I would guess too high a voltage. From Clay's EM guide:

Some feature lights on these games use solenoid voltage (28 volts) as the power for these 6.3 volt #47/44 bulbs. Gottlieb uses a large sand resistor to load the 28 volt current down to 6 volt levels for these feature lights. Often the resistors are broken or out of spec. Also in the 'old' days, line voltage was 110 to 115 volts. Now it's more like 120 to 125 volts. Because the solenoid voltage is not regulated, this means the 75 ohm resistor (even if good) is not enough ohms, and the feature light bulbs burn too bright (cooking the bulbs and any plastics or backglass art around them). In addition, if you have the game on high tap, the 75 ohm resistors are definitely not enough. I usually end up at 125 or 150 ohms for proper lamp brightness.

Can 6.3 volt burn the wood of a PF if it touching?

You’d need a lot more at play for that to happen. If you have burn marks it’s probably from soldering.

As an aside, if you are converting an EM to LEDs don’t forget to lower your fuse value

Can you elaborate on the lower fuse value for leds. I never heard this before. I sometimes run a mix of gi incandescent and led.

Yes please elaborate. Is there an easy conversion?. 15 Amp fuse is replaced with? Amp. A 10 Amp fuse is replace with?
Or a formula x Amps for Y LED bulbs?

Juggernaut was always a cool dude.

Just playing around with my Slick Chick now with the meter. I have 5 incandescent burning and the rest of the playfield is LED. I can force it up to 0.001 amps if I’m lucky.

I happen to have a big bag of 3amp fast blows so that’s what I use. Even with all the relays and wipers I shouldn’t have much more current draw than above. If there’s a problem I’d rather see a low fuse blow asap than something grind away with a 10 amp fuse in there.

Is this all necessary, nah probably not. But when I have 20 to 30 EMs being played all day not under my direct supervision I don’t want a problem sneaking under a 10 amp fuse when I require a very small fraction of current.

I don't think it's necessary to lower the fuse value. Any potential short (the reason you're protecting the circuit with a fuse) would occur in the wiring. It doesn't matter what the load is. The circuit is designed to handle the current load of incandescent lamps, and even with them, an overload is unlikely. You'll never overload the circuit with LEDs, so the only reason you're fusing the circuit is to protect against a short. Yeah, you have the luxury of lowering the fuse value if you prefer, but it's really not necessary.

….lots of other EM Pinsiders breathing a sigh of semi-confident relief. Like me.

I've never heard of lowering the fuse

If you want to protect against a dead short, yes any fuse will do. I had a Big Brave with corrosion slow cook on me that I LED’d and my 3A fuse saved me.

Let me throw another question out there as a teaser.

How much are we wanting to spend up front to convert an entire machine from incandescent to LED? LEDs are 50-60ish cents ballpark last I checked. I do some feature lights with those PCBs which can run anywhere from 80c to a dollar per bulb. Some of those boutique bulbs are over a dollar.

The price of a fuse for all those bulbs is less than the cost of one of those bulbs. Why stop short (pun intended) in the cheapest part of your circuit. For some machines you could be closing in on $100 easily to bulb a game another 55c is ok to have a fuse in tune with your load in mind.

In some instances you probably have your fuse dragging your (incandescent) lights down by a bad fuse socket connection based on the age of the game depending how it was stored. Fuse might even fall apart when you reseat it too, it’s 50 years old.

There certainly is no harm in lowering the fuse value if you want to, and you surely would want to replace any fuse or holder which is adding excessive resistance to the circuit because of age or corrosion. The cost of the fuse is obviously not a concern. However, I don't think anyone needs to have any anxiety over having the original value fuse in the clip when converting to LEDs.

1) Costs for LED from Comet for a modern-ish title run about $50 to $75 per title.

2) Lowering the fuse value is not necessary as the wiring itself which the fuse protects has not changed. You can with no harm however since LED's pull less current.

FYI some Gottlieb EM you CANNOT install LED's on certain inserts. Ship Ahoy for example the spinner insert draws power from the coil circuit and Gottlieb uses a ceramic resistor to step the voltage down based on a #44 bulb. I ran into this also with Outer Space/Orbit.

Installing an LED in this location will cause the LED to be VERY BRIGHT and it will have a very short life. Even installing a #47 bulb will run hot since they are less of a load on the circuit. I have actually taken to marking the playfield underside with "ONLY #44 HERE" with an arrow as a warning to the next owner.

Gottlieb continued to do some odd stuff with bulbs into the solid state era; The Gold Wings pilot cockpit insert lighting is actually 2 #44 bulbs wired in series. This caused me some confusion till I looked at the wiring diagram and spotted it.

Yup, went through the same experience. I've not had a Comet LED melt in any other circumstance.

Was the same true for Buccaneer? I made my own ground strap and mounted comet 555s with no problems.

If you bypassed the coil feed and ceramic resistor then it doesn't apply of course.

One more example is Melody/Sing Along, the "walking mech" is lit from below when the hole is ready to be collected on.

Have to use #44 bulbs.

Any lamp with a sand resistor in series. I wonder though if you were to use a 150 ohm ceramic resistor in series, would an LED work?

Maybe or you could just change about the voltage feed.

Yes. On a Gottlieb Gridiron the shoot again light uses a 47 Ohm resistor. Put two 47's in series in there (it's what I had, no 150 laying around) and so far so good with a Comet LED. The voltage is still a tad high as the LED is a bit brighter than the others LED's, so will have to get a few 150 ohm sand resistors.

You could use a ceramic resistor instead of the “sand” ones, just make sure it’s of the correct wattage to handle the power dissipation

Alberto

I believe those sand resistors are obsolete. Ceramic resistors are the modern alternative. You can get them cheap on eBay.

If that's possible, why didn't Gottlieb do it in the first place?

Cheaper to slap a resistor in is the obvious answer.

Resistors cost money!

I dont disagree.

Where did he go?

Now you have me curious I didn’t make any changes to the wheel other than LEDs I wonder if someone before me modified it.