Microswitch connections seem loose !Problem! Help - any fix?

[shaunti]

 
I have a finished cabinet and great control panel.

www.arcadiasystem.com/controllers.html

(My cab pictures and web site are coming soon.)

The problem is:

Even though I have soldered all of the push buttons and joysticks, some seem to have a jump in the connection.

I run notepad and witness stuttering keys. You would think that when the switch clicks the connection is fine,  but some buttons at various levels of pressure seem to have a loose looking connection.

For example:  
I can turn player one joystick left.  It makes a letter "g" in notepad (fine ... that's what it's assigned too).  But as I bring the joystick to center slowly I can see another letter "g" popup, sometimes a few more letters popup before the switch clicks back into NO (normally open) position??!!?!?!?!
 
I wouldn't care less but it's f*^%ing up my mame game session by freezing my direction.  Plus after careful inspection I have around ten or more faulty switches!

These are all new Happ buttons and cherry microswitches that aren't more than seven months old!

THIS IS FREAKING ME OUT>>>>>

OK.    Does anyone know what the hell is happening?  Is there any microswitch maintenance things I need to do or know about?

All I have noticed I that I can play with the common end with my finger as the switch is closed and see the letters stutter out  g..ggg.....g....g.g....g......g.g.g...g...
And it's not just one or two keys so it has something to do with the switch itself.  I've taken the switch apart and cannot find what the help the problem is.

I'm about ready to go completely with leaf switches if I could only find enough joysticks.
 

Thanks in advance for any help.

[electricd]

Dont switch to leaf switches just yet!  I had the same issues in notepad, but it worked fine in MAME.  Also, not sure if you are using an IPAC or not, but make SURE if you are that it isnt grounding itself out.  Mine was sitting directly on top of my metal case, and would go whacko whenever i hit one switch.  Check those two things, and I think you will be fine.  Good luck.

ED7

[gtjoe]

I use the happ horizontal pushbuttons and I have a lot of buttons that double punch like you are talking about.  

I ordered 12 extra cherry switches so I can switch out the ones the affect gameplay.  joystick switches and p1 buttons 123 are the most used, so if they act up I replace.  My coin buttons do this also but they don' t mess the game up so I don't bother fixing it.

I guess this may be a common problem  What are other seeing

[shaunti]

Thanks, but it was fine for a while.  Just lately some keys may stutter at various pressure points on the switches.

I'm rigged up to a Hagstrom LP24 in a 3X22 matrix with the key-repeat turned off.

[electricd]

I guess the question everyone is going to have for you is what method are you using to connect the buttons to the keyboard port on your computer?  Keyboard hack, IPAC, hagstrom encoder, etc?  The more info you can provide us about your setup, the easier it is for us to help.  It seriously sounds like you have a short...i can almost guarentee you it isnt your switches...those things either work or they dont.

ED7

[electricd]

Sorry shaunti...was writing my post as you were writing yours...thanks for the info.

[hyiu]

Errr..... I could be a complete idiot.... but... like...
would there be a chance you hooked up the NC instead of NO ??.... I know like coin door microswitches, they're like the opposite of the normal ones.... but they look alike....

I hooked up the wrong one (NC) with my coin door and its like acting strange... (not completely not working...) but strange... sometimes good.. sometimes bad...

[Chris]

If you hook up NC, the system will think you're holding the key all the time.  Activating the switch will make the system think you let go briefly and hit the key again.

Do you have a multimeter handy? If so, set it for continuity mode, hook it up to the switch, hold down the switch and see what you get.  My multimeter makes a tone in continuity mode; if yours does, and if the switch is bad, you'll hear stuttering in the tone.  (If you don't have a multimeter... well, get one!   There just too handy for projects like this; they can be found at Radio Shack, Sears and Home Depot.)  This will tell you if the problem is in the switch or somewhere farther down in the wiring or circuit.

When I bought my (used) buttons, three of them had bad microswitches...

--Chris

[AGarv]

Trust me fellas it has absolutely nothing to do with how he has them wired up; it is a problem with the switches.  I have the same problem with the microswitches on my happ supers. I've tested mine with a multimeter, and some switches are just plain flaky.  I'm actually going to switch to competitions so I don't have to buy the "levered" microswitches when this happens.

The problem is exactly what he described; at various levels of depressing the microswitch, the connection opens and closes sporadically, whereas it should remain closed the entire time.

Anyplace else we can buy microswitches besides happs?

[Chris]

Any good electronics house will have them.  Radio Shack does NOT have them.

Mouser has them at http://www.mouser.com/index.cfm?handler=fra_pdfset&dir=612&pdffile=621 , both with and without levers.

--Chris

[madk]

Windows->Control Panel->Keyboard->Repeat Rate

[shaunti]

Thanks all for the input .....At least I'm not going crazy.  This appears to be a common problem.

--------
Hey Chris,  have you tried the mouser switches, and if so, are they more reliable?

Are there any reliable switches found anywhere?

Would leaf switches eliminate this problem?

Thanks...

[Chris]

Mouser carries a number of different switches; the ones I pointed to are made by Mountain Switch.  No, I haven't tried them; all my switches are Cherrys.

Mouser carries lots of good stuff; I'd suggest going to their site and having their free catalog mailed to you.

--Chris

[liche]

What you are seeing here is something that is common with ALL mechanical switches.  Whether its a pushbutton, leaf switch, toggle switch, or whatever, what you are experiencing in technical terms is called SWITCH BOUNCE.

When you push your microswitch, there are two metal contacts which come together.  However, the time that it takes for these two contacts to make complete connection is NOT instaneous.  There is some mechanical bounce associated with the switch.  If you looked at any mechanical switch with an oscilloscope you'll see make "spikes" or bounces as you make close the contacts.

The only real solution to this is a "de-bounce" circuit.  There are two ways to accomplish this:  Software and Hardware

Your keyboard encoder's microprocessor or encoder chip should already have a built in circuit or algorithm to make the input from your switch "bounceless."  Basically it triggers off of and captures the first state-change transition, but will ignore any further bounce for some finite period of time (usually micro-seconds)
Sounds like though your encoder isn't doing this too well.

Another way to get around this is (which is daunting if you aren't familiar with electronics or digital logic) is to actually build your own debouncing circuit.

Basically your microswitch is wired into a flip-flop which is being clocked by an external clock source.  The output of this circuit will only send an output during a trigger from the external free-running clock source.  This thereby eliminates any erroneous "bounces" between clock transitiions.

If anyone is interested in this circuit, let me know.

[Chris]

There are actually chips with debounce circuits; you need a separate debouncer for each switch.  Reading his description of the problem, though, I dont think it's bounce he's describing....

--Chris

[liche]

Agreed.

[shaunti]

Ok.

Will these be any better
http://www.happcontrols.com/wp/item_search.html?item-no=95-4114-00

The gold microswitches are $3.00 each!  Ouch!

Does anyone know if they are worth it?