Newbie asking about circuit boards. (NES related)

[Chris2]

Hello all. I'm still very new to the MAME arcade scene. I decided, however, that before I would take on something like PC work that I wanted to try making an arcade controller for something simpler, like the NES. One problem, however, is that I, in my inexperience, can't tell the difference between the button's solder points and the ground solder points. Does anyone know which are which and where to solder the parts to?

Also, I remember reading that the NES actually uses an NO format, rather than the NC format. Can anyone confirm this and whether or not it has any effect?

Again, sorry If I'm asking some stupid or redundant questions. I'm still very new at this.

Thanks!

[SavannahLion]

Whuh??

OK, I think I know what you're getting at.

If you're hacking out a NES controller to make a arcade panel to attach to your NES, you can avoid the whole "what is ground" problem by just running wire pairs from each button to each pad. A little messier, but less of a hassle.

If you're jonesing to make things simpler in terms of wiring, the traces from IC to pad would be "hot" and the traces leading away from the pad to the wire would be common, or ground.

If you're using cherry switches, look carefully on the side, you should see that next to each metal tab is a C, NO and NC. Wire it up to the NO and C and leave NC alone.

The NES uses an inverted system where low or off denotes a button press. Don't think of that and just wire it up, you should be fine.

[ChadTower]

The NES doesn't do straight-thru wiring for its controllers. 

[SavannahLion]

The NES doesn't do straight-thru wiring for its controllers. 

Is he talking about straight-thru wiring? I was under the impression he was hacking an NES controller.

[ChadTower]

Possibly not, but given that he's mentioning MAME and NES in the same sentence, I figured it may be worth pointing out to him, just in case.  There are some NES specific issues here, as you know.

[Chris2]

Whoops. Sorry to make that unclear. I mean to figure out how one would wire a stick and some buttons to an NES PCB, much like an I-PAC would with a MAME setup. I know that the NES used an NO setup from what I've been reading about the controller, but I can't really tell the difference between the wiring for buttons and wires for common. Anyone got an idea on this?

[SavannahLion]

Whoops. Sorry to make that unclear. I mean to figure out how one would wire a stick and some buttons to an NES PCB, much like an I-PAC would with a MAME setup. I know that the NES used an NO setup from what I've been reading about the controller, but I can't really tell the difference between the wiring for buttons and wires for common. Anyone got an idea on this?

I'm still confused. You're saying you're going to wire some buttons and joystick to a PCB. Then you start talking about wires for buttons and wires for common. Do you mean the traces on the PCB? The only wires that I can recall on the controller are those leading to/from the console itself.

The schematic for the NES controller is really simple. There's a small chip with the numbers 4021 on it. Here's a schematic showing both the NES and SNES controller Be sure to make note of pin 15 which is A on the NES. The traces that lead away from the chip to the button pad is the anode or positive line. Then it would stand to reason the trace on the other side of the pad would be the cathode, or in this case, the common.

I seem to recall someone else on here tried to do the same thing as you by daisy chaining the buttons with a commone cathode and ran into some problems. I think he resolved it by giving each button a dedicated pair of wires back to their respective solder pad on the PCB.

[Chris2]

So, in other words, solder the NC connector on the cherry switch to the positive anode and the common connector on the cherry switch to the cathode that sits opposite of the positive anode?