How to troubleshoot, diagnose and repair Nintendo NES common problems
| March 5, 2011 | Posted by Steve0h under Nintendo NES, Repair and Modding |
Nintendo NES Toaster
A very common problem for the original style “toaster” NES is when you put in a game and turn on the NES that you only get a blinking red power light and the system won’t play the game…This symptom can be caused by multiple factors so lets first understand what’s really going on here.
Nintendo installed a lockout chip (also known as the C.I.C. Chip) on the motherboard of the toaster NES. Note: The newer style “Top Loader” NES does NOT have a lockout chip on the motherboard. Nintendo implemented the lockout chip to try to stop non licensed games from being produced for the NES. Because of this lockout chip every officially licensed NES game has a chip in the game cartridge that syncs with the NES’s Lockout chip when you turn on the NES. When you turn on the NES the lockout chip on the motherboard looks to sync with the game chip. If the game doesn’t have the chip present the NES will then restart once every second because it “thinks” you have a non licensed game. Now that you understand the lockout chip and how it works you can better understand how to fully diagnose the NES.
Nintendo NES Motherboard Version 10 from 1987
NES Motherboard with Lockout CIC Chip Highlighted
It’s pretty simple to disable the NES lockout chip. You need to open up the NES and get it down to the motherboard. I’ve attached a picture for you to see where the lockout chip is located on the NES motherboard. All you need to do is cut pin 4 on the lockout chip. The way I cut it was by using a pick tool (looks like the one a dentist uses to scrape your teeth). All I did was pull pin 4 out of the chip and viola! No more NES lockout chip! Once you do this your NES will not restart once every second if you don’t insert a game.
Nintendo NES Motherboard after Lockout Chip (CIC chip) has been cut
NES Lockout CIC Chip Close Up View
Repair Nintendo Problems
Another common problem with the NES is a bad connection between the game and the NES motherboard itself. This is caused by the infamous “72 Pin Connector” that the Toaster NES has. This connector is very sensitive to dirt and dust and dirty connections will almost always be the culprit. Sometimes the 72 pin connector itself is bad due to it getting bent or broken but this is more rare and a good cleaning should at least be tried to restore it back to original functionality.
I hate the Nintendo NES 72 pin connector from the Toaster!
Once you take apart the NES you need to slide off the 72 pin connector. Just wiggle it back and forth until it slides off.
Pulling the 72 pin connector off the Nintendo NES motherboard
With the 72 pin connector off the NES motherboard you can now clean the pins with a 50/50 mix of alcohol. I’ve always had good luck with the 50/50 alcohol but there are other ways you can do it. I dipped Qtips in alcohol and then scrubbed off the pins on the motherboard. Using the other end of the Qtip or a clean rag wipe off the contacts until they are clean and dry. As you scrub the contracts your Qtip will turn black. The black is all the dirt and crud accumulated of the 25 plus years the NES has been around.
Now that the NES motherboard is clean you can turn your attention to the actual 72 pin adapter. Over time it gets worn out and dirty so the first thing you want to do is clean it off using the same 50/50 alcohol.
The infamous Nintendo NES 72 pin connector in all it's glory!
Take a Qtip and dip it in the alcohol and run it over both rows of pins on the 72 pin connector. Use the other dry end of the Qtip to scrub the rows clean and dry. Just like when you clean the NES motherboard your Qtip will turn black.
Since the toaster NES has you put in the games and then press the game down into place, this bends the pins on the connector over time. They get stuck bent down and it give you little or no connection from the game to the motherboard. To fix this you can use a dental pick or a very small flat blade screw driver to bend these pins back up into place.
How a Nintendo NES game cartridge looks in the 72 pin connector
Thanks so much for the tips! I was able to get my NES working again after taking it apart and cleaning the 72 pin connector.
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No problem and glad I could help!
Your information Helped me Thanks you Much
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This is a very helpful walkthrough of common NES issues. We offer all of the nes repair parts found in this guide on our site http://www.nintendorepairshop.com, and we also offer a number of additional nintendo repair guides and videos for free!
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If they hadn’t all been stolen, I’d be taking apart my old Nintendo systems right now. Not even sure how I stumbled across this. You did a good job with the pics, and explaining not only the steps, but what YOU did to complete them. And I didn’t get the feeling your were talking down to me.
One suggestion. If you could circle or highlight the correct chip for the people who don’t know what a microchip looks like. I’m pretty sure I can see where the pin is missing in the 2nd photo; and if I’m not positive, there are plenty of people who won’t have a clue.
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I edited the picture to better show you which chip I’m talking about. Thanks for the suggestion =)
i read everything on here cause i had a problem with that chip you said. my sistem and games run so much better. you genious thank you so much
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I have the red flashing light problem in one unit and the other unit has a solid gray screen. Cleaning and bending pins had no effect. Do you think I am not being aggressive enough with the pins or something?
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For the NES unit that has the red flashing light problem: Make sure you clean the NES motherboard pins where the 72 pin connector installs onto. If it’s dirty it causes a poor connection and will cause your NES to reboot over and over. It’s not reading the game so the lockout chip (called 10NES) causes the NES to reboot over and over in 1 second intervals.
To troubleshoot the NES with the sold gray screen I would first make sure the game you’re testing it off of is clean and will work in another NES. Sometimes you need to “wiggle” the game after you press it down into the NES. The far left and right pins are the most picky.
I’m assuming you cleaned and tried to align the “front” par of the 72 pin connector where the games get inserted into.
Look at the back of the 72 pin connector and see if any of the pins are bent or sticking out. It should look uniform all the way across or else you have a problem. Sometimes especially with the far left and right end connectors they can get bent and will not make a firm connection.
If all this does not work your 72 pin connector will most likely need to be replaced.