Audio CD Repair – Disc Repair – Scratched CD – Damaged DVD – Damaged discs.
Badly scratched or damaged CDs or DVDs can ruin the playback of the audio or video content and sometimes prevent copying of master CDs or DVDs.
Contrary to what many people expect, in many situations light surface scratches will not affect the playback of the content as the playback systems are designed to correct these types of problems.
Where scratches are severe there are a couple of repair paths we can take, one is polishing the disc surface with a special machine and compounds that can sometimes return playability to a faulty CD or DVD. – Unfortunately at ProCopy we often find that if the damage is bad enough to cause a playback problem then the disc itself may not be able to be repaired. Often domestic scratch repair kits are ineffective in making the discs play for any lenght of time. There is more technical information on CD production here in our CD Basics Section.
For many years CDs and DVDs have been promoted as being “indestructible” this is far from true, it’s just that many problems are hidden by sophisticated error correction circuitry and complicated mathematical algorithms. It's not until these problems become uncorrectable that the discs appear to have major problems. Due to the manufacture of the discs there are a number of things that should be taken into account to prevent untoward damage of your important data.
CDs contain a molded polycarbonate base of around 1.1mm thickness and there is a molded layer that contains the data and a fine layer of aluminium (sometimes gold) that reflects the laser to read the data. A very thin top coat of plastic and a printed layer with the disc artwork on it completes the disc mechanical structure. Total CD thickness should be around 1.2mm when completed.
DVDs are essentially the same in structure as CD, but the base of the disc is slightly different. In order to allow the varying formats in Dvd storage capacity the disc is actually two 0.6 mm discs bonded together.
Due to the structure of the disc the top coat and printing is not very thick ( less than 0.1mm), this means that any damage to the label side of the disc is very close to the data (audio, video, text etc) and therefore extreme care should be taken not to damage,nick or put holes in this layer.
Scratches that are radial, that is, they are like spokes on a bicycle wheel and go from centre to outside edge are often corrected by the error correction electronics in the player as the data is only corrupted for a few bytes. Scratches that are concentric (Parallel to the data flow on the disc) are very bad and often corrupt too much information for the error correction circuits to fix. It is important therefore that discs are treated with care and put back in a box when not in use. Leaving a disc data side down on a table or other surface is also likely to damage the disc surface and is not recommended. Other types of audio repair and restoration can be read about here.
"Fatal flaws" include damage to the Table of Contents area on the disc (See TOC in our CD Glossary) This means that the player may not be able to boot up the disc or critical information stored in the TOC cannot be read and therefore the laser doesn’t know where to go on the disc to retrieve information.
Damage to the Silver reflective layer can be viewed easily if it is held up to the light and you can see light coming through a small pinhole or scratch, then this type of fault cannot be fixed.
Severe concentric scratches will often damage large sectors of data and depending on where they are located can either be a fatal flaw or make some parts of the data irretrievable.
At Procopy we have methods for reducing these problems and vary between physical disc polishing to electronic reconstruction and extraction of the disc data.
Once the problems have been reduced or corrected a new master disc or further copies can be created. Data extraction on a DVD can be a very slow process, we have had to spend up to 2 weeks retrieve data off a 4.7GB DVD, but had a great deal of success in recovering some valuable family memories that were stored on the DVD
- for explanation of these and other audio terminologies see our Audio Glossary in our Audio Section.
If you have a CD or DVD with a problem where it won't play or is erratic then contact us for some information by clicking one of the links below or call ProCopy on 1300 4 PROCOPY or 08 9375 3902.
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