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kogami
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Re: Zig's SNES Repros

by kogami Fri Sep 09, 2011 8:53 am

I do not well manage to see what you made

You raised two pines (Pin 23 and 33) and you connected them together?
Similar for pine 1 to the GND?

Image

But I understand not the blue thread?
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Ziggy587
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Re: Zig's SNES Repros

by Ziggy587 Fri Sep 09, 2011 1:55 pm

The blue wire is going to the 5v pad (23). That's where I took the power from (but you can take it from anywhere after the cap). Pins 1, 23 and 33 are all connected together, getting roughly 3.3v. Look at the pinout for the 29L3211:

IMAGE

Pins 23 and 33 are Vcc and BYTE. The board supplies 5v on these pins, but the 29L3211 needs a 3.3v (+/-10%) power supply, that's why those pins are lifted (you could cut the trace if you want, I decided to lift the pins). Pin 1 is WE, which also needs Vcc (WE is active when set low). That pad on the board is NC, so you can leave that pin down. The white wire going to the negative side of the cap is the ground for the voltage divider I used to step the 5v down to 3.3v. So this is sort of what I did:

IMAGE
Last edited by Ziggy587 on Sun Jan 08, 2012 5:07 pm, edited 1 time in total.
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kogami
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Re: Zig's SNES Repros

by kogami Fri Sep 09, 2011 4:57 pm

OK thus if I well understood :D

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Ziggy587
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Re: Zig's SNES Repros

by Ziggy587 Fri Sep 09, 2011 6:34 pm

No. The SNES board only has +5v power. You have to step the +5v down to +3.3v for the 29L3211. I used a voltage divider: http://en.wikipedia.org/wiki/Voltage_divider

Code: Select all
Ground----------Resistor 1-------------{+3.3v}-------------Resistor 2-----------------+5v



You don't have to use a voltage divider to get 3.3v, that's just the way I did it. You can use diodes or a voltage regulator if you wish, what ever you want.
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kogami
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Re: Zig's SNES Repros

by kogami Sat Sep 10, 2011 11:12 am

I admit you that I had not well understood :oops:
But now it is good

A last question
R1 and R2 = ?? ohm

Because I think that I am going to proceed as you
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Ziggy587
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Re: Zig's SNES Repros

by Ziggy587 Sat Sep 10, 2011 11:20 am

I don't not remember the values of the resistors I used, but it shouldn't be too hard to figure out. Besides, I believe the values will differ depending on where you take the +5v from (directly from the cap, before or after a resistor on the board).
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Mute City Electronic
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Re: Zig's SNES Repros

by Mute City Electronic Sat Sep 10, 2011 12:35 pm

kogami wrote:I admit you that I had not well understood :oops:
But now it is good

A last question
R1 and R2 = ?? ohm

Because I think that I am going to proceed as you

Code: Select all
Ground----------R1 (2 ohm)-------------{+3.3v}-------------R2 (1 ohm)-----------------+5v


That should do the trick, i worked that out quickly and I havn't test it yet so keep that in mind.
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Ziggy587
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Re: Zig's SNES Repros

by Ziggy587 Sat Sep 10, 2011 9:17 pm

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).
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Spitfirethunderbolt
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Re: Zig's SNES Repros

by Spitfirethunderbolt Fri Sep 16, 2011 4:16 pm

Hi Ziggy587, I'm new on forum and I would like know, if is possible send one repro of Star Ocean to Brazil ? :D
16bitz
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Re: Zig's SNES Repros

by 16bitz Sun Sep 25, 2011 11:48 pm

Hey guys. Long story short i used to make a lot of repo's but then as usual life got in the way :cry: I used the stacking method which worked like a treat, but obviously a hr of soldering and $50 on eproms and doners was a joke and gave the tsop adapter a try but failed miserably and raged quit :oops:

nways, now i got a bit of free time and determined to get these to work! Im pretty sure half my original problem is that i was using (and still am) a crummy $20 soldering iron and tip. Is there a good iron and tip(s) somebody could recommend for these? I do use it quite frequently so im willing to justify $100+ as i will get some good use out of it.

Regards,
16bitz :D
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