If your games just aren’t playing right, your console isn’t starting correctly, or it is just perpetually rebooting, it might be time to replace your 72-pin connector. The 72-pin connector is what allows your game cartridges to communicate with the NES motherboard, and due to its design, it can be particularly finicky and prone to failure – especially after almost 30 years of use. The connector is designed to be “Zero Insertion Force” unlike a standard game cartridge – this however results in a very tenuous connection between the PCB in the cartridge and the contacts in the 72-pin. This connection is very susceptible to dirt, dust, and oxidation. Poor contact can prevent the cartridge from fully communicating with the motherboard, resulting in everything from graphical corruption to a continuous reboot loop if the lockout chips cannot communicate adequately. If you are having problems playing games on your NES (and you’ve adequately cleaned your games), it might be time for a new 72-pin.
72-pins are available lots of places online, including eBay and Amazon, as well as other websites. I purchased mine from Nintendo Repair Shop (not an affiliate link), and have always been very happy with the website. Once you get your new 72-pin connector, start by following the steps in my post on Accessing the NES Motherboard. Once you have access to the motherboard, it’s time to continue on to replacing the 72-pin connector. The first step is to remove the game tray, which should slide right out from 72-pin connector at this point:
We now should have just the 72-pin connector hanging off the motherboard PCB. Unlike the part of the 72-pin connector where the game cartridge goes, the part attaching to the motherboard is definitely not ‘Zero Insertion Force.’ In fact, it is a standard card edge connector, and is actually fairly stiff. It will probably take both of your thumbs to push the old 72-pin connector off the motherboard, but don’t worry, there is nothing but friction holding it in place at this point. Be careful not to touch the PCB except on it’s edges.
Once the old connector is removed, you should have just the bare card edge of the motherboard left. At this point, it would be a great opportunity to go ahead and clean the card edge just like you were cleaning the PCB in a game cartridge.
Once you have the contacts polished up, go ahead and slide the new 72-pin back onto the card edge. Slide the game tray back into place in the middle of the 72-pin, making sure the holes in the tray line up with the holes in the PCB as shown in the next picture.
At this point, just reverse the steps in the post on Accessing the NES Motherboard, paying attention to the installation of the two RF shields as called out in that post. Once you have everything back together, go ahead and hook your NES back up and test it out. Everything should work first try! Note: It’s very important that you make sure you thoroughly clean your games as well. Now that you have a new 72-pin connector, you should make sure to only put clean games into your console, to help guarantee lots of use out of your new 72-pin.