NES repair - strange controller symptoms - how to fix?

[karokoenig]

So, I got a set of NES with games from a friend, and it does fire up and the games start... BUT:

 

Very strange. The controllers don't work. It seems like only the the "A" button does anything, but it acts as Start button. Nothing else does anything at all. So everything works up to the start screen. Then it's back and forth and nothing else.

 

I haven't opened it yet, but I'm pretty positive no one ever tinkered with it inside. My friend was the first ans only owner of this set, and she's not the person fiddling with electronics. She also takes very good care of her stuff (so most likely no dropping or kicking the console etc).

 

Any idea how this can happen? Some broken cap or resistor sending wrong signals? A broken wire?

Edited April 30, 2017 by karokoenig

[crazydean]

Have you tested it with another controller? Do you know if it's a problem with the console or the controller?

[karokoenig]

Three controllers, consistent results. I doubt it will change if I try more controllers. Relatively unlikely that they all can be broken.

[icemanxp300]

I had an nes last year that had a bad controller harness assembly. I guess I "could" have tried to fix it but I have a parts system I took and swapped it out of. They are simple to change. Just pull out the wire harness and pop the new one in.

 

What you need to do is try to get a 2 player game working and see if controller port 2 reacts the same as controller port 1. Try to get player 2 working and see what happens.

[karokoenig]

Will try that and get back to you. May take a while. I'm away from that particular NES right now.

[7800fan]

If it's behaving the same with different controller, it could be the buffer chip has failed (U6 for right port or U7 for left port)

 

http://www.freeinfosociety.com/electronics/schemview.php?id=2405has schematic that could help you troubleshoot.

[karokoenig]

No luck on two-player games, at least not yet. I reckon most two-player games still use left controller for menu control. No game I tried has yielded any response from the right controller. Can anyone recommend me a specific game of which he knows that on the start screen, the right controller works?

 

No luck on schematics either... I can't read those things :-(.

[supercoupe91]

Have you tried cleaning the contacts on the controller ports? That solved my NES controller issues.

[crazydean]

You could swap controller ports when the system is open. It's easy enough to do.

[karokoenig]

Will do that, too. Need to open up that thing anyway, clean everything inside and outside, fix the cart connector (which is pretty loose) and clip the lockout chip.

[rickdeckard]

Hi,

I have exactly the same issue, just wondering if you ever sort this problem?

 

Many thanks