Repair Nes Game with a Board Swap: Mega Man

Unfortunately, it happens to all of us from time to time. You find a game you have been looking for at a great price just to get it home and……nothing. You clean it and clean it, still nothing. You make sure the console itself is clean, and that’s not it because your other games work. Eventually, the rush of the deal fades when you realize the game is broken. No need to sweat however because most of the time you can repair that Nes game.

Finding a Suitable Donor

Thankfully a lot of these Nes games are pretty much based on a handful of boards with the game data store on one chip. It wasn’t until later in the console’s life that special addon chips came into play and even then you could find a donor for those games by just finding a game that also utilizes those chips. To search for what board is used for what game I like to utilize the Nes Cart Database.

If you type Mega Man into the search bar, it will pull up all the Mega Man Nes games. Since the original Mega Man is my defective game I will select the first. All the cart information is then shown.

Repaire Nes Mega man

As you can see the Mega Man board PCB is NES-UNROM. That means, in theory, any UNROM board SHOULD be compatible. Clicking on the NES-UNROM link on the site will actually bring up a list of games that utilized the PCB.

Mega man nes compatible donors
As you can see Double Dribble is listed as a UNROM board, and to my knowledge is the cheapest available donor. I hate to really destroy carts, but it just makes more sense for Mega Man to survive since it is a much higher value game.

batman joker donors
Unfortunately not every game has a suitable donor. Batman: Return of the Joker actually utilizes its own board in the USA and does not cross with another board. To repair that Nes game with a board defect would require finding and repairing the break in the circuitry. That is assuming that none of the chips have went bad Just something to keep in mind as I was surprised when I looked to repair my copy.

Removing the PRG Chips

Now that you have your donor game, the fun starts. Both cartridges need to be opened and the PRG chips desoldered. It sounds more intimidating than it actually is. My video below will show you how to both clean and open your NES cartridges for repair. I recommend this tool set on Amazon for opening your games, and my video below will tell you how to open your carts.


repair nes games donor cart


Looking above you see both games open. The Mega Man board has heavy damage and was sanded as a last resort before committing to the board swap. I do not generally recommend doing this because it removes the plating causing the game to oxiz\dize easier and not make good contact. In this case, it did not work.

The large chips on the lower right are the ones we will have to remove/swap. You can see that they are upside down on the board and say PRG. That particular chip houses all the game data and is the only difference between these two games. Be sure to note which chip is which when removing.

To remove the chips you will need to desolder the existing solder to be able to remove it from the board. I use this desoldering iron because I am “thrifty” (ok its a good word for cheap…) and it is under $20. The problem is that you have to hold the rubber bulb squeezed until the solder liquifies and then release it to suck it up. This for me causes my hand to cramp over time if I have to do much desoldering. I recommend if you have the budget to invest in a vacuum desoldering gun to make it much easier on yourself.

Keep in mind also that these old games and electronics use lead-based solder, so avoid breathing in the fumes.

repair nes game solder








As you desolder the pins they will look like the first three in the image below.








After all pins for the PRG have been desoldered on both boards you will be ready to remove the chips. In an ideal world, you will get them so clean that you can pull the chip out with your fingers, that doesn’t happen very often however especially with the bulb type desoldering iron. What I normally end up having to do is very carefully prying up on the chip, I would recommend a nylon spudger for something like this to keep from marking the board and causing damage.  You will see me use a small screwdriver in the picture but I do not recommend it. I have done these swaps many times and still should not be using a screwdriver so take caution, this is a “do as I say, not as I do” situation.

removing nes rom chip








Eventually, you will have both chips out and be ready to solder the chip from the game you are trying to save onto the donor board. During removal, the legs on the chip will most likely get a little tweaked or misaligned for the holes in the board. Just simply bend them back and get them straight to the best of your ability. As long as you can get it to go in the holes on the board, you will be fine.

Soldering onto the Donor Board

Slide the PRG chip into the donor board being careful to get it pushed down, but do not force it. If it does not go in rather easily there may be solder still that must be cleaned from the holes on the board. Remember that the writing on the chip must face down on Nes games.

swapping eprom in nes








Now flip the board back over and solder the chip back in. You can find guides on Google that can probably explain how to solder better than I can but these are the basic steps. Here is a basic soldering iron set I recommend.

  • Plug in iron and let get nice and hot.
  • Melt solder onto the tip of the iron, this is called tinning.
  • Again, don’t breath in fumes.
  • Wipe excess onto a wet sponge that is included in most kits. (You must wet, tap water is fine)
  • Touch and hold the tip of the iron to leg you are about to solder to get warm, touch the solder to the same leg to flow solder. Do not get too hot and damage board.
  • Remove solder and iron from the leg. The point should now be soldered and is called a joint.
  • Repeat for all legs of the chip. Cleaning the iron and tinning the iron as necessary.
  • Repair complete. I normally tin my iron again before unplugging to keep it from oxidizing.

When done it should look like the picture below. At this point put the board back in the cartridge and close it up.

repaired nes game









Mega Man Nes








If all goes well your game should boot right up like mine did! I have managed to save quite a few games destined for the scrap heap by using this method. Most times you do not even need to go this far and the issue is just that the game is not clean enough to make good contact. Sometimes you can even get away with just using your soldering iron to head up the existing solder points on the chip and the reflowing of that solder will regain contact. Even better is that even though all consoles are different, this technique works to fix your games for Genesis, N64, SNES, etc. as long as you know what needs to be transferred.

Unfortunately, sometimes none of this will work. I have run into games where the PRG chip itself has failed, and at that point, there isn’t too much you can do. That tends to be few and far between however so do not be afraid to give repairing your game a chance!

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