Should Congo allow stage flipping?

Mine doesn’t. Should it?

Additionally, are there any (other) 90s Bally/Williams games that don’t allow it? I’m told Demo Man doesn’t, due to the handles.

I’m not positive, but Congo might use them for the Gorilla flips.


Yeah the Congo I used to op didn’t stage flip and it’s probably for the Gorilla. For some reason I want to say it would stage flip in switch test but not during game play. Or maybe it was just obvious in switch test that the switches themselves were staging.

they use fliptronics. Can’t stage flip unless you are using actual mechanical cabinet flipper switches.

1 Like

There isn’t much of a sweet spot with Fliptronic games but stage flipping is definitely doable. The opto interrupter blade closest to the top of the cabinet will move outside the top opto before moving out of the opto beneath it.

It’s not an adjustment in this case. I can register the optos separately in test mode by staging, but during gameplay, both flippers on the left always trigger simultaneously.

Sorry if you thought I was pointing at your original post, I meant to reply to recordboy above me that stage flipping is possible with the opto triggered flippers in WPC games.

Does the top (lower flipper) opto always fire both flippers? That would be the way to find out for sure… I don’t remember, will WPC fire the solenoids in switch test if the interlock is disabled?

1 Like

Ah, that makes more sense. Okay, so generally stage flipping should be a thing on Fliptronics, both opto, and otherwise.

(Though I still do think there may be some exceptions.)

I don’t see why the gorilla would require the secondary optos. It’s no different from a lane change

Actually it’s extremely different. Lane changes occur on active edges only, whereas flippers and gorilla flips pay attention to how long the button is held, etc.

1 Like

Can you explain in more detail what you mean by this? A lot of beginners seem to think that the harder you press the button, the stronger the flip is, and I always tell them that it’s a binary on/off, so it doesn’t matter. But…maybe that’s not the case?

Also what do you mean by “active edges”?

For something like lane change, the only thing that matters is the transition of a flipper button being inactive to that button being active: that’s what Keefer is calling an “active edge”, where “edge” refers to the transition from “off” to “on”. (If you look at the button’s switch output on an oscilloscope, it looks like an abrupt vertical line, a hard edge.) In most (all?) cases, holding a flipper button doesn’t repeatedly lane change while you hold the button. The deactivation edge (releasing the button) does nothing for lane change. In short, when the button transitions from inactive to active, the code does one thing for lane change, and that’s the end of that story.

(Occasionally, a game might pay attention to the deactivation edge instead of the activation edge. For example, if you have an on-screen selection where the player uses the flipper buttons to move a cursor left and right and double-flip to select, the code will probably use the deactivation edge of the flipper buttons to move the cursor, because you don’t want a button press that was meant to be part of the double-flip to move the cursor unexpectedly.)

Working the flippers is a bit more complex. When you press a flipper button, the code energizes the corresponding flipper(s). When you release the flipper button, the code stops energizing the flipper(s). Depending on the game system, there may be an additional transition to a “hold” state (either by switching to a lower power hold coil, or by doing PWM on the primary flipper coil), based on how long the flipper button has been held, and/or a timeout, and/or in response to a flipper EOS switch.

So if you’re able to press and release a flipper button within a span of, say, 5 milliseconds (ms), you’ll get a 5 ms impulse on the flipper coil. This is probably a limited motion of the flipper bat; perhaps a nice skillful tap pass. Whereas if you press and release the flipper button over a span of 50 ms, you’ll probably get a full range of motion on the flipper bat, and under the covers the flipper coil has probably transitioned to “hold” mode, however that’s implemented on the game in question.

Compare all that to lane change: doesn’t matter if you press the button for 5 ms or 50 ms or 5000 ms, you get one lane change.

Of course you, like many here, have been under the hood of a pinball machine, so you know there’s no pressure/force sensor on the flipper buttons: they have a simple leaf switch or opto that generates a binary on/off signal to the game system. But timing certainly affects flipper performance, while having no effect on lane change.


Now high voltage switches are another story. How good the contact is impacts the resistance in the circuit and the power the flipper gets. How fast and / or hard you press the button can impact the strength the coil fires.

That’s not my point. I mean that the gorilla is software controlled. There’s no reason that the lower flipper optos can’t control the gorilla along with the flippers, in the same way that they control the lane change, ball search, etc. It’s all going through the MPU, whether there’s some extra logic to pay attention to the hold vs power windings, etc or not. I’m not super familiar with the workings of the gorilla mech, but from the manual it seems it’s just powered by two normal coils (not flipper coils), and not through the fliptronics board. I assume it just fires the left or right gorilla coil when it sees an active edge on that flipper, since WPC to my knowledge didn’t support PWM, or at least avoided it. Maybe if the ‘flip’ is shorter than the maximum pulse time it turns off the pulse? But still, no reason why it would need to monopolize the upper flipper opto inputs.

Nothing in the manual indicates the optos used for anything out of the ordinary. Seems to me, the flippers should stage. One way to check and see if the game is definitely using the lower left opto to fire both the lower and upper flippers would be to remove the interrupter and then interrupt them manually. Maybe stick a little piece of electrical tape in between the top opto and then manually activate the bottom one to see what happens.

Thought it was on tilt but it must have been on pinside since I’m seeing this. I had asked the same question several months ago and the programmer confirmed it’s not stage-able and that was by intent.


To answer Ryan first. Congo have both the left side button switches control both left flippers. Intentional, you say, but why?

On WPC, flippers, as well as pops, slings and kickback, are handled by the real-time system for short and uniform switch-to-action latency. What was known as special solenoids on System 11 (of course flippers were direct on there).

Everything else including flipper controlled mechs and lane change is handled by the game engine. Which is more slack and run by a more coarse clock.

Switch inputs are interpret individually. There are no exclusivity rules. Both systems have debounce implementation.

Though special solenoids are never run at the same time. Pulse plus a cool-off tail. I believe this is why it sometimes seems like pops go numb during multiball pop nest action. Ever notised this?

Game engine switch handlers may be configured active for rise-edge, fall-edge or both. And by the way, be careful with these terms. Are we talking physical state (closed/open) or logic state (active/passive).

1 Like