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Maintaining Optical & Magnetic Media

Retaining/restoring the health of CDs and DVDs (and their players), as well as dealing with damaged tape

By Patrick Killianey December 1, 2015

A while back, I took some aspiring engineers to a trade show where some “antiques” were on display. Namely, CD/DVD players, along with a few analog multitrack players.

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 most consumers have long abandoned magnetic tape and have ditched 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 play back 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 do our best Frisbee throw across the room. As the technology became familiar, CD and DVD media got more scratched up than ever before.

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 don’t know is that the scratch itself is not usually the problem.

There is a clear protective layer on a 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 data layer of a CD is simply a reflective piece of aluminum, with a protective lacquer on the back and a clear polycarbonate on the top.

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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Graham says

Those were some great suggestions had never heard about the hot water trick,However I don’t know about the explanation of why not to use rubbing alcahol.The biggest hazard of rubbing alcahol is the mineral oil they usualy put into it without listing it as a ingreident.

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