The Best Way to Clean Your NES Cartridges

Mouth end of three NES game cartridges

When I first started out playing my new-to-me NES, I would just pop a game in and… it didn’t always work. I know you always see people blowing into their cartridges, but I had heard that was a bad idea. So what is the right way to get a game working properly?

What’s the best way to clean NES cartridges so they consistently work? Do a deep cleaning on your game carts, opening them up for full access to the board, so you can fully remove anything from the contacts. It’s easy to learn how. My carts all work 100%, every time I put them in.

Table of Contents

When you insert a cartridge into your NES, the circuit board in the cartridge needs to fully connect with the 72-pin connector slot inside the NES console. If this connection point isn’t in optimal shape, your games will work only inconsistently, or maybe not at all. So, to make your NES setup work consistently every time, You need to cover two areas:

  1. Make sure the contacts on your game cartridge are clean, and in working order
  2. Make sure the 72-pin connector inside your NES Console is working properly

This article is about point #1. If you haven’t sorted out #2 by replacing or rehabbing your NES console’s 72-pin connector, you’ll want to read up on that.

Bonus tip: It’s always a rush to get a new game, and I know I get excited to try it out ASAP. BUT - once you have your 72-pin connector sorted out, it’s best to follow quarantine procedures, and not insert any cartridges that haven’t at least been through Level 1 cleaning below. If you put a funky, uncleaned cart into a nice clean 72-pin connector in your NES, you can transfer problems from the cart to the connector. Don’t do it! At least do a Level 1 cleaning below before you put a game into your system.

The Best Care for 30 Year Old Game Cartridges

NES game carts are artifacts from a good 30 years ago. They have three decades of history. If you get a game from a friend, a yard sale, even a store - assume you have no idea what it has been through, and that it has not been properly cleaned.

Contact pins in the mouth of an NES game cartridge

Any time you’re considering buying a game cartridge, give the pins in the mouth of the cartridge a good look. Examine for dirt, corrosion, or other damage. Most of the NES games I have bought were relatively clean looking - that is, no visible gunk, but that doesn’t mean they’re clean. I bought one that had some brownish goo on a few of the pins (ancient soda spill, maybe). Another one ended up having corrosion on a few of the pins, but unfortunately, it wasn’t visible until I opened the cartridge, and it was a Famicom (Japanese NES) game, which can be challenging to open. So, the more valuable the cartridge is you’re looking to buy, the more you should probably open it up to get a careful look (and also to make sure it’s not a reproduction cartridge). More on opening cartridges below.

Famicom cartridge corroded pins
This close-up of the pins on one of my Famicom cartridges was shot through a magnifier. The rusty corrosion is very plain, but was not visible with the cartridge closed. You would think that the heavily corroded pin toward the center would have been obvious, but it only looked darkened when looking in the mouth of the cartridge.

Cartridge games were designed to be pretty tough, and hold up to countless insertions and removals. As long as cartridges haven’t been seriously abused through scratches, or corrosion on the connector pins, the cleaning methods below should get everything into good shape. Do a thorough cleaning on all of your cartridges, and they should perform well for you.

I have broken the steps out into progressive levels - from a quick, light cleaning, to heavy work for ones that are having real problems. I put all of my games through Level 2 before I even put them in my NES. I like having them all sorted out, and don’t want any mysterious issues spreading to the console (goo or dirt that comes off in your cartridge slot!). Levels 1 and 2 should be good for most games. The other levels are for situations where your game is being very resistant to working consistently (or at all), even after the thorough Level 2.

NES Cartridge Cleaning: Level 1 - A Bare Minimum

Don’t put anything into your NES unless you have at least done this much. Really. It’s so easy, and can save you frustration from an unknown cart (even one that looks good to the eye) gunking your system.

You Will Need

  • Cotton swabs, the kind with the paper/cardboard shafts, like Q-Tips
  • 91% isopropyl alcohol

I prefer the swabs with paper shafts because the plastic ones often don’t hold the swab part during serious use.

High-purity isopropyl alcohol is recommended for the cleaning of electronic contacts. Computer techs use it to clean the contacts on expansion boards like graphics cards, which are essentially the same thing as your game cartridge’s contacts. Get 91% isopropyl. You may have to look a bit to find it. I got mine at Walmart. Don’t go for the more common 70% rubbing alcohol, since higher purity is better. Lower percentage can give non-optimal results.

The NES cartridges say right on them not to use alcohol to clean them. The reason seems to be that they wanted you to buy their cleaning kit - which of course used alcohol. Go figure.

Saturate an end of a swab with the 91% isopropyl alcohol. Holding the cartridge firmly in one hand, insert the wet end of the swab into the cartridge mouth, all the way to the back. Now bring it up against the contact pins on one side of the bit of circuit board that is in the cartridge mouth. Firmly, and vigorously rub the swab back and forth - in small areas, then end-to-end, making sure you have rubbed the whole side thoroughly. Turn the swab a little every so often to expose clean cotton to the contact pins. Keep going until you can rub a clean portion of swab vigorously across the contacts end-to-end and pull it away without the slightest tinge of dirt (really, oxidation, usually).

Once you have cleaned one side of the contacts, start with the fresh swab end, and repeat the process on the contact pins on the other side. It often takes me 2-3 swab ends to get the contacts on both sides cleaned completely. I rub vigorously enough that the paper shafts often end up bent. Don’t be ginger with it. Really rub.

Once the contacts are clean, I like to take the spent ends and run them around the inside of the cartridge mouth to wipe out any dust, dirt, etc that might be around.

NES Cartridge Cleaning: Level 2 - Open Case For Better Contact Access

I do this for all of my games. The reason is because I had thoroughly done Level 1 on all my carts, and then I replaced my 72-pin connector, but the new connector didn’t make all of my games run every time I put them in. I got more serious, and did this Level 2 cleaning on all my games, and now every one of my NES cartridges comes right up every time I put it in the system.

You Will Need

You will need a special Nintendo style screwdriver to open your cartridge. It comes in handy as you work on making sure your games are properly clean. You can buy a single screwdriver, a tip for a replaceable tip screwdriver, or I bought this little kit on Amazon, which gave me a 3.8mm screwdriver for NES/SNES cartridges, a 4.5mm screwdriver for various Nintendo and Sega system consoles, and several other tools with specialized tips for use on electronics.

A gamebit screwdriver for opening Nintendo items, such as cartridges
This 3.8mm game bit screwdriver came in the kit mentioned above.

Please note that there are some cartridges, especially those that have 5 instead of 3 screws holding them together, that actually use a very small flathead screw. I got my small screwdriver kit years ago at Radio Shack. This screwdriver set on Amazon looks very similar.

Use a pencil eraser that’s fresh - not an old, hard one that’s shiny looking, or a really grungy one. You want fresh rubber to use on the contacts. If your eraser is still soft, but lightly used, try rubbing it on something clean to rub off the dirty bits and expose fresh rubber.

If you’re using an eraser on the end of an actual pencil (I find these are very useful, since the pencil gives me great leverage when vigorously rubbing it on the contacts), be certain you don’t wear it down too far, and end up scratching your contacts with the metal ring that crimps the eraser onto the pencil end. Yikes!

Start out by using your screwdriver to unscrew the 3 (or 5 on some cartridges) screws in the holes on the back of the cartridge case. Whether the tri-wing screws, or the flat head, they are all very small, so make sure the driver tip bites in, then apply steady pressure and turn firmly, but slowly to make sure you back them out without stripping the heads (grinding off the part the screwdriver tip grabs).

An opened NES game cartridge

Open the cartridge case, and remove the circuit board. You can see the contact pins MUCH more clearly now, and examine both sides in detail. Place the board on a flat, stable work surface where you will be able to rub vigorously on the contacts with an eraser. I recommend that the surface is both non-metallic, and covered with something like a piece of cardboard, so that as you press down, the sharp pin stubs on the back of the board don’t dig into something and damage it (like a dining room table).

Take the eraser in one hand, and hold the board in place with the other, while you vigorously press down and rub on the contacts.

Ready to rub the NES cartridge contacts clean with a pencil eraser

As you go, expect to see a lot of rubber bits, and any marks on the contacts wearing away. When they are done, you should expect the contacts to look pretty clear - no obvious marks on them from dirt or oxidation. Very minor marks are normal. See these images for how they should look.

The way clean NES cartridge contact pins should look

Flip the board and repeat the process on the other side. Once complete, brush off any loose eraser bits, and do a Level 1 cleaning to remove any residue. The pins should shine when you are done.

When you go to re-insert the board into the cartridge case, note that the slots in the edges of the circuit board are designed to puzzle-fit into the plastic guides in the cartridge case front with the chips down. You’ll see that you can only get it in one way, and only in the exact right spot (see photo below).

The NES game board should fit in the shell by matching the plastic guides
The plastic guides for fitting the circuit board into the shell are marked with green indicators. The left is higher than the right, so the board will only fit in the proper way, and not flipped.

Now replace the case back, and screw the screws back in. For all normal cartridges, this along with the 72-pin connector replacement should be sufficient to get your carts working 100%.

NES Cartridge Cleaning: Level 3 - More Serious

If a thorough (you really have to rub that eraser like you MEAN it) Level 2 cleaning doesn’t get your game going consistently (and you see no obvious corrosion/rust on the contacts) then it’s time to up your game.
Start Level 3 with an open cartridge like you did in Level 2. Look closely to see that there aren’t other visible issues, like broken/corroded traces (the light lines going from the contact pins to the chip pins on the board). If there are not, then it’s time to try cleaning the contacts with something a bit more aggressive.

You Can Try

  • Electronic contact cleaner
  • Baking soda
  • A melamine sponge - aka Magic Eraser sponge

Since we’re cleaning electronic contacts, dedicated electronic contact cleaner products are a good thing to try. They come in an aerosol can, with an applicator straw. Spray some on, let it sit briefly, then rub it off with cotton swabs. You want to make sure what you use is plastic safe. CRC makes an economical contact cleaner you can find on Amazon. CAIG makes a more premium, highly respected product called DeoxIT that’s also on Amazon.

To use baking soda, create a paste with water, and apply to the contacts. Scrub with paper towel, cotton swab, or a new tooth brush. Be sure to thoroughly clean off all paste and residue, and then do a Level 1 91% isopropyl and cotton swab finish. Be sure to let this dry a while before trying it again, since this involves water.

When using a melamine sponge, select a clean end, and either leave dry, or dampen lightly before vigorously scrubbing the contacts. Finish with 91% isopropyl and a cotton swab, and let dry for a while before testing because this uses water (assuming you used the water option). You can get a package of generic melamine sponges on Amazon. I had already had sponges around the house, because they are a great way to clean a turntable stylus, as well.

These last two (baking soda and melamine sponge) are more abrasive, but still relatively mild in the universe of possibilities.

NES Cartridge Cleaning: Level 4 - Getting Medieval

DO NOT jump to this step just because you think you want to get your stuff as clean as possible. Really, Level 2 should be sufficient for most cartridges, and the stubborn ones should be good with Level 3. This level is only when the only other option is to throw the cartridge away. Yeah, I know some people are quick to use metal polish on their contacts, but you really should try everything else before this.

Worth noting: Ammonia-based polishes break down the brass in the contacts at a molecular level. This can save an otherwise dead cart, but use with caution!

You Can Try

  • Brite Boy metal polish
  • Brasso metal polish
  • Other metal polish (do some research)

All metal polishes work by removing a thin surface layer of metal. This should not be used more than maybe once! Brasso is what a lot of people use as their go-to. It leaves a residue, though. If you use it, be SURE to get all of the residue off, so it doesn’t continue to eat your contacts, and by transference - the pins in your NES 72-pin connector!. I read a comment from an electronics expert who said that after cleaning a game cart with Brasso, then inserting/removing several times from his system, he could smell the Brasso on the slot pins in his console. That doesn’t sound good to me.

I list Brite Boy first in the list above, because while still a metal polish, it is more favored now by those in the know, because it does not leave the residue Brasso does. You should still finish off with 91% isopropyl. Brite Boy can be purchased on Amazon as well (this is nice, because it used to be only 3rd party sellers, with high shipping prices).

I am convinced that other metal polishes might offer better options, or better prices, but have not yet dug in to call manufacturers and do the research. If you are the curious type, do some calling around. You might find something worth using.