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 Post subject: N64 component (aka YUV aka YPbPr) output
PostPosted: Sun Mar 10, 2013 1:07 am 
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So a co-worker gave me his N64 stash (which includes 2 USA N64s, so I don't mind modding one), and I finally got around to testing it out a bit on a spare LCD TV. The composite video quality is terrible, and the S-Video versus composite comparison pictures I've seen online don't have me excited about spending money on an S-Video cable (which is apparently the best that the N64 can officially do).

It looks like the N64 unofficially has the ability to output RGB, however (click images to see the sites I found them on):
ImageImage

Also: http://www.mmmonkey.co.uk/console/nintendo/ntsc_nintendo_64_rgb.htm

This doesn't do me much good, though, because I don't have any TVs or monitors that take RGB inputs. I'd like to do component video (a la the Nintendo Wii), and I've come across some stuff on converting RGB to component for other applications. Here is the most promising DIY converter circuit I've seen:
Image

Notes/Questions:
  • Does anyone have armchair opinions on whether this should work, whether it might be worth attempting, and whether I'm on the right track?
  • The ICL7660 IC on the upper-left is a voltage converter that is being used to invert the 5V input to -5V. I'm guessing that the diodes around it should be zener diodes.
  • The 74HC4053 IC is a Triple 2-Channel Analog Multiplexer.
  • The MAX4451 ICs are 210Mhz op-amps.
  • The LM1881 IC is a video sync separator.
  • Vcc across the whole converter circuit appears to be 5V, but my understanding is that the N64 only has 12V and 3.3V internally. A 12V->5V voltage regulator would therefore likely be required to drive it from the N64's internal 12V line. Would a voltage regulator remove the need for the diodes and/or capacitors around the voltage inverter?
  • I'm not sure whether the "composite sync" line could/should be used for the sync input of the RGB->component converter circuit. If not, then I'm at a loss as to how to deal with this.
  • What the heck is this guy on about? The info there doesn't seem to gel at all with the other RGB info I've encountered.
  • I know there are various RGB-to-whatever converter boards/kits out there, but most of them are expensive and/or overkill. If anyone knows of one for under $20 USD that should work for this, I'd prefer it over a DIY solution.

Edit: Would something like this work if I connected the RGB + sync outputs of the N64 to the corresponding inputs of the SCART connector? It sounds like I might run into trouble with the output not being high enough resolution? I'm not interested in buying a $50+ scaler.

Edit 2: Based on Link83's motherboard revisions sticky, I'm guessing both of my N64's are way too new for RGB modding. One has a serial starting with NS24 and the other with NS27. Maybe I'll just mod in a built-in S-Video port so that I don't have to go buy a cable :P


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 Post subject: Re: N64 component (aka YUV aka YPbPr) output
PostPosted: Sun Mar 17, 2013 2:38 pm 
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Location: behind you, don't look, I'll just be behind you.
The difference between s-video and composite is totally worth the $5 for a cable that works with the SNES and GC, too.
http://www.amazon.com/s/ref=nb_sb_noss_ ... ideo+cable

Of course, I've mostly used it on CRT tv's, but I do have a capture card that I can get some comparisons that are probably better than what you've seen with.

Also, the "This Guy" you're wondering about is completely replacing the video out chip, much like what marshalh is working on; rather than converting the existing chip's output.


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 Post subject: Re: N64 component (aka YUV aka YPbPr) output
PostPosted: Sun Mar 17, 2013 3:34 pm 
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I'm a bit hesitant to buy one because the only one listed for $5 or less (price + shipping) has reviews from customers saying they got stuck with a composite-only cable.

Maybe I'll pick up this one for a few cents more though: http://www.amazon.com/Universal-AV-S-Vi ... B000067QIG

The other option is to just open up one of my consoles and hard-wire an S-Video cable to the motherboard. I do have a spare cable and a Nintendo screwdriver bit around somewhere.

Edit: I should also mention that I've currently got it hooked up to a small 720p Samsung LCD TV that doubles as a VGA monitor for my Linux box. I'm not sure that it has the most amazing video ADC hardware.


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 Post subject: Re: N64 component (aka YUV aka YPbPr) output
PostPosted: Tue Nov 19, 2013 9:13 am 
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I've tried a similar setup. I got a PAL 64 with an rgb-DAC-mod and it looks very good on most of my tvs with scart input, however my main setup with a receiver and a projector doesn't have rgb inputs. So I ordered a pretty cheap rgb-component converter. Running it to my receiver upscales it and it works, but the colors wash out a bit and the lag from all the processing is pretty bad, putting this setup on par with just using composite... That sucked, so I tried to connect directly to my projector, and what do you know, another problem arises... With a 240p component signal, the projector doesn't know what to do so the image gets screwed up pretty badly... I sum up my problems in detail in my post here: http://nfggames.com/forum2/index.php?topic=5081.0

If you manage to get an rgb mod going, the absolute best solution is a XRGB - Framemeister, a fantastic upscaler! A tad expensive, at least for me :lol: RGB to VGA might be a good budget bet.

On the other hand, you could just wait for marshallh to finish his hdmi video-out board, which no doubt will be the best solution for connecting a 64 to most tvs :)

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 Post subject: Re: N64 component (aka YUV aka YPbPr) output
PostPosted: Fri Nov 29, 2013 7:40 pm 
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I ended up buying a cable that had inputs for various consoles on one end and S-Video plus composite plus audio outputs on the other end. This made it really easy to compare S-Video to composite video by switching inputs on the LCD TV that I'm using. Unfortunately, however, I almost regret upgrading to S-Video due to the fact that N64 games seem to use a ridiculous use of dithering, which looks very checkerboard-y with the sharper S-Video pixels.


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 Post subject: Re: N64 component (aka YUV aka YPbPr) output
PostPosted: Fri Nov 29, 2013 8:15 pm 
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Yeah, I've tried s-vid on my 64, very bad checkerboard-effect indeed :/ However, I'm not too sure the console itself is the problem, but rather the cables. If you have a multi-system cable, I'm led to believe that your cable isn't top-notch. I found this site explaining the checkerboard-effect and it would seem that a better cable almost completely removes it! http://www.micro-64.com/features/svideo.shtml

Also, and don't quote me on this, but I seem to recall that the pal 64 doesn't send a "correct" s-vid signal, maybe it's using composite on either the chroma or luma line, or maybe the signal isn't bright enough? I can't remember what it was :/

Anyways, you'll probably want to google about and find a better cable and just get that ;)

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nobble wrote:
thewise1 wrote:
Super long, but incredibly epic.

YESSSSSS!!!

Oh my gosh! What have I done?


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 Post subject: Re: N64 component (aka YUV aka YPbPr) output
PostPosted: Fri Nov 29, 2013 8:15 pm 
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Yeah, I've tried s-vid on my 64, very bad checkerboard-effect indeed :/ However, I'm not too sure the console itself is the problem, but rather the cables. If you have a multi-system cable, I'm led to believe that your cable isn't top-notch. I found this site explaining the checkerboard-effect and it would seem that a better cable almost completely removes it! http://www.micro-64.com/features/svideo.shtml

Also, and don't quote me on this, but I seem to recall that the pal 64 doesn't send a "correct" s-vid signal, maybe it's using composite on either the chroma or luma line, or maybe the signal isn't bright enough? I can't remember what it was :/

Anyways, you'll probably want to google about and find a better cable and just get that ;)

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thewise1 wrote:
nobble wrote:
thewise1 wrote:
Super long, but incredibly epic.

YESSSSSS!!!

Oh my gosh! What have I done?


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 Post subject: Re: N64 component (aka YUV aka YPbPr) output
PostPosted: Fri Nov 29, 2013 8:44 pm 
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My N64 is NTSC.

And it looks like you're right. Damn. I didn't want to believe it, but it looks like it's a common issue with S-Video: http://preservation.bavc.org/artifactat ... osstalk%29

The problem is that I don't know how to tell if a cable is going to be good or not before I buy it, and I don't want to spend more than $10 or so on it.

I wonder if I could hack the connectors off of the existing cable and rewire them to get better results? I did something similar to convert a stock XBox (first generation) composite cable into a component cable, and it works fine even at higher resolutions.


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 Post subject: Re: N64 component (aka YUV aka YPbPr) output
PostPosted: Sun Dec 01, 2013 12:18 pm 
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Update: After reading the reviews on all the sub-$15 cables available on Amazon, and finding serious issues mentioned for all of them, I got an idea.

I looked up a pinout for SNES/N64/Gamecube and put a piece of electrical tape over the composite video pin, then plugged it back into the N64 and turned it on. Voila - no more checkerboard/dithering artifacts!

The only problem is that the electrical tape solution is not 100% reliable. I should probably grab some pliers and rip the composite pin out completely, since I have at least 2 other official Nintendo composite cables anyways.

Edit: Note that NTSC does not use Composite Sync, just signal and ground.


Last edited by HunterZ on Mon Dec 02, 2013 9:48 am, edited 1 time in total.

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 Post subject: Re: N64 component (aka YUV aka YPbPr) output
PostPosted: Mon Dec 02, 2013 7:36 am 
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Aaaaha, so simple, yet so genious! Yeah, go ahead and butcher your cable, and just taking out the pin is probably the best way to go about it as well, considering how it may or may not be wired internally. This way you'll retain composite-compatability for the other systems, very nice;)
Consider opening up the "head" (the plug that goes into the system, *giggety*) somehow and disconnect the pin from within, could be easier depending on how the head is made.

However, I can't wait for Marshallh to complete his FPGA-board! Until then, I would hold off on rgb-modding your system and settle with S-video as well. Hopefully It'll be done soon!

_________________
thewise1 wrote:
nobble wrote:
thewise1 wrote:
Super long, but incredibly epic.

YESSSSSS!!!

Oh my gosh! What have I done?


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 Post subject: Re: N64 component (aka YUV aka YPbPr) output
PostPosted: Mon Dec 02, 2013 9:46 am 
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After modding an original Xbox composite cable into a component cable, I'm not sure I want to try hacking the console end of A/V cables any more. There's usually a ton of heat-welded plastic around thick RF shielding/grounding metal, which forces you to all but destroy the connector to get at the pins.

A third option may be to cut the insulation off of the N64 end of the cable and snip a break in the composite wire. This may be somewhat suboptimal, though, as just having the composite signal running in parallel to the S-Video signal seems to be enough to result in crosstalk artifacts (since disconnecting the composite connector on the TV end did not eliminate the checkerboarding/dithering artifacts). The upside is that I could always wire in a switch to reactivate composite output on that cable in the unlikely case that I ever want it.

I should probably take some closeup pictures of composite, S-Video with artifacts and S-Video without artifacts.


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 Post subject: Re: N64 component (aka YUV aka YPbPr) output
PostPosted: Mon Dec 02, 2013 3:28 pm 
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If possible I would stick to nudging out the pins in the N64-end of the cable with a pair of pliers, yeah :)

And those pictures would be interesting to see if that's not too much trouble 8)

_________________
thewise1 wrote:
nobble wrote:
thewise1 wrote:
Super long, but incredibly epic.

YESSSSSS!!!

Oh my gosh! What have I done?


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 Post subject: Re: N64 component (aka YUV aka YPbPr) output
PostPosted: Mon Dec 02, 2013 6:27 pm 
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Took some pics with and without the electrical tape over the pin. Sorry for the quality; it was the best I could do without a lot of fiddling.

S-Video with crosstalk:
Image
Note the checkerboard pattern on the yellow circle in the upper-right.

Composite video:
Image
Note the lack of pixel definition. It's most notable in light-colored spots, in the green circle at upper-left, and in the diagonal black line above the green circle.

S-Video clean:
Image
Note the superior pixel definition without accompanying checkerboard pattern.


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 Post subject: Re: N64 component (aka YUV aka YPbPr) output
PostPosted: Mon Dec 02, 2013 7:16 pm 
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Well now I'm not so sure that it's related to the composite signal at all. After putting the tape back on, I still got intermittent checkerboarding. I cut into the insulation at the N64 end of the cable and cut the composite wire, and still get checkerboarding.

Now I'm thinking it's more likely due to the wires not being shielded from each other. They have the audio (left/right), S-Video (luma/chroma) and ground (uninsulated) wires separated from each other only by plastic insulation, with RF shielding foil wrapped around all of them together. This means that everything is potentially able to crosstalk.

I guess the next thing to try would be to strip the N64 end of the cable (from the rectangle where all the N64/Xbox/PSX cables come together, to the N64 end of the cable) and put foil around the luma and chroma wires (or, more likely, one around everything but the luma wire and then another around everything).

Edit: Cut open the N64 end of the cable and spread the wires apart. Noticed no difference in checkerboarding, so shielding just that end probably isn't going to help. Now I'm thinking I should hack the end off of an S-Video male-to-male cable and use it to carry the video signal from the N64 connector to the TV, since it will probably be properly shielded.

Edit 2: Cut into a male-to-male cable I had laying around in the garage, and it looks promising: The chroma and luma wires are each their own small coax cable, with stranded wire surrounded by hard plastic, surrounded by stranded shielding wire, surrounded by flexible plastic insulation. There's an unshielded twisted stranded ground wire that runs in parallel with those, and then the whole thing is wrapped in a foil shield (which presumably makes contact with the ground wire).

After I finish stripping the signal wires on this cable, I will cut the chroma and luma connections on the N64 video cable and solder the N64 end to the stripped cable, which will result in a much better-shielded signal path. I will probably keep the audio connection intact, because the only sacrifice-able twin RCA cable that I have handy is substantially shorter and I don't want to lose any length.


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 Post subject: Re: N64 component (aka YUV aka YPbPr) output
PostPosted: Sat Mar 15, 2014 4:11 pm 
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Sorry for the late update, but I did manage to get the better S-Video cable wired to the cheapo connector and the picture looks great. The problem is that I've been too busy to properly solder and heat-shrink insulate the connections, so it's currently in a rat's nest of hand-twisted wires. The only thing I've done in the past couple months is to impulse buy some heat shrink tubing from Fry's while I was there to buy a new wifi router.

I've attached a picture below. In the process of writing an explanation of the current state of things, I just noticed that the hand twists have come loose again - damn!

At any rate, the thick black cable is the true S-Video cable, with the blue and red colors being the outer insulation around the coax-shielded signal wires. Below that are some horizontal-pointing thin black and brown wires, which are the unshielded S-Video signal wires of the cheapo cable.

I really need to get this cleaned up so that I don't have to repair it every time my 3-year old daughter wants to play "the monkey game" (Donkey Kong 64 - currently inserted) or "Link" (Ocarina of Time) or "Yoshi" (Yoshi's Story). I still haven't decided if I want to reconnect the composite wire; it's kind of a don't-care since I have one or two official Nintendo composite A/V cables already.

UPDATE: Finally got out the soldering iron and finished it up. Turns out the heat shrink tubing was too small to be useful, so I just used electrical tape to cover the connections after soldering. I also taped the big cables together to try to provide strain relief in case small hands tug on it, as without it the stress would be on the small wires and/or solder connections.

Image


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