A lot of folks have been asking for my "Stealth LED" recipe lately, so it's time to share. Note: I lean toward the conservative side of LED lighting and so this is a "best of both worlds" approach which strives to maintain the original character of the machine as closely as possible while delivering higher light output, longer life, and the power savings of LED technology. It's also great for pop bumpers... no more twisted filaments and premature burnouts.
So... here ya go.
Nico's STEALTH LED recipe v1.0:
Install type 47 bulbs in all GI locations. Wherever your eye can see direct filament, that's where the bulbs go. Typically this will be on top of the playfield under plastics and lane guides. By doing this, your eye will assume the rest of the lights are also bulbs... aha! Stealthy!
Install Comet twin 2835 SMD "intense brightness" warm white frosted lens in always-lit locations (typically backbox illumination and under inserts which always stay lit). For red star inserts, use the red frosted version and ideally install a second lamp socket and LED to illuminate the other side of the star.
Install Comet 1SMD "supreme brightness" non-ghosting warm white frosted under all inserts and backbox locations which turn on/off (ball count, match numbers, bonus countdown, game over, etc). **
For pops, the Cointaker premium super warm white non-ghosting was my go-to. However, as of 2016, the newest batch no longer delivers an optimal warm white. The color temperature now exhibits an unacceptable greenish hue common to many "warm white" LED varieties. Thus, I now recommend the Comet 1SMD non-ghosting for pops which turn on/off... or the Comet twin 2835 for always-lit pops.
With few exceptions, this is how all of my EM's are outfitted by default. Works great, saves power, looks original enough to please nitpicks, provides better illumination overall, and saves time.
I have rolled every LED sold by Cointaker, Comet, and some from Nifty to achieve this solution.
**BONUS STAGE: If you want to dial in a slightly whiter-white (somewhere between warm and sunlight), you'll need to buy a handful of Comet 4 SMD Supreme Brightness non-ghosting warm whites. THEN, you will need to test and sort them into two piles... because half of them will look yellowish-warm. The others are the "whiter-white" version... use them ideally under inserts. Probably will be too bright anywhere else.
Why the hassle? The not-quite-sunlight-white is the result of a manufacturing tolerance issue. You can't officially order anything in this color... it's a beneficial quirk. Thus, Comet can't guarantee which ones you'll get (though Art says he will accept returns for whichever batch you don't use). I used this method to tune the LED's on Snow Derby a bit whiter, because the predominant color scheme of the game is blue... and this particular white looked just a little bit better. But in general if you'd rather have an easy one-size-fits-all solution without the fuss, the 1SMD works fine.