There are a number of reasons you might want to access the motherboard on your NES-001 console.  You might be getting a solid color screen on bootup, or have a console that constantly reboots and needs a new 72-pin connector.  You might want to identify what revision of the motherboard you have in order to determine if you can play certain unlicensed games.  Or, you could be ready to burn the fleet and disable the lockout chip on your motherboard altogether.  In order to do any of these things, you’ll first need to get access to the motherboard.

DISCLAIMER:  I am in no way responsible for any damage you cause to your console by following the steps below.

To start with, flip your NES over, and with a #2 Phillips screwdriver, undo the 6 recessed screws that hold the top of the console to the bottom.

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Remember, righty-tighty lefty-loosey!  Important note, all of the screws we will be dealing with today are identical, so you don’t need to worry about segregating them as you remove them.

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Once the 6 screws are removed, flip the console back over and carefully lift the top of the console off of the bottom.

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Once the top of the console is removed, you should be greeted with something like this.  In the future, it’s probably a good idea to remove the game from the console before you start to operate on it.  Whoops!

IMG_1597The next thing to do is remove the large RF shield covering the top of the motherboard (well, technically the backside of the motherboard) as well as the game tray.  The top RF shield is held down with 7 screws, shown in the next picture.  Go ahead and remove the seven screws.

Top RF Shield

Once the top RF shield is removed, there should be 8 more screws holding the motherboard into the bottom of the console.  6 of them should be around the game tray, and two should be around the RF box.  In my case, I only had 2 holding down the game tray, and 1 next to the RF box.  Someone shorted me!

Here you can see one of the power supply screws in the center of the photo, the other one should be in the vacant hole on the opposite corner of the power supply enclosure.

Here you can see one of the power supply screws in the center of the photo, the other one should be in the vacant hole on the opposite corner of the power supply enclosure. 

Once those 8 screws are removed, you can gently lift the motherboard, power supply, and game tray out of the bottom half of the console.  Be careful, however, because the wire bundles for the Power/Reset switches and the controller ports are still attached.  So gently lay the motherboard down, out of the console, but without stressing the attached wire bundles.

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Unfortunately, the cables route through the RF shield as shown below, so we will have to disconnect them.

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Gently grab the connectors and work them out of the sockets on the motherboard.  It is good to take note here of which controller port hooks up to which socket on the motherboard, but if you forget, there is a I and a II on the motherboard right next to the appropriate connector:

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You can see the ‘I’ next to the upper socket, and the ‘II’ next to the socket on the right edge of the board. 

Now that the motherboard is free from the console, we can remove the lower RF shield, exposing all the components on the motherboard.

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We are now all set to do whatever we need to with it.  From here, we can identify the CPU revision, replace the 72-pin connector, or disable the lockout chip (coming soon).  To reassemble the console, you essentially reverse all the steps we just completed.  A couple things to watch out for:

When you replace the lower RF shield, ensure the three tabs around the expansion port all slide along the edges of the port, and do not get them stuck in the port itself.  These tabs will also provide a little bit of resistance when you slide the shield back on, just push gently and it should seat itself fully:

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Also, when reassembling the top RF shield, ensure it is positioned correctly by indexing it against the small plastic nubs that key into the shield as shown in the following photo:

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Continue on to the other tutorials involving the NES motherboard: