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getafixx
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Re: Zig's SNES Repros

by getafixx Fri Jan 06, 2012 12:13 am

If that fixes it let me know. I would like to get this one fixed if at all possible, so if the RAM or the PPU chips (ppu 1 or 2, or both) is replaced and works good i will try it as well. Its not for the hassle of buying another one, but for the sentimental value. And its still in really great shape, whereas a lot of used snes units look like they've been through a war.
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Ziggy587
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Re: Zig's SNES Repros

by Ziggy587 Fri Jan 06, 2012 9:50 pm

Yeah, I hear ya about the sentimental value. That's exactly why I would bother to try and fix my SNES (even though I own three others already).

Anyways, my SNES that needs the fix is one of the earliest, if not thee earliest model SNES. The broken SNES that I have that I can savage parts from is a mini. So right there is a problem with the PPU. The original SNES had the two PPU chips, some later SNES as well as the mini have one PPU. So if the problem is with the PPU, I can't swap them. I haven't investigated it much, but I was hoping that the problem was bad video memory. And that the video memory was it's own IC on both models of the console so I can swap them.

Either way, I probably wont get around to doing this for some time. Way too much other stuff going on. I'm gonna keep an eye out for a busted SNES though, one that is the same revision so I can get the PPU from it if need be.
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zitoun
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Re: Zig's SNES Repros

by zitoun Sun Jan 08, 2012 4:46 pm

Ziggy587 wrote:That doesn't sound right. I don't remember the values off the top of my head, but I remember them being a little higher than that. Some where around 50 Ohm?

Do yourself a favor and get the voltage right BEFORE you put the EEPROM on. If you only drop the voltage to 4v (for example) there's a good chance you can fry the chip. The 29L3211 has a 10% tolerance, so you don't have to hit the 3.3v right on the nose. Any where from 3v to 3.6v should be alright, though I would still try and get it as close to 3.3 as possible (maybe 3.1v the lowest and 3.5v the highest, lower better than higher).


Hi Ziggy you have pm :)

P.S. Do I have to introduce my self somewhere in the forum ???
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Ziggy587
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Re: Zig's SNES Repros

by Ziggy587 Sun Jan 08, 2012 5:04 pm

Hey, zitoun. I've replied to your PM.

You don't have to introduce yourself, but if you'd like to, you can do it here: viewtopic.php?f=15&t=210
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zitoun
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Re: Zig's SNES Repros

by zitoun Mon Jan 09, 2012 6:59 am

replied too :)
hias
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Re: Zig's SNES Repros

by hias Sat Jan 14, 2012 10:34 am

Nice thread going on here! :)

PMed you too, Ziggy! :)
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Ziggy587
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Re: Zig's SNES Repros

by Ziggy587 Sun Jan 15, 2012 7:10 pm

Ever since I posted this pic, a lot of people have been asking me questions about it. I don't know if I was the first person in the world to do this, but apparently I was the only one to post about it. I'll consolidate all the info about it into this one post.

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That's a Star 0cean cart that I put a 29L3211 flash memory on. Common practice has been to wire in a 27C322 EPROM. The 27C322 is a compatible replacement, but it only comes as DIP. The only way to use it on the cart is to wire in each individual pin. This has obvious drawbacks. The 29L3211 is in SOP form, same as the mask ROMs found on the cart. And since the pinout is more or less the same, it can be installed with out any rewiring. The catch is that it requires 3.3v and not 5v like what the cart supplies. You have to step down the 5v to 3.3v in order to use it.

If you look in the data sheet for the 29L3211 (linked above) you'll see that you need to put 3.3v to pins 1, 23 and 33 for read mode. That is why I lifted those pins. And actually, you don't have to lift pin 1 since that pad isn't connected to anything. Leaving it down will give the pin more strength (the pins are really fragile, especially when you lift them). After everything is said and done, I recommend using hot glue to secure the lifted pins in place. Hot glue is great because it will securely hold the pins in place to safeguard against accidental breakage, but it is also fairly easy to remove if you ever want to restore the cart to stock.

The goal is to achieve 3.3v, and there's a number of ways you can do it. I'm not an electrical engineer, so I really can't say what the best way to do this is. I used a voltage divider, but I suppose you could use a voltage regulator. I've seen people use diodes to successfully step down the voltage for flash memory. Again, I don't know if there's any drawbacks to using a voltage divider, but that's what I used.

Just be aware that the 29L3211 requires 3.3v with a 10% range. I don't believe you can damage the chip if the voltage is too low, but if it's too high you'll fry the chip. There's a 10% range, so you can probably go as high as 3.6v, but I would recommend trying to get as close to 3.3v as possible. Lower better than higher.

If you look at the pic, I have a wire going to the capacitor. It's going to the NEGATIVE side of the cap, that's where I got the ground from for my voltage divider. I'm pretty sure you can take the ground from anywhere, but the cap just seemed like the best place to me.

If you look at the pic, there's a surface mounted resistor between the battery and the mask ROM. This is where I took the 5v from. This is the same as taking it from the solder pad, but I decided to take it from the resistor for space reasons. I'm not sure if it matters where you take the 5v from, but it just seemed like the best idea to take it AFTER the cap, and even better, AFTER the resistor. Also note that the resistor connects 5v to ground, so you have to take it from the appropriate side. If you take it from the wrong side, you'll have ground on both sides of the voltage divider so I would think the output voltage would be zero.

If you look at the Wikipedia page for voltage dividers you can see that it's a fairly simply thing. The Wiki page will also give you the formula you need to figure out the correct values for the two resistors needed (V out = R2 divided by R1+R2 multiplied by V in). But if you don't feel like doing the math, there are calculators online that will do it for you. Like this one. I forget the values of the resistors I used, but using that calculator, it looks like a 50ohm and a 100ohm resistor will do the trick (3.3333333v). I think I might have used slightly different values and ended up with about 3.2v. It is important to realize that it DOES matter which side of the voltage divider each resistor goes on. They are not interchangeable. If you have two different value resistors, you'll get different output voltages depending on what side you put them on. It should look like this:

(Vin=5v)-----(R1=50ohm)-----(Vout=3.3v)-----(R2=100ohm)-----(Ground)

And like I always say, if you don't know what you're doing, for God's sake, please don't try to mess with video game carts. If you're inexperienced with soldering and working with these kinds of components, please don't make an attempt.

It is worth noting that the common Willem programmers cannot program the 29L3211. I was gonna make an adapter to use for myself, but I don't plan on using the 29L3211 again. Like all these other old memories, it's a phased out part. You can only find them used, unless it's new old stock.

I don't plan on using this chip again because I don't plan on modifying Star Ocean carts anymore. The expanded version (96Mbit) is playable on the SNES PowerPak, which is why I went through the trouble of getting permission and uploading this hacked version to RHDN. And Retro Zone makes a Star Ocean reproduction cart now (from scratch - no donors used). It is unnecessary to modify real Star Ocean carts.
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DinnerX
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Re: Zig's SNES Repros

by DinnerX Sun Jan 15, 2012 7:46 pm

Interesting technical post!

Ziggy587 wrote:And like I always say, if you don't know what you're doing, for God's sake, please don't try to mess with video game carts.
:lol:
Since this signature affects old posts, I'm leaving a message here in case anyone searches for my username. This account died in early 2013. I am no longer a fundamentalist.

Don't add to my problems by pretending my past views are still held in the present. I do not have any patience for that. Feel free to ask me what I think now.
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Ziggy587
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Re: Zig's SNES Repros

by Ziggy587 Sun Jan 15, 2012 7:59 pm

Since I've started making "repro" carts, I have always advocated the use of flash carts over repros. Now, I'm going hardcore. I will no longer be making repros with the use of donor carts.

What I will continue to do is modify a Super Famicom cart with that game's translation. But as always, I will only do this for games that were not released outside of Japan. For example, NO, I will not put Earthbound on a Mother 3 cart. And this no longer includes Star Ocean, as an actual reproduction is now available from Retro Zone.

I will only do this for my friends here on Racketboy. For established members, if some one wants to send me their SFC cart to modify with a translation, I will do it. Any one else, sorry. It is a fun hobby, but I just don't have the time to be doing it all the time. And really, one could always use a flash cart.

Why? Using a donor cart means you're destroying one game to create another. Some might say, "Who cares? One less copy of some shitty game." I care, and you should too. I plan to create a thread for this topic, so I don't wanna go off on it here. But I am now against the use of donor carts. The carts I made for the charity auction were an exception because, well, it was the charity auction!

"Well what about Star Fox 2? It's unreleased and not playable on flash carts. You NEED to use a donor to be able to play that game on real hardware!" I say, oh well. Star Fox 2 isn't even that good of a game. Yeah, I said it. It's kinda cool to read about and check it out in an emulator. But it really isn't a must have game. Its only real appeal is due to it being canceled. If it was released (as the patched ROM we have available now) it would be known as the horrible sequel to that awesome SNES game, and forgotten after Star Fox 64 came out.

Maybe one day we'll have something that emulates the GSU (aka Super FX) chip on a flash cart and Star Fox 2, along with any other game that uses the GSU, will be playable on real hardware. The CX4 (used in Mega Man X2 and X3) is now emulated on hardware. There's a flash cart that's coming out that uses this emulated CX4. So there's hope of this one day happening for the GSU too.

Anyways, I've talked about it a few times, but haven't officially announced anything yet. Jeffro and I have been working on SNES repro boards. We've been working on it for a while, but unfortunately I have this job and a life that gets in the way of my hobbies. Basically, I don't wanna be using donor carts any more, and I don't want others to use them either. So we're coming up with a board from scratch so that people can make their repros with out the use of a donor cart. Don't worry, scammers will not be able to pass them off as real carts. I plan to make a thread about this soon, so I wont go into much detail here about it.

TL;DR:

1) I'm against using donor carts, I will be making a thread about this some time soon.

2) I'm working on repro boards to stop or at least curb the amount of donor carts used, I will be making a thread about this some time soon.
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fvgazi
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Re: Zig's SNES Repros

by fvgazi Sun Jan 15, 2012 8:40 pm

I'm actually really interested as to why you're against using donor carts of bad games. I love to tinker and repurpose things. I'm looking forward to an informative post!
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