Not really sure about the wrappings other than coil identification??

This won't work. A heatpipe has water (albeit a very tiny quantity, but enough to move heat around through a structure effeciently), coil wires are solid. You can't conduct enough heat from the bundle of windings down a single strand to make any kind of noticeable difference in the winding core itself. Literally, you will be doing LESS cooling if you were to try this, as the conduction from direct contact (sans the insulation material they put on the wire itself) will be a million times better than down the structure you're proposing.

A fan is about as good as we're going to get without going into completely ridiculous and impractical territory.

Definitely won't work. As a simple example of why it won't work...think about this: Take a flipper coil and unwind about half of it. Let's say that's about 10 feet (just made that up). Then on the end 10 feet away, add some heat...the heat will never make it to the other end.

That was a VERY oversimplified example, and the coil itself is much more complex thermally. But that scenario above somewhat demonstrates what is going on (high 'thermal resistance'). The heat is trapped in the core of the solenoid. The varnish or enamel on the wire acts as a thermal resistance, windings not wound for the best thermals, round wire instead of square, and the wire itself being skinny all add up to a poor thermal path to get the heat out.

I always thought the wrapping was to help prevent other metal parts from shorting out on it if they touched. It's cramped in there.

That's the purpose of the enamel or varnish on the wire.

One possible (and very impractical) solution is to use a Sil-Pad or Poly Pad. These are sheets of thermally conductive material. Various thicknesses, from very thin to rather thick. I've used these in the past. You could wind a layer, lay in a strip of Poly Pad to the outside world. Repeat. Then attach to a heatsink to wick the heat out.

Would it work? Yeah, this probably could be pulled off with some effort. But you'd likely end up w/a $200 flipper coil!

I'm amazed that nobody is talking about the 'actual problem' here?

POOR engineering and ultimately VERY POOR DESIGN just to save a few bucks on a $10K machine.

That's poor form IMO.

Probably won't help. To me (and I haven't measured any coils), fan cooling probably just helps the upper layers of the coil. Sure, it will help some on the inner layers, but I suspect it's diminishing results.

Just as a FYI, here's a link to the Sil-Pads: https://www.farnell.com/datasheets/99609.pdf

You have to be careful with Sil-Pads, a person can actually go backwards if not implemented correctly.

Would a box fan or a general ventilation fan in the cabinet help?

I’m nowhere near the technological arena you guys are!(not sarcasm) I have had the idea of between 2-4 computer fans,1-2 on one side of the back blowing air into the machine 1-2 on the other blowing air out. A piece of balsa wood that runs down the middle of the machine controlling the intake and exhaust. You would have to put some filter floss in front of the intake to stop any dust or debris.
It would cool everything in the machine (as long as you don’t put it in front of a home heat register).

Nah, wouldn't make any difference.

I do want to add, I didn't design solenoids, but I did design coils (i.e. inductors, with cores and w/o) and high power RF transmitters. So I'm familiar with trying to keep things cool, or design it in such a way it doesn't get unreasonably hot in the first place.

Getting the heat out of a dense part like a coil can be a tough nut to crack, or at least do it so it's not overly expensive. If I'm not mistaken, Stern even pulses the coil at a high frequency to reduce the heating.

Water cooling comes to mind, but not sure if I want a fluid being pumped around my pin cabinet!

How about ditch this (obviously POOR) idea and go back to the tried and proven two windings idea that WMS perfected over many years and hundreds of thousands of machines.

I'm talking about pulsing a single winding which is the root cause of this problem and, basically, cannot be overcome as the basic idea is flawed from the start.

A pull winding does the heavy lifting and the hold winding is designed EXACTLY for this purpose.

This whole pulsed coil thing is for one reason only - more profit - but it results in electrical problems that we are all seeing and trying to resolve by adding patches (fans etc). This problem will NEVER be resolved while these manufacturers keep using a single winding coil.

You'll have to take that up with the pin manufacture's, not me.

Stern's have a EOS switch, you'd think someone could just rewire it w/a dual winding coil.

No....they're not. A heat pipe by definition is *not solid*....they've never been solid, you just thought they were.

https://en.wikipedia.org/wiki/Heat_pipe

No. The air volume inside the cabinet is several times that of a computer case, and computer case has far higher heat output than a few coils. Unlikely to gain any tangible benefit. I would've said in the past that the head was a good target to cool down the PCBs up there, but with the way modern machines are, and having switched to a metal head, they're basically giant heatsinks anyways.

Mineral Oil.

https://www.pugetsystems.com/submerged.php

How about thermoelectric cooler with a fan instead of just a fan, there's a palm sized one for cooling pc boards & chips. I dunno, put the big heat sink around the coil and somehow attach the cold side of the cooler to the heatsink so it can soak up the cold.

But I agree it's the single coil design. Only pin I ever had where the flippers would start weakening was LOTR and it really pissed me off. I think I put heatsinks on them but my memory fails me. My WPT didn't seem to weaken that I could notice though.

Reminds me of this:

pasted_image (resized).png

pasted_image (resized).png

LOL, I thought about that too! Attach using some Sil-Pad material. I think they take a fair amount of current (at least the ones I saw), plus you'd need a heatsink and fan to cool the hot side. Wonder if vibration might be an issue?

What am I missing here? Why do pinball machines now suddenly need cooling fans for flipper coils? Is this a design thing? What has changed with pinball machines from the past that did not require flipper coil cooling?

The one I googled is a self-contained unit with a fan that blows the hot air out the top. I think they are made for people to cool the back of their smartphones. The cold side is just a big metal plate so the issue would be sinking the plate to the coil, or to a heatsink on the coil. But no idea how much power one of these things would need in order to compare to a fan blowing on the coil, this size might be totally insufficient..

Agree

I installed coil fans on my lotr 15+ years ago when I couldn't destroy the ring after long sessions. Terry started selling stronger coils for lotr but the coil fans worked great to fix the problem. I've only had a few pins that really needed them and the only thing new is the 3d printed mounts and modders selling them.

The problem with peltiers is twofold....

1. Pretty power ineffecient
2. Condensation

Shouldn't be. Peltier is a solid state tech, but I suppose bonding between the layers might be susceptible to vibration? They've tried to use them for PC cooling multiple times, but there always seems to be a snag.

Link? I want to see this. If people are using peltiers to cool their phones....the battery life must be absolute ass...lol...

I am obviously not an engineer but will brainstorm with the crew a few ideas. Letters correspond to following image.
A: Does the plunger have to be made solid? It seems to me like if it were hollow it increase surface area and allow for air to come in. We only focus on cooling the outside of the coil.
B: What if we changed the material the coil sleeve was made out of and expanded it so that it acted as sort of a heat sink on its own?
C: We focus on cooling this, but what about giving the coil itself more space and airflow to dissipate heat? The paper wrapper is there to stop shorts, but does it have to be paper? What if a small heatsink was attached to this. Imagine the photo in reference 1 with a coil in the center, and the whole thing except the outside being made out of metal. This would give much more surface area for air flow and to dissipate heat. The scale is way off but you get the idea. Could something like this be 3-d printed out of plastic, have it still be effective, and just snap over a coil? If you could get something like this to rotate around a coil it would be nifty.
D: The coil stop has direct contact with the coil. Could this be turned into a heat sink? Would it be possible to make a hollow coil stop letting air flow through the middle?
E: Can we use the magnetic field that is driving the coils to spin a fan on its own without an external power source?
F: This mount is one of the few areas to come into contact with the coil… could a small heatsink be attached to this?
Just a few ideas I could never engineer that are fun to speculate about.

Flipper (resized).png

REF1 (resized).png

It is really sad consumers have to solve this. Making a pinball machine whose flippers performance degrades after 30 minutes is like making a car that doesn’t steer or brake as well after 30 min (granted the safety aspect isn’t comparable). It’s vital to the function of the machine and should just be unacceptable to customers. But I guess we keep buying them. Add this to the list of things the customer must do to make up for all the cut corners: replace the coil stops, replace the bottom-of-the-barrel speakers, replace the crappy balls that come with the machine, and now add coil coolers.

Don’t forget we have node boards close by too. Fans blowing metallic dust around circuit boards make me nervous.

Actually... there seems to be a product line specifically designed for cooling cylinders about the same size. DC remote control car fans.

There seem to be a large variety of plug and play kits on Amazon. I wonder if any of these would work?

https://www.amazon.com/dp/B093KMSYR1/ref=sspa_dk_detail_1
sink (resized).jpg

Snap on heat sinks. 2 for $15

https://www.amazon.com/dp/B01DIOV756/ref=sspa_dk_detail_3

sink2 (resized).jpg

A: Yes, if you want it to work. You could have a solid slug at the bottom that steps into a lesser diameter (classic stern had this). Hollow shaft wouldn't hold up I don't think, and the air inside would be not enough

B: They used to have aluminum sleeves, they really suck. Nylon all the way. Friction is too high on other types.

They don't need to fix the fan/cooling issue... they need to stop driving the flippers the way they are. Like others have said, this has already been solved. I'm kind of surprised as well that no one has just ripped out the system and kept the triggering so regular wpc style flippers can be used.

The old designs aren't perfect either, but you need a lot of playtime for them to fade. System 11 era games can get fade but the game has to go on for a long time (black knight 2000 for an hour or so....)

The fading occurs because the single winding coil has pretty thin wire. With increasing temperature, the wire resistance gets higher, thus decreasing the current through coil - and its strength.

"Old style" double winding coils have pull-in winding in heavy wire with less turns, so the increased temperature affects coil strength much less.

I see it somewhat amusing that flipper coils today need cooling, since for over 50 years nobody would even think about coil cooling.

I literally bought a neck cooler to put in my R&M. It works great and is less than $20. That above is just another version of the same thing we are already doing. The goal should be to get rid of the need for fans. Maybe just weld fins to the actual coil ends themselves.

A redesign is really what is in order...but I don't see it happening. The real solution would be to move away from coils completely. It's the like the combustion engine, decades have went by and you are telling me there is no better / more economic solution?

The better solution is to get back to the known good system of double winding coils.

This whole situation is all so ridiculous.

"Oooh yay! Single-wound coils! So much cheaper and simpler than double wound: Mech is the same but we get rid of extra coil wire, a terminal, a length of lead wire... sometimes an extra diode and/or an EOS switch... all that saves just a few bucks... what's not to like?"

"Um, it turns out they get hot and fade and decrease performance over time, making the game unplayable."

"Well forget about going back to dual wound, because that's stupid when you can just add some fans that draw more current and have a finite lifespan, more wires, cram in additional mechanical mounts and fasteners, and possibly other crap... all of which ultimately costs more, gets in the way, and won't always fit an otherwise universal mechanism... because clearly, single-wound is superior!"

I ran into the fading coil problem on my led zeppelin premium. Instead of fans, I replaced the coils with the PBLife upgraded LOTR coils. The coil wiring is noticeably thicker and heavier. I then lowered the flipper power way down to compensate for the more powerful coils. This seems to have fixed my issue. So, is it because of the thicker wire combined with less power = less heat therefore better even performance? I have played 40 min games without issue since. Id personally rather do this instead of fans. Nothing against the fan makers or doers.

Mike

Fans blow around the black dust that forms from all the moving parts. Might cause other problems blowing the dirt around and get on everything in the game eventually. Should just make a software mod, so the game stops for cooling breaks automatically when the flippers get too warm! GameBreak! Please wait for flipper coil cooling! Game will resume 30 minutes! LOL!

Yes it must be solid or you will have an incredibly weak flipper. You need that moving mass to produce enough force to launch a ball. Remember Force= Mass x Acceleration

B: What if we changed the material the coil sleeve was made out of and expanded it so that it acted as sort of a heat sink on its own?

The coil sleeve is there to reduce friction. Even if you used one of the old metal coil sleeves, there is no where to reject the waste heat to in that configuration. It will just heat up to the same temperature as the coil.

C: We focus on cooling this, but what about giving the coil itself more space and airflow to dissipate heat? The paper wrapper is there to stop shorts, but does it have to be paper? What if a small heatsink was attached to this. Imagine the photo in reference 1 with a coil in the center, and the whole thing except the outside being made out of metal. This would give much more surface area for air flow and to dissipate heat. The scale is way off but you get the idea. Could something like this be 3-d printed out of plastic, have it still be effective, and just snap over a coil? If you could get something like this to rotate around a coil it would be nifty.

If you move the coil outward from the playfield to gain more clearance, you will need longer flipper shafts. Adding heatsinks with fins increases the surface area and increases the effects of convention (both natural and forced). Being in a cabinet, there is very little air movement, so convection is mostly natural based on the buoyant force of hot air rising. Many plastics in general are poor thermal conductors and would not make good heat sinks.

D: The coil stop has direct contact with the coil. Could this be turned into a heat sink? Would it be possible to make a hollow coil stop letting air flow through the middle?

The coil stop is only in contact with the plastic end of the coil. The plastic is acting as an thermal insulator and would do a poor job conducting heat away from the windings.

E: Can we use the magnetic field that is driving the coils to spin a fan on its own without an external power source?

The duty cycle of the coils means that the fan in this configuration wouldn't run after the coil is deactivated, so it wouldn't be effective.

F: This mount is one of the few areas to come into contact with the coil… could a small heatsink be attached to this?
Just a few ideas I could never engineer that are fun to speculate about. [quoted image][quoted image]

The mount has minimal contact with the coil, so its ability to conduct heat would be minimal.

The thicker gauge wire reduces resistance. Less resistance=less heat

Yes that is exactly what I did and used. I had to remove the the diode for the newer stern. Seems to work great without fade.

It's getting hot in here.