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PostPosted: Wed Oct 01, 2014 1:58 pm 
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So here's the itemised list of shit that's supposedly been tried:

- Swapped composite cables; no change
- Different LCD; no change
- Using a CRT television + RF output; no change
- Three (3) other NES control decks (original models ("toaster")); no change
- Using a Sega Genesis AC adapter; no change
- Some insanity about swapping cartridges/games and suddenly the problem being lessened


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PostPosted: Wed Oct 01, 2014 2:01 pm 
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I'd say just get over it, I see the lines all the time on nearly every NES. It's just what it does, is it that bad? Play on an emulator if you want it perfect.


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PostPosted: Wed Oct 01, 2014 2:13 pm 
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Changing cartridges changing severity ... vaguely implies lousy power regulation?


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PostPosted: Wed Oct 01, 2014 6:17 pm 
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Oh sorry, I missed where you said you tried 3 different TVs.

I have no idea, unless it's some kind of house-wide issue with the power or some kind of global interference. I dunno what it is. :P


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PostPosted: Wed Oct 01, 2014 6:34 pm 
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Haha, any chance there's a solar flare screwing around with EM interference the last week or so? :P


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PostPosted: Wed Oct 01, 2014 7:25 pm 
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Hm. Since you have an open one, it'd be pretty easy to test for whether this is due to voltage rail noise or something else—tap a small capacitor (maybe a 100pF?) between Vcc and Vout (pins 40 and 21 on the PPU). If it gets worse, then the answer is probably ... if so, try then moving that capacitor between ground and Vcc (pins 20 and 40) .


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PostPosted: Fri Oct 03, 2014 10:00 am 
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A wire connected only at one end makes a rather effective antenna.

A bad ground pin on one end of the cartridge (perhaps it's just dirty?) leaves the cartridge's ground plane connected only on one end.

Is it possible that this is what's happening?


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PostPosted: Fri Oct 03, 2014 1:45 pm 
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Maybe you could rule out EMI by putting your NES in a Faraday cage. I suppose a box lined with heavy-duty aluminum foil, with holes cut for controllers and A/V cables would do it. Not sure if it would need to be grounded, probably not.


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PostPosted: Sun Oct 05, 2014 4:54 pm 
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Joe wrote:
A wire connected only at one end makes a rather effective antenna.

A bad ground pin on one end of the cartridge (perhaps it's just dirty?) leaves the cartridge's ground plane connected only on one end.

Is it possible that this is what's happening?


It's possible, but, I would tend to say unlikely... when I cleaned my NES games, I used a very heavy duty oven cleaner to take off the 25 years of grime and tarnish. My carts are basically like brand new. I suppose it's possible, as I did this cleaning about four of five years ago, but, they appear fairly pristine.

Quote:
Maybe you could rule out EMI by putting your NES in a Faraday cage. I suppose a box lined with heavy-duty aluminum foil, with holes cut for controllers and A/V cables would do it. Not sure if it would need to be grounded, probably not.


I actually did try this, but, no luck.

EDIT: So, after giving a rest for a couple of days, I tried the system again. A few matches in Punch-Out!! and a couple of Dr. Mario rounds and the waves were still there. After about 10 minutes powered off, I tried the Genesis adapter again, just for laughs. First, with no cartridge in, just powered on. The waves were present on the purple screen of purgatory, so, I tried it with a game in. They were gone.

Image

This is really confusing, considering that I tried the Genesis adapter a few days ago and it didn't help at all. I tried it with the official NES adapter again immediately after and they were still gone. I'm wondering if something in the system needs time to "warm up", which would cause the waves to dissipate over time? Does that seems logical and, if so, what component would it be and why would it suddenly happen now after years of reliable performance?

EDIT #2: After they had gone from the screen, I went up to press the POWER button. As soon as my finger touched the button, without even pressing it, the waves returned. I also noted a peculiar buzzing sound coming from the speakers when these waves were visible on-screen. I wonder if the power switch needs some kind of insulating?


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PostPosted: Sun Oct 05, 2014 9:49 pm 
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It could be crosstalk between the A/V ports on the side of the NES. Mine are like that, and I have to wiggle them to get the best picture and to minimize the buzzing on the audio.


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PostPosted: Mon Oct 06, 2014 7:48 pm 
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I don't know but most times I've run into something like this it was caused by capacitors. A few times the fix was a serious cleaning job.

The NES seems to be some magical exception but electrolytic capacitors just don't last this long. Especially if the board was used a lot or had dirty power. I'm amazed that I don't hear much about NES recapping. I've never seen an NES that needed a recap but I've had to recap a genesis and a ton of old 68k macs. The forums for the macs are all about recapping. Game gears, portable turbos, all sorts of old systems are notorious for it. I know the NES isn't from the capacitor plague era but good electrolytic capacitors still have a limited lifespan and we're way past it. Your NES hasn't been recapped has it? Might be worth a thought. There's nothing I trust less than a capacitor.

I've had a lot of luck washing boards too if you don't want to go that far. Had some pretty finicky carts that ended up being a lot more reliable after scrubbing lightly with a toothbrush and some alcohol, and then washing the whole board under the tap. Even though I already q-tipped them with alcohol. If you see evidence of capacitor leaks this has a really good chance of working though it's obviously temporary at that point. I've had good results with a clean looking board too though. I haven't washed an NES motherboard just games and mac boards.

With the macs a lot of people bathe the board in alcohol/water, water and soap, or just water. Even a really clean board with no signs of leaks that's acting up can come back to life with a serious cleaning. It sounds ridiculous but everyone seems to get away with it. I've even put stuff in the dishwasher (without hot water). Just put a fan on it after and leave it for a long long time to be sure it's completely dry.


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PostPosted: Mon Oct 06, 2014 9:53 pm 
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So, give it a good cleaning, you say? How water tight is the RF modulator? I wouldn't want to get any drops in there. As far as the circuit board goes, just scrub it with a toothbrush and rubbing alcohol and rinse under the tap? I'm game for it as long there's no risk to the motherboard by doing this.

I'd sooner give that a try than have to worry about soldering and recapping - I'd rather save that as a last resort type scenario as I've never attempted it before.


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PostPosted: Mon Oct 06, 2014 10:59 pm 
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Yeah... I was wondering about the RF part. I'm not sure if it would really be any worse to wash it but I don't know much about it.

I've definitely scrubbed the hell out of some boards and had them still work. I use a paintbrush if I can, though. You probably don't even need to scrub it much just a gentle pass to loosen up whatever might be on there.

Alcohol might take off some of the green on the board but nothing too bad unless you go crazy on it. Don't grind hard at it. I usually run water over it and scrub it a bit, then do a little alcohol and scrub that a little, then lots of water to rinse it all off. I scrub chips a little harder than traces. Some people use distilled water at the end to get the tap water minerals off but I've never bothered.

One place you can really go crazy with a toothbrush and alcohol is the cartridge slot btw.

Just make sure its dry. If I'm in a hurry I'll hang the board above a dehumidifier and it's dry as a bone in no time. That could be bad advice though.

Really all of this could be bad advice but I haven't had any problems with it. Made me feel like these boards are a little less fragile than you might think. Some boards are washed at the end of manufacturing I believe.

You can look for something like "washing circuit board" on youtube, there's a few videos of people's favourite way to do it and some of them talk about the risks.

Recapping isn't too bad. The thing that saves you a lot of grief is that you can clip the leads off the caps since you don't need them anymore (if they're not surface mount). Then just grab one lead at a time with pliers, heat it up and pull it out gently.


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PostPosted: Tue Oct 07, 2014 10:37 am 
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I tried the cleaning the motherboard method, very carefully, with Q-tips, rubbing alcohol and oven cleaner. Hit all the areas that looked dirty, sticky or corroded, including the main cap in the RF mod (which didn't look puffed up or dirty to begin with) and still no dice. Still catching waves!


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PostPosted: Tue Oct 07, 2014 11:38 am 
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Here's a silly question: What if you put an AM radio right next to the NES when you see the wavy bits? You might need to explore with what exact band it's tuned to. My NES doesn't produce those wavy bits, but the cartridge itself radiates weakly at 1340kHz.


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