CD Scratch Repair Devices - Page 2

MacDEF:

I saw what you wrote in your earlier post. I didn't know that this 2nd step made the CD look like new again. Does it? If so, pretty cool. The "Wipe Out" solution, as I was commenting on my post, does not.

It's not really "like new" but definitely much better. The first solution is pretty coarse, and (as you saw) while it buffs out the bigger scratches, it leaves fine scratches of its own. The second solution buffs out much of the smaller scratches. Still not perfectly shiny and smooth, but pretty good

I have a skip doctor machine. It kind of works, I bought it mostly to use on the kids PlayStation games. It will occasionally fix a CD or game.

The cheapest thing to use is a common household item (at least I hope it's common in your house).

Toothpaste.

Toothpaste and a soft damp cloth will polish out a lot of scratches. Rub in a radial direction, like the spokes on a bike wheel. Rinse and polish with your favorite cleaner.
Usually works for me.

I actually have the Skip Doctor and to answer your question..... it works.... it does repair a cd, it removes dirt and even scratches on the disc (as long as it is not badly scratched)......the result = you'll have cd's that look and sound ALMOST as good as new..........but to let you know new cd's are new cd's and these used cd even though repaired will never sound as good as the new ones........the only annoying thing is the Polishing/Buffing of the cd ...........a pretty good product for 29 bucks.

Huh? many of my cds have millions of scratches and they work good-as-new.

Some scratches aren't big enough to make a cd skip but are still large enough to force some error checking which degrades sound quality marginally.

This is actually completely untrue. As long as the errors caused by the scratches on the CD fall within the error correction ability of your CD player, you will never know the difference.

Could you explain this concept MacDEF? It seems like it would have to sound better if the cd was completely new. A scratch or scuff would destroy original data on the cd, consequently degrading sound, right? Also, wouldn't forcing the player to make error corrections degrade the sound, even if ever so slightly? Isn't it the same sort of thing as anti-skip? Putting the information into some buffer and stuff like that? I am woefully ignorant of this technology, so if the great hi-fi shamans of this board could teach me their ways, I would bang a drum really loudly for them.

CD players may use three or more laser beams to stay on course on the CD. The CD is kinda like a vinyl with a continuous spiralling track that starts from the inside and goes outside. One beam reads the information in the middle of the track, the two other beams on both the left and right side of the track stays steadies the head (ie: like a rail road). Small radial scratches are mangeable. The worst is a scratch that parallels with the track because it will disrupt data readability completely and the tracking mechanism may fail beyond correction. Further, these fixing kits are suspect because they try to fill in the scratch with a different material that may improperly affect the refraction properties associated with the laser beam.

If the data is corrupted and detectable, the cd-player may try to apply error correction (some funny math-bit manipulation stuff here). If the corruption is really bad, then it wll try to interpolate. Expensive cd players will try to read ahead and determine the smoothest interpolation. Cheap CD players will try to read somewhat ahead and do a liner interpolation. Older cheap CD players give up and just put a blank signal their (annoying and dangerous to speakers).

The information on the CD audio is scrambled time-wise so a big scratch will disperse the "energy" of the error across a chunk of time reducing the noticeablility of the error. In other words, a single gash on the CD may produce tiny periods of errors dispersed in time. Without this, that big gash may produce a notiecable error over a single period of time.

So what MacDef said is true only up to the point the CD player cannot manage the errors. Of course, if you listen to a perfect CD copy next to a severaly scratched copy, you may notice a difference (I actually have exprienced this too).

There you go

Although:

Actually, these kits don't work that way. Since a CD is basically an aluminum-based substrate encased in (theoretically) non-refractive plastic, a scratch is simply a scratch in the encasing plastic. Scratch-repair solutions work in one of two ways: 1) they "melt" the area around the scratch so that the scratch is smoothed out; or 2) they buff the scratch out (meaning they actually "sand" down the area around the scratch. So in many cases they can indeed make the CD "good as new."