Every console in this store is decades old, and plenty of them have been opened, cleaned, repaired or modified along the way. The listing title rarely tells you which. The photos and a couple of questions to the seller usually do. Here's how we'd check one, from the first photo to the first long session on arrival.
Start with the photos
Look for a photo of the console switched on with a game running on a screen. A lit power light on its own proves very little. A front-loading NES is the classic case. When its lockout chip can't talk to the cartridge, it resets the console about once a second, so the red light blinks on and off. A single photo can catch it in the on half of the blink.
Then look at the back and the bottom. You want the label, the model number and every port in the shot. The label tells you the region and revision, and the ports tell you which cable you'll need. If a listing only shows the top of the console, ask for the rest before you buy.
Power: get the right supply
These consoles don't share a power standard. AtariAge lists the Atari 2600 supply as 9 volts DC at 500 mA with the center pin positive. The Nintendo 64 uses its own external brick that supplies 12 and 3.3 volts DC. The original PlayStation has its power supply built in and takes a plain mains cord, while the smaller PS one moved to an external 7.5 volt adapter.
A generic adapter with the wrong voltage or polarity is a risk you don't need on an old board. Read the input rating on the console's label or by its power jack and compare it with the label on any adapter in the photos. A listing with the original supply is the easy choice. If it's missing, order the correct one before the console arrives, so you can test it the day it lands.
Video: know which cable you need
Each console has its own set of outputs. The Atari 2600 and the top-loading NES-101 give you RF only, through the TV's antenna input. The front-loading NES adds composite video on RCA jacks. The SNES and N64 share one multi-out cable that carries composite and S-video. The Genesis Model 1 has an RF port plus an 8-pin DIN port, and the Model 2 swapped both for a 9-pin mini-DIN. The PlayStation's AV Multi Out can carry composite, S-video and RGB, though the cable that came in the box only uses composite and stereo audio.
For a test, a plain composite cable is enough on anything that has the port. If you're testing an Atari 2600 through an old switch box, use a manual one. AtariAge notes that the 2600's signal is too weak to fully trip the automatic switch boxes that came with the NES and later consoles. For the full story on modern TVs, read NTSC, PAL, NTSC-J and RGB explained.
Test with a real game, for a real stretch
Booting to a title screen proves the console powers on. Play for half an hour or more, with the sound up. Faults that come from heat, a tired drive or a loose connection often wait until the console has warmed up.
Disc consoles need the most care. Early PlayStations had plastic drive parts sitting close to the power supply, and those parts wore unevenly. Some owners kept them reading by standing the console on its side or turning it upside down. Later revisions moved the drive and switched to die-cast metal parts. If a seller mentions the upside-down trick, treat the drive as on its way out.
On an N64, open the lid on top and check the memory slot. The console won't boot without a Jumper Pak or an Expansion Pak in it. Donkey Kong 64 needs the Expansion Pak, and the North American Perfect Dark needs it for the story mode, so test with one of those if the listing includes the Pak.
On a Genesis, consoles from about 1991 on show a short line at power-on saying the game is produced by or under license from Sega. That's TMSS, a trademark check Sega added to the hardware, and it's normal.
Dirty connectors cause a lot of dead listings
Some consoles sold as "not working" just have dirty contacts. The front-loading NES is the worst for it. Its spring-loaded tray is more prone to dirt and dust, and years of inserting and removing carts wear the pins in the connector. A console that boots one game and not another usually needs a clean, of the cart or the slot or both.
Clean the cart contacts on arrival with isopropyl alcohol on a cotton swab and let them dry before you insert the cart.
Controllers
Test every button and the d-pad in a game that uses all of them. On the N64 controller, the analog stick is the part to watch. Heavy use can leave it loose, which makes precise movement hard. Push it to each edge and let go. It should snap back to center and the character should stand still. See the N64 controller page for more.
Some bundles come with third-party or clone pads in place of the originals. Those can be fine for a spare, but they aren't what the photo of an original pad promises. Our guide to spotting reproduction carts and fake controllers covers the tells.
Yellowed plastic and retrobright
Gray consoles from this era often turn yellow. The ABS plastic in the shell yellows with ultraviolet light or heat, which breaks down the polymer and can leave it brittle too. The plastic on some older SNES shells is especially prone to it.
Retrobright is the popular fix. It's hydrogen peroxide with a small amount of TAED as a catalyst, applied to the shell and exposed to UV light. It works, with catches. Some owners see the yellowing come back, and there's concern that it weakens the plastic and only bleaches the damaged surface. A ten-year study found that treated surfaces yellowed again and picked up streaking and blotching that untreated surfaces didn't.
So ask whether a very white console has been treated. We'd take an evenly yellowed stock shell over a streaky treated one.
Screws tell you if it's been opened
Nintendo used security screws on much of its hardware. The SNES console closes with 4.5 mm Gamebit screws and its cartridges with 3.8 mm ones, and the N64 uses both sizes. Look closely at the screw heads in the photos. Chewed heads, mismatched screws or empty holes mean someone has been inside.
That isn't automatically bad. A cleaned or repaired console has been opened too. It should be in the description, though. Ask what was done and why, and if the answer is a region mod, an RGB mod or an HDMI kit, read our guide to modded consoles before you buy.
Recaps
Electrolytic capacitors age. The liquid electrolyte slowly dries out, the parts drift out of spec, and the service life runs out. A recap replaces them with new ones, and repair references like the Console5 tech wiki keep capacitor lists for each board revision of consoles like the Genesis Model 1 and for the NES power section.
A recap done well is a fair repair on a console this old. Treat it like any other modification, though. Ask who did it, look for clean solder work in an inside photo, and buy it as titled.
Shipping and the first week
Ask for the console to be boxed with padding on every side, with the game taken out of the slot and the disc taken out of the drive.
When it arrives, check the shell for new cracks, then run the same tests you would have asked the seller for. Play a full game session, try every controller and use every port you plan to use. Do it inside the return window, so a problem becomes the seller's to fix. Then browse the consoles in the store with a better idea of what each listing is showing you.
