How To: Connect NES controller to Famicom

[keiffer01]

Nope...nothing changes. I have another broken Famicom, so I'm wondering, would it be a good idea to switch the PPU's from one another? Or what else shoould I do? Does it look like something hard to fix? Only the graphics are the problem everything else works fine.

[133MHz]

Sounds like a PPU problem, if you can, try to replace the PPU.

Only the graphics are the problem everything else works fine.

Yeah, that gives the PPU as the culprit. The CPU processes the game program, sound and joystick input, while the PPU does the graphics and connects directly to the Character ROM on the cartridge. It receives the orders on what & where to draw from the CPU and outputs composite video as the result. If everything else works fine the video system seems very likely to be busted (be it the PPU itself or something along its path).

[keiffer01]

So...you're saying my Famicom is dead? Would there be any places where they could sell spare parts or Mother Boards for a Famicom system? And the PPU, is it the biggest chip on the bottom part of the famicom, towards the EXT port, or the big one in the middle?

[133MHz]

The big one in the middle. It says 2C02. The CPU is 2A03.

Maybe you could get a broken NES for cheap (NES almost always fail because of its cart connector) and donate its PPU for your Famicom.

[keiffer01]

The NES and Famicom use the exact same PPU?

[133MHz]

Yes, but NTSC NESes only .

[satoshi_matrix]

Hey keiffer01, I'm sorry to hear about your Famicom. I hope it feels better soon! 


133MHz: okay long post, please try to forgive my noobness this is all new to me.

Okay, so I read your post and its real informative, thank you. just to confirm: I need to completely remove the IC chip on the NES 2 controller labeled GD14021BP so I have 16 holes in the controller for which to place Genesis wires into.

The spaces where the cords need to go are

8 for Ground
4 for Up
5 for Down
6 for Left
7 for Right
14 for Select
13 for Start
15 for B
1 for A

But what about the remaining spaces 2, 3, 9, 10, 11, 12, 16 on the NES controller? Do I just leave them empty?

Moving on: Luckily for the infornation you provided, it is indeed a standard run of the mill 3 button Genesis controller I want to use the cord off of. I have other Genesis pads, but this is the one that's most expendable.

I opened open the controller and inside luckily Sega clearly numbered the wires, which from left to right, read:

6 (blue) 9 (white) 8 (black) 4 (yellow) 3 (orange) 7 (grey) 5 (green) 2 (red) 1 (brown)

I'm not sure if the colour of the wires matters or not so I listed them as well.

Since the Genesis's wiring is set up as:

1  for Up           
2  for Down
3  for Ground & Left
4  for Ground & Right
6  for A & B
9  for Start & C

then what would inputs 7 and 8 be for?  Do the wires that go into the Genesis leads 3 4 6 and 9 carry two different inputs, making them useless without the Genesis's 74HC157 chip?  Does any of this even matter?

In other words, how do I know which inputs of the 9 Genesis controller wires corrispond with which inputs of the NES pad's now missing IC ports? Does this matter or does all that matters here is that there is a wire, regardless of what it did on the original Genesis controller, going into the NES's pin 1 and when I press the A button, the A button responds accordingly? If that's all that I need to know then I'm going to go ahead and preform the mod.

I want the NES controller to corrispond with this Genesis controller layout:

NES inputs = Genesis inputs
+pad = +pad
B = A
A = B
Start = Start
Select = C

[keiffer01]

Hey 133mhz, on what side chip I put the NES chip in the Famicom board? And do you have any tips to unsolder the chips out properly? And by the way, I have this NES clone which is broken, but both of the CPU and PPU chips are removable because they are only installed in sockets. Since I have another clone which is exactly the same and working, I switched the chips and found out they are working perfectly. So I'm wondering, could they be compatible with my Famicom? Maybe the data in them is completely different from the Famicom, making it incompatible, no?

[133MHz]

Hey 133mhz, on what side chip I put the NES chip in the Famicom board?

Check for a small dot on one of the corners of the chip. It indicates Pin 1.

Mark this corner on the board with a magic marker before removing the PPU, and when installing the new one check the orientation. DON'T PLUG THE PPU BACKWARDS! DOUBLE CHECK! TRIPLE CHECK! QUADRUPLE CHECK! I can't stress this enough . It's very easy to make a mistake like that, even if it doesn't seem like so.

And do you have any tips to unsolder the chips out properly?

Buy some desoldering braid. A small roll costs a buck and it will be more than enough for this purpose. Use a low wattage soldering iron (a high-wattage one could lift the traces off the board and ruin your Famicom!). Apply fresh solder to all of the PPU pins (that will loosen the decades-old machine solder), then apply the braid over one pin, put the soldering iron tip over the braid spot which covers the pin and it will absorb all the solder in the pin hole. Repeat the process for all the pins, then you can lift the PPU without problems . If one pin is stubborn, apply a little fresh solder and try again. It will come all out eventually.

And by the way, I have this NES clone which is broken, but both of the CPU and PPU chips are removable because they are only installed in sockets. Since I have another clone which is exactly the same and working, I switched the chips and found out they are working perfectly. So I'm wondering, could they be compatible with my Famicom? Maybe the data in them is completely different from the Famicom, making it incompatible, no?

If they're standalone chips there's a 99% probability they are pin-compatible with Nintendo's PPU (they may be identical copies). I recommend you buy and install a chip socket like the ones your Famiclones have and install it on your Famicom once you remove the PPU from it, that way you can test various PPUs without soldering and desoldering them which is a pain in the ass. That way you can plug one of your clone's PPU and if it works, leave it. If it doesn't, get a broken NES for cheap and steal its PPU .

Oh and BTW, chips like the CPU and PPU don't contain any 'data' in them, like memory chips (well if you get pedantic they do contain some data, but for practical purposes we're ignoring microcode and that stuff ), incompatibilities can arise if the pinouts between them are different, but if your Famiclones have separate CPU and PPU chips just like a real FC, I can say with 99% accuracy they're identical copies .

[satoshi_matrix]

Hey what about me?  lol sorry to be impatient I just want to get started on this as soon as I can.

You are the tech guru around here 133 I know its tough everyone relying on you!!

[Milky B]

hmmm, that's pretty interesting about the genesis controller.  I always use a genesis controller with my Atari 2600 but I never realized that sega went specifically out of their way to design it to be backwards compatible.  That's really weird.  I wonder why they did that.

[Arnold101]

The big one in the middle. It says 2C02. The CPU is 2A03.

Maybe you could get a broken NES for cheap (NES almost always fail because of its cart connector) and donate its PPU for your Famicom.

hi  today my famicom that worked perfect before, is dead  after searching the problem on av circuit, that was ok, i find that the cpu became very hot  (i remember here that another have this problem, what is the thread?)
now it don't read games and output gray screen like when no games in, and no sound.

i have put the 2 audio cables on cpu pin 1-2, with 10uf capacitor for each cable, negative pole on cpu side, positive on jack output. (on one of them i have soldered the capacitor leg directly on cpu pin, is correct? or maybe it has broken for this?

maybe is the tv? because i have connected audio cables first on tv  (switched on) and then connected to famicom, then switched on the famicom: gray screen-cpu hot

now i want find the cpu  (pal cpu is not good for famicom?)

[133MHz]

Wow sounds pretty bad. Check the resistance between the power pin(s) of the CPU and the ground one(s). Too low of a resistance (as in the tens of ohms) means the poor CPU is toast. Maybe you'll have to remove the CPU, turn on the Famicom and see if the voltage normalizes and no other components short/blow/etc.

Maybe the regulator shorted, applying the full ~13V to the system (seen it happen on an old amplifier system, the 7812 shorted applying around 24V to the mixer board for ages, until the thing was f*cked beyond repair). Check the 5V line. Too low of a voltage could be the shorted CPU overloading it (releasing massive amounts of power as heat). Remove the CPU and check the 5V again if this happens. If removing it makes the voltage shoot to oblivion, then the 7805 is shorted, and maybe other components have suffered. If it gets back to a stable 5V (+/- 10% is OK), there is hope in revival by replacing the CPU .

Could it be your stereo audio mod? I don't think so. But check your TV if you are in doubt. Maybe it's leaking current through the A/V connections (some TVs use a 'hot' chassis, where everything is connected to one side of the power line - like sticking your finger into a power plug! All connections to the outside world are isolated through capacitors, some of these can fail or another fault can make the TV leak current). Get one of those screwdrivers which light up when you insert them into a wall plug (used to find the 'live' wire on an electrical installation). Put the end into the AV connector shell on the TV, touch the back of it and with your other hand touch the floor (or do it barefoot). If it lights up, your TV is leaking current. Another not-so-accurate test is just touching the connector while barefoot or with one hand on the ground. If you feel 'teh tingles', you know what it is.

Sorry to hear about your Famicom. Fortunately a replacement CPU can be obtained from a NES !

[133MHz]

As you added '(pal cpu is not good for famicom?)'

A PAL CPU will not make a PAL Famicom, but it does run at a little different clock speed, so the games may run a little faster or slower, or the games will have the quirks they would have if played on a PAL machine. Do you live in a PAL territory?

[Arnold101]

yeah pal territory. what are the quirks?
so if clock is different i don't think is good for famicom. or not?

i've tried with the screwdriver on the tv audio connector, the external side, it don't fit inside it, and it light up.

i've tested on samsung lcd and no light.

if i find the cpu how i desolder it? i don't think i can do it