(Topic ID: 285561)

1970s Gottlieb LED--Ghosting?


By Gott72

3 months ago

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  • 14 posts
  • 9 Pinsiders participating
  • Latest reply 55 days ago by Dono
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#1 3 months ago

I've searched around and read and read, but couldn't find a cogent answer...

Do LEDs ghost in the 70's Gottlieb EMs?

Is it necessary to buy anti-ghosting LEDs for these machines?

And additionally...

Has anyone replaced 70s incandescents with brighter LEDs and been disappointed?

Anyone used BriteCaps classic pop bumper lights in a 70s EM and liked/loathed them?

Have colored LEDs enhanced the playfield, especially under colored inserts?

I'm going to switch over a machine and would hate to order loads of useless bulbs that go into the trash.

Thanks!

#2 3 months ago

They might ghost. They might not. The safe play is to order non ghosting.

My experience is LEDs as GI above the playfield just don't look right on EMs. Inserts are a different story. It just depends. You have to try them and see. So much of this is personal taste.

If you are going to do it warm white is a better look.

#3 3 months ago

If it's a light that isn't always on, it's possible to have it flicker when off in an EM. Non ghosting bulb will fix that. But sometimes it doesn't happen. Depends on wiring, etc.

#4 3 months ago
Quoted from Gott72:

Do LEDs ghost in the 70's Gottlieb EMs?

Is it necessary to buy anti-ghosting LEDs for these machines?

No and no.

Ghosting is primarily a cause of certain flaws in solid state games. None of that circuitry is present in EMs.

Quoted from Gott72:

I'm going to switch over a machine and would hate to order loads of useless bulbs that go into the trash.

If you don't like them, you can always resell them. I've sold a bunch of LEDs I wasn't going to use, and I've seen others do the same. No need to trash them if you don't end up wanting to use them.

#5 3 months ago
Quoted from ForceFlow:

No and no.
Ghosting is primarily a cause of certain flaws in solid state games. None of that circuitry is present in EMs.

If you don't like them, you can always resell them. I've sold a bunch of LEDs I wasn't going to use, and I've seen others do the same. No need to trash them if you don't end up wanting to use them.

Well I've had them in EMs and they ghosted so I'll disagree here. They don't always but they can.

#6 3 months ago
Quoted from EMsInKC:

Well I've had them in EMs and they ghosted so I'll disagree here. They don't always but they can.

Agreed. Every Gottlieb EM I have ever worked on would ghost in the feature lamps. GI circuit generally not. I use non-ghosting in the feature lamps under the playfield. Avoid LEDs on top for ascetics.

#7 3 months ago
Quoted from stashyboy:

Agreed. Every Gottlieb EM I have ever worked on would ghost in the feature lamps. GI circuit generally not. I use non-ghosting in the feature lamps under the playfield. Avoid LEDs on top for ascetics.

The Gottlieb EMs I've owned or worked on didn't have ghosting issues.

Since there's no electronic circuitry, what could even be a possible cause?

#8 3 months ago

I have had them ghost on a williams upper deck and 1956 williams rifle game.
I think there is enough back feed in an em that they can ghost.

#9 3 months ago
Quoted from ForceFlow:

The Gottlieb EMs I've owned or worked on didn't have gosting issues.
Since there's no electronic circuitry, what could even be a possible cause?

The back EMF spike that is generated when a coil turns off and the field collapses around the winding can cause enough magnetic induction in nearby circuits to make LEDs flicker briefly on an EM. You're right that it doesn't happen on every game. In my experience, it most often happens on games that contain at least one 6-volt relay coil, which Gottlieb used on several 70s EMs for bonus detection.

That coil can act like a little transformer secondary winding, transferring EMF spikes directly into one or more lamp circuits. This also happens when incandescent lamps are in the circuit, of course, but the filaments of those lamps respond relatively slowly and require so much current that they don't flicker from the spikes. LEDs respond super fast, and will emit light with very small current, so you can see them flicker in some EMs during game play.

- TimMe

#10 3 months ago

Yes common in EM switched lamps. It's not technically ghosting but flickering caused by steppers and score motors. Using non ghosting lamps helps but doesn't eliminate it completely.

#11 3 months ago
Quoted from ForceFlow:

The Gottlieb EMs I've owned or worked on didn't have gosting issues.
Since there's no electronic circuitry, what could even be a possible cause?

I'm no electronics guy but my understanding is there can be enough flow of current that isn't enough to light an incandescent but is enough to flicker a LED before it collapses. I would assume something like what you get with EMF on a coil.

It doesn't always happen on every feature lamp
But it does happen.

I just installed a green LED under the double bonus insert on my Old Chicago. The incandescent was dim and I wanted more pop. That light is lit by the ball count unit stepper. It really pops now and no ghosting. I put them in a different Bally game and they did. Only way to know is try it.

#12 3 months ago

To weigh in on some of the other questions raised in your original post:

I do not like the look of LEDs in an EM, but that is just a matter of personal taste. Lots of people like them. They are very good for the machine (cooler running, use less energy, last a long time) and they are a 100% reversible mod, so there is no reason (other than cost) not to check them out if you want to see how they look.

As others have already noted, using LEDs for GI in an EM tends to be where you will really notice a much different visual effect, compared to the original lamps. This difference is usually in the overall color and intensity of the light, and in the way the light spreads over the area. Many LEDs tend to create a more focused spot of light, while incandescents generally spread light all over the place. The focused and intense light effect of certain types of LEDs also makes the illumination of the backglass look very different when you use them for GI in the head.

For the PF inserts, LEDs can work really well, as long as the color emitted by the LED and the color of the insert are compatible. A yellow LED under a yellow insert will look good, while a blue LED under a yellow insert will hardly show any light at all. That's because a blue LED produces virtually no yellow-spectrum lightwaves, while the yellow insert only allows yellow-spectrum lightwaves to pass through, and so the net result is mostly nothing.

The same applies for the use of LEDs on feature lamps behind the backglass in the head, such as the ball-in-play and match numbers. This will look good as long as the color emitted by the LED and the color of the screened ink being illuminated are compatible.

There are two unusual visual effects I've seen with LEDs on EMs. The first one has already been discussed in this thread, and that is the tendency of certain insert lamps to flash and flicker while you're playing. This effect occurs when the lamp is supposed to be off. It doesn't happen with every game, but if it does happen to you, the easiest fix is to use a traditional incandescent lamp in those places where there is flickering.

The other visual effect has to do with the use of GI LEDs. Because the GI supply voltage is AC (60 Hz in the USA), many GI LEDs will actually be blinking on and off at a very fast rate. This blink rate (in the USA) will either be 60 Hz or 120 Hz, depending on the internal drive circuitry of certain types of LEDs. In either case, when you are playing a game and your eye is moving rapidly to track the ball, you may see a visual trail effect from these types of GI LEDs due to the after-image of the blinking on your retinas. Whether you think this looks good or not is, again, a matter of personal preference. I find this effect to be very distracting while I'm trying to play the game, so I don't really care for it.

- TimMe

#13 3 months ago

Thanks for those replies! It's an education, for sure.

1 month later
#14 55 days ago
Quoted from TimMe:

The back EMF spike that is generated when a coil turns off and the field collapses around the winding can cause enough magnetic induction in nearby circuits to make LEDs flicker briefly on an EM. You're right that it doesn't happen on every game. In my experience, it most often happens on games that contain at least one 6-volt relay coil, which Gottlieb used on several 70s EMs for bonus detection.
That coil can act like a little transformer secondary winding, transferring EMF spikes directly into one or more lamp circuits. This also happens when incandescent lamps are in the circuit, of course, but the filaments of those lamps respond relatively slowly and require so much current that they don't flicker from the spikes. LEDs respond super fast, and will emit light with very small current, so you can see them flicker in some EMs during game play.
- TimMe

Perfectly stated. I bought a few comet LEDs to use under an Old Chicago CPR playfield that unfortunately sported washed out color inserts (special - red and extra ball - orange). The ghosting on those LEDs was VERY NOTICEABLE. Ordered some non-ghosting and those did the trick.

Added 53 days ago:

Just an update to my Old Chicago feature lamps... what's interesting is that an earlier poster stated he placed a green LED underneath the double bonus insert on his OC... I did the same by putting a green non-ghosting LED in that spot on mine. I also placed non-ghosting colored LEDs underneath the special and extra ball inserts. Although the ghosting was reduced, the very slight flickering as so well explained by TimMe was DEFINITELY distracting during gameplay, so much so that I took them out and replaced with painted 44s. Moral of the story is you gotta try non-ghosting LEDs in your particular game if that's the look you want. It might be fine, might not.

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