adjusted the tracking and got a viable repair out of it, is the shape of the beam distorted or is it a dust pattern ? There is no easy way to tell of course.

In the beginning lasers were expensive and it would make sense to peruse something like that, but when they dropped in price it would be a waste of time. I remember a cheap two head VHS for which the entire upper and lower drum with motor and everything only cost $20. We joked around at the shop that the thing wasn't worth cleaning. Toward the end really, the only reason to clean them or some of the CD pickup lenses was to avoid realigning it.

Another factor in CDRs is that while the reflectivity MIGHT be lower initially, it gets lower with time. Put one out in the sun and you will reduce the reflectivity of the whole thing.

Also the printed pattern is nowhere near as effective as the pits on a stamped CD because those pits are precisely ¼ of a wavelength of light and absolutely null the reflection. No photographic emulsion **** could ever be as effective.

These limitations apply to DVDs as well, and when any of the burned ones are played they to degrade a slight bit. This is very slight compared to mechanical media such as vinyl or magnetic tape of course, but still measurable..

They have now come out with a special type of burnable DVD which is said to last alot longer than the conventional ones, but the burner has to be designed for it. It seems reasonable to conclude that it needs a more powerful laser to write to it.

Seems they should be able to make a long life CDR, but there is probavbly little reason to do so. We're getting to the point where not only are DVDs obsolete because of the holograqphic disks, disks period are getting obsolete. I rarely use them, all my stuff is on harddrives now, or streamed off the net.