Wednesday, April 13, 2011

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How to Fix a Scratched CD

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While compact discs (CDs) are remarkably durable, it’s nearly impossible to prevent scratches and scuffs from occurring from time to time. The resulting damage can be either a skip in your favorite music track or, in the case of data CDs, the loss of that spreadsheet you worked on for two weeks. Don’t despair — repair! While commercial CD repair kits and CD refinishing machines are available, you may be able to repair the damage on your own with products you already have.


Steps

  1. Clean the disc. Even if a CD isn’t actually scratched or scuffed, dust, oil, and other surface contaminants can prevent it from playing properly. Thus cleaning the disc should always be your first move.
    • Run warm water over the damaged disc to remove dust.
    • If there is stubborn dirt or grease on the disc, gently rub it with your finger while you are washing it, and use a gentle detergent or liquid soap (with the water) or rubbing alcohol (in place of water). Any time you rub or wipe a CD, you should do so by starting at or near the center of the disc and rubbing straight outward toward the edge to prevent further scratching.
    • Shake the water off and let the disc air-dry (do not dry it with a towel or cloth, and don't sun-dry it either).
  2. Try to play the disc. Many times a good cleaning is all that is needed. If, however, problems persist after cleaning, try to play the disc in a different CD player. Some players handle scratches better than others; computer CD drives and car stereos tend to be the best.
  3. Burn a new disc. If you can get the CD to work in one CD player - especially your computer’s - but not in others, try burning a new disc. The CD burner on your computer may be able to read the CD well enough to produce a perfect copy. You may wish to try this even if the CD doesn’t play correctly on the computer.
  4. Locate the scratch. Actually looking at the disc will be easier if you can figure out where the offending scratch is. Visually inspect the CD’s playing surface for scratches or scuffs. Scratches that run perpendicular to the CD’s spiral - that is, those that run generally from the center to the rim - may not affect playing at all, and in any case are generally less damaging than those that roughly follow the direction of the spiral. If there are several scratches, but the CD only skips in one or two places, you may be able to approximate the location of the offending scratches based on which track skips. The first track of a CD begins near the center, and the direction of play proceeds outward to the edge.
  5. Data Recovery. Many burning programs can be set to continue reading after getting an error (such as not being able to read a section due to a scratch). If the program can't read a section at all, it will fill it with random data. They can also try to read the bad section by reading at a very slow speed multiple times. For Windows, Nero does this; Linux has the Ddrescue tool. This can often fix damaged CD's, and is especially effective with audio CD's (where accuracy isn't as important). Also, this doesn't risk damaging the CD (like the following methods), so it is a good idea to try this before trying the more drastic methods. If they damage the disk, the data recovered by this method can still be used. Note that due to the slow reading, and multiple attempts at trying to read a damaged section, these programs can take a very long time to complete (a Windows XP disk recovered with this method took about 2 hours).
  6. Polish the CD. WARNING: this can damage the disk further! Use only as a last resort, and read the instructions carefully!! Though counter-intuitive, polishing a disc can repair a scratched CD by removing some of the outer plastic coating and thus making existing scratches shallower. A number of common household products can be used to polish the CD, but toothpaste — especially baking soda toothpaste — and Brasso are probably the most tried and true. You can also use a fine-grit polishing compound that's used for cars or hard finishes.
    • Apply a small amount of toothpaste (must be paste, not gel) or Brasso to a soft, clean, lint-free (old undershirt) cloth: an eyeglass-cleaning cloth works well.
    • Gently rub the cloth on the scratch or scuff in a radial motion, (start at the center and rub out to the edge, like spokes on a wheel). Do this 10 or 12 times all around the CD. Rubbing in a circular motion can cause small scratches that throw off the laser tracking system in the player. Try to focus your efforts solely on the scratch or scratches you’ve identified (if possible).
    • Polish in this manner for a couple of minutes, reapplying Brasso or toothpaste to the cloth as necessary. Be careful not to apply much pressure, although you will still be able to feel the cloth gently rubbing the CD as it polishes.
  7. Remove polishing product from disc. If you used toothpaste, rinse the disc thoroughly with warm water and let dry. Make sure to remove all of the toothpaste and let the disc dry completely before trying to play it. With Brasso, wipe off excess product and let the rest dry. Then, using a clean cloth, gently wipe disc again.
  8. Test the disc. If the problem persists, polish again for up to 15 minutes or until the scratch is almost completely buffed out. The surface around the scratch should begin to look shiny with many tiny scratches. If you still don’t notice any difference after polishing for a few minutes, the scratch may be extremely deep, or you may be polishing the wrong scratch.
Wax Method
  1. Wax the tracks. If polishing doesn’t work, apply a very thin coat of Vaseline, liquid car wax, neutral shoe polish, or furniture wax to the CD’s playing surface. Wipe excess off using clean, soft, lint-free cloth in a radial (inside to outside) motion. If using wax, follow manufacturer’s instructions (some need to dry before you wipe them off, while others should be wiped off while still wet).
  2. Test disc again. If the wax or Vaseline does the trick, burn a new copy of the CD immediately. The waxing method is only a temporary solution.
Light-bulb Method
  1. Turn on your desktop lamp, or any other lamp with a 60W incandescent filament bulb (DJs usually use the small lamp they use for finding their CD's). Hold the CD with your forefinger in the center opening and the recorded side towards the lamp. The distance from the bulb should be about 10 cm (4 in). Hold it there for about 20 seconds, rotating it slowly around your forefinger. Then, while it's still hot, play it in the CD drive (sometimes doesn't work).
Professional Refinish Method
  1. Have the CD professionally refinished. If the disc still doesn’t play correctly, bring it in to a music store (especially one that sells used CDs) or a DVD rental store and ask if they can repair the disc for you. Many of these businesses have CD refinishing machines that do a remarkable job, and they’ll probably charge you less than five dollars to repair the CD.
    • If you have a lot of discs to repair, you might want to buy a CD refinishing machine. These can cost as little as $25, but highly effective industrial machines cost anywhere from $300-6,000. You can search the internet for companies which build and market these.
Repair Foil Scratches
  1. To determine if you have a scratch in your disc's foil, Hold it in clear view of a light, shiny side up, and look to see if there are any small areas of the disc that show signs of the foil missing. Flip the disc Logo side up, and mark where these ares are with a whiteboard marker pen. Get 2 small strips of masking tape, and lay them one on top of each other over the area you have just marked. The CD may run a little loudly, but it will more than 70% likely repair the little missing pieces of foil.

Video


Tips

  • Tracks on a musical CD go from the inside to the outside of the disk. Thus, scratches in the shape of a concentric circle is cause the most damage due to the interruption of many consecutive data bits. This makes it possible that the Reed-Solomon error correction algorithm will not be able to apply guesses and generate the missing data.
  • If it still does not work after you tried everything, use it as a coaster for your beverages.
  • Severely damaged CDs may not be repairable. Very deep scratches and cracks that reach the CD’s foil may render a CD forever useless. It doesn't take much to damage a CD. As a matter of fact, the Disc Eraser utilizes this principle to render CDs and DVDs unreadable, which is useful to have if you want to get rid of sensitive discs.
  • You can buy a disc scratch remover at game stores. It works for all types of CDs that have light scratches.
  • To determine if the foil layer of your CD is scratched, hold the CD up to a fairly bright light and see if any pinholes are visible. Holes in the foil layer of a CD are generally not repairable, even for a professional.
  • Use a quality CD Drive from a desktop computer. If you are trying to read a dual layer disc or scratched disc with a front loaded (slip in) CD drive, like the ones on Mac Books or Mac Book Pros. You can pretty much forget about getting a good read. These drives are notorious for having poorly calibrated/calibrating lasers and are practical useless for anything but brand new unscratched CDs. This has been documented by one repair technician in more than 10 mac books / pros.
  • Practice repairing scratched CDs that you don’t care much about before you set out to repair your favorites.
  • It’s a good idea to create a backup of any data disc before damage occurs.
  • If a CD is scratched but continues to play correctly, make a backup, but don’t bother trying to repair it yet.
  • Make sure the disc is indeed scratched. If the disc is not visibly scratched, the problem likely lies elsewhere. Other problems could be surface dirt or a malfunctioning CD player. The steps above should help you to clarify where the problem is.
  • Deep gouges are not repairable. However, because of the way redundancy is used in the data on the disc and the way the data are distributed along the spiral track, cleaning a disc area away from a scratch can improve data recovery; a number of smaller defects distributed along the track can be as bad or worse than one larger defect.
  • The polycarbonate bottom layer of the disk acts as a lens, which focuses a larger patch of laser light down to a smaller size needed to see the track on the data layer. This lets the laser look through some small imperfections on the plastic surface which are much larger than the track on the data layer. Removing a lot of plastic can affect the refractive property of the lens making the data unreadable. This means that even a visibly scuffed or spider-web of scratches may play well because, though the defects are visible to your eye, the laser sees around/through them. This is why waxing can help. A repair doesn't have to look perfectly polished to work.
  • If the disc has important data on it, your best choice is probably to pay the money to get the disc repaired professionally before you try to repair it yourself. That way, you can make sure you don’t damage the CD any further in your repair attempts.
  • A number of CD cleaning and repair kits are available for sale, but many users report that these don’t work any better than Brasso, and they’re far more expensive.
  • To remove deep or stubborn scratches quickly, try using a dry “Mr. Clean Magic Eraser”. This is a sponge impregnated with a micro abrasive. Use light pressure, wiping from the center of the disk to the outside edge just as described with other polishing methods. The repaired area can be buffed until shiny using the other polishing or waxing techniques described.
  • If the disc is an Xbox 360 game, attempt to return it for an exchange. Your mileage may vary, but Microsoft saved about 25¢ on the build cost of the Xbox 360 by not including safety measures which would prevent a lot of scratches. Most stores have deals worked out with the distributors to where they can get credit for damaged discs, but only discs that were damaged inside the 360. Such discs will have deep radial scratches, sometimes not around the entire circumference of the disc. It couldn't hurt to try. (Try a few stores actually, the worst they can do is say no.)
  • Also, with Xbox 360 disks, if you use one of the temporary methods, you can install the game to the hard drive by going to the game library, clicking on the game, then install game. this doesn't always work, as the xbox has to access the disk to verify it as legit.

Warnings

  • A CD's data is actually stored in microscopic grooves in material immediately under the thin but fairly hard paint side, which would bear any label.[1]. Generally one leaves that side alone and repairs a disk's readability by smoothing defects in the thick clear-plastic side, through which a light shines to read the data.
  • If you hold the CD up to a bright light to check for holes in the foil layer, remember not to stare at the light for long. A 60-100 Watt bulb should be more than enough to see pinholes in the foil layer. Do not use the sun!
  • Doing this incorrectly (e.g. applying too much pressure while polishing or rubbing the CD in a circular motion) may shorten the life of a CD.
  • To prevent damage to your CD player, make sure CDs are completely dry and free of excess polishing products or waxes before you attempt to play them.
  • If you are using Brasso, make sure to do so in a well-ventilated area, and avoid breathing in the fumes. Always read the safety instructions and warnings on any chemical product as many (such as rubbing alcohol) are flammable and / or can cause skin, eye, or respiratory irritation.
  • When touching the CD do not use a circular pattern (circumferential pattern, like when a CD is spinning). Go from the inside to the outside in a perfect line (a radial pattern) so you prevent data loss.
  • When polishing the disc, make sure the surface upon which the disc is laid is flat and firm but not hard or abrasive. Data is stored on the foil or dye layers on the top of the disc (label side) and the protective top layer is very thin by comparison to the polycarbonate plastic bottom layer you will polish. The thin top layer can easily be scratched or perforated. If this happens the data is lost forever as it is not repairable by any means. Pressing on a disc upon too soft a surface may crack it or cause it to de-laminate.
  • Don't touch the CD, or you'll leave finger prints, causing it to get dirty again, and that may cause the CD to skip a track or pause. Hold it by the hole in the middle.
  • No solvent is to be applied as this shall change the chemical composition of the polycarbonate substrate resulting in an opaque finish and an unreadable disc!
  • When trying the procedure described in step 3, don't hold the disc near the light bulb for more than 20 seconds. Even a 60W bulb produces enough heat to melt the CD if exposed longer than 30-40 seconds.
  • Understand that you can cause further damage if you use toothpaste. It may scratch it even more.

Things You'll Need

  • Clean, soft, lint-free cloth (microfiber cloths are excellent)
  • Water (or rubbing alcohol)
  • Brasso metal polisher, fine polishing compound or toothpaste
  • Liquid car wax or Vaseline (optional)
  • Cotton gloves or plastic food-handling gloves make handling CDs easier.
  • A Lamp

Related wikiHows


Sources and Citations


CD recovery software

  • Recover Disc Recover data from scratched and damaged CD and DVD
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