Broken NES

[topper]

My NES is poorly. Changed the ZIF connector with no joy. Still intermittent results, games work about 1% of the time, the other 99% is split between blinking red light, solid red light with solid white screen, and the occasional corrupt game screen. I have also cleaned the games and motherboard connector with switch cleaner.

Is there anything I can do to bring the console back to life? Also, does anyone have a USA NES and is willing to try a couple of my games, so I can definitely rule them out?

[honeymustard]

Sounds like the 72 pin connector has bit the dust. Try replacing it, they only cost about £5.

Edit: unless that's what you're referring to by ZIF (thought it was a ribbon cable connector or something?)

[topper]

Sorry, that's what I replaced, I thought it was ZIF but on reflection the new one has plenty of IF.

Still not working though. When I run it with the cover off and jiggle the motherboard, it intermittently works, then a slight further tap and it ****s up, sometimes lines down the screen, sometimes completely. I have tried silver polish on the motherboard connector. Hope this is a better description of the issue.

[MattyD]

When games fail to boot up in this way or get corrupted it's usually down to two things: either the cart connector (which we can rule out as you've replaced it) or the 10NES lockout chip.

Fortunately this is easy to fix, and as a side-effect you'll be able to play any region NES games on the machine. Open the machine up, locate the 10NES chip, and cut the fourth pin. That's it! If you want to be extra careful you can bend the remainder of the pin away from the board and solder it to ground on pin 15. This just closes the loop for extra electrical safety.

There's an easy to follow guide with helpful photos at http://www.mmmonkey.co.uk/console/ni...es-lockout.htm

The reason this works is, when you boot up the machine, the 10NES lock chip tries to talk to the 10NES key chip on the cartridge. If it can't talk to it, either because it's not there or the pins aren't connecting properly, it holds the CPU in a reset loop, hence the flashing grey screen. If the chip contact is successful however, the 10NES 'unlocks' and breaks the reset circuit, letting the CPU boot up properly. If you cut this pin you'll stop the chip working all together so the CPU will never be 'locked' into a reset loop. Et voila!

Let us know how you get on. If you still need someone to test some US games I can do that.

[chaoticjelly]

Erm, when you replace the 72 pin connector, you do have to clean your game cartridges as well.. the ones I've cleaned have come off on the cloth dark black, even when sometimes they look relatively clean.

If you use dirty carts with a new connector it just dirties up the new connector, as MattyD has said the lockout chip on the cartridge isn't communicating with the one in the NES therefore it won't boot the game.

If you cleaned just that specific pin it would probably start working, but the graphics would likely be corrupted due to other pins being dirty and therefore not making connection, and various graphics that make up the on screen image not getting through..

[MattyD]

I forgot to mention that, actually - bearing in mind some of these carts are now 20 or so years old they tend to have a layer of filth and corrosion on the pins so it's worth giving them a good clean with cotton buds.

[chaoticjelly]

Easiest way I find is to unscrew the cartridge using a gamebit, apply some isopropyl alcohol to a cloth and just rub with a decent amount of pressure across either side of the edge.

I used to sell these connectors on eBay and I always recommended cleaning the cartridges after fitting the connector. Did get the odd email saying it hadn't worked, when really it was because the cartridges were covered in crud..