NES repair, different colored flashes...

[e5frog]

I bought five used NTSC NES from a Swedish company, one of them worked out of the box, one worked but has a constant hum on the sound and sometimes I get a red screen there the other three just flashes. One flashes with yellow screen, one with purple screen and one with blue - same if there's a game in it or not.

 

Is there a guide somewhere to what these colors usually mean?

 

I had plans to take them apart anyway for a clean-up, one needs to get the cartridge chute fixed (I have a spare somewhere in worst case).

 

 

Thanks for your help.

[nathanallan]

As for the colors, that has been a great mystery for years. I have no idea what the colors mean, if anything.

 

But it sounds like the Nes10 chip has gone on the flashing/colors ones, and that can be disabled. Just google "disable nes lockout chip" without quotes and you can see a really quick way to do this. Also might be the cart ports on them, or a combination of both.

 

As for the hum, sounds like the capacitors have started to go, that one might or might not be worth your time to fix. I would personally want to replace the whole motherboard with one from a beater unit (but still worked well).

 

Hope this helps!

[e5frog]

The hum was apparently from too little voltage, I'm guessing the ripple from the 9VDC power supply (that I have successfully used with other NES consoles) induced some nice 50Hz hum. This unit however required a little more voltage. The original supply of about 9VAC has a top voltage of about 12V so it worked just fine with a 12VDC supply instead (I should perhaps look for one of the original supplies instead).

 

The flashing is the CIC (or Nes10) setting in yes, I just wondered if the colors meant anything. I'm going to fix the connectors on all three and see what happens. I've had a blue-flashing Spanish unit once, it seemed to work just fine. Someone else mentioned having a yellow-flashing unit once, and that one was dead, he wasn't able to fix it. It seems to me there should be a reason for the colors - why would they otherwise be there?

[e5frog]

The blue-flashing unit works fine, only needed to fix the connector, cleaned everything off also, there was a lot of dust in it, a little moisture on that and you'd have some nice short circuits there. NES TEST ran fine, everything seems to be OK.

 

On to the next one, only two left...

[gdement]

The different colors are probably just a result of whatever background color happens to be active in the graphics chip. If it weren't for the 10NES chip, it would simply be a solid screen of that color. I don't think it's any more meaningful than the TIA bars on an Atari.

I've noticed that light blue is the most common color I get when that happens. I think not coincidentally, this is the typical background color games use to make the sky.

 

It does sound weird that the other units are consistently getting purple or red, regardless of whether a game is inserted. But my guess is still that the background color value is just floating towards something in the absence of anything to drive a proper setting. As to why each console floats to different values, maybe it's just random variation between boards.

[e5frog]

I was thinking it could have something to do with capacitors and/or resistor values.

 

Different tolerances sometimes make it not appear grey.

 

My blue one was dark blue, not the light kind.

 

 

The purple one is up and running, TLC on the connector helped, I cleaned everything else as well of course.

 

Only the yellow-flashing left.

[e5frog]

The yellow-flashing now also works, same problem, the connector.