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 : )

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

LTG : )

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

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

LTG : )

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

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.

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

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.

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

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

This is a very informative thread. I just have one other question in regards to substitutions. So I have a Allied Leisure 264-1-46 (9 ohms) and I plan to change it with a Williams AE1-26-1200. It's the same size, same gauge wire. But the diode is on the opposite leg of the coil. Do I just hook up the new coil with the wires in reverse or do I flip the diode over on the coil and hook the wires up the same way as the original. Just wanting to make sure I do this substitution right as I don't want to fry anything on this board as they are difficult to repair. Thanks in advance.

You can do either, leave the diode as is and flip the wiring, or flip the diode and use the same position of the wire - whichever is easiest. As long as the correct wire goes to the banded side of the diode you're good.

that's what I figured just wanted to make sure. Thanks very much!

Hey, when I bought my Phantom of the Opera, it had this exact problem! Locked on kickback coil, due to a shorted TIP Transistor. I replaced the transistor and that fixed the issue. I also noticed that the transistor had been replaced before. You know your stuff!

Interesting old post. Hoping to re-spark this one.

I’m working on a road kings. The outhole coil is cooked.

It’s an AE 23-800.

I have an AE 26-1200.

By the above logic of both Lloyd and cfh this coil will be less powerful but it’s the outhole coil that simply needs to advance the ball a few inches up the trough.

Would I be ok to use this as a substitute?

You can certainly try, but a 26-1200 (10.8 ohms) is considerably weaker than a 23-800 (4.5 ohms).

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

23-800 is likely the most widely used coil in pinball. Plenty available.

on the Roadkings outhole, a 26-1200 won't work. it may work for one ball, but if you drain in multiball, and both balls are in the outhole, the 26-1200 won't have enough power to kick both balls over. 23-800 or 24-900 would be best here.

Thx guys. Appreciate it.

Hi everyone,

Just got into the hobby, and have a couple of pins that have a few issues that I am using to slowly learn how things work, so please excuse me if my questions are simplistic, but I'd rather err on the side of caution.

I purchased a LOTR that I thought was in good shape, but the more layers of the onion I peel the more inconsistencies I find on the machine. One where I am unsure on what to do is the flipper coils. I can see that the coils installed on the machine are not stock, or even recommended anywere as a replacement anywhere I can see. I looked the details up on flipper.com:

The ones that are currently installed
Coil Number Manufacturer Size Resistance AWG # of Turns (Windings)
090-5025-00 STERN (SPI) FLIPPER 9.5 24 1570

Recommended for LOTR:
090-5020-20T STERN (SPI) FLIPPER 3.4 22 900

As you can see the resistance is difference as is the gauge and turns. I have purchased the recommended as a replacement, but wanted to check if I can just switch it out to the recommended coils, or whether i need to check anything else first.

Regards, Paul

Bringing it back alive. Want to increase strenghth of my left vuk in a Gottlieb stargate. According to manual it’s 16570. Supposed to be 15.5 ohms 27 gauge and 1450 windings, size is regular.

Mine already has a 5195 which is 11.6 ohms with 26 gauge and 1305 windings but still not all balls come out ...

which stronger alternative could be used?

Arguably my favorite new LTG quote.

Nice!

https://pinside.com/pinball/forum/topic/stargate-woes

Have you seen pinballinreno 's thread on his stargate and what he's done to address the VUK?

Obviously, a 26-1200 is a standard, easily obtainable coil. 10 ohms.

Now, what I'm going to tell you, real pinball enthusiasts would consider very bad advice indeed.

On the route, when a small (non-flipper) coil failed, the only substitution technicians carried in their toolbox was a 23-800. It would be put in for any coil size. This obviously caused premature failure of some parts, but depending upon the situation and how many thousands of games, it caused surprisingly few problems. In home use you might get a lifetime of play before the mechanism you've put a more powerful coil into actually shows wear or fails.

It's your machine, you can get replacement parts for a mechanism if you notice undue wear on the mechanics due to too strong a coil.

Go all the way to 23-800, and see what that does to the power of the mechanism.

I know we are talking a radical difference in the stats here. From 15 ohms to 5 ohms. But the effect you will actually notice, that actually causes parts to have premature wear and tear, is less than you'd think.

You are already out of 'factory recommended' territory here. I think you'll see a vanishingly small difference with the 26-1200 coil, and a modest, but noticeable difference with 23-800.

The mechanics associated with the mechanism matter here, so the effect you are looking for might be easy to come by, or require quite a radical change in coil strength.

Finally, in my experience, VUK that the balls don't come out of are due more to the cage above them not being aligned perfectly, and the ball 'rattles', losing it's upward momentum. No amount of coil strength change will overcome poor physics.

In general, if you are upping coil strength, you are not on the right path toward proper repair of the machine.

It's far more important to find out what is mechanically happening that causes the instability or malfunction than to try to overpower through the problem.

But if you want to see what a more powerful coil does in this situation, put in a more powerful coil. Pinballs can be built with quite a bit of tolerance in their designs, and as I said, any problems you have from overpowering a coil might not show up for a lifetime of play.