question for pad hackers - modding types

[burgerkingdiamond]

this is a link to another forum where I posted a question relating to pad hacking (sort of)... I figured I'd repost here too to try and get a fast answer.

http://forum.arcadecontrols.com/index.p ... c=116269.0

thanks for looking

[matrigs]

instead of testing it witl a multimeter for resistance, apply some voltage to the pad and measure if anything goes through after pressing it.

[toodles]

There's no information about what the transplanted dpad is now connected to, so I dont know if there's much help we can give. If you see the resistances drop as you smoosh down on it, and raise as you let go, then that's it. If the other board doesn't recognize that, then the resistance when smooshed may not be low enough to drop the voltage low enough for the other pcb to see.
At best, use a potentiometer/rheostat in parallel with one of the directions and adjust until the sensitivity is how you like, then measure the resistance, and solder a resistor of that value in parallel for each direction.

If its for an NES pad MP3 player, do you know what value of pull up resistors are on the board? Can you tell us the unpressed resistance and pressed HARD resistance of the directions? With those numbers, a suitable parallel resistor can be calculated.

[burgerkingdiamond]

There's no information about what the transplanted dpad is now connected to, so I dont know if there's much help we can give. If you see the resistances drop as you smoosh down on it, and raise as you let go, then that's it. If the other board doesn't recognize that, then the resistance when smooshed may not be low enough to drop the voltage low enough for the other pcb to see.
At best, use a potentiometer/rheostat in parallel with one of the directions and adjust until the sensitivity is how you like, then measure the resistance, and solder a resistor of that value in parallel for each direction.

If its for an NES pad MP3 player, do you know what value of pull up resistors are on the board? Can you tell us the unpressed resistance and pressed HARD resistance of the directions? With those numbers, a suitable parallel resistor can be calculated.

I think that the problem is that I don't understand how these rubber things work. All I'm trying to accomplish is using the dpad contacts as extended switches from the buttons on the MP3 player. So press a direction on the dpad and skip a song on the MP3 player for example. I have my meter
set to test continuity with the lead connected to the end of each wire coming from a dpad direction. So the circuit is only open at the dpad. When I bridge those traces with the dpad membrane the circuit should be closed and I should get a reading on the meter (this was the idea anyway). If there is more to it, like a voltage that needs to be applied to the NES PCB then this isn't going to work for my purposes.

I know I would have this working now if I had just used mechanical switches, but I want that soft feel of a real NES controller.

[burgerkingdiamond]

found this on wikipedia, explains how these type of keyboards work.

http://en.wikipedia.org/wiki/Chiclet_keyboard

It seems like the only possible thing that could be keeping it from working is insufficient pressure, but I think I was pressing plenty hard when I was trying to test it.

[toodles]

If there is more to it, like a voltage that needs to be applied to the NES PCB then this isn't going to work for my purposes.

There is more to it, but its not anything complicated. Touching wires to wires, like tactile switches and microswitchs, is pretty much zero ohms resistance. Smooshing carbon like that dpad, has a resistance. Yes, the resistance gets lower the harder you smoosh. The MP3 player will see the button push when the resistance between the two spots is less than some value X ohms. The numbers I asked for were to try and determine what X is, and what value your Dpad is ending up with. If I know the value you need, and the value you're actually getting, it's easy to add one resistor to each direction to make it work.

But I cant be of any help without those numbers.
a) Resistance of direction when not pressed.
b) Resistance of direction when pressed hard.
c) Pullup resistor value on the MP3 player. This one can be hard to figure out. If you dont know it, use your meter to test these with the MP3 on and powered.
c1)the voltage between the two points
c2) and then measure the current between the two points

[burgerkingdiamond]

I may need to take a picture of the mp3 player to get help identifying the pull up resistors. Im not home now so cant do much.

Between which two points are you saying to check voltage and current?

Thanks for helping btw. And i happen to have couple of your cthulus in my cab. Excellent work.

[burgerkingdiamond]

Toodles

Thanks for the suggestions but I decided to just pull a MacGuyver because I don't want to solder any more resistors. It's going to be hard enough to get everything to fit as it is.

I ended up scraping off the black stuff and exposing the bare copper on the NES PCB. I cut out little circles of aluminum foil and superglued them to the black circles on the dpad rubber. It works perfect and still has the exact same feel.

[antron]

superglue? that might be corrosive over time. also, I'm surprised it even worked

next time use the glue that is used to connect the wires to the back window of your car for defrosting. you can get it at an auto store.

[toodles]

Between which two points are you saying to check voltage and current?

The two points going to a direction. It looks like you cut the traces connecting the common line on the pads and have each half, two wires per direction on the dpad, going to the mp3 player. Pick a direction, put the probes on the two wires for that direction and measure voltage and current there with the MP3 player on.