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Salvaged Circuitry

Adventures in Tinkering

NES Repair

To start things off, I found this Nintendo Entertainment System (NES) in the recycling bins at my college, where it was carelessly discarded along with three controllers (yes the duck hunt one too) and 6 games.

For those of you unfamiliar with the NES, it was basically THE gaming system of the 1980's. This console brought back gaming after several major game console companies, such as Atari, went bankrupt.

Before I dissect the game system, lets pay a little respect to 80's gaming systems, and take a full tour of the device. On the front there is a cartridge slot (under the Nintendo flap) two buttons and two controller connectors. One button is the reset button, one button is the power button. Oh, and there's even a power led.

Here's where the NES game cartridges go. You put them and push them down to load the games.

Here's a view of the backside. The ports on the back include the standard DC power adapter jack, a "channel 3-channel 4" switch and an "AF Switch" port which is a white RCA connector. This is used for hooking up the NES through an adapter which converts the signal to coaxial, so you can have a TV channel devoted to NES.

There you go. analog RCA connectors. Classic. Old-school video connectors. Yellow = video Red = audio

Here's the bottom of the device. I wonder if that Mattel number is in service anymore...

Well, now here comes the test....Does it work? Since there was no included power supplied, I wired up a 9volt, 1 amp PSU I had. The NES takes 9 volts at 850 miliamps, so the 150 extra miliamps wont make a difference. It happened to be an Atari power supply odd. No luck, the NES gave me a blinking red light, even with a Nintendo game in it. This indicates that there's a significant problem with the NES, because the blinking red light was supposed to designate a foreign game inserted into the NES. In this case, Super Mario is as Nintendo as Nintendo gets, so there must be something wrong with the internals. This issue is well documented online, being called the "security chip" problem or the NES10 chip issue. Basically, Nintendo incorporated a chip into the NES that restricts the NES to reading ONLY Nintendo produced games, serving as a way to rid the console of fraudulent knock off games. While this may seem to be a good idea, after a while, the cartridge slot becomes work and the connections are not as flush. because of this, the console begins to read every game as foreign and does not play them. to fix this issue, you can remove the security chip (as Nintendo did in the next NES revision) or just sever the connection of pin 4 on the NES10 chip.

Ok, lets get started. There's 5 Phillips-head screws on the bottom of the case. These five screws hold the top of the console onto the bottom.

All of the inner electronics are screwed onto the bottom of the case, so you can set aside the top shell.

Here's a better view of the inside with the topmost metal RF shield removed.

Top view, front. There's 6 screws that you need to remove to gain access to the main circuit board. Basically, remove the outer most screws and you should be able to remove the guts of the device.

here's a better shot of the internals.

With all of the metal shielding removed and the case set aside, we can really get down to debugging the NES console. To do this, make sure the main board is on an insulator, such as wood. Now, before we go cutting off leads to Nintendo chips, lets put the essentials back on the board and try the console removed from it's case.

If the red light continues to blink, proceed to cutting the pin off the NES chip. if not, then there was probably just a loose connection on the cartridge slot. If there is a loose cartridge slot connection. take a flat head and bend down the pins, so they come closer in contact with the cartridge. If the problem persists, proceed to modifying the NES10 chip.

Now, lets take a little closer look at the problematic NES10 chip. The chip highlighted in a red oval is the NES chip. This is the chip which you will have to modify.

Well, with a little research, you need to sever the connection to pin 4 on the NES 10 chip. To do this, ready a pair of small pliers with cutters on the end. Cut the 4th pin from the left from the mainboard. make sure that there's no possibility of connection between the 2 severed leads, so try and cut as much of it off as you can. Now, you can leave the connection open or put a dab of hot glue over it, it's your choice.

Now, get ready to reassemble the NES. Remember to put back all of the metal shielding and the cartridge slot in the right spot!

And there she is, all in working order. No better way to spend your leisure 1984 style.