NES (frontloader) video interference issues - not RF related

[MoxManiac]

Howdy folks,

I just picked up a spare NES at a yard sale today. Just tested it out, and it works - took some doing to get it to actually boot a game, but I expected that as it probably needs a new 72 PIN.

The issue i'm having is there is wavy interference in the picture - during both a/v and rf output, so it's not a case of it being a bad rf connection. Compared to the existing NES I had hooked up, which was crystal clear. I'm using an official NES adapter in both tests.

Is there a fix for this or is the console fubared? I have a sinking feeling I know a possible cause - the dude was using some sketchy offbrand adapter to power it. It said the output is 10v but the NES clearly states 9v - although I've read the NES can tolerate between 7 to 12v. But I dunno.

Anyone have any idea about this?

Thanks!


EDIT: Took the sucker apart and noticed a glob on the board underneath the shielding on the modulator unit (where the a/v and rf ports are) Is this evidence of a capacitor leaking or is it supposed to be there? I took a pic:

6676

[Polygon]

I would say no. However, that doesn't mean you don't have leaky caps. I would inspect each cap and look for any bulging. I doubt it's your 72 pin connector. That's not something that would cause wavy lines. However, it's easy enough to swap the connectors between units to check.

[ApolloBoy]

That glob you see is just hot glue that was applied over the coils in the RF box to hold them in place. However, I would definitely suggest changing out the big 2200 uF filter cap in the RF box, it usually causes problems like that when it's on its way out.

[sonicfan]

I have had this issue before in two different NES'es. The 2200UF electrolytic cap was the problem both times. Replaced them and they're back in business.

[MoxManiac]

Ah okay. I'll try replacing the capacitor then.

Thanks guys!

[BetaWolf47]

Wait, the video output isn't supposed to be wavy like that? And all you need to do to fix it is replace the 2.2 mF capacitor on the video output? I've got to do that!

[raylydiard]

All if not most nes consoles i worked on i had to replace the caps.
in the rf box not a easy job but would make life easier with hot air tool.

[ApolloBoy]

but would make life easier with hot air tool.
That's a sure fire way to lift some traces.