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(Topic ID: 273939)

Big Guns randomly scores 10 points at start of ball


By jscaptura

85 days ago



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  • 31 posts
  • 9 Pinsiders participating
  • Latest reply 2 days ago by jscaptura
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#1 85 days ago

Williams Big Guns - System 11B

Intermittently scores 10 points when the ball is fed into the shooter lane.

Have checked diodes on all the stand up targets as well as the switches in the shooter lane, ball trough, cannons, ball popper, and the king’s chamber.

No multiple switches in switch tests.

Slings switches have a good gap.

Knocking on the playfield with my fist doesn’t trigger any switches in switch test.

Not sure what else to check.

Always 10 points. Doesn’t happen every ball. Doesn’t seem to correlate to number of balls locked.

Scratching my head. Any ideas?

#2 85 days ago

You need to find out what switches score 10 points and go from there

#3 85 days ago
Quoted from Jmckune:

You need to find out what switches score 10 points and go from there

As best as I can tell, that would be the slings and the Forecfield Up target.

#4 84 days ago

Ok. I’m not sure what the force field up target looks like but check the gap on that. I had a similar issue on my BOP and it ended up being the sling at the top of the ball shooter lane. Was gapped enough that it wouldn’t jackhammer but not enough to stop it from firing at same time as ball eject and due to the noise from the eject couldn’t hear it firing

#5 84 days ago

Not on a big guns, but I had this happen on a game. My sling rubbers were too tight across the leaf switches. I just pulled some more slack across the playfield side of the sling and the switches were free to work properly.

#6 84 days ago
Quoted from Jmckune:

Ok. I’m not sure what the force field up target looks like but check the gap on that.

It's the green standup target way at the top of the playfield in front of the VUK. Being that far away from the trough I'd suspect the slingshot switches (see my next post) first but it's probably fair game still.

#7 84 days ago
Quoted from jscaptura:

Slings switches have a good gap.

This might sound stupid or redundant, but, did you check gap all the way through to the bottom AND the lugs where the wires attach under the playfield?

Having a good gap at the rubber is key, but I've had some switches with a close gap closer to the base on some of my EMs and caused score reels to lock on.

I just played around with my Big Guns too and found those are the only switches that give 10 points. There are some confirmation switches under the ramps and those don't seem to award anything.

#8 84 days ago

Agree, it’s usually slingshot switches but I wouldn’t rule out anything that scores 10 points until the problem goes away after adjustments! it is a good point to note though that every single game I’ve had and replaced rubber on upon getting the game, at least one of the slingshots have needed adjustment every time.

#9 84 days ago

I placed heat shrink tubing over a leaf in each sling switch on both slings, as well as the Forcefield Up target.

That didn’t stop the issue.

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#10 84 days ago

That's a really good idea!

#11 84 days ago

What do they look like underneath? Is a diode touching the two lugs in a way it shouldn’t be? Eg both lugs touching on one side of it?

#12 84 days ago

Edit: this info only applies to system 11 and 11A, and *not* to OP's game (11B)

I may be wrong here, but i think the 10 point switches for the slingshots are separate from the activation switches you cleverly insulated in those pics. The 10 point switch is actually triggered by the slingshot coil when it pulls in. Take a good look at the sling mechs under the playfield, if I'm right you'll see an additional switch buried near the slingshot assemblies, mounted to the bottom of the playfield. *That* is hopefully the switch that's likely gapped too close (or has the solder lugs mashed too close together etc)...

(Edited to take less space, add correction)

#13 84 days ago
Quoted from frunch:

I may be wrong here, but i think the 10 point switches for the slingshots are separate from the activation switches you cleverly insulated in those pics. The 10 point switch is actually triggered by the slingshot coil when it pulls in. Take a good look at the sling mechs under the playfield, if I'm right you'll see an additional switch buried near the slingshot assemblies, mounted to the bottom of the playfield. *That* is hopefully the switch that's likely gapped too close (or has the solder lugs mashed too close together etc)...
Again i *think* that's how these are designed...
Edit: got confirmation from Clay's guide--look for those sling switches under the playfield.
Quoting Clay's system 9-11 guide:
"On system9 and system11, there are six coils on the CPU board known as "special solenoids". Special solenoids work differently than the other CPU controlled coils. Special solenoids are used in pop bumpers and slingshot kickers, and since they must act quickly, the CPU does not control them. Closing of a special solenoid's playfield trigger switch enables solenoid power directly through TTL (Transistor to Transistor) chip logic and two transistor, without any processing by the CPU chip. A second switch matrix switch is closed when a special solenoid pulls in, which tells the CPU to score the solenoid points (CPU controlled solenoids do not need this second switch)."

I’m not finding a second switch for scoring. Additionally, I can manually move the kicker arm in switch test and no switch closure is recorded.

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#14 84 days ago

Darn, maybe that only applies to certain system 11 games.

Edit: upon further research, Big Guns is the first System 11B game which handles the coils differently from system 11 and 11A.

#15 84 days ago

not sure if this applies or not but I had a game that used to make an extra sound effect occasionally upon ball launch. Sometimes the ball would launch out and bounce slightly up the lane and then back onto the switch causing it to trigger twice. Not sure that this would score any points, but figured I'd throw it out there

#16 84 days ago
Quoted from yzfguy:

not sure if this applies or not but I had a game that used to make an extra sound effect occasionally upon ball launch. Sometimes the ball would launch out and bounce slightly up the lane and then back onto the switch causing it to trigger twice. Not sure that this would score any points, but figured I'd throw it out there

I had that thought, but I’m getting random 10 point awards when the ball is fed even with the shooter lane switch disconnected.

#17 84 days ago

I had a game that did that, and it was the coin switch was stuck closed

#18 84 days ago

Scratch that, think that was a different problem

#19 84 days ago

I would disconnect one sling completely. Both switches. See if it still happens. If it does, disconnect other side and see if it happens. If it doesnt you have found your issue.

#20 84 days ago

How often is this randomly happening?

It may not hurt to disconnect your switch matrix from the backbox and see what happens depending on what shape your CPU board is in. You wont be able to start a game but you could put it in test first and see if anything fires off in a 10 minute period or something like that. I know you said you had it in switch test awhile ago but not sure if it was long enough to flush out an issue.

I know this is a bit of a stretch, BUT, this is something you can do EASILY and CHEAP (free).

#21 84 days ago

I drew on your picture.

That hardware is aftermarket. Is that hardware conductive and could it be shorting your switch blades?

There is should be some insulation tubes inside of there normally but I wonder if they could be missing.

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#22 84 days ago
Quoted from dsuperbee:

I would disconnect one sling completely. Both switches. See if it still happens. If it does, disconnect other side and see if it happens. If it doesnt you have found your issue.

I actually disconnected both slings and the Forcefield Up target just to see if one had an intermittent short. It still racked up 10 points every few balls.

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#23 84 days ago
Quoted from EJS:

I drew on your picture.
That hardware is aftermarket. Is that hardware conductive and could it be shorting your switch blades?
There is should be some insulation tubes inside of there normally but I wonder if they could be missing.
[quoted image]

I had that thought, too, but the issue happens even with the switch disconnected.

#24 84 days ago

Wild guess, but is this a problem?

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#25 83 days ago
Quoted from jeffc:

Wild guess, but is this a problem?[quoted image]

I’ve got no continuity between the two brackets, but I moved them even more apart just in case.

I’m leaning towards an electrical issue instead of physical. I zip tied the ball feed so that it couldn’t move, any it still awarded 10 points when the coil powered. It with perfectly in sync with the coil hum. I also went through the switches and made sure none of the blades had continuity with the rivets holding them together. Some switches had screws holding them together, but there was still no continuity between the scores and any switch blades.

Now I’m wondering if there’s a bad ground somewhere that’s allowing the coil pulse to activate a switch input. That should be fun to troubleshoot and find.

#26 80 days ago

For giggles, I put my DMM across each suspected switch, and measure 120mv at idle, and 0mv when the switch is closed. When another switch in the column or row is activated, it drops to around 32mv. All that seems normal. Watching the meter when the random 10 points scores, there is no change from 120mv. I was expecting to see an upswing if a coil was backfeeding into the switch matrix, or a momentary dip if there were a switch shorting, but it stays solid. I think that would point to a board issue, wouldn’t you agree?
If so, I’m thinking it would be in the area of U30, U39 and maybe the PIA U38.
Am I barking up the wrong tree?

2 weeks later
#27 66 days ago

I’m still scratching my head on this one. I’ve pulled the mpu board and reflowed the pia chips. I’ve also pulled and reseated the roms. No change.

I then added a diode across each coil that fires when a new ball is stared in case it was current between the coil and the aux power board being induced into the switch circuit. That caused the issue to be less frequent, but it’s still happening on occasion.

2 months later
#28 3 days ago

Eureka! (No, not the vacuum). I finally found the issue. It turned out to be the right troll target. If the troll drop targets haven’t been hit, the stationary target scores 10 points. Turns out that the stationary target had an intermittent short. Banging on the playfield wouldn’t trigger it, but the drop targets resetting would. I repaired the stationary target and all is well now.

#29 2 days ago
Quoted from jscaptura:

Eureka! (No, not the vacuum). I finally found the issue. It turned out to be the right troll target. If the troll drop targets haven’t been hit, the stationary target scores 10 points. Turns out that the stationary target had an intermittent short. Banging on the playfield wouldn’t trigger it, but the drop targets resetting would. I repaired the stationary target and all is well now.

nice find. How did you go about finding that ?
Yoy had disconnected it at one point and it still did it ..?I would have thought disconnecting should have eliminated it from happening

#30 2 days ago

Nice work! Must be a relief to finally put that problem to rest.

#31 2 days ago
Quoted from topkat:

nice find. How did you go about finding that ?
Yoy had disconnected it at one point and it still did it ..?I would have thought disconnecting should have eliminated it from happening

I hadn’t disconnected that target before. I didn’t think it scored 10 points, because I only had tested it with the drop targets down. I ended up noticing that the 10 points only scored when the drop targets reset at the start of a ball, but not after a cannon had loaded. I kept going back to the Forcefield stationary target, as I knew that was a 10 point target. Only when I triggered the troll with a pencil without knocking down a guard did I realize that it also scored 10 points.

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