Forcefield Post Adjustment - Big Guns

[Andy B]

Anyone with a Big Guns can tell me what the knack is to adjusting the Forcefield post so it stays down when it's supposed to please? Also give me an idea of when it's supposed to be up and when it's supposed to be down?
#I get that if you hit the top target when it is lit the post is supposed to pop up and guessing that it's supposed to pop up when you get "you're invincible".

The one on the machine I am working on is up all the time.

I can push it down so it catches at the start of a game (since as I have the glass off - I obviously can't do that once I put the glass back on!) but first time it pops up it stays up. Seems to pull down 3 times and then stay popped up - like it's not catching in the down position properly.

I have checked the plastic actuator and it appears to be in good nick. I've also replaced the old extension spring which was loose and saggy but if anything that seems to have made it worse as it pulls the actuator over to the left preventing it from catching in the down position all the time.

Also, any clues as to what lock I need for the backbox? It seems to have some kind of bespoke cam on it (I had to drill the old one out to get in to it)?

Thanks

Andy

 

[Jay Walker]

The Forcefield post uses what I believe is called the 'flatcam'. The solenoid linkage has a metal pin attached, which rides in the groove of the flatcam. There's a ledge in this groove, so that the pin can only move in one direction around the groove. From memory, the solenoid pulls the pin (and post) down, over the ledge, so it can't return the same way. Then the extension spring pulls the cam over, so that the pin comes to rest in the 'cup' placed at the bottom of the groove, holding the post down. Operating the solenoid again releases the pin from the cup, and the spring pulls the cam further over, so the pin returns around the other side of the groove, leaving the post raised.

That is from memory, though, but there should be a point where the pin clicks over the ledge as it moves. It may just as easily be at the top of the loop, to make the pin go round again the next time, rather than simply up and down the same side; in fact that's more likely. I've always thought it's a scaled-up variation of the wire attachment on the centre Diagnostic switch on the coin door, which latches Up/Down.

Work didn't have a Big Guns, due to its height, but going by that age of game I think it would be a normal 'Fort' brand lock, with as you mention a special cam used to operate the linkage.

 

[Andy B]

The Forcefield post uses what I believe is called the 'flatcam'. The solenoid linkage has a metal pin attached, which rides in the groove of the flatcam. There's a ledge in this groove, so that the pin can only move in one direction around the groove. From memory, the solenoid pulls the pin (and post) down, over the ledge, so it can't return the same way. Then the extension spring pulls the cam over, so that the pin comes to rest in the 'cup' placed at the bottom of the groove, holding the post down. Operating the solenoid again releases the pin from the cup, and the spring pulls the cam further over, so the pin returns around the other side of the groove, leaving the post raised.

That is from memory, though, but there should be a point where the pin clicks over the ledge as it moves. It may just as easily be at the top of the loop, to make the pin go round again the next time, rather than simply up and down the same side; in fact that's more likely. I've always thought it's a scaled-up variation of the wire attachment on the centre Diagnostic switch on the coin door, which latches Up/Down.

Work didn't have a Big Guns, due to its height, but going by that age of game I think it would be a normal 'Fort' brand lock, with as you mention a special cam used to operate the linkage.

Thanks for the comprehensive answer Jay. I see the ledge in the flat cam. I think the new spring I have put on is too powerful so it’s pulling it over to the left so the pin is always going down the left side and not down the right side, being pulled over to the left side and catching under the ledge. I’ll try a weaker spring. When the post is in the down position it triggers a switch so the post trying to pull down multiple times is clearly the cpu recognising that switch is not triggered, the post is not down so it’s triggering the solenoid to pull it down again (though why it only tries 3 times and doesn’t constantly keep trying I don’t know?).

 

[Fantazia2]

Have you got a picture of the Mech, sounds similar to the issue I had on a Mousin Around where the diverter gate on the top ramp would try to close on start up of the game and wouldnt latch so gave up after a few attempts.

That too had a latching mechanism where the solenoid fires to latch on and then again top latch off, ended up having to adjust the plunger length as it would never latch on and I think that was due to the plunger not firing far enough to reach the latch point.

I could manually latch it on and off by hand, which sounds like what you can do by manually pushing it down.

 

[Andy B]

 

[Andy B]

 

[Andy B]

 

[Andy B]

 

[Andy B]

You can’t really see it in last photo but there is what I would call a chevron shape cut in to that plastic piece and it looks like pin is supposed to be pulled down, plastic thing moves over, pin is cut in the centre of the chevron. It’s not catching.

However it is working fine when I am activating it with my hand.

 

[Fantazia2]

That looks almost exactly the same type of mech and same issue, pushing the plunger in by hand would latch it but fired electronically it wouldnt latch

I had to loosen the 2 thinner nuts and adjust the length by screwing in or out the threaded bar, cant remember which way I had to do it.

Heres the Mousin around mech for reference, slightly different as it uses a cam to move a diverter instead of the up/down motion on Big Guns.

 

[Andy B]

That looks almost exactly the same type of mech and same issue, pushing the plunger in by hand would latch it but fired electronically it wouldnt latch

I had to loosen the 2 thinner nuts and adjust the length by screwing in or out the threaded bar, cant remember which way I had to do it.

Heres the Mousin around mech for reference, slightly different as it uses a cam to move a diverter instead of the up/down motion on Big Guns.

Nice one. That’s exactly it albeit a different mech on the top end as you say.

Video doesn’t show him adjusting it just saying he cleaned it up but I think I can go off your description of how you adjusted yours and see if that works for me.

Cheers!

 

[Fantazia2]

Sorry, yes should have mentioned that wasnt a fix for it not latching correctly and just an example of the mech itself. I couldnt actually find anything about the issue back in 2016 when I searched for it.

 

[Jay Walker]

Fantazia's picture is similar to the latching in/out diverter on Police Force. It's also used for the opening 'Fault' on Earthshaker, and (I think) the lifting 'skateboard' diverter on Radical, apart from between-flipper posts, which began with Fire!

I'd suppose that the software makes three attempts to latch the post, and then packs it in to avoid overheating the solenoid. Could the solenoid bracket not seeming straight be affecting things? The adjustment for the length of the assembly would probably alter the height of the post, leaving it not flush with the playfield when lowered.

 

[kevlar]

I had to play around with the same mech on Bally Atlantis a few years ago, the results were very much dependent on the spring strength. I played around shortening and lengthening the spring until it finally started working reliably.

 

[Andy B]

Fantazia's picture is similar to the latching in/out diverter on Police Force. It's also used for the opening 'Fault' on Earthshaker, and (I think) the lifting 'skateboard' diverter on Radical, apart from between-flipper posts, which began with Fire!

I'd suppose that the software makes three attempts to latch the post, and then packs it in to avoid overheating the solenoid. Could the solenoid bracket not seeming straight be affecting things? The adjustment for the length of the assembly would probably alter the height of the post, leaving it not flush with the playfield when lowered.

I fettled with it a bit. I have no idea how but moving the top nut further away from the bottom nut, leaving a space in between seemed to do the trick! Probably a happy accident and the nuts will shake themselves loose at some point and I’ll need to fettle again but for the time being it seems to work as it should.

It pops up when you hit the Forcefield target when it is let. It also seems to pop up when a ball is launched out of a cannon also - which is a nice trick as it stops it draining if it comes down the wireframe to the flippers too fast - and then pops back down again after a short time.

Seems like quite an enjoyable game - particularly the bagatelle in the back glass but needs to be sold to top up the post holiday bank account deficit

Look out for it in For Sale thread soon.

 

[Mfresh]

i had the same problem with Mousin' Around but fixed it by messing about with the spring and also giving the cam a good clean.

Incidentally, if the cam wears out you can get a 3D printed version here:

Shapeways Marketplace Update - Shapeways Blog

We wish the circumstances were different, but unfortunately the marketplace won’t be available in the way it existed before July 2024. We understand this

www.shapeways.com

 

[Fantazia2]

Fantazia's picture is similar to the latching in/out diverter on Police Force. It's also used for the opening 'Fault' on Earthshaker, and (I think) the lifting 'skateboard' diverter on Radical, apart from between-flipper posts, which began with Fire!

I'd suppose that the software makes three attempts to latch the post, and then packs it in to avoid overheating the solenoid. Could the solenoid bracket not seeming straight be affecting things? The adjustment for the length of the assembly would probably alter the height of the post, leaving it not flush with the playfield when lowered.

My thought was that it was possibly the other way round. The post comes down and has a positive stop that prevents the plunger going all the way into the solenoid and hence not getting latched in place, where as screwing it out would allow more stroke on the plunger to be able to latch in place, and it would sit higher when up possibly.

 

[Fantazia2]

i had the same problem with Mousin' Around but fixed it by messing about with the spring and also giving the cam a good clean.

Incidentally, if the cam wears out you can get a 3D printed version here:

Shapeways Marketplace Update - Shapeways Blog

We wish the circumstances were different, but unfortunately the marketplace won’t be available in the way it existed before July 2024. We understand this

www.shapeways.com

That would be the one you bought from me.

 

[Mfresh]

That would be the one you bought from me.

Yes indeed. It’s a thing of beauty and I thank you for it every time I play it…
(Sorry for derailing the thread!)

 

[Andy B]

i had the same problem with Mousin' Around but fixed it by messing about with the spring and also giving the cam a good clean.

Incidentally, if the cam wears out you can get a 3D printed version here:

Shapeways Marketplace Update - Shapeways Blog

We wish the circumstances were different, but unfortunately the marketplace won’t be available in the way it existed before July 2024. We understand this

www.shapeways.com

Nice one.

 

[Jay Walker]

My thought was that it was possibly the other way round. The post comes down and has a positive stop that prevents the plunger going all the way into the solenoid and hence not getting latched in place, where as screwing it out would allow more stroke on the plunger to be able to latch in place, and it would sit higher when up possibly.

Yes, there'd be two considerations - the ability of the solenoid plunger and locating pin to reach the latching point (or in fact slightly beyond), but also the mechanical travel of the attachment (post, diverter, etc) itself. If that hit its lowest point before the solenoid reached far enough, it could fail to latch.

Kev, I couldn't recall if the post on Atlantis used the flatcam or the older solenoid and release latch type.

 

[kevlar]

Yes, there'd be two considerations - the ability of the solenoid plunger and locating pin to reach the latching point (or in fact slightly beyond), but also the mechanical travel of the attachment (post, diverter, etc) itself. If that hit its lowest point before the solenoid reached far enough, it could fail to latch.

Kev, I couldn't recall if the post on Atlantis used the flatcam or the older solenoid and release latch type.

It was the flat cam, only time I've come across one. Clever design when it works.

 

[Jay Walker]

Also, any clues as to what lock I need for the backbox? It seems to have some kind of bespoke cam on it (I had to drill the old one out to get in to it)?

Going by the manual, it's the same part No. as Black Knight 2000, '20-9549'. I do recall with that game that when our pair were let go, to Bob Thompson, he was irked that when taking out works' own locks I'd fitted them both with 'keyed alike'* left-over factory fitted front door locks (as I thought, 'Fort' brand, from a storage tub) for back-box locks.

* i.e. they had the same key; I'd found one lock without any keys in that tub which had the same key No. as another with two still attached.

The information given in the parts listing is 3/4" diameter, 27/32" length/depth. The tricky part would be the cam plate and linkage(s) attached to the lock.

 

[Andy B]

Going by the manual, it's the same part No. as Black Knight 2000, '20-9549'. I do recall with that game that when our pair were let go, to Bob Thompson, he was irked that when taking out works' own locks I'd fitted them both with 'keyed alike'* left-over factory fitted front door locks (as I thought, 'Fort' brand, from a storage tub) for back-box locks.

* i.e. they had the same key; I'd found one lock without any keys in that tub which had the same key No. as another with two still attached.

The information given in the parts listing is 3/4" diameter, 27/32" length/depth. The tricky part would be the cam plate and linkage(s) attached to the lock.

The linkage and cam are in the backbox so I’ll just buy one of those dimensions. Thanks.

 

[PinballDaze]

Replace the spring and Nyliner. The latter has giving my Atlantis reliability and that was over a year ago.

 

[Jay Walker]

A final point;

When folding down the machine, I'd recommend securing the display panel in place. Factory shipment included putting a hex-head screw into the backbox woodwork, to stop the U-bracket(s) on the rear of the display panel from slipping off the wooden blocks they're hooked over. There'll be a hole left, next to the r/h block. One of those Black Knight 2000s had enough movement in the display and backglass, even when locked, for the whole lot to move in transit (though it was actually a Renault van) and the display to come loose from the blocks. This left them precariously placed in a very wide V-shape, jamming the lock and awkward to juggle back into place. The larger size of the glass on Big Guns may make this worse.