Cooling off flippers with a fan?

(Topic ID: 218501)

Cooling off flippers with a fan?


By KurtWehrli

8 months ago



Topic Stats

  • 71 posts
  • 32 Pinsiders participating
  • Latest reply 8 months ago by MrBally
  • Topic is favorited by 3 Pinsiders

You

Linked Games

No games have been linked to this topic.

    Topic Gallery

    There have been 8 images uploaded to this topic. (View topic image gallery).

    img_thermal_1528424915358 (resized).jpg
    jd_backbox (resized).jpg
    Screen Shot 2018-06-07 at 1.29.59 PM (resized).png
    image-33.jpg
    extruded-heat-sinks (resized).jpg
    pasted_image (resized).png
    9cb12a113d4380bedb38d5fb51e27342 (resized).jpg
    197a0e7b3bb11cc63d7a8583dee6714a1cbc1f68 (resized).jpg

    Topic index (key posts)

    2 key posts have been marked in this topic

    Post #41 Explanation of why the flippers heat up to being with. Posted by xTheBlackKnightx (8 months ago)

    Post #50 More technical points and analysis. Good discussion. Posted by mbwalker (8 months ago)


    Topic indices are generated from key posts and maintained by Pinside Editors. For more information, or to become an editor yourself read this post!

    There are 71 posts in this topic. You are on page 1 of 2.
    #1 8 months ago

    It seems to be a fact, that flippers are getting weaker while warming up, having less power after 10, 20 minutes of being played.

    Does anybody have experience with fans, cooling the flippers?

    #2 8 months ago

    i saw a black rose with a computer fan cooling off the boards, so it stayed working. i walked away as fast as i could. flipper fans? really? how about coil replacement

    #3 8 months ago

    coil replacement ... well, in the German pinball community www.flippermarkt.de, people report that stronger coils didn't help.

    #4 8 months ago

    Im guessing its a Stern. The only time ive ever seen that is on a LOTR and TSSP. If its a williams you more than likely have something else wrong.

    #5 8 months ago

    Indeed, personally I observe the phenomenon with my Avatar, but not at all with the Haunted House.

    Other European pinball owners complain about e.g. Pinball 2000 RFM, and yes, LOTR.

    But even Scared Stiff tends to become less powerfull.

    Anyway, it's hart to measure "feelings", although some people clearly state, that after longer, intensive playing, some ramps are much "harder to climb" than right after having turned on the cold pinball.

    #6 8 months ago

    Williams Hyperball had a fan on the ball shooting coil.

    #7 8 months ago

    I have mounted 2 computer fans in my LOTR, works perfect. 12V fans, mounted at the alu rails of the playfield, connected with the reserve power supply in the cabinet. Easy to install and reversable. There should be more threads in the forum already, search for it.

    #8 8 months ago

    IMHO, why add a fan at all? Fix the problem, a fan is a patch. These games are designed to run for years without them, and many exceed those expectations with the type of care we give them. Flipper coils should never get hot. They should survive plenty well even if they should get warm....but this is usually the sign of a lurking issue. Fans themselves draw in extra dirt and dust, they add noise, add current draw, and they'll need attention sooner or later. Even when I add supplemental power supplies, I avoid fans and go for open frame fanless supplies. The only game I know of that requires a fan is Pin2K, because the design uses an off the shelf computer system.

    #9 8 months ago
    Quoted from wayout440:

    IMHO, why add a fan at all? Fix the problem, a fan is a patch. These games are designed to run for years without them, and many exceed those expectations with the type of care we give them. Flipper coils should never get hot. They should survive plenty well even if they should get warm....but this is usually the sign of a lurking issue. Fans themselves draw in extra dirt and dust, they add noise, add current draw, and they'll need attention sooner or later. Even when I add supplemental power supplies, I avoid fans and go for open frame fanless supplies. The only game I know of that requires a fan is Pin2K, because the design uses an off the shelf computer system.

    Generally I agree with you. However, LOTR is famous for heated up coils and then they loose power dramatically. So before you do not make the ring ramp, add a fan. Additionally the fans Keep the coil temperature constant and you have no changes in the flipper strength. The fans are not noisy, you won't notice them at all. And I had no issue with them at all.

    But I am not fighting for the fans. Everybodies decision.

    #10 8 months ago
    Quoted from Zora:

    More
    Generally I agree with you. However, LOTR is famous for heated up coils and then they loose power dramatically. So before you do not make the ring ramp, add a fan. Additionally the fans Keep the coil temperature constant and you have no changes in the flipper strength. The fans are not noisy, you won't notice them at all. And I had no issue with them at all.
    But I am not fighting for the fans. Everybodies decision.

    They made updates coils for LOTR no? That would fix the issue and no fans needed.

    #11 8 months ago
    Quoted from Zora:

    More
    Generally I agree with you. However, LOTR is famous for heated up coils and then they loose power dramatically.

    The better fix is to work through the service bulletin #151 regarding this problem ( http://www.sternpinball.com/upload/downloads/sb151.pdf )

    #12 8 months ago

    Wow, so the older code doesn’t utilize the EOS switches to turn off the 50v to the coils?!? No wonder they overheat. Yes, fix the code instead of adding fans. No brainer. Add fans if you want, but get those EOS switches working correctly first

    #13 8 months ago
    Quoted from KurtWehrli:

    It seems to be a fact, that flippers are getting weaker while warming up, having less power after 10, 20 minutes of being played.
    Does anybody have experience with fans, cooling the flippers?

    Which game? If LOTR, order the APB Enterprises replacement coils. They are PERFECT

    #14 8 months ago
    Quoted from wayout440:

    These games are designed to run for years without them, and many exceed those expectations with the type of care we give them. Flipper coils should never get hot.

    Basically I think you are right.

    However, there is some material physics involved.

    Coil, plunger, sleeve (nylon, brass), spring may have different thermal expansion coefficients and friction coefficients.

    I wonder if pinball designers have really considered all interdependencies, including temperature, dust, humidity ....

    Dynamics seem to change during a pinball session, but this is obviously hard to quantify. Room for scientific analysis?

    #15 8 months ago
    Quoted from KurtWehrli:

    I wonder if pinball designers have really considered all interdependencies, including temperature, dust, humidity ....

    I’m sure the engineers have ignored this for the last 60 years...

    #16 8 months ago
    Quoted from KurtWehrli:

    Room for scientific analysis?

    It's been running for 32 years on the original flipper mechs.

    197a0e7b3bb11cc63d7a8583dee6714a1cbc1f68 (resized).jpg
    #17 8 months ago
    Quoted from Black_Knight:

    I’m sure the engineers have ignored this for the last 60 years...

    It's an amusement game. Built to sell at a profit. Engineer at quick reasonable speed to make it work, produce it and sell it - then on to engineer the next one. Nobody got time for super-analysis.

    9cb12a113d4380bedb38d5fb51e27342 (resized).jpg
    #18 8 months ago
    Quoted from wayout440:

    It's an amusement game. Built to sell at a profit. Engineer at quick reasonable speed to make it work, produce it and sell it - then on to engineer the next one. Nobody got time for super-analysis.

    You guys crack me up.

    #19 8 months ago
    Quoted from wayout440:

    Nobody got time for super-analysis.

    Fully agree ... and not for quality.

    Unfortunately nowadays a global megatrend: no time for quality products (unless manufactured by robots, which have been manufactured by robots and a few dedicated professionals).

    And sometimes not the seriousness to build quality into products.

    Time is money ... a modern, but misleading guideline.

    Sorry for this aside, just my senior opinion

    #20 8 months ago

    We still don’t know which game this is for. Or is this a general question ? If it’s a general question, there is NO reason a coil should be getting hot if properly maintained

    #21 8 months ago
    Quoted from Rdoyle1978:

    We still don’t know which game this is for.

    There are a couple of games mentioned, please see above.

    #22 8 months ago
    Quoted from KurtWehrli:

    There are a couple of games mentioned, please see above.

    Aha! Avatar

    #23 8 months ago

    Any game with single wound coils that 'hold' the flipper with a rapid pulse, rather than using a lower power 'hold' coil like WMS does will heat up if you hold the flippers a lot, won't it?

    #24 8 months ago
    Quoted from epthegeek:

    Any game with single wound coils that 'hold' the flipper with a rapid pulse, rather than using a lower power 'hold' coil like WMS does will heat up if you hold the flippers a lot, won't it?

    Seems like games with this setup are the only one I have seen coils heat up to the point is causes a flipper strength problem.

    My baywatch had an issue with coils heating up and causing them lose power. I put a couple of 12v fans taken from old computer boxes and have them blowing on the flipper coils. It really does help with the flipper power giving out after many games in a row.

    I found a cable with 120v on it in the cabinet. I think it was for a bill acceptor or whatever. I used that to connect to a 12v wall wart to power the fans only when the game is on.

    #25 8 months ago
    Quoted from barakandl:

    It really does help with the flipper power giving out after many games in a row.

    Clear statement, thanks a lot !

    Quoted from barakandl:

    I put a couple of 12v fans taken from old computer boxes and have them blowing on the flipper coils.

    "a couple of" ... what does it mean exactly (sorry, I have to translate this into Swiss German): more than one fan for each flipper coil? Or just one for each?

    #26 8 months ago

    “Couple of” generally means 2

    -8
    #27 8 months ago

    A flipper assembly cannot be effectively cooled by any type of fan. Keep assemblies clean, reduce slop, maintain the electronics, circuitry, and wiring properly. This includes areas such as excess solder. No shortcuts. Friction is the the number one generation source of excess heat and reduced power, not increases in coil resistance due to the heat itself. The other main reason is improper voltage, which if exceeded shortens a coil's lifecycle or causes burns or melting.

    Historically, the reason coil sleeves were switched from brass to plastic was due to cost, and ease of replacement. Engineers did consider the thermal properties of components, but also durability. I have games that continue to play wonderfully with 60 year components, that were kept serviced.

    Prior to code updates, I upgraded several Stern Whitestar games with WMS flipper components for better performance. The difference was significant. This was a problem with Stern, not historical pinball coil design.

    Do this if you must.

    10
    #28 8 months ago
    Quoted from xTheBlackKnightx:

    A flipper assembly cannot be effectively cooled by any type of fan. Keep assemblies clean, reduce slop, maintain the electronics, circuitry, and wiring properly. This includes areas such as excess solder. No shortcuts. Friction is the the number one generation source of excess heat and reduced power, not increases in coil resistance due to the heat itself. The other main reason is improper voltage, which if exceeded shortens a coil's lifecycle or causes burns or melting.
    Historically, the reason coil sleeves were switched from brass to plastic was due to cost, and ease of replacement. Engineers did consider the thermal properties of components, but also durability. I have games that continue to play wonderfully with 60 year components, that were kept serviced.
    Prior to code updates, I upgraded several Stern Whitestar games with WMS flipper components for better performance. The difference was significant. This was a problem with Stern, not historical pinball coil design.
    Do this if you must.

    pasted_image (resized).png

    So how does "improper voltage" happen in these DE/Sega/Whitestar games happen. Someone install too powerful of a bridge rectifier *sarcasm*

    I can assure you 100% the fan is effectively cooling them. I forget the exact numbers but the temp differences was measured and it was substantial. When I have league night at my place after hours of play baywatch flippers are still plenty strong enough to rocket the ball around the tall ramp. Before the fan flippers would be very mushy and weak after a heavy play and the ball would not have enough speed to make the watchtower ramp shot.

    Take a coil. Set a DMM to resistance and place across the lugs. Heat the coil up somehow and watch the resistance of the coil change.

    Its not friction heating up the coil its the single wound coil pulse duty cycle. When a coil locks on and burns it isnt the friction that does the burning. The issue with hot coils is strictly how data east pulses the coil for the hold circuit and the strength of coils installed into baywatch. If the duty cycle for the holding was less or DE implemented the dual wound coils like WMS it probably wouldnt be an issue.

    #29 8 months ago
    Quoted from barakandl:

    Its not friction heating up the coil its the single wound coil pulse duty cycle.

    Or any poorly adjusted EOS physical or logical switch too. I think the LOTR issue was solved by shortening the eos logic? (maybe)

    xBKx is right, cleaning and proper maintenance is the #1 solution, however, some coil designs are not condusive to flipper usage.

    12
    #30 8 months ago

    Personally I like to go liquid cooled. I take small tuperware containers and use L brackets to attach them to the underside of the PF cradling the coils. I've used water before but it's tough to lift the PF that way so you have to keep a small wet/dry vac handy to suck the water out first. I've been trying a lot of gels that are inside those cooling freezer bags for coolers and such? Not huge success but I'm getting close. I wish I was rich then i would just cut holes in the bottom of the cab and have tiny people stick their heads in and continually blow on the coils to keep them cool. Ha one time they got so hot i had to piss on them to cool them down. Sounds weird i know but it was a real "Red Dawn" moment believe me.

    #31 8 months ago

    My essentially new LOTR(150-200 plays) has this problem with the stock coils. Diminished power after say 15-20 min. It's not a simple flipper rebuild that's for sure. I might eventually try the APB coils, but for now I can hit any shot I need to, albeit it's a little tougher to hit the ring shot deep into a game.

    Interestingly my low plays TSPP, I have zero concerns with flipper power even after the longest games. They get a little softer, but no concerns making shots. Must just be the nature of the Ring shot on LOTR that magnifies it.

    I think a lot of games suffer from the coils heating up, but most of the time we just kinda forget about it and play on.

    #32 8 months ago
    Quoted from TheLaw:

    Personally I like to go liquid cooled. I take small tuperware containers and use L brackets to attach them to the underside of the PF cradling the coils. I've used water before but it's tough to lift the PF that way so you have to keep a small wet/dry vac handy to suck the water out first. I've been trying a lot of gels that are inside those cooling freezer bags for coolers and such? Not huge success but I'm getting close. I wish I was rich then i would just cut holes in the bottom of the cab and have tiny people stick their heads in and continually blow on the coils to keep them cool. Ha one time they got so hot i had to piss on them to cool them down. Sounds weird i know but it was a real "Red Dawn" moment believe me.

    hah... yeah yeah, i understand that point of view.

    Quoted from Black_Knight:

    Or any poorly adjusted EOS physical or logical switch too. I think the LOTR issue was solved by shortening the eos logic? (maybe)
    xBKx is right, cleaning and proper maintenance is the #1 solution, however, some coil designs are not conclusive to flipper usage.

    True a mechanically sound mech is #1 important to good flippers, but the coil warm up problem is a different thing. Looking at a baywatch book the hold circuit is actually voltage controlled not pwm like i though. There is 50v timed pulse circuit on the flipper board that would not be software controlled. Changing that pulse time would mean messing with the flipper board.

    Perhaps a different coil, like one with a fatter wire gauge wouldn't heat up as fast. Could get creative and drop the hold circuit voltage with a hack... or just point a PC case fans at each flipper coil and be done with it.

    #33 8 months ago
    Quoted from TheLaw:

    Personally I like to go liquid cooled. I take small tuperware containers and use L brackets to attach them to the underside of the PF cradling the coils. I've used water before but it's tough to lift the PF that way so you have to keep a small wet/dry vac handy to suck the water out first. I've been trying a lot of gels that are inside those cooling freezer bags for coolers and such? Not huge success but I'm getting close. I wish I was rich then i would just cut holes in the bottom of the cab and have tiny people stick their heads in and continually blow on the coils to keep them cool. Ha one time they got so hot i had to piss on them to cool them down. Sounds weird i know but it was a real "Red Dawn" moment believe me.

    Did you ever try replacing the coin door with a window unit air conditioner pointed inward?

    #34 8 months ago
    Quoted from TheLaw:

    Personally I like to go liquid cooled. I take small tuperware containers and use L brackets to attach them to the underside of the PF cradling the coils. I've used water before but it's tough to lift the PF that way so you have to keep a small wet/dry vac handy to suck the water out first. I've been trying a lot of gels that are inside those cooling freezer bags for coolers and such? Not huge success but I'm getting close. I wish I was rich then i would just cut holes in the bottom of the cab and have tiny people stick their heads in and continually blow on the coils to keep them cool. Ha one time they got so hot i had to piss on them to cool them down. Sounds weird i know but it was a real "Red Dawn" moment believe me.

    #35 8 months ago

    Maybe we can use the loud Spike fans that everyone is replacing.

    (fixed my spelling above, meant to say conducive, not conclusive)

    #36 8 months ago
    Quoted from pacmanretro:

    More
    Did you ever try replacing the coin door with a window unit air conditioner pointed inward?

    MIND BLOWN

    Aka patent pending

    #37 8 months ago
    Quoted from TheLaw:

    MIND BLOWN
    Aka patent pending

    Damn! I should have kept my mouth shut....800 dollar mod right there I just missed out on manufacturing

    #38 8 months ago

    DE games are known to have this issue. GNR in particular. Can be hard to get the ball up that G ramp when you've been pumping games through it all night!

    #39 8 months ago

    Flipper fatigue is a real issue even with perfectly maintained assemblies.

    I have seen it on games like Wizard of Oz and The Hobbit that have excessively long game times and continuous multi-ball modes.

    Game times often exceed one hour and 15 minutes.

    The Flipper coils get excessively hot almost too hot to touch or touch for very long.

    Deep into these games the flippers do lose a lot of power.

    I'm thinking of adding fans or heat sinks to the coils. Much like the heat sinks added to RC car motors.

    But even with a heatsink you would still have to add a fan to cool off the heat sink.

    #40 8 months ago
    Quoted from pacmanretro:

    Damn! I should have kept my mouth shut....800 dollar mod right there I just missed out on manufacturing

    I'll give you a free one of course.

    Minus shipping & handling.

    #41 8 months ago

    I will explain this as a basic physics principle without being overly technical.

    If voltage is increased in a coil, it allows the electrons to flow faster. This also increases the current sent more electrons per time unit through the wire. Both lead to more heat in the wire. This heat is energy that is lost for the magnetic field being built.

    To prevent the coil from producing too much thermal energy you must scale the wire diameter or to use parallel wires which in the case of wound pinball coil is not practical. The same consideration should be reflected when using motors, or generators, which essentially use wound coils as well either for power or electricity.

    Keep flipping.

    #42 8 months ago

    Maybe we can cover "Passive cooling" and "Active cooling" next

    #43 8 months ago
    Quoted from gtxjoe:

    Maybe we can cover "Passive cooling" and "Active cooling" next

    We make a fanless audio processing CPU engine that uses thermal transfer pads and heat sink chassis to eliminate the requirement for a fan.

    Perhaps a fanless coil heat sink could be the part of a new passive solution?

    extruded-heat-sinks (resized).jpg
    #44 8 months ago
    Quoted from xTheBlackKnightx:

    Friction is the the number one generation source of excess heat and reduced power, not increases in coil resistance due to the heat itself. The other main reason is improper voltage, which if exceeded shortens a coil's lifecycle or causes burns or melting.

    The heat is a result of the magnetic field. The energy has to go somewhere. 60volts through a low resistance becomes a lot of energy. That is why the Williams/Bally/Gottleib/early Data East design is a much better design. Increase the resistance with an end of stroke switch, decreases the current and lowers the energy that needs to be dissipated.

    Friction is negligible. Why does a locked on coil that was designed for intermittent use (such as a flipper) burn up? Not due to friction....nothing is moving. It is due to the energy of the magnetic field being converted to heat, eventually melting the lacquer of insulating the winding and shorting out the coil. It also does other bad things like the thermal expansion of the wire decreases the diameter of the coil and locking the sleeve in the coil.

    #45 8 months ago

    Could someone please post a pic of the shooter coil fan on Hyperball and Rapid Fire please?

    They were not toy PC type cooling fans. Rapid Fire's was a high speed squirrel cage fan that was quite loud. I sold my Rapid Fire over ten years ago. I haven't looked in a Hyper Ball in aboot 35 years. That one was loud as well.

    #46 8 months ago
    Quoted from MrBally:

    Could someone please post a pic of the shooter coil fan on Hyperball and Rapid Fire please?
    They were not toy PC type cooling fans. Rapid Fire's was a high speed squirrel cage fan that was quite loud. I sold my Rapid Fire over ten years ago. I haven't looked in a Hyper Ball in aboot 35 years. That one was loud as well.

    From IPDB image-33.jpg

    #47 8 months ago

    It is estimated that a clean coil sleeve and polished plunger, and rebuilt parts can increase coil power by an average 25-40% dependent on manufacturer and era. Measured by a force gauge meter after restorations.

    I am not here to teach people physics, they have do that on their own. The fundamentals and properties of electromechanical parts have been known for centuries. I already explain heat conversion in coils which also is based on generated resistance of the wire gauge, not exclusive to the electromagnetic field itself, or friction from unoptimal parts condition.

    I try to open people's eyes to other major causes of weak flippers not just residual coil heat from electromagnetism. I understand the principle of entropy and the law of conservation of energy.

    What people might not know is why pinball machines use "coils" versus other methods of activation. The answer is simply they remain the most efficient method both in speed and electrical energy usage for conversion to mechanical work, except in circumstances where more torque is required, or controlled speed applications.
    Dual wound coils were invented to solve some of these heat problems, but Stern decided to cheap out. An owner can actually retrofit these games, but it is beyond the scope of this thread.

    If someone wants to make a new type of improved flipper assembly or even a better electrmagnetic coil (with baffling or fins), I welcome the innovation. Unfortunately, a patent has already been granted (for magnet coils, not wire coils but the principle is the same in application).

    https://patents.google.com/patent/US20120023969

    So, why is it not already included on games by manufacturers?
    Extra cost for minimal benefit.
    The engineers already know.

    #48 8 months ago

    I have fans on LOTR, WOZ, Metallica, AFM, Tron and the lower right flipper on TSPP. All of these games experience slightly weaker flippers over long games... convection simply isn't enough to draw sufficient heat off the coils during long, intense games. I want these games to play as snappy on the 10000th flip as they do the 1st, and fans help greatly towards that goal. The flippers could still make all shots without the fans, but this helps keep action consistent throughout the game (and day).

    Also check to be sure the plunger is not angled at all as it goes into the plunger - the clamp on the flipper bat must be properly aligned vertically so there is minimal friction as the plunger is drawn into the coil.

    #49 8 months ago
    Quoted from xTheBlackKnightx:

    It is estimated that a clean coil sleeve and polished plunger, and rebuilt parts can increase coil power by an average 25-40% dependent on manufacturer and era. Measured by a force gauge meter after restorations.
    I am not here to teach people physics, they have do that on their own. The fundamentals and properties of electromechanical parts have been known for centuries. I already explain heat conversion in coils which also is based on generated resistance of the wire gauge, not exclusive to the electromagnetic field itself, or friction from unoptimal parts condition.
    I try to open people's eyes to other major causes of weak flippers not just residual coil heat from electromagnetism. I understand the principle of entropy and the law of conservation of energy.
    What people might not know is why pinball machines use "coils" versus other methods of activation. The answer is simply they remain the most efficient method both in speed and electrical energy usage for conversion to mechanical work, except in circumstances where more torque is required, or controlled speed applications.
    Dual wound coils were invented to solve some of these heat problems, but Stern decided to cheap out. An owner can actually retrofit these games, but it is beyond the scope of this thread.
    If someone wants to make a new type of improved flipper assembly or even a better electrmagnetic coil (with baffling or fins), I welcome the innovation. Unfortunately, a patent has already been granted (for magnet coils, not wire coils but the principle is the same in application).
    https://patents.google.com/patent/US20120023969
    So, why is it not already included on games by manufacturers?
    Extra cost for minimal benefit.
    The engineers already know.

    The heart of this thread is lost to you. You are just spouting off technical crap.

    Yes binding causing excessive friction in a coil mech will make problems. This thread is about single wound flipper coils heating up with extended use which causes flip strength problems and the solutions like using a fan to cool them.

    #50 8 months ago

    Hi Guys,

    This topic really caught my attention because I deal with this daily and thought it was very interesting. Can it be true? Let's take a closer look. Apologies for a slightly long winded thread.

    First off: I'm not a thermal engineer, but rather a EE. But I design with it in mind. Thermal engineers don't tell me what to do, but rather did I do it right? I need to get the heat out of a part to the thermal guys so they can deal with it. No means an expert, far from it. But I design with an understanding of it and maybe I can clarify some of the comments here at the '70,000 ft level'. Not entirely from a flipper/solenoid standpoint, but a thermal issue in general - but it does apply to solenoids (and even transistors and heatsinks) so I will try to focus on solenoids and I hope you find it interesting. The 'things' I design can dissipate upwards of of ~700W in the space of a thumbnail. Ouch! Getting the heat out HAS to happen...no "if, and, or buts" about it or it's a 'bad design day' with big ramifications.

    So here it goes...

    1st important topic: Kurt and others mentioned thermal expansion, which is a real issue. But we will assume that is not an issue here (or could be easily determined) - but I surely won't discount his (and others) comment because it is valid concern, just maybe not here. Let's assume everything remains friction free.

    2nd important topic: Thermal resistance. This is a key aspect and directly relates to the coil temperature (but it gets more complicated in a bit!). This is measured (in my case) C/W (celsius/ per watt) into an ambient thermal sink. In other words, if the thermal resistance of a device (i.e a solenoid) is 10C/watt...for every watt dissipated in a device, the device temperature rises 10 deg celsius. NO clue what a coil dissipates, NOR the C/W, but C/W is the standard by what we go by. Let's say for argument's sake a coil really is 10C/W (into a heatsink). Also let's say it dissipates 5W, that would equate to a 50 C rise in coil temperature...but where does it go? Another heatsink (great)? Or just air (bad)? That is an important question. Everything has a thermal resistance. Let's say there was a heatsink to cool a flipper coil - that connection between the heatsink and flipper also has a C/W number assigned to it and it's not perfect - it can't dump all 100% of the heat. Of course, we all know there's no heatsink to the outside world in a flipper coil - it's all sort of stuck there all by itself w/heat going nowhere, which means the C/W is actually higher since most manufacturers quote C/W into a heatsink. At least the parts I deal with do, don't know about solenoids. Sure, there's metal around it with the brackets, plunger in the middle, etc...but no direct thermal path (i.e. low C/W path) between it and something else...so honestly - I'd write all that off as thermally not connected and it falls out of our equation entirely. So whatever the C/W is in air..that's what it is. A coil is a nice little heat source with no where to go, and therefore, it gets hot! Some manufactures only quote the C/W into an ideal (translate: doesn't exist) heatsink.

    3rd important topic: The C/W I mentioned above...guess what? It's not uniform. It varies in the depth of coil windings (yeah, now it is getting a little more complicated, but hold on it gets worse). At least the windings near the outside have air it can dissipate into. But air thermally sucks compared to metal, plus there's no air FLOW across. So almost nearly terrible as nothing, but at least there is stagnant air, for what it's barely worth (ugh!). What about the windings inside the coil? There is zero air movement there and basically zero thermal path. The insulation on the winding has a C/W that basically acts like thermal insulator. The nylon sleeve..great thermal insulator too. The plastic form? Forget it thermally - useless. The bottom line..it can get hot and the only way to tell what's going on in there is to insert a thermal probe in the coil itself and measure (which would make a great white paper). If people mention the outside of the coil is toasty, the inside will be REALLY toasty. Thermal resistance of the wire itself (i.e. heat in one end, heat out the other end) is so high it doesn't count unless maybe the wire is ~0.5 inch long - doesn't apply here. Bottom line- the coil is really sitting there all by itself thermally with no place for the heat to go. Wait...we're not done...it's get's slightly more complicated.

    4th important topic: So what about the wire? Nerd alert. Copper wire has a thermal coefficient of resistance of +0.00393 per C based on 25C (room temperature). Simply put, as the coil increases temperature (remember it can really heat up on the inside of the coil?), the resistance will increase, current therefore will decrease (more on that later). Spoiler alert: Generically speaking...YES, the coil will become less 'powerful' as it heats up since it is drawing less current. Therefore, it will actually will cool down slightly due to self-regulating w/respect to temperature, which means it will then get hot again since the resistance lowers, which means it will cool down again, which means... Wait, what did I just say? Now even I'm getting getting confused myself! OK, nitpicking there with minor details.

    5th important topic: "So my coil draws less current when hot and becomes wimpy, HA! I knew it!" Maybe...the other piece of the puzzle is what about the transistor or FET that drives the coil? It is essential acts as a very small resistor when on. When you draw less current, it drops less voltage and the coil gets a little more voltage which which inherently helps the coil gain just a bit back in current. Not much, but it does happen with a cheap transistor (that's why some transistors have a heatsink). But it can't be ignored. BTW, in this case, the 'on' resistance can be referred to as the 'source impedance'. The rail voltage also has a source impedance, but should be fairly low. There's also some thermal aspects of the driver transistor/FET which I won't cover which can impact the the 'on' resistance on the transistor.

    6th important topic: Let's not forget, exactly "How hot is the wire getting and how does it impact resistance?" 1%? 10%? 20%? Real temperatures are needed, not "it's hot" because it doesn't hold its weight (not picking on anyone ). But it is very important to this discussion.

    So let's wrap this up: Theoretically, YES a fan can help. The thermal resistance of everything in the coil/bracket/etc. still royally sucks - but on paper, a fan blowing air on the coil will make a difference, the solenoid will be cooler. I hear the grumbles already - "you're full of BS". I'd be the first one to say 'won't help much', but at the same time it DOES help. If it's enough, then 'good for you'. It sure doesn't make it worse. In this case, cooler is better. Pulsing coils and a low power switch mode on a coil can also help immensely. Again, I'm not going to cover it in depth.

    In closing, I've just barely scratched the surface. But perhaps I've shed a little light on what's going on. Please don't nitpick my comments - I get it, but I wanted to keep it at a simple level for everyone (and I'm very tired of typing and it's getting late) in at least a somewhat brief explanation (failed at that). This can easily turn into a Ph.D topic if warranted!

    There will be a test later!

    Regards,
    Mark

    Promoted items from the Pinside Marketplace
    $ 90.00
    Lighting - Under Cabinet
    Rock Custom Pinball
    £ 58.00
    Cabinet - Decals
    Sillyoldelf Mods
    From: $ 99.99
    Cabinet - Other
    Lighted Pinball Mods
    From: $ 9.99
    Eproms
    Matt's Basement Arcade
    $ 35.00
    Cabinet - Decals
    Bright Lights Pinball
    $ 109.00
    Cabinet Parts
    Tilted Pinball
    $ 8.00
    Cabinet Parts
    RPGCor
    $ 9,995.00
    Pinball Machine
    Flip N Out Pinball
    From: $ 40.00
    Cabinet - Other
    ModFather Pinball Mods
    $ 229.99
    Lighting - Led
    PinballBulbs
    $ 40.99
    Electronics
    PinballElectronics.com
    $ 49.00
    Cabinet - Other
    Chrome Candy
    From: $ 200.00
    Lighting - Interactive
    Professor Pinball
    From: $ 49.99
    Playfield - Toys/Add-ons
    Medisinyl Mods
    $ 25.00
    Apparel - Unisex
    Project Pinball Charity
    From: $ 11.95
    Playfield - Toys/Add-ons
    ULEKstore
    $ 29.99
    Cabinet - Sound/Speakers
    Lighted Pinball Mods
    $ 999.00
    Flipper Parts
    Mircoplayfields
    $ 32.25
    Playfield - Toys/Add-ons
    The MOD Couple
    $ 119.95
    Playfield - Toys/Add-ons
    Hookedonpinball.com
    $ 239.00
    Cabinet - Toppers
    Tilttopper
    $ 86.95
    Cabinet - Shooter Rods
    Super Skill Shot Shop
    $ 99.99
    Playfield - Toys/Add-ons
    Lighted Pinball Mods
    $ 9.99
    Eproms
    Matt's Basement Arcade
    There are 71 posts in this topic. You are on page 1 of 2.

    Hey there! Got a moment?

    Great to see you're enjoying Pinside! Did you know Pinside is able to run thanks to donations from our visitors? Please donate to Pinside, support the site and get anext to your username to show for it! Donate to Pinside