(Topic ID: 187756)

Guidelines for coil substitution


By arolden

2 years ago



Topic Stats

  • 15 posts
  • 5 Pinsiders participating
  • Latest reply 2 years ago by cfh
  • Topic is favorited by 6 Pinsiders

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#1 2 years ago

Hi all.

I have a coil I need to replace (AE-25-1000) on a Shadow machine.

I don't have a replacement coil but I do have a bunch of other spares. So I started to think about coil substitution. When substituting a different coil (even from a different manufacturer), what is the best way to ensure the coil is a similar strength? Is resistance the best indicator? So two coils with similar resistance should be of equal strength. Is that line of thinking correct?

Of course there are other things to consider such as physical coil size, coil tube size, and diodes. But that is easy to sort out once you figure out which coil you're going to use.

Thanks for any advice.

#2 2 years ago

25 is the wire gauge, get that right or real close.

1,000 is the number of turns. Less turns is stronger, more turns is weaker. Up to you and where it's needed.

LTG : )

#3 2 years ago
Quoted from LTG:

25 is the wire gauge, get that right or real close.
1,000 is the number of turns. Less turns is stronger, more turns is weaker. Up to you and where it's needed.
LTG : )

Thanks, Lloyd.

So if I'm understanding you correctly, coil resistance actually doesn't matter that much?

How close does the wire gauge need to be? I have a Capcom 23-800 coil on my bench. That's a similar gauge and a little stronger. But I also have a Williams 26-1500 coil, which is a closer gauge but a little weaker. At what point does the difference in gauge make a difference?

#4 2 years ago
Quoted from arolden:

At what point does the difference in gauge make a difference?

Myself, I wouldn't go more than 2 in either direction for gauge.

LTG : )

#5 2 years ago
Quoted from LTG:

Myself, I wouldn't go more than 2 in either direction for gauge.
LTG : )

Good tip! I will adopt it myself

I will try both coils and see which works better.

My second question is this: if I have a coil with no wrapper, and resistance is not a good indicator of the strength of the coil, what is the best way to identify it?

#6 2 years ago

Here is a very useful coil reference table put together by John Robertson at John's Jukes in Vancouver, BC.

https://www.flippers.com/coil-resistance.html

#7 2 years ago
Quoted from arolden:

what is the best way to identify it?

At the bottom of a garbage can. Too many unknowns. Especially if it is good or not.

LTG : )

#8 2 years ago
Quoted from CrocRod:

Here is a very useful coil reference table put together by John Robertson at John's Jukes in Vancouver, BC.
https://www.flippers.com/coil-resistance.html

Thanks for the link. I reference this table often but unfortunately it is missing a fair few WPC coils and it did not have the Capcom coil I mentioned.

Quoted from LTG:

At the bottom of a garbage can. Too many unknowns. Especially if it is good or not.
LTG : )

Sound advice!

Thanks for the assistance everyone.

#9 2 years ago

Has anyone here ever replaced a continuous duty A-9740 with an A-16890 on an EM? I'd like to do this on Royal Flush Q and U relays. PBR recommended replacing it with the original spec. I think I can do this, but the Note about a 47mfd cap confused me. Is it needed or not, and where can I find one? http://www.pinrepair.com/em/index3.htm

#10 2 years ago

i do that EM replace all the time. on 100s of games. it's dumb to put a 30 ohm coil back in place, unless you like "the burn". it's just silly to do that.

on coil substitutions, it's best to start with resistance values. what LTG said frankly is just wrong. resistance is where it's at. It's always better to go to higher resistance. That puts less strain on the system (especially on solid state games.) Lower resistance will give you a strong coil, but there's risk involved in that.

for example on the 25-1000 coil mentioned (from memory) i believe this is about 10 ohms. a more common coil is the 26-1200, which is used in the pop bumpers, and is about (from memory) 14 ohms. This is a good substitution. There will be less strain on the driving TIP transistor. As long as the feature "works", you'll be good. Now if you listened posted advice above, and went in the *other* direction, you could be causing some pretty serious damage. say using a 23-800 (which would follow that ill advised "two step" rule), that coil comes in at 4 ohms. Depending on the programming pulse length, that could cause the driving TIP to smoke very easily, and then you're doing board repair.

look at it this way. think of a coil as a faucet. the higher the resistance, the less water that gets through. if you have a low resistance coil, a lot more current gets drawn. That can be a big deal depending on the application. you can smoke things. But if you use higher resistance, less current (water) goes through. The only risk with that is you may not have enough power to control the device (or clean that pan.)

Let me give another application of this... Early Dataeast games *love* to smoke the left lane kick back coil. The original is an 23-800 coil, and the pulse length driving that coil is too long. The TIP driving transistor loves to bake, and the coil locks on, and burns. I go tired of replacing the coil/transistor on our Time Machine for example. So after a TIP replacement (which burned and shorted), i changed the coil to a 26-1200 (14 ohms). That's significantly less current draw, and i haven't had to deal with a burned coil since. Is the kick back less powerful? Yes it is. But it's still powerful enough to do it's job.

Another thing to remember is coil frame size. Gottlieb and Bally (1987 and prior) used a slightly (1/16") shorter frame size on their "general use" coils (like pop bumpers and slings.) Williams use 1/16" longer. Sometimes this is a problem, sometimes not. But it's something to consider. Usually the leter prefix (at least on williams and bally) specifies the coil frame.

Gottlieb didn't do that generally, they used an "A" for assembly number on nearly all cols, with a sequencial numbering system. For example, a A-9740 coil was designed before an A-16890, in time. For example the 4 digit numbers are all 60s and 70s parts. The 5 digit coils are pretty much 80s and newer. The 3 digit coils are late 40s/early 50s in their design.

There is some science in the "henries" of coils too. That is, if two coils have the same resistance, but different windings/coil wire, are they the same? In terms of the electronics, they are. But in terms of the actual usage, maybe not. The henries will be different, and the coil *could* act differently. But for the most part it's all about the resistance, and that's where you should concentrate your substitutions.

#11 2 years ago
Quoted from cfh:

i do that EM replace all the time. on 100s of games. it's dumb to put a 30 ohm coil back in place, unless you like "the burn". it's just silly to do that.
on coil substitutions, it's best to start with resistance values. what LTG said frankly is just wrong. resistance is where it's at. It's always better to go to higher resistance. That puts less strain on the system (especially on solid state games.) Lower resistance will give you a strong coil, but there's risk involved in that.
for example on the 25-1000 coil mentioned (from memory) i believe this is about 10 ohms. a more common coil is the 26-1200, which is used in the pop bumpers, and is about (from memory) 14 ohms. This is a good substitution. There will be less strain on the driving TIP transistor. As long as the feature "works", you'll be good. Now if you listened posted advice above, and went in the *other* direction, you could be causing some pretty serious damage. say using a 23-800 (which would follow that ill advised "two step" rule), that coil comes in at 4 ohms. Depending on the programming pulse length, that could cause the driving TIP to smoke very easily, and then you're doing board repair.
look at it this way. think of a coil as a faucet. the higher the resistance, the less water that gets through. if you have a low resistance coil, a lot more current gets drawn. That can be a big deal depending on the application. you can smoke things. But if you use higher resistance, less current (water) goes through. The only risk with that is you may not have enough power to control the device (or clean that pan.)
Let me give another application of this... Early Dataeast games *love* to smoke the left lane kick back coil. The original is an 23-800 coil, and the pulse length driving that coil is too long. The TIP driving transistor loves to bake, and the coil locks on, and burns. I go tired of replacing the coil/transistor on our Time Machine for example. So after a TIP replacement (which burned and shorted), i changed the coil to a 26-1200 (14 ohms). That's significantly less current draw, and i haven't had to deal with a burned coil since. Is the kick back less powerful? Yes it is. But it's still powerful enough to do it's job.
Another thing to remember is coil frame size. Gottlieb and Bally (1987 and prior) used a slightly (1/16") shorter frame size on their "general use" coils (like pop bumpers and slings.) Williams use 1/16" longer. Sometimes this is a problem, sometimes not. But it's something to consider. Usually the leter prefix (at least on williams and bally) specifies the coil frame.
Gottlieb didn't do that generally, they used an "A" for assembly number on nearly all cols, with a sequencial numbering system. For example, a A-9740 coil was designed before an A-16890, in time. For example the 4 digit numbers are all 60s and 70s parts. The 5 digit coils are pretty much 80s and newer. The 3 digit coils are late 40s/early 50s in their design.
There is some science in the "henries" of coils too. That is, if two coils have the same resistance, but different windings/coil wire, are they the same? In terms of the electronics, they are. But in terms of the actual usage, maybe not. The henries will be different, and the coil *could* act differently. But for the most part it's all about the resistance, and that's where you should concentrate your substitutions.

Interesting. Thanks for the input.

While I've marked this topic as solved I am happy to hear other opinions on this.

#12 2 years ago

cfh is my pinball repair hero. Now about that 47mfd cap.... Needed or not?

#13 2 years ago

You can try it without the cap but most the time you need it. If you have the game on high tap you might be able to get away without. But for the most part the Is needed or the relay will buzz.

4 weeks later
#14 2 years ago

I finally got the parts and courage to try this. I haven't turned it back on yet because I'm going to convert a second crispy one. Does this look okay?

20170528_113058 (resized).jpg

#15 2 years ago

it looks good to me but hard to tell exactly if everything is perfect from a picture.

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