Help with baby pacman problem

[2PacMan]

Was wondering if anyone could help me with this problem i'm having with my baby pacman.  When I first got it, the right flipper was weak and would get stuck, so i tried to sand out the inside of the coil with a dremel tool.  Well, it unstuck the flipper, but then the coil got really hot when i played.  So I ordered a new coil.  I got the new coil installed, the flipper works great, but the coil is still getting real hot.  I'm not sure what to do, is this normal?  All the other coils stay pretty cool, but they are still the original coils, so maybe the replacements just run hotter?  Also, when i push the flipper, and hold the button down, there is a buzzing sound coming from the flipper, it's only on the right problematic flipper, so i'm thinking maybe this has something to do with it.  The left flipper doesn't buzz at all.  My question is:  Is this something i should worry about?  THe game appears to play fine now, the coil is just generating alot of heat, but the heat is staying pretty local around the coil, like it isn't making the entire inside of the cabinet get hot.  Any suggestions/comments would be great, thanks!

[ChadTower]

Yes, it is a problem.  The problem isn't friction inside the coil, it is excessive current.

That sound is directly related to the problem.  First guess is the transistor that drives it.

[D_Zoot]

Sounds very much like you have an "end of stroke" switch  problem and the pull in coil is staying energized when the flipper is at full travel.  When this happens the coil gets hot and will melt the sleeve inside the coil causing the flipper plunger to drag or stick.

I've never had the good fortune to look under the hood of a baby pac, but I would assume that the flippers in that machine are the same as any Bally flipper of that era.  If so there are no transistors that control the flippers, it's all done with high current switches.  I'm guessing your EOS switch isn't opening.

Read here:
http://www.marvin3m.com/bally/index.htm

This will explain flipper operation and repair (if flipper repair isn't fully covered in the Bally guide, check out some of the other repair guides at that site, non-electronic flipper operation and repair is generally the same in other pins)

Regards,
D

[ChadTower]

He's right, I wasn't familiar enough with Baby Pac.  No flipper driver transistors.

You should find all the info you could possibly need here.

Without driver transistors to worry about, it's very likely your EOS switch as he says.  Double check to see if they are normally closed or normally open and then adjust accordingly.  Clean the contacts and if they are pitted (little holes), file it very gently so that they are flat and make good contact.  If either is burned, replace entirely.

[2PacMan]

Yes!  It looks like you 2 are right, the switch was bent very badly under the playfield.  The old coil I replaced did have the sleeve melted to the coil.  It looks to be a normally closed system, as when the flipper extends, the contacts come apart.  The contacts are pitted real bad, but i can't find any replacement normally closed switches.  This one looks weird, as it's got 5 blades on it.  It looks similar to this one: http://www.pinballlife.com/index.php?p=product&id=152&parent=102 although this one is a normally closed one, not the normally open one that pinball life sells.  The one in the baby pac has like 5 contacts on the opposite side too, where as the pinball life one only has 2.  Here's an under the playfield pic i found on the net.  As you can see, the right flipper switch is completely different than the left.  One of the little plastic spacers was missing on mine, thus, making the switch stay closed all the time.  I'm gluing a spacer on the switch now, in a few hours i'll try it and see if the heat dissapates.  here's the pic:

thanks so much for your help guys....i'll let you know if this works out, but i'm thinking this has to be it.

[ChadTower]

Email Terry at PinballLife.  He might have what you need and just doesn't have it listed.  I cannot stress enough how great Terry's service is.  Best arcade parts vendor I use.  Not even close.

The extra contacts are a switch stack and are usually independent of (just clamped in line with the screw) the actual EOS switch.  You can probably take the stack off the EOS switch and just replace the switch.  See if you can't repair the one in there, though, just for giggles.  Bend it back properly and file down that contact pad. 

You'll find in pinball you can often improvise repairs with stuff you have on hand.  I've made more than my share of McGuyver repairs in the past couple of years.

[RayB]

The 5-bladed switches are for pinball machines with multiple sets of flippers.

The first blade is just a protective arm. Then the set of 2 blades is to activate one flipper (the bottom one), then you keep pushing further on the button and it closes the second pair, which activates the "top" flipper.

[ChadTower]

Doesn't Baby Pac only have two flippers?

[2PacMan]

Thanks, yes this is a McGyver repair for sure, i'm using a thin piece of rubber tubing for my spacer, so hopefully it works.  I'm a little confused about how the EOS switch works.  I read up on it, but i'm still confused.

So in the normally closed system, the minute i push the button, high voltage goes to the coil, then as the flipper lifts up, once the contact is opened, the high voltage cuts out and the low voltage automatically kicks in?  Seems like there'd need to be another contact of some sort to start the low voltage.  And i'm guessing now, since when i push the button and the contact remains closed, the high voltage remains in the coil the whole time when i hold the flipper up and it melts the coil sleeve?  Is that how these work?

[2PacMan]

Yes, it only has 2 flippers, i don't know why there are so many switches on that one side.  There's another leaf contact at the top of the stack that appears to do nothing.  There isn't even a wire connected to the other end.  But on the game is says "push right flipper to put ball into play"  But from everyone i talked to, the ball is just automatically put into play, so i'm wondering if that top contact was originally for that and then they changed their mind?  I don't know.

[ChadTower]

The low voltage is always there.  It's just not enough to move the flipper on its own, only hold it.

If the switch doesn't open, the high voltage remains, and the solenoid gets hot enough to melt the insulation in its winding.  Then it melts the sleeve.  It's a cumulative process, sort of a downward spiral that gets a little worse every time.

Don't assume that it's the right switch.  Never assume a 20+ year old machine has original or correct or correctly installed or sane parts.  You have no idea who was in there or if they had any clue.

[2PacMan]

OK, i think i got it, so when you first begin the flipper push, both high and low voltage are present and push the flipper up, then, when the contact opens, the high voltage is cut off but the low voltage remains, thus holding the flipper up?

One more question too....so if the flipper works, but the contacts are pitted/burned.  Is that OK?  Should i only replace it if the flipper stops working?  The worst that can happen, if the contacts get fried, is that it'd only get low voltage to the flipper and not push it up, right?  So i can just watch for that?

[RayB]

Doesn't Baby Pac only have two flippers?

Yeah so? I was explaining why the switch he linked to existed.

For all we know, someone repaired this Baby Pac, and used whatever switch they had on hand as a replacement.

[ChadTower]

OK, i think i got it, so when you first begin the flipper push, both high and low voltage are present and push the flipper up, then, when the contact opens, the high voltage is cut off but the low voltage remains, thus holding the flipper up?

While not being absolutely specific to Baby Pac, since I'm not familiar with the machine and thus not 100% sure that's how Baby Pac is, that's about right.

One more question too....so if the flipper works, but the contacts are pitted/burned.  Is that OK?  Should i only replace it if the flipper stops working?  The worst that can happen, if the contacts get fried, is that it'd only get low voltage to the flipper and not push it up, right?  So i can just watch for that?

No, since that contact has to bear all of the current coming through the coil, it should be in decent condition.  If it's not, it has higher resistance, which means heat, which means it gets worse, and will fail itself.  At best it will cause a weakened flipper though Baby Pac is small enough that it may not matter.  It's a 1 minute fix to file the thing down a bit and get a cleaner pad.  You can do it with sandpaper if you have rough enough grit around or even a metal fingernail file.  Those switches are pretty much consumable parts by now.  A good shop job would replace them entirely but you can get away with just cleaning up the contact pads.

If there are no wires connected to the other switches then someone put in a different replacement switch at some point.  Or there is a loose wire or two hanging somewhere nearby that broke off its solder joint, which is less likely here.

[2PacMan]

The only thing that's throwing me is that the picture i provided above is from a baby pac that someone had on the internet and it also has that five bladed switch.  So the odds that his and mine would both have the same type of different leaf switch put in there seems low. 

I will certainly try to file the contacts down a bit just to be on the safe side.  I would definatly replace it if i could find a new leaf switch that matched this one.  4 of the 5 contacts have wires attatched to them, so if i put a different switch in there, i wouldn't know where to put the extra wires.  Hopefully some filing will do the trick.  The machine will get very minimal useage now that it's in my home, maybe one or two games every few days, so hopefully a little extra heat won't be a big deal.  Thanks again for all your help everybody.

[ChadTower]

Are you talking about 5 blades?  The contacts are just the little circles that are attached to the blades (or arms if you want).

If his has it too, you're right, maybe they just put that in there that way because they had a surplus of that part.  Or maybe it was a function that was removed at production time.  A search on rec.games.pinball will almost certainly turn up the reason.

[2PacMan]

Right, sorry, i didn't mean the wires were connected to the contacts, i meant they were connected to the other side of the leaf blades (not the side with contacts but the other side where the wires connect)  Didn't mean to make this more confusing....sorry.

[ChadTower]

Everyone has to learn the terms at some point.  What was throwing me off a bit was the idea of there being an odd number of contacts.

What causes those little pits in the contacts is arcing between contacts as they close or open.  It's actually pretty cool to watch if you are in a dark room with the playfield up.  It can be fixed by putting a capacitor in line but the arcing was accounted for in the design and is expected.

[2PacMan]

Yeah, there appears to be 2 sets of contacts, the normally closed one, which opens as the flipper raises, and then at the top of the switch stack, there's another contact that closes when the flipper raises completely up.  It's the top contact (the one that closes) that appears to do nothing, although i'm not positive.

[ChadTower]

If it helps you fill in the picture, the switch that puts the high voltage in the circuit is on the flipper button itself.  Then the solenoid's EOS switch takes it back out.

[D_Zoot]

The additional sets of contacts on the switch stack are to signal the cpu board when a flipper is flipped.  The cpu needs to know this for features such as lane change and so forth (features may or may not be present on this machine).   These additional contacts are not used in making the flipper operate.  Just make sure when you are all done that they open/close with flipper operation.

As mentioned above, the contacts for the flipper pull in coil (eos switch) are replaceable in the stack without replacing all of the contacts.  If you take the stack apart you would find that the EOS switch will separate from the stack.

You mention the switch is bent and the contacts are pitted.  You should replace it.  When the contacts become badly pitted the resistance of the contacts increases and reduces the available current to the coil, resulting in a weak flipper.  They can be filed to freshen them up, but for a long term repair replacment is the best option.  Besides, the switches are pretty cheap in the big scheme of things..


D

[ChadTower]

Lane change is a good example.  Not all machines of that era had lane change and many of them only had it on one of the two flipper buttons, which leads of course to having a stack on one flipper but not the other.

Now that I think about it, when multiple flippers are controlled from the same button, the switches for that are on the button, not the solenoid, so a second simultaneous flipper would never be the reason for there to be a stack on the solenoid.

[D_Zoot]

Now that I think about it, when multiple flippers are controlled from the same button, the switches for that are on the button, not the solenoid, so a second simultaneous flipper would never be the reason for there to be a stack on the solenoid.

Actually, sometimes they are.  Some pins with upper flippers are wired with a switch on a primary flipper so that the upper flipper doesn't flip until the lower reaches full travel.  I would assume that this was done to slightly stagger (not in a noticable way) pull in coil current draw and lower current surges.

If I recall, either my Meteor (Stern) or Space Invaders (Bally) is like that.

D

[D_Zoot]

2PacMan,

I neglected to mention this earlier,  but if there is a capacitor wired across the EOS switch make sure you replace that as well.  Due to the high current of the pull in circuit and the transients induced when the coil shuts off arcing can occur across the switch contacts and burn the contacts.  The cap (if present) helps reduce this arcing.

D

[2PacMan]

I don't notice any capacitors on the leaf switch, so i'm assuming they don't have any.

Thanks for all the info, i think i understand this much better now.  I have 2 other pins, but they have never caused me any problems, so i guess i haven't needed to really read up on all this until now, but now i think this extra knowledge will come in handy in the future for my other 2 pins as well.

[ChadTower]

Actually, sometimes they are.  Some pins with upper flippers are wired with a switch on a primary flipper so that the upper flipper doesn't flip until the lower reaches full travel.  I would assume that this was done to slightly stagger (not in a noticable way) pull in coil current draw and lower current surges.

If I recall, either my Meteor (Stern) or Space Invaders (Bally) is like that.

Odd.  That obviously removes the ability of the player to flip the upper or lower flippers independently.

2PacMan, the Ballys wouldn't have caps on the leafs.  You could add them if you wanted, probably, but replacing the switches is a better course of action.

[2PacMan]

Well, great news, the flipper is fixed!  The spacer is just what i needed to make the switch open up.  The coil stays nice and cool now.  Thanks for all your help everybody.

[ChadTower]

Awesome.  I'm envious, BabyPac is one of my top wants long term.

[2PacMan]

Yeah, it was on my want list for a long time as well.  Probably paid too much for this one, according to what people on here say, but local baby pac's don't come around very often, so i had to jump on it.