I was hoping someone could tell me what the problem might be with my pop bumpers. I have 4 bumpers on my Radical, one of them started poping constantly without anything toucing it. It just keeps kicking and racking up points, doesn't stop. Now, the next time I turned the machine on, none of the bumpers work. The lights work and they register points when a ball hits them, but they no longer pop or kick the ball. I checked all the fuses on the boards and they are ok.

Anyone know what the problem might be?

Take a look under the pf, look up the pop bumpers switches and see if they are ok (touching when you roll a ball on the skirts and not while no ball is touching them..).

The switches might need replacing or might be dirty.. just a little idea. Or the wire bringing power to the pops is unsoldered somewhere... just take a look and see if everythign looks normal (post pics maybe others would see something).

To me sounds like the leaf switch is stuck.

Ok the problem began with a machine-gun coil, this is usually a switch adjusted too close. So the action of the coil firing jiggles the switch and activates it again. Most likely blowing a fuse. You checked the fuses, but how? The proper method is to pull at least one end of the fuse (breaking the circuit) and test for continuity with a multimeter. A visual inspection or in-circuit measurement does not always reveal a blown fuse.

If you have a manual for this game (unfortunately this part of the IPDB manual download in PDF format is not readable), go to page 1-47 "Fuse locations", it should tell you exactly which fuse to look at. There are several fuses on the aux power board for solenoids. The pop bumpers are considered Special Solenoids. But after you replace the blown fuse, don't start a game until the problem is resolved.

Underneath the playfield, examine the pop bumpers and compare the one which was firing repeatedly with the others. Maybe something has fallen off or broken, applying pressure to the switch. They should all have a similar gap between switch contacts.

You can use the diagnostic mode of the game to test both the switches, and the coils. Go to pinrepair for an in-depth discussion of coil problems. Hopefully there are no blown transistors or anything like that.

These are Special Solenoids which means they can be fired independent of the CPU by the skirt's leaf switch.  I'm pretty certain on Williams 11C Pop Bumpers "machine gun" when the switch is stuck on (rather than adjusted too close), earlier versions would just lock on and burn out coil, fuse or worse transistor (and they might machine gun for bouncey switches, but this is more likely on a Sling Shot solenoid). Machine gunning likewise heats up coils until the coil, fuse or circuitry gives.

Things can fall in the hole and short the switch, or it can be old, bent with existing arcing and short. At the very least the switch will first have to be cleaned or replaced and adjusted.  

So as ethous pointed out, likely the pop bumper solenoid has stuck on, and hopefully burned out a fuse (as mentioned by tinyrodent). If the fuse isn't blown, then you should check the coil and its associated diode, then further upstream in the circuitry.

The pinrepair site (this section to begin with: http://www.pinrepair.com/sys11/index1.htm#intro )is helpful to troubleshooting fixing the associated potential problems, but don't attempt if you aren't comfortable with electronics, there is a good 50 volts going to those coils...

Hi Everyone....

Thanks for the suggestions. After futher inspection, I discovered that it was indeed a fuse that was bad. I checked under the playfield and everything looks ok, but I am a layperson not a pinball mechanic. After replacing the fuse and restarting the game all is well and the bumpers are working fine again.

Cheers!