Modified Saturn stick, directions work but buttons don't. Why? HELP!

Well, today I’ve tried (yet again) to mod my Saturn stick to work with my supergun, this time with the correct pin-out. Well, I’ve obtained a partial success (or partial failure):

The 4 directions work OK, but none of the buttons work. The stick uses microswitches, and the buttons are regular pushers. Could that be the reason?

The stick is designed like this:
There’s one big PCB where all the buttons are. From the direction stick there are 5 wires attached to the PCB, one for each direction and the other is ground. Each button has one terminal that is ground and the other went to the chip (which I’ve totally isolated) but I’ve put a wire to each button that go to the female 15-pin plug in the correct pin. I soldered the ground wire that comes from the supergun to the spot where it was supposed to go in the stick, from there there are connections printed on the board that go to every button that needs it. The ground that went to the chip has been cut. With a multimeter I’ve checked every connection and all the ones that must have ground are truly connected, and so does each button with the correct pin.

I’ve entered the test controller MVS screen with the moded stick’s PCB visible in order to make some tests. I unsoldered the ground wire in order to make direct contact to the button spots. Well, each time the ground wire directly touched the some button’s terminal, the corresponding button was in fact pressed (that is a 1 appeared for that button on the screen). But if the contact is made through the PCB channels it doesn’t work at all.

It’s very strange the directions work and not the buttons. If there was a short somewhere nothing wouldn’t work. So I think the buttons must be dealt in some other way. Also, take care that if I try to use the Neo Geo CD pad in my sgun the directions (that are microswitches) work but the buttons (pushers) don’t, while my AES (all microswitches) stick works perfect. The modified PSX controller I got with my supergun works all OK although all are pushers. However whoever modified it only used the channels in the PCB of the controller for putting ground to the directions, but for the buttons he added a very thin wire that went to every button from the spot where the ground wire was connected to the PCB.

So does anybody know why oh why the buttons don’t work? Is truly needed to add ground that way? Why? I guess I should try to do like the PSX pad and directly connect each ground terminal from each button to the ground spot via a thin wire. Uf, that’s gonna require lots of soldering skills. But I won’t give up now that I’m so near.

According to <a href="http://www.gamesx.com/controldata/neocont.htm" target="_blank">http://www.gamesx.com/controldata/neocont.htm</a> , it mentions somthing about the NGCD pads problem been related to +5V / gnd . My sgun doesn't output +5V (unless I add a wire to a pin from the psu I guess). Could that be related to my problem?

Thanks a lot for all your <img src="graemlins/help.gif" border="0" alt="[Help]" /> .

[ May 07, 2002: Message edited by: Amano Jacu ]</p>

"According to <a href="http://www.gamesx.com/controldata/neocont.htm" target="_blank">http://www.gamesx.com/controldata/neocont.htm</a> , it mentions somthing about the NGCD pads problem been related to +5V / gnd . My sgun doesn't output +5V (unless I add a wire to a pin from the psu I guess). Could that be related to my problem?"

that may be possible....but uh... i'm not sure....

I've sent some mails to the makers of the pages where I found most info and got one reply:

"From a quick glance at your problem,
try feeding the +5V from your arcade
powersupply to the appropriate line
where the saturn stick expects a +5V.

I dunno if this will solve your problem,
but it seems like a good try.

Which stick is it you are trying to use,
a saturn virtua stick? It may be since
the stick has autofire functions, you need
to feed it the +5V or else the buttons wont work.
That's just my guess."

The stick is an "Ascii Saturn Stick" and it doesn't have any autofire function or anything special. However I kinda "destroyed" all the parts of the PCB that weren't needed for my circuit (including that chip), so I don't think that will solve my problem, as that 5V is likely to be totally cut right now. Oh well, I'll make some tests anyway.

[ May 07, 2002: Message edited by: Amano Jacu ]</p>

OK, here's another reply from <a href="http://www.students.uiuc.edu/~jplayer/Joysticks.html" target="_blank">http://www.students.uiuc.edu/~jplayer/Joysticks.html</a> (thanks James!)
"
It seems like your design should work from what you've described. You wanna make sure that the buttons only work as switches (and there's not some connection running off through the PCB connecting it to some IC), and it sounds like you've done that. Another thing you may wanna check is the current flow through the button switches. The impedance in your saturn stick's buttons may be higher than your typical Neo push buttons. So make sure that the current flow going through a pushed button is the same magnitude as the current through one of the directional switches that you have working already. I don't see any reason to add a +5V pin to your joystick line unless you are trying to power the IC's that are in your joystick. Just ground, the direction lines, and the button lines are all you should worry about. Other than that, I'm not sure if there's any other advice I can give you. Keep at it though, it sounds like you got the right idea.

The other point is that I'm pretty sure the GameSX page is wrong about the common for the NeoCD pad being +5V. When I tested it on a live system, I came to the conclusion that it used ground as the common. I even emailed GameSX about this and the guy told me he was going to fix the error on his page, but that was 2 years ago. There is at least one (maybe 2 if I remember correctly) of the pins in the Neo pin-out that are +5V which are only used in the NeoCD pad and the new style joystick. All I can say is try and check as much on your own before accepting what someone says on a web page as truth. Things get confused while putting together pages, and the user suffers sometimes.
"

Yes, definately that's my problem. I've made more tests and, as I said, if the ground wire directly touches any button terminal it is pressed, but there's no way to make it work if contact is made through the button mechanism. I've tried adding a thin wire for communicating gound as in that PSX pad and it also doesn't work. So it has something to do with "Another thing you may wanna check is the current flow through the button switches. The impedance in your saturn stick's buttons may be higher than your typical Neo push buttons. So make sure that the current flow going through a pushed button is the same magnitude as the current through one of the directional switches that you have working already." as James says.

OK, I hereby renounce to mod that Saturn stick, also it's been totally destroyed to be used with Saturn. Well, it costed me 12€ brand new and I don't play with my saturn anymore, so that's not a problem.

The good news are that I bought a DC original Arcade stick and it's all microswitches and it's extremely easy to be moded, and I managed to do so in around an hour. In fact I haven't even damaged it, so it would be quite easy to unsolder the 15-pin wire I've added and put again the DC cable for it to work (it can be plu/unplug easily in the PCB, no soldering needed). This stick works very well, the only problem is that it only has 6 buttons+Start and I would have needed 7 (3 standar JAMMA buttons, D Neo Geo extra button and 3 kick buttons). Oh well, nobody is perfect.

So that's all, thanks a lot for all your help.