If you've just rediscovered an old console in the back of your closet, or you're newly into retro gaming and want the genuine experience, you've probably stood in front of your shiny new LCD or plasma TV with a console made in the age of CRTs, wondering what to do. Luckily, it's not too difficult to plug everything in and get your game on. Here's how:
Use the Highest Quality Connector Available on the Console
The newest consoles use HDMI, but older consoles can usually connect to new HDTVs over either component video or composite video. Consoles like the PlayStation 2 and the original Xbox all connect over component, and while composite is an option, you'll get better video quality by going with component if it's available on your TV.
Older consoles won't necessarily support component, and in those cases -- especially with older think the Dreamcast, the Nintendo 64 or the GameCube, composite is your best option. With even older consoles, S-Video may be your best choice. Bottom line: Use the highest-quality video connector on offer that's also available on your TV. The only time you should worry is if your console uses a connector that's not available on your TV.
Try Composite If Your Old Console is RCA-Only
With some consoles, such the original NES and several others from around the same 1980s time period, you may be get away with connecting your RCA cables to the red and yellow composite video ports on the back of your TV. Some older consoles, like the Sega Genesis, have full composite video cables, with all three red, white, and yellow connectors. If yours only has two, connect red to red and try the white one in either the white connector or the yellow one. As long as those cables aren't actually carrying audio, one of them is almost always audio and the other is video -- if you can get video in the yellow port and audio into the red or white port, you're in business.
Go Coax For Older Consoles
If the console you want to connect uses a connector that your TV just doesn't have, you'll need a converter or an adaptor that will connect to a port your TV actually has. The easiest way to do this is to connect via coax, since most modern sets still have one for over-the-air antenna connections.
Some of the older consoles, like the NES, Sega Genesis, and some older Atari models, use that old RF connector box that many of us remember and love. You can still use it if you want to and don't feel like buying anything new. Just connect your single RCA cable from the console to the box, then connect a coaxial cable from the box into the cable or antenna port on the back of your TV. Switch the box to "game" when you're using it, switch to the TV/Cable input manually, and don't let your TV try to auto-tune its way to a signal. This article at Retro Games Collector goes into more detail about this, and can help if it's still not working for you.
If you still have the box, great, but if you don't, you're not out of luck. All you need is a coaxial to RCA (female) adaptor. >. Just connect the RCA cable from the console to the female end, connect the male coax end to your TV, tune to TV/Cable manually, find the right channel and you're off and away playing your favourite classic games. This method is actually easier than using those old switchboxes, so consider it even if you do have one.
Get Around a Display Without Coax Inputs Using a VCR or DVD Player
If none of the above options really work for you, you could potentially get around dealing with your TV entirely by going through a device already connected to your TV that has an auxiliary input. If you still have a VCR attached to your TV via composite or component video, or you have a DVD player connected via component or even HDMI, check the back. If it has an RCA or a coaxial input, you're in business.
Just connect your console to the back of the VCR or DVD player using your preferred coax trick above. Then connect the VCR or DVD player to the monitor or TV using composite or component (whichever is better, or available), and set the device to its auxiliary port. You'll lose some video quality because you're running the signal through a second device on its way to the screen, but it's better than having no signal at all.
These aren't the only ways to get the job done of course, but they're some of the easiest and most broadly applicable to the widest set of old consoles, from old school Ataris and Commodore PCs all the way up to not-really-old-but-still-retro consoles like the N64 and the Dreamcast. With a little time and attention to all the ports on the back of your TV, it should be a snap.