Not long ago, I took some aspiring engineers to a trade show where some “antiques” were on display.

Namely, some CD/DVD players, along with a few analog multitrack’s.

Over the last 30 years, audio equipment has certainly followed the better-smaller-cheaper model of the computer industry.

But like the computer market, repairs are no longer typically done at the part level. If the laser in a CD player goes bad, the chassis with the whole drive motor and optical track will typically be swapped out.

At this point, it’s probably safe to say that for CD decks, the bag of tricks for in-the-field repair is limited to smelling for burned electronics, scanning for loose wires, and the tried and true whack on the side of the box.

While at this point many consumers have long abandoned magnetic tape and are well on their way to ditching optical storage in favor of solid state, on any given day engineers may come across a number of relic formats long presumed dead.

Thus, it’s always handy to have a few tricks on hand for recovering damaged media and maintaining the devices it takes to playback the formats of old.

Optical Disc Repairs
When CDs first came out, everyone held their breath while handling these shiny discs only by the edges.

We gently placed them into the player with the level of care typically reserved for open-heart surgery. Today, we’ll do our best Frisbee throw across the room. As the technology becomes familiar, our CD and DVD media are getting more scratched up than ever before.

Figure 1: 1. Use 90 percent or higher denatured or isopropyl alcohol on lint-free cloth. Do not use rubbing alcohol. 2. Start by placing the cleaning cloth between the heads on the drum. 3. Rotate the drum counter-clockwise with light pressure on the cleaning cloth.

Most people know that scratches following the circular reading pattern on the CD will be more likely to cause a problem than scratches that are perpendicular to the reading pattern. What most people don’t know is that the scratch itself is not usually the problem.

There is a clear protective layer on the CD’s read side, which guards the data layer from damage. Since the player’s optics are normally focused beyond the protective layer, the systems typically read past the scratches.

The problem actually comes from the dirt that collects in the nooks of the scratched area; the dirt is what the laser can’t read through. The way to solve this, oddly enough, is to wash the CD or DVD, much like you would a dinner plate.

Using cold water (so the plastic doesn’t melt), take a sponge with some dishwashing liquid, and wipe from the center of the CD to the outside.

Don’t wash in a circle, since that might cause new scratches that follow the reading pattern. To dry the disc, dab it with a soft cloth. Then put it in your ROM or player. Chances are, it’ll work.

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