Ah the NES! It's old but still great. And with a few mods and tweaks, it can get even better.

This page resumes some of the improvements or mods that can be done to a NES system.

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I own a nintendo game cartridge named 260 in one, which is full of fun games. The only drawback is that once you select a game, you must reset the nes to return to the main menu.

My NES console is near the TV, so when I want to change the game I have to get up and go to the other end of the room...

To fix this little problem, I have added a connector to my NES where I can connect a long wire to reset the NES remotely.

As you will see, it is very easy to do:

	1) Open your NES and remove the metal sheet isolating the mother board. Also remove the motherboard. This is necessary to gain access to the small PCB where the Power and Reset buttons are located.		2) You also need ot remove the reset/power PCB from the case, since you need to solder on the solder side of the PCB.
	3) Solder your wires on the reset button.		4) Install the connector on the case, and solder the wires coming from the reset button on it.

As you can see, it is very simple. I used a 1/4 jack, as for headphones. The cable is so simple that I will not include pictures of it on this page. I did not install a button at the other end, I just touch the wires together.

The result:

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The NES has been designed to output mono sound. This was acceptable back then, but nowadays we expect/need stereo outputs. If you wish to connect your NES to a stereo amplifier, you need an Y cable. You will hear the same sound in both speakers.

It is possible to do better by modding the NES to add "real" stereo sound. The NES CPU (2A03) has 2 sound outputs. One carries the 2 square wave channels and the other one carries the triangle wave channel, the noise channel and the sample channel. By tapping directly on the CPU pins (that is, before the mixing is done), it is possible to direct the 2 sound outputs to different speakers, thus obtaining stereo sound.

The knob on the picture is not a volume adjustment, it controls the stereo separation. The games were not designed for stereo, and it can be heard. Keeping a small amount (adjustable) of mono sound gives better results.

Here is a page containing detailed instructions (that's where I got the idea):
http://www.zyx.com/chrisc/nesstereo.html
Since the original website does not work anymore, here is my schematic (different from the original):


Here are a few pictures:
On the left: The sound is taken right from the CPU pins. I used a shielded cable, to prevent picking up noise.

On the right: I tapped on one of the pins connecting the [power supply, RF modulator and RCA Mono audio/video output module] to get mono sound. Better be carful to use the right pin since there's the 12 Volts AC from the AC adapter on the same connector.
I routed the cable over the motherboard in a way that makes it possible to easily reinstall the metal shield. I few drops of hot glue here and there helped keep the cable in place.

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This is not a mod on the NES itself, but it is on topic. I modified a cartridge in a way that makes it reprogrammable.
This project is on it's own page.

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(Based on the text 'Disabling the NES "Lockout Chip"', by Mark Knibbs)

When nintendo designed the NES, they equipped it with a lockout chip. The main reasons why they did this was (1) to prevent unlicensed companies to distribute their own software and (2) make it harder to copy games. (Just imagine yourself buying a game and reading in the manual that you must mod your NES in order to be able to play!...). The chip also makes it impossible to play imported games.

How does the chip works?
The lockout chip is used in both the console and the cartridge. Depending on the logic level on pin #4, the chip will run in lock mode (console), or key mode (cartridge). When the NES is on, the chips normally try to communicate together using 3 signals. As long as the communication is not working correcly (no chip in cartridge or bad chip in cartridge), the lockout chip inside the NES will generate resets at 1 second intervals.

Why disable it?

• To be able to build your own NES cartridge without needing to remove the lockout chip from another cartridge.
• To be able to solder roms (or sockets) directly on the NES motherboard. (no cartridge and no lockout chip)
• To be able to use imported games without special adaptors.
• To be able to use unlicensed games which may have incompatible lockout chip immitations or even no chip at all

How to disable it?
All you need to do is put both chips in key mode. When both lockout chips are in key mode, nothing happens (so no resets). To do this, you must disconnect lockout chip pin 4 from the motherboard and connect it to a ground (lockout chip pin 11,12,13,14 or 15). It will also work if pin 4 is not connected at all, so dont worry if you accidentally rip it off. Even though it works without connection pin 4 to ground, I beleive it is better to do it anyway.

I was a little worried that some cartridges would stop working due to this mod (cartridge with smarter lockout chip?) so I added a switch to control the voltage on pin #4. I have not encountered such cartridges yet, but the switch is there, just in case.

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Nowadays, Blue leds are very trendy and are used everywhere. I tried to resist the temptation, but couldn't. So that's right, I've replaced the boring red power led by a blue led, because "It's cool"!
You simply unsolder the old led, and solder your blue led. In my case, I had a surface mount led so I soldered it on the old led's leads.

I bought the led from digikey. They have shipping and handling fees so if you only need one led, find a local electronic component store and buy the led from them.

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The original power supply is of the linear type, which means it uses a bulky transformer. This power supply has a few disadvantages:

• It is bulky, which is not very convenient when you're carrying your NES in a pack sack.
• It covers almost 3 sockets when you plug it in a power bar.
• Mine is old and has started to fail (you need to pull the plug in the right direction to make it work!)
• It has an AC output, which is rarer. It is hard to find a perfect replacement.

By looking at the NES schematics, I saw that the power coming from the power supply is converted to DC and lowered to 5 volts using a simple lm7805 voltage regulator. This means that giving 12 volts to the NES will not damage it (however, please note that the regulator will generate a little more heat). Since the NES expects AC, you can supply the NES with DC power without having to check the polarity.

Switching power supplies are usually smaller than linear power supplies, so I have used the switching power supply that came with my old cable modem. It gives 12 volts up to 0.6 amps. So far, it has worked flawlessly with the NES.

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So you have a game that does not start anymore? The screen repeatedly blinks? This could be caused by a dirty NES cartridge connector or dirty cartridge contacts. Since it's easier to clean the cartridge, it is better to try this first. If it does not work, you might need to restore the cartridge connector inside the NES.
I will now show you how I clean my NES cartridges.

1: First, I open the catridge. To complicate things, Nintendo used unusual screws. Here are a few ways to remove them:

• Buy the right tool. nintendorepairshop.com sells it.
• Take one or two small flathead screedrivers and try to use the notchs in the screw's head to unscrew it.
• I remember reading somewhere that you can heat the screws with a soldering iron and pull them out when the plastic starts melting. You use slightly bigger screws to close the cartridge.
• Use the force (not recommended)
• Build your own tool.

My favorite technique is to build my own tool. Someone named Naisho told be about this technique by email after reading this page. You take a small plastic rod (or similar object) and heat the tip with a lighter. Once it's squishy, quickly apply it to the screw. Let it cool down. Once removed, it will have the perfect shape to remove this type of screws, as on these pictures:


2: Once the cartridge is open, I inspect the connector. This one here is moderately dirty: (click for a close view)


3: Cleaning
I scrub the contacts with an eraser until they are clean. Sometimes, they dont get perfectly clean, but there is always a great improvement. On the following picture, I have cleaned only the right half. We can clearly see the difference: (although the picture is not as good as I wanted it to be...):

While I have the cartridge open on my desk, I check the battery (if there is one):



Finally, I close the cartridge with ordinary screws so it will be easy to open in the future.

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Idea from the text MAKE YOUR NES RUN BETTER THAN NEW!, by XBJ-9000

Blinking screen and non-working games? If cleaning your cartridge does not do it, you probaly need to restore or replace the internal cartridge connector.

The cartridge connector inside the nes it very bad. The problem is that the metal contacts are applied to the cartridge PCB vertically instead of horizontally (which would move the dust and oxyde out of the way).

Fortunately, there is a way to fix this problem. You need to tweak the connector such that the contacts are closer together. There will be more friction when a cartridge is inserted and the fact that the contacts are more tightly pressed on the cartridge pcb will result in a more relable cartridge connector.

If you would prefer to replace the connector, you can buy one from the Nintendo Repair Shop.

Step 1:
Disassemble your nes and remove the cartridge connector.

Step 2:
Find a cloth pin and bend the tip.


Step 3:
Using the pin, try to pull the contacts closer to the center. Do this for the upper row (the one near the square holes) and the bottom row.

Step 4: (optional)
A small flathead screwdriver can help to bend the upper contacts a little more:


Step 5:
The contacts should now be nearer to each other than they were before.
Left picture: before.
Right picture: after.

You dont need to do anything to the part of the connector which connects to the NES motherboard.

Reassemble your nes, and enjoy! The games should work pretty well now. They will even work without pushing the cartridge down!

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Si votre connecteur de cartouche n'est plus utilisable mais que votre système NES fonctionne encore, vous pouvez installer un jeu en permanance et y cablant la cartouche comme sur ces images et dites adieux aux NES clignotant et autres problèmes de démarrage et corruption graphique.



Voici quelques conseils:

• Regardez les traces sur le circuit du jeu et ne câblez que les contacts étant utilisés pour sauver du temps.
• Attention à l'orientation. C'est facile de se tromper.
• Pour remettre le circuit en place comme j'ai fait, il faut tronquer le pilier central arrière.
• Je pense qu'il serait préférable de ne pas faire cela avec des jeux rares.

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Games feel different when played with an arcade style controller. Also, if you are playing arcade game ports, you will get a more authentic gameplay.

Please visit my Arcade style controller for Snes, Nes and PC page for instructions to build one yourself.

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I modified a NES to be able to play old Nintendo arcade roms on it. This project is quite complex so it has it's own page.

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I cannot be held responsible for any damages that could occur to you or your equipment while following the procedures present on this page. Also, I GIVE ABSOLUTELY NO WARRANTY on the correctness and usability of the informations on this page. Please note, however, that the procedures above have worked in my case without any damages or problems.

Now you cannot say that I did not warn you :)

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