One-chip SNES Build

I recently used the onechip snes serial number page:

https://docs.google.com/spreadsheet/pub?key=0AvE57-VbN9_HdEpkUUR0U1hzMHFWVWw3VXhORHFIanc&output=html

To find myself a onechip model 1 american snes.

The system arrived today and indeed is a onechip.  This system wasn't well taken care of, there was pop spilled all over it.  I cleaned up the pcb, adjusted the s-video circuit, removed the rf box, swapped the back plate with a super famicom back plate, and installed it into a very nice super famicom case:







I'm going to use the stock video encoder in this thing the picture is sharp enough and it's nice to say I'm getting a more "authentic" experience.  I do prefer the colour encoding of the sony cxa2075 but this looks good enough.  I'm expecting one snes digital audio chip to arrive shortly in the mail which I'll install into this.  The hole where I removed the rf box is where I'll install a rca jack for digital audio out.  I'll probably install a 2 pin connector where the rf switch used to be to connect the power cord for my external spdif to analog box.

Nice job! The 1CHIP really is a thing of visual beauty. I am just a bit confused because I thought you had one for ages? So all of the SONY CXA encoders you were putting into your SNES systems were on non 1CHIP systems? Man the image quality difference must be blowing you away!

Don't put the coaxial audio port in yet; I sent a few optical audio ports with your package. When you eventually do get a flat TV and/or stereo receiver, they are way more likely to have optical ports than coaxial. I've actually never seen an HDTV with coaxial audio pass through; every one I've seen uses optical. Plus, come on...red beams of light out of the back of your SNES are awesome.

If you aren't replacing the encoder, what did you mean by "adjusted the s-video circuit"?

Congrats on your 1CHIP; you have another coming your way.

OnyxDomain wrote:

Nice job! The 1CHIP really is a thing of visual beauty. I am just a bit confused because I thought you had one for ages? So all of the SONY CXA encoders you were putting into your SNES systems were on non 1CHIP systems? Man the image quality difference must be blowing you away!

Don't put the coaxial audio port in yet; I sent a few optical audio ports with your package. When you eventually do get a flat TV and/or stereo receiver, they are way more likely to have optical ports than coaxial. I've actually never seen an HDTV with coaxial audio pass through; every one I've seen uses optical. Plus, come on...red beams of light out of the back of your SNES are awesome.

If you aren't replacing the encoder, what did you mean by "adjusted the s-video circuit"?

Congrats on your 1CHIP; you have another coming your way.

Thanks to Onyxdomain I found this.

.....you really let yourself get carried away by your imagination and many many many constant complete misinterpretations of things I say.  Why is it so hard to consider that you're doing it wrong?

...yes I've been using onechips before, but they were snes mini systems.  The snes mini is a onechip, it's the same ppu.  This is the first onechip I've gotten where s-video comes wired up.  My spdif to analog box connects by rca.  I don't have any digital audio equipment.  I don't drill any extra holes to add that rca jack so I can always remove it later.  Why would I wire audio into a tv with small tinny speakers?  I've been wiring audio into my 1979 pioneer amp since 1993, when I turned 13.

"Adjusted the s-video" means adjusting the strength of the luma and chroma lines.  I adjusted both of them without removing any parts from the original circuit.  For chroma I added a pull down resistor to weaken it.  For luma I found where the 75 ohm output resistor is and attached a 43 ohm resistor to encoder side of the 75 ohm resistor and the other side to the luma pin on the multi av port.

Anyway with all onechip systems the s-video signals have diagonal lines passing through chroma.  For some reason this one the diagonal lines are weaker than my snes mini systems.  This system there's also no translucent bar, which is why I just stuck to using the built in video encoder.  The colour encoding isn't as nice from the built in encoder as the cxa2075 but since I have more onechips coming I might save the cxa2075 bypass for one that has that translucent bar.

I've never seen diagonal lines via s-video on any SNES revision. Are you sure it's not your s-video cables? I've seen this when using certain s-video cables:



Is that the type of lines you are referring to?

This comes from using certain s-video cables, namely the ones that aren't made by Nintendo. I have had good luck with Hori and Monster Cable (meant for Gamecube) s-video cables, but anything else gives me those ugly lines.

To be technical about it, the SNES model 1 (1CHIP ones) still give off a better picture than a modded SNES Mini. For whatever reason, the SNES Mini has a slight issue with image ghosting. It's kind of hard to see, but here's how you can see it:

"To see the ghosting you need to move. I suggest to go in level Donut plains 4 and run till the end of the level. Check for ghosting of the Green bush in the sky."

That's the type of lines but it's not my cable.  I use the exact same cable on my gamecube and it doesn't have them.  My tv is just more sensitive.  The onechip model 1 snes has ghosting too, it's just the same as the mini.  I noticed the ghosting even before I modified the s-video circuit.

I did some playing on my onechip today.  The built in encoder colour encoding is so darn ugly I said screw it, I'm going to build a cxa2075 circuit and drop it into this machine.  The cxa2075 looks wayyyy better in these machines. CXA2075 fo life.

Drakon wrote:

I did some playing on my onechip today.  The built in encoder colour encoding is so darn ugly I said screw it, I'm going to build a cxa2075 circuit and drop it into this machine.  The cxa2075 looks wayyyy better in these machines.  CXA2075 fo life.

Don't order any, I sent you quite a few.

OnyxDomain wrote:

To be technical about it, the SNES model 1 (1CHIP ones) still give off a better picture than a modded SNES Mini. For whatever reason, the SNES Mini has a slight issue with image ghosting. It's kind of hard to see, but here's how you can see it:

"To see the ghosting you need to move. I suggest to go in level Donut plains 4 and run till the end of the level. Check for ghosting of the Green bush in the sky."

https://16bitgamer.canadian-forum.com/t290-super-famicom-nintendo-1-chip-debunking-the-overhype

This linked thread tells the truth.

OnyxDomain wrote:

I've never seen diagonal lines via s-video on any SNES revision. Are you sure it's not your s-video cables? I've seen this when using certain s-video cables:



Is that the type of lines you are referring to?

This comes from using certain s-video cables, namely the ones that aren't made by Nintendo. I have had good luck with Hori and Monster Cable (meant for Gamecube) s-video cables, but anything else gives me those ugly lines.

To be technical about it, the SNES model 1 (1CHIP ones) still give off a better picture than a modded SNES Mini. For whatever reason, the SNES Mini has a slight issue with image ghosting. It's kind of hard to see, but here's how you can see it:

"To see the ghosting you need to move. I suggest to go in level Donut plains 4 and run till the end of the level. Check for ghosting of the Green bush in the sky."

RGB Bypass the 1 chip then you will notice that it is the same quality as the SNES mini. Out of the box the one chip is a bit brighter which blurs the image just enough to hide the ghosting. This unfortunately results in a less sharp image. On a properly configured crt the stock one chip does not look better than the SNES mini, its worse. Once RGB bypassed the only difference is a slight change in colors which is neither better or worse.

Take a look at the link Drakon posted for more info, i don't feel like retyping it all.

As I said before, the onechip model 1 completely unmodified and stock I see ghosting in mario world on s-video. I'm also glad you made that thread, it's basically the book of truth on this subject.

The video encoder built into this system is garbage, no matter how much tweaking I did the image still didn't look nearly as good as the cxa2075 looks.  Unfrotunately installing a cxa2075 is a huge amount of work.  First I built a cxa2075 circuit with just s-video output:





Nice and compact.  Next I probed where the s-video pins of the av port connect.  The luma and chroma lines each connect to one 75 ohm resistor and one cap.  I moved the surface mount parts so they only connect to one solder pad.  I wired the outputs of my circuit to the av port it works great.  I managed to make the circuit small enough for it to fit under the heatsink:





A little tweaking of the luma resistance and this system should be done.

I should also add finding where the luma and chroma lines connect is a royal pain.  Typically in snes systems each line connects to one resistors and one cap so you can isolate those pins by desoldering one side of the resistor + cap for each line.  Finding which resistor + cap requires probing the surface mount resistors + caps that're close to the multi av port on the solder side of the pcb.  The location and particular part depends entirely on your pcb revision.  I'm not going to post pictures of which parts it is because I don't want people to mess up onechip snes s-video circuits messing around with surface mount stuff.  Sorry people I firmly believe advanced level modding should only be performed by advanced level modders. For beginners I recommend installing a separate s-video jack in the case (not the backplate) of a fugly snes case, not like you can make that thing any uglier.

It's done:







I call this thing: Onechipicom.

This is a onechip snes converted into a super famicom. I bypassed the built in video encoder wth a cxa2075 for improved s-video. RGB is still connected to the ba6596f. There's no translucent bar on this machine. The digital audio mod has been performed digital audio signal is fed from the rca jack on the back. The small connector sticking out the back plugs into my spdif to analog converter box and powers it from the super famicom.

The super modded onechip next to the super modded onechip snes mini in a sfc case:



*edit*

took a better pic:

More gameplay footage recorded from this system:

People need to be cautious about finding these 1-chips in the wild. nothing people know about finding them is true because...

I bought a Un316 snes which was way into 1-chip territory and it had a GPM board in it.

i also had one that was UN321 that had an APU board in it.

The only way to know for sure is if its listed for sale as a 1-chip.

I dont know if aware sellers are swapping them or if nintendo was just using up old stock that they had forgotten about.

i would say that the basic rule could be - every 1-chip has been between Un301 and un323 but not every snes between those numbers was a 1-chip.