Leaf switch buttons

[MaximRecoil]

I've been using a machine with leaf switch buttons for a couple of weeks now and it seems like it will randomly fire off 1, 2 or even 3 shots for one press of the button. This is not a case of holding the button too long and triggering the game's autofire (which is a slow rate of fire compared to what I am talking about); this is a case of a single quick button press sometimes touching off 2 or 3 shots near simultaneously, faster than I could press and release the button 2 or 3 times. I put a microswitch button in place of the leaf switch button and of course, it is always one shot per button press, which is the way it is supposed to be.

Is this how leaf switch buttons always work or is there something wrong with the leaf switches? The switches are clean and they appear to be in good condition.

I've heard people claim that you can fire faster with leaf switches than with microswitch buttons. Is this what they are talking about? Accidentally firing faster?

[Texasmame]

You might want to get in there and widen the gap at the area the leafs make contact a bit.  Just gently move them apart a bit.  I was big at adjusting the fire button on Defender/Stargate so that not much pressure was required to fire off a shot.  The smaller the gap between the contact points, the "quicker" the button will be.  Sounds like your gap may be very small.

[MaximRecoil]

I found the problem. I looked closer at the switch where it makes contact and it was very worn at that point, both on the top leaf and the bottom leaf. Being the player 1 fire button, I suppose that isn't a surprise. I swapped the switch with the least worn one in the CP, which was the player 2 start button, which had no visible wear at all, and it works perfectly, 1 shot for each button press, every time.

I don't really know why that worn contact points would cause that issue, since it is still just metal touching metal to close a circuit, but it did. Maybe with the contact points being so worn, it allowed the leaves to contact each other in other areas past the intended contact points, resulting in multiple button presses being registered for a single physical button press. 

[RayB]

Initially it sounded to me like the button was "bouncing" and a small gap, like already mentioned, would cause several contacts to be made with one press.

[MaximRecoil]

Initially it sounded to me like the button was "bouncing" and a small gap, like already mentioned, would cause several contacts to be made with one press.

The worn switch actually had a slightly larger gap than the unworn switch I swapped with it, but about the same size gap as all the rest of the buttons' switches.

Maybe it was "bouncing"; I didn't even think of that. But if it was, it wasn't because the gap was too small. Maybe loss of tension in the leaves through excessive use over time could allow "bouncing" to happen?

[Kremmit]

Initially it sounded to me like the button was "bouncing" and a small gap, like already mentioned, would cause several contacts to be made with one press.

The worn switch actually had a slightly larger gap than the unworn switch I swapped with it, but about the same size gap as all the rest of the buttons' switches.

Maybe it was "bouncing"; I didn't even think of that. But if it was, it wasn't because the gap was too small. Maybe loss of tension in the leaves through excessive use over time could allow "bouncing" to happen?

Maybe the bad contact was only making intermittent contact while the switch was closed; in effect, closing and opening and closing again in very rapid succession as the bad contact failed to provide a steady electron path even when the leaves were held together.

Wow, that's a long sentence.

[MaximRecoil]

Maybe the bad contact was only making intermittent contact while the switch was closed; in effect, closing and opening and closing again in very rapid succession as the bad contact failed to provide a steady electron path even when the leaves were held together.

Wow, that's a long sentence.

I would say that you're right. I don't know why I didn't think of that. In fact, the night before I made this thread, that fire button stopped working briefly during the game. The next time I played it was working again, but of course, it was still doing multiple shots fired for one button press thing. I chalked it up to a fluke and didn't think of it again until now. So if the switch was worn enough that the button could be pressed and close the leaves but sometimes not close the circuit at all, then it follows that when the pressed button was closing the circuit that it was intermittent at best.

I was looking at it from the wrong angle, trying to figure out what could cause the leaves to physically make contact, lose contact, and make contact again so quickly; never considering that the actual circuit could be opening and closing with the leaves retaining physical contact all along, due to worn contact points.

[bvicarious]

I put a microswitch button in place of the leaf switch button and of course, it is always one shot per button press, which is the way it is supposed to be.

I've been having the same exact problem with my microswitches! A single press will register multiple times, usually 2 or 3. They are in brand new condition and have hardly been used, and I had the same problem with my joystick microswitches until I got fed up and went optical.

I thought leafswitches would be more reliable since they're just pieces of metal connecting, so I was going to get some from ponyboy (http://forum.arcadecontrols.com/index.php?topic=36770.0), are these the ones you're using? I'm wondering if oxidation played any role in the malfunction, would one of these things help? - http://www.radioshack.com/product/index.jsp?productId=2104394 

[MaximRecoil]

I've been having the same exact problem with my microswitches! A single press will register multiple times, usually 2 or 3. They are in brand new condition and have hardly been used, and I had the same problem with my joystick microswitches until I got fed up and went optical.

I don't know what would cause that issue with microswitches, though I suppose they could have the same intermittent connection problems as a worn leaf switch. Seems unlikely with new microswitches though...maybe the quick disconnect tabs needed to be cleaned?

I thought leafswitches would be more reliable since they're just pieces of metal connecting, so I was going to get some from ponyboy (http://forum.arcadecontrols.com/index.php?topic=36770.0), are these the ones you're using?

No, the leaf switches I am using came stock on Ikari Warriors, Victory Road and probably other SNK machines of the time as well. They are nothing fancy; the contact points are nothing more than dimples pressed into the ends of the leaves.
 

I'm wondering if oxidation played any role in the malfunction, would one of these things help? - http://www.radioshack.com/product/index.jsp?productId=2104394 

No doubt that dirty contact points could cause something like that. In my case, I'd cleaned all the contacts recently with isopropyl alcohol (91%) and they were plenty clean. All of the switches worked fine aside from that one. In this case I'd say that excessive wear of the contact points was the problem (the wear was very visible).

That pen should work fine if you have an oxidation problem, though you can accomplish the same thing with alcohol or a pencil eraser, or both.

[Izrun]

If you're having problems with microswitches, I'm guessing it is bouncing.  If you look at the picture below, that is a scope reading of a microswitch with a 5ms duration.  As you can see, it transitions from connected to disconnected many times before staying constant.  This is caused by the physics of any two surfaces.  If you zoom in really close to pretty much anything, the surface is not truly smooth.  The interaction of two non-smooth surfaces causes this phenomenom, called switch bouncing.  There are many methods to debounce a switch (both physically using caps or buffers) or in software.  What switch encoder are you using?  It might be a mixture of you having a bad (really rough) microswitch and you software having two small a buffer.

Hope this helps.

[bvicarious]

Yeah, I've been told it was probably bouncing. The problem has been present since day one, and I've used them with old ipac2, an optipac, and currently with a minipac. How do you go about debouncing switches through software? Is it something that can be done through the operating system, or is it done through the encoder firmware or something? I'll probably get the leaf switch brackets anyway to cut down on the clicking sounds, but I can still use the switches for something else.

edit: I forgot, my switches also fire intermittently if I hold the button down and ease up on it slightly, but far from enough for it to click. I suppose it's just losing the physical connection though, and I simply should not do that.