The Atari 2600's RF Shield

The Atari 2600 is a fairly easy console to take apart; it has a few screws
which can usually be removed without complications. Once you get it open,
however, the tinkerer is confronted with a prominent metal box enclosing most
of the inner circuitry of the machine.

The metal box is actually the 2600's RF shield. The Atari 2600 uses an analog
RF video output, and such analog signals tend to pick up interference from
nearby digital circuitry, especially the older "noisy" digital circuity like
that used in the 2600.

The RF shield is just a piece of sheet metal whose purpose is to protect the
console's RF output from getting corrupted by stray electromagnetic
interference from the logic circuitry. The RF shield can be easily removed by
using a pair of pliers (preferably needle-nosed pliers) to bend the twisted
posts holding the shield in place, then simply lifting the shield off. The
console will work properly without the shield, but the quality of the video
output will be degraded because of all the interference the video signal will
pick up. If you're going to be working underneath the RF shield, you can
safely remove it, but put it back on (and twist the posts again to secure it)
when you're done.