Recently, I was in a home in Bel-Air that rents out for parties and video productions. The place had a home theater system that was pretty good when it was installed—but when it was installed, Clinton was president and Google didn’t exist. I was enlisted to figure out how to put in a high-def projector temporarily, and to interface an HD DVD player with the system. No easy task, given that the long-neglected system was squeezed into a tight cabinet, and screwed into two old-school Middle Atlantic racks, built before the company had figured out how to make racks that were really easy to access. But the tip I got from the property manager was worth all the effort.

With his help, I’d slid the main rack out and propped it precariously on these things that look like automotive jack stands. Still, I couldn’t see the back panel of the Yamaha receiver, so I couldn’t figure out what was connected to what. I was about to climb higher on the ladder and wedge my body dangerously behind the rack so I could see, but then the property manager offered, “I always use a CD.”

I looked at him like he’d just suggested I gain access to the rack by turning myself into a gnome, but then he explained, “Use a CD as a mirror, and light up the jacks with a flashlight. That way you can see them. You don’t know that trick?”

Now, I’ve been working pretty seriously with A/V gear for about 30 years, and I haven’t missed much, but it is possible everyone but me already knows this trick. Anyway, if you haven’t tried it, do. It works surprisingly well and might save you the hassle of having to slide a surround processor out of your rack and accidentally disconnecting something in the process. Any DVD or CD will work as long as it’s not terribly scratched up. I’m happy to say that this trick finally got me my money’s worth out of a Destroy All Planets DVD I picked up at Target for $1.