The easiest mod, involves removing the metal bar, so you can put carts with EPROMs in, else they won't fit.
http://www.54.org/condev/NESMods/NESMod ... _Piece.jpg
Next, to disable the chip that give you that annoying flashing screen,
http://www.54.org/condev/NESMods/NESMod ... t_Chip.jpg
And finally, this mod (a 100K resistor in series with a 4.7uF non-polarized cap) gives you sound input on pin 18 (EXP). If you combine it with a modified Famicom->NES converter, you can get sound from Famicom games that have a sound chip. Just solder a wire from the Famicom side pin 46 (sound out) to NES pin 18.
http://www.54.org/condev/NESMods/NESMod ... Pin_18.jpg
Ok thanks for information.
The third modification looks to be very easy to do.
As for the disabling the lockout-chip, you don't need to do anything
else than cutting pin#4.
True,
I've cut off pin 4 in a few NES's and it always worked.
Someone mentioned it is suppost to be soldered to GND, not sure why...
Perhaps its pulled to ground, by being left floating?
I'm in an electronics class, and when you leave something floating, it tends to pick up charges that are in the air...
For example, I had a binary -> decimal 7-segment encoder, and I left the inputs of that floating, and the display kept showing really weird stuff, like "in between 6-7", it'd drift to 9, it'd go to 3, it'd do really weirdo floaty stuff.
Not necesarilly bad, but if you want the input to be a definitive 0, without a doubt a 0, then put it to gnd.
Cutting the pin may not leave it electrically floating. Since it is an input to the PPU, it is likely that it has an internal "pull down" resistor connecting it to GND, which is why when left unconnected externally it reliably reads as "low". This is just a guess, maybe the PPU patent documents have a diagram showing this? If it does not, and it really is floating, then I agree you should tie it to GND just to be sure. Although, I don't think floating this pin will cause damage to your NES, simply odd behavior whenever it doesn't read low.
I think CMOS and TTL both act differently when left floating.
By default, I think TTL is always high, when left floating.
CMOS on the other hand is different, and can act strange if left floating. You always want to pull up or pull down a CMOS device.
But you usually don't want to float anything, because it can cause oscillators, noise, spikes, etc.
Of course the way to definitively fix this is to go to the copyright office and ask for the lockout chip's tapeout. (Unlike the perpetual copyrights on almost everything else, copyrights on chip masks and boat hulls expire after only 10 years.)
A question about that sound mod.
First, is the mod applied to the system or to the Famicom-to-NES converter?
Second, you mention that the converter is "modified." Modified how? Is it easy to do?
Quote:
system or to the Famicom-to-NES converter
Both.
For the Famicom->NES adapter...
Just solder pin 18 on the NES side of the connector to pin 46 of the Famicom side of the connector.
For the NES,
Solder pin 18 of the NES cart connector to a series resistor 100K then a 1uF or higher non-polarized cap to pin 3 of the EXP connector on the bottom.
Also, where might I find such a converter other than buying every copy of Gyromite in the world and opening it up? Google only seems to return NES-to-Famicom converters (one of which I already have), Lik-sang also only has NES-to-Famicom, and I don't really know where else to look. Would this one suffice:
http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... eName=WDVW
I ask because the NES-to-Famicom one is basically just a chip with a slot on one end and pins on the other, whereas this one actually has some casing around it. Trivial, I know, but I want to make sure I'd be getting the right thing.
For one thing, the Fami-to-NES converter has a lockout chip inside, which means that only Nintendo can manufacture them.
...Great. At least I didn't bid on the eBay one. So where might I find a real one?
......Wait. Couldn't I just mod out the lockout chip on the hardware to be able to use a converter without a key chip?
If you're willing to open your NES and cut pin 4 of the lockout chip, then you can be assured that most aftermarket Fami->NES converters will work fine on any NTSC NES. Famicom games that use raster effects or the DMC might glitch on a PAL NES.
by bending up pin four on the lockout chip, you disable the whole thing? If that is the case, couldn't you just take the whole chip off? I'm not going to do that, but by bending up pin four, does it do any harm to your system at all? Or was it just for security?
Anonymous wrote:
by bending up pin four on the lockout chip, you disable the whole thing? If that is the case, couldn't you just take the whole chip off? I'm not going to do that, but by bending up pin four, does it do any harm to your system at all? Or was it just for security?
See this thread:
http://nesdev.com/bbs/viewtopic.php?t=350
Is there any other purpose for the lockout chip than for security? or can you just disable it, and everything will be fine?
It's there for a couple reasons. To stop unlicensed developers from making their own carts, and to prevent people from importing games from other countries (smells of price fixing). It serves no other purpose at all.
Dude, so you could really just take it off, and throw it in the garbage? I just want to be sure so I don't screw my NES over and have to throw the classic grey box in the trash. So you can really take the whole chip off and do no modifications after removing it? In that case, that's easy.
The reset signals are routed through the CIC chip (obviously, given the blinking that happens when it doesn't authenticate successfully), so it might be easier to disable it (cut pin 4) than to desolder it completely and reroute the reset signals.
Did the famicom sound modification... I effecticvely got MMC5 sound from Just Breed... but my TV output is gabrage now, so there is no correct image on the screen...... this also aplies for all normal games so I've no longer any working NES........ any suggetions ?
PS : I used a 2.2 uF capacity, and the MMC5 sound sounds to get a bit too lood (additionnal to the cracks due to the incorrect output signal it's hard to determine exacly what's wrong). Should I use a smaller capacity ?
Me stupid !! I moved the kanal 3 / kanal 4 switch, given the wrong video output form. It actually works just fine.
But, the volume of the MMC5 channels is really too loud. It is so loud that you nearly cannot hear other channels. Should I increase or decrease the capacity ?
Me stupid again !! I solvered a 100R resistor instead of 100K, making it 3 times louder (log 1000).