Questions about hacking a cheap dreamcast joystick

[LsLSpamMatt]

Hiya,

A buddy and I have gotten to the control panel stage of my cabinet.  I've got the 4 player top cut out, base built, and yada yada.  What I'm wondering is if it would be possible to dual-wire my panel for dreamcast and pc support.  I have a cheap off-brand Dreamcast arcade stick.  I opened it up and was checking out the wiring, and the thought of running a second wire off each microswitch and splicing it in place of the crappy off-brand buttons came to mind.  I'll then just screw the encoder board from the joystick into my CP, and plug it into the Dreamcast. 

My question revolves around the wiring of the buttons.  The joysticks have actual microswitches that have a GND (COM) and a NC terminal.  They 4 switches are wired in common and run to the GND on the circuit board.  That's easy enough to transfer to my control.  The buttons however, do not have clearly marked GND and NC terminals.  They just have 2 plugs with a wire soldered to each, and run to the circuit board.  For example, the wires from the "A" button will go to a "A" plug on the mother board, and the second will go to an "A-A" plug.  I can't figure out how the buttons are grounded. 

I guess my big question is, "Do buttons need to be grounded?"
Will it cause problems if they're not?  Should I just hack away and see what happens? 

Anyone with any experience or suggestions, please throw them this way.

Thanks,

Matt

[Shape D.]

i've never tried hacking one of these but if your switches aren't connected to ground they wont work, they need a path for the current to flow, and the ground provides one of the paths for the current.

[seanp]

I'm wiring up my first cabinet right now... I'll be running a MAME PC and a Dreamcast.  I took apart two different controllers, and the easiest to hack is the Interact Quantum Fighter pad.  It's even got two extra buttons that act as digital buttons instead of the analog triggers.  I ordered two more off of Ebay for $10.

If you're going to use your existing control to hack, look at where the wires are soldered onto the gamepad.  On my pad, the ground circuit path is connected to all the buttons, while the "hot" wires would only run to one of the buttons. 

I'm only running a two player control panel, and decided to run the controls through a parallel switchbox to switch between the IPAC for the PC and the Sega controls for the dreamcast.  Check out the "consoles" section - lots of good info there. 

-Sean

[LsLSpamMatt]

Shape D:  thank you for answering the ground question.

SeanP:  My joystick works like yours in that it has 2 digital buttosn instead of the triggers.  I guess I'm going to attempt to hack it together.
My question to you is:  Are you going to have the Dreamcast and PC plugged in at the same time?  I'm not sure how to solve the problem of wiring it.
My thought is to just have 2 wires come off each NC terminal.  One to the IPAC, one to the hacked DC controller.
There's no way that could go wrong I hope.  haha!

[seanp]

I read some old posts talking about doing what you are talking about, but needing diodes, etc. to limit the electricity from going places you didn't want it to.  My electrical ability isn't that advanced - I can hook point A to point B, but I'm not designing circuits.  So I went with the parallel cables and a switch box.  It works great!

-Sean

[LsLSpamMatt]

Sean,

I think I will have to let the hackery begin.  We shall see.
Could you maybe go into more detail or suggest some links on that
Switch Box idea?

Thanks,

matt

[seanp]

OK, so I got a parallel switchbox, and two switchbox cables.  These are 25 pin male-male cables, so if you're going for a four player control panel you'd need two switchboxes and three cables, i think.

I cut the cable in half, stripped the ends of the 25 wires, and labeled them according to the pins on the cable 1-25.  I found out what wires went to what pins using my multimeter, but it may be standards based on wire color also.  One cable went to my controls on the control panel.  I wrote down what number went to which control - ie #1 - 1 player up, #2 - 1 player right, etc.  Ran this cable to the main input of the switchbox.  Then ran the two other cables from switch A to the IPAC, and from switch B to the dreamcast controls.  I matched up the numbered wires to the appropriate connections on the ipac and controller, and voila!  I can switch the control panel back and forth.  I used a manual switchbox because it's much cheaper than the auto-sensing kind...  If I was motivated I could get that switch externally mounted, but I'll have to open the cabinet to access the dreamcast anyway, so for right now I'm leaving it inside.

Another slightly related tip - I found out that the dreamcast supports VGA PC monitors by default - you just need a VGA cable (ebay again).  I've got mine being shipped right now, and when it gets here I'll experiment to make sure it works as expected.  If that works I'm going with a 21" VGA monitor in the cab...

-Sean

[LsLSpamMatt]

Ahhhhhh

That seems like one of the descriptions I need to be looking at whilst
I work on the project.
Right now it's really freaking me out.
I may go to radio shack and just ask them for parts

Thanks for the info

Matt