Alright my favorite dudes of the internet, I was hoping for some insight here.

As a kid, from about 88-98 the NES was our only console. When our first one started flashing constantly my mom picked us up a used one that started doing the same eventually. When I got back into the NES in the 00's I just bought a refurbished NES off ebay. Recently, I acquired these first two consoles from my childhood again and attempted to fix them by replacing the pin connectors and disabling the lockout chip.

After doing both of these things all that happened was I got a solid colored screen when the console powered on. After some messing around, one of them works about 30 percent of the time and the other never does. Solid black screen is all I get.

Searching Youtube, there are 100's of "how to replace your pin connector" videos but it's hard to find anything beyond that as far as NES repair. One guy advised that you must use jewelry cleaner, not alcohol, on the board connections in order to get rid of all the residue. I am going to try this tonight. Does anyone have any other tips?

With your new connectors and the lockout chip disabled, have you tried not pressing the game down?

Yeah that doesn't make a difference.

Clean your games and your connector, don't push the games down, and I can assure you there is absolutely nothing else wrong with your system.

Did all of that. First boiled the old pin connectors then replaced them with new ones. My games are always cleaned before being placed in a system.

What do you clean your games with?

Well, odds of that are basically zero....if it worked once, and was shaky before that, something is wrong with the connections....and well, that's all there is to it. Good luck finding the solution. Tear it down and mess with it some.

rubbing alcohol. and they all work fine on my main NES systems.. the refurbished console I bought off ebay several years ago is in my game room and my toploader is in the living room. my games work perfect on those two systems.

but yeah i'll take everything apart again and try jewelry cleaner on the board contacts.

Try cleaning the inner NES main board edge connector. The thing the 72 pin connector attaches to. You'd be surprised how absolutely filthy that connector can get. Cleaning it resolved a couple of NES front loaders I had which refused to work well.

I've done this and it worked as well. Cant hurt to try.

Yeah that's what I meant when I said I am going to scrub the "board contacts" again. I did it with alcohol already but I am going to try that jewelry cleaner stuff.

Use brasso on the main board...

Try using weiman glass stove top cleaner on the connector thats on the main board and go back over it with the alcohol, prob wouldn't hurt to hit the carts with it as well.

Also are you using an original power supply or an aftermarket? reason I ask one of my toasters was having similar issues and I cleaned the hell out of it and it would turn on but keep a black screen so after more cleaning and working just for it to end the same way I decided to take a guess and just maybe the power supply was going bad, at the time I didn't have a second original so I tried a spare I had but the voltage was a tad higher but it worked, I then tested the orignal again and was back to the black screen. So I got the ideal to dig out another toaster and used the original plug on it and it worked just fine. So somehow or another the first toaster is having issues and will only work with the higher voltage plug and is the only one out of the five I have that is like that. Pretty sure its not going to be good using it that way for long peroids of time but its the only way to get it to work.

This.  I use this on my games as well.

I bought Tarn-X jewelry cleaner at the store tonight and have been working on the system that is in the worst shape. I scrubbed the board with the cleaner using a toothbrush and paper towel. I tested about five games on it and three of them work with lots of maneuvering of the cart. I keep getting this damn black screen. The fact that it is working at all is awesome though, I at least feel like I am making progress.

I am using a radioshack 9V power supply that is like 15-20 years old, probably. I am going to switch it with a working power supply and see if that helps. Thanks for the help guys..

I've heard that name a lot from collectors, I'll try to get some of that.

Brasso works great. After wiping the Brasso off use alcohol to wipe off any residue.

Yeah, that probably wasn't the greatest idea ever. The NES adapter used AC (for some goddamn reason) and wouldn't cooperate with DC that great. Before I got an original NES power adapter, I used a 9v power supply from a Genesis, which was reccomended by many, many other websites. It made the system heat up quickly, sometimes not read games, and it always made an annoying hum through the TV.

So yeah, switch it as fast as possible. If there's still any problems, then, well, I'd suggest sending it to someone who can fix it.

Man, that Brasso stuff is some tough shit. I went through about twenty q-tips and I still didn't get rid of all the black stuff. I cleaned off the excess residue with alcohol and tested the system. All the games work now but it takes lots of maneuvering to get them to do so. I am going to take it apart again later and clean the board with Brasso until I get the rest of the dirt off. Thanks to the dudes who recommended Brasso.