question about lens cleaning.

  9nailer9 16:55 28 Sep 2005

Hi guys,

is the CD player in my computer the same as in my Hi Fi system and if so does the lens need to be cleaned periodicaly if it needs to be cleaned can i use the same cleaning disc that i use in my Hi Fi system?

  Jackcoms 16:55 28 Sep 2005


  Fruit Bat /\0/\ 16:57 28 Sep 2005

CD lens cleaning discs
Every CD, stereo equipment, department, discount, store - and even sidewalk venders - carries CD lens cleaning discs. Are they of any value? Can they cause damage?

I generally don't consider CD lens cleaning discs to be of much value for preventive maintenance since they may just move the crud around. However, for pure non-greasy dust (no tobacco smoke and no cooking grease), they may not hurt and could even do a good enough job to put off a proper cleaning for a while longer.

However, it's also possible they will ruin the lens. Consider that the worst thing to do to a precision optical surface is to wipe it with a dry cloth as this is likely to scratch the surface as it rubs the dust over it. To the lens, a speck of dust is like a boulder. Once the lens is scratched, replacement of the entire optical pickup is the only remedy. And, since there are absolutely no sorts of standards for these things, it is possible for a really poorly designed cleaning disc to damage the lens even if the dust itself is non-abrasive. In addition, if the cleaning disc doesn't look like a CD to the optical pickup or disc-in sensor, the lens it may not even spin. So, the drawer closes, the drawer opens, and NOTHING has been accomplished! (But at least no damage will be done.)

As if this isn't enough, NEVER put one into a high-X CDROM (DVD player or DVDROM drive). The high speed rotation may cause the cleaning disc and/or player/drive to self destruct. And, don't try a cleaning disc on an automotive CD player that sucks in the disk - it will get stuck.
CD protection and handling
Although CDs are considerably more tolerant of abuse than LPs, some precautions are still needed to assure long life. Also, despite the fact that only one side is played, serious damage to either side can cause problems during play or render the CD totally useless.

It is important that the label side be protected from major scratches which could penetrate to the information layer. Even with the sophisticated error correction used on the CD, damage to this layer, especially if it runs parallel to the tracks, can make the CD unusable.

The CD is read by focusing a laser beam through the bottom 1.2 mm of polycarbonate. As a result of the design of the optical system used in the pickup, at the bottom surface, the beam diameter is about 1 mm and thus small scratches appear out of focus and in many cases are ignored and do not cause problems.

At the information layer with the pits, the beam diameter has been reduced to under 2 um. Still, scratches running parallel to the tracks are more problematic and can cause the optical pickup to get stuck repeating a track, jumping forward or back a few seconds, or creating noise or other problems on readout. In severe cases, the CD may be unusable especially if the damage is in the directory area.

This is why the recommended procedure for cleaning a CD is to use soap and water (no harsh solvents which may damage the polycarbonate or resin overcoat) and clean in a radial direction (center to edge, NOT in the direction of the tracks as you would with an LP). While on the subject of CD care, CDs should always be returned to their original container for storage and not left out on the counter where they may be scratched. However, if there is a need to put one down for a moment, here are some considerations:

* The label side is probably to be preferred since minor scratches have no effect on performance as long as they do not penetrate to the storage layer below (in which case the CD is probably history). Protectors are available to prevent damage to the label side of the disc. Personally, I think this is taking care to an excessive level but, hey, if you use your CDs as frisbies, go for it!

* However, the opposite argument may apply as well: Slight damage to the readout-side will be ignored by the optical system or corrected for by the decoding process And, there are ways of dealing with scratches should they occur.

Thus, I won't offer a hard and fast rule other than to avoid leaving CDs out where the dog can get to them. :)

Never apply sticky labels to the readout-side of a CD or to the label-side unless they are specifically designed for this application. And, if a label was stuck on despite the warnings, don't attempt to remove it (or at least exercise the utmost care) as the lacquer layer and some of your valuable bits may come away with it. This is especially critical for CD-Rs (and maybe CD-RWs) which seem to be more fragile than normal CDs. I've seen samples of CD-Rs literally self destruct due to slight stress on the label side.

  Fruit Bat /\0/\ 16:59 28 Sep 2005

CD cleaning
You do not need a fancy CD cleaning machine.

Use a soft cloth, tissue, or paper towel moistened with water and mild detergent if needed. Wipe from center to edge - NOT in a circular motion as recommended for an LP. NEVER use any strong solvents. Even stubborn spots will eventually yield to your persistence. Washing under running water is fine as well.

Gently dry with a lint free cloth. Do not rub or use a dry cloth to clean as any dirt particles will result in scratches. Polycarbonate is tough but don't expect it to survive everything. Very fine scratches are not usually a problem, but why press your luck?
Should I really worry about cleaning my CDs?
Something that not everyone is aware of is the multilevel error handling technology in a CD player. Therefore, a dirty CD may not produce instantly obvious audio problems but can nonetheless result in less than optimal audio performance.

Very severe errors - long bursts - will result in audible degradation including noise and/or muting of the sound. Even this may not always be detectable depending on musical context.

Shorter runs of errors will result in the player interpolating between what it thinks are good samples. This isn't perfect but will probably not be detected upon casual listening.

Errors within the correcting capability of the CIRC code will result in perfect reconstruction.

Not all players implement all possible error handling strategies.

Therefore, it is quite possible for CD cleaning to result in better sound. However, a CD that is obviously clean will not benefit and excessive cleaning or improper cleaning will introduce fine (or not so fine) scratches which can eventually cause problems.
Can a dirty CD or dirty lens damage my player?
So the droid in the CD store warned you that dirty CDs could do irepairable harm to your CD player, your stereo, your disposition, etc. "Buy our $19.95 Super-Laseriffic CD cleaning kit".

The claim made at one major chain was that dirt or dust on the laser eye would cause heat build-up that would burn out the mechanism. This is different from a dirty disc. The cleaner he was pushing was a little brush attached to a CD that brushed off the lens as it played.

This is total rubbish. The power of a CD laser is less than 1 mW and is not concentrated at the lens. And, as noted elsewhere, those cleaning CDs with the little brush are next to useless on anything but the smallest amount of dry dust.

There are a lot of suckers out there. Save your money.

The worst that can happen is the CD will not play properly. There may be audible noise, it may fail to track properly, abort at random times, or not even be recognized. The electronics will not melt down.

It is just about impossible for a dirty CD to do any damage to the player. A dirty lens will only result in disc recognition or play problems similar to those caused by a dirty CD. The laser will not catch fire.

The only way damage could occur is if you loaded a cracked CD and the crack caught on the lens.

You do not need any fancy CD cleaners in any case - soap or mild detergent and water and a soft cloth are all that are required. If the CD looks clean, it probably will be fine. If there are serious smudges or fingerprints, then cleaning could make a significant difference in performance.

  Stuartli 17:05 28 Sep 2005

CD and DVD-ROM drives, rewriters and players are all very well sealed from external dust and are normally only open for a few seconds at a time.

I've never, ever needed to use a lens cleaner over many years of ownership of such products.

  sinbad1 17:37 28 Sep 2005

I agree with Stuarti used cdr's and dvd roms for years no prob. I certainly wouldn't use any water inside there beit with soap, any residue of water could affect the surrounding metals causing oxidation. Water and electrics don't mix

  Mr Mistoffelees 17:45 28 Sep 2005

My CD player is a Technics machine dating from 1990. I have never cleaned the lens and the reproduction is as fine today as when it was new. So I agree with those above who say cleaning of the lens should not be necessary.

  Fruit Bat /\0/\ 17:58 28 Sep 2005

The soap and water is used for cleaning the CDs not the player

  sinbad1 19:19 28 Sep 2005

Fruit bat /\o/\

Your reply to the original thread is somewhat lengthy and confusing.

i agree cleaning of a lens beit cd/dvd rom or camera lens care should be taken to use the correct cleaning method should it be necessary.

So the answer to his problem is yes providing he takes care to use the correct solvent to prevent any lens damage


  Fruit Bat /\0/\ 19:54 28 Sep 2005

"To the lens, a speck of dust is like a boulder. Once the lens is scratched, replacement of the entire optical pickup is the only remedy. And, since there are absolutely no sorts of standards for these things, it is possible for a really poorly designed cleaning disc to damage the lens even if the dust itself is non-abrasive. In addition, if the cleaning disc doesn't look like a CD to the optical pickup or disc-in sensor, the lens it may not even spin. So, the drawer closes, the drawer opens, and NOTHING has been accomplished!"

Care and Cleaning of the disk is much more important, soap and water is the best and safest way to prevent scratches which are a CD's worst enemy.

I used to test and repair CD players for a living until they became so cheap as to make repair uneconomical.

  9nailer9 09:22 29 Sep 2005

Thanks everyone for your imput into my question the message seems to be leave well alone ( which i intend to do )and thanks to Fruit Bat we all know a great deal more about how to take care of our CDs.

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