The Clear-Vu Zenith Pac locking DVD case is a ubiquitous fixture in
libraries and video rental stores across the country. It uses a magic
yellow tab to keep you from opening the case. A gizmo mounted to the
checkout counter can open the case easily by sliding the DVD across its
slot. A similar case called One-Time has a built-in red slider.
Ever wonder how it works?
The secret is two very powerful magnets. From reading the sales literature
for the locks, these magnets are supposedly only available to sooper-seekrit
authorized personnel. What they don't tell their customers is that these
magnets are also available inside every hard disk drive made in the
last 15 years. They are part of the head seeking motor.
To take apart a disk drive, just get a small Torx screwdriver and have at it.
Be sure to look for the screws hidden under the "warranty void if removed"
stickers. I won't explain more than that... it should be obvious.
On to the fun part. Here's what a yellow locking pin looks like after it's
been removed from the DVD case.
Notice that the lock has two metal lumps, each suspended by a sort of plastic
spring so that they stick out past the narrow sliding part of the locking
pin. The object of this exercise is to make those two metal lumps pull in
towards the center of the pin, so that they will no longer block the sliding
action of the pin.
In order to remove a locking pin from a DVD case, the magnets have to be
positioned so that they pull both metal lumps inward at the same time. It
may be easier to do if you have a look at where the magnets go:
To make sure that the magnets are in the right place, you will be able to
feel two spots along the DVD case where the magnet has an attractive force.
One spot is more attractive than the other, because the metal lump is closer
there. That's NOT the spot you want. The spot you want is where there's a
weaker attraction.
First rub a magnet slowly up the right edge of the front side of the case,
feeling the two sticky spots. Make a note of where the strong one is...
that's where the magnet goes on the *back* of the case. The weak sticky spot
is where the magnet goes on the front of the case.
Put both magnets in place (you may have to hold them and jiggle them a
little), and the locking pin will slide out. Ta-da!
There is a different type of case with a red locking tab that's permanently
installed in the case. This one works the same way, but you can look inside
an opened case to see where the metal lumps are, so it's even less
challenging than the yellow one.