Great idea BUT I strongly suggest you use a 1/2 watt SMD resistor instead of that piddly little thing. Even a 1W.

There is almost no price difference and you certainly have the space for it. There is no point using a tiny resistor that will almost certainly get hotter than it needs to.

Job looks fine so far but it is annoying (to me anyway) when engineers carefully calculate that a resistor needs to be 1/5W so they use a 1/4W.

WHY? There is no need unless you are really pushed for space. As I mentioned you have no space problem and the cost is only very slightly higher so if you use a 1/2 or 1W resistor it is never likely to give any trouble. Using a 1/4W will likely cause failures down the track. Your actually looks like a 1/8W and I certainly wouldn't use that in this application.

LEDs use more power than many realise.

Overall a great idea and you should pursue it.

I'm guessing this is not for GI or any bulb whose glass bulb sticks ABOVE the playfield.
Putting a flat led level with the bottom of the pf shooting up through the empty round socket hole is just gonna make a circle/spot on the bottom of a plastic, right?

.....and...this is EXACTLY what I mean by engineers carefully calculating the EXACT requirements when there is no need to 'cut it so close' in this application.

Always err UP rather than make something "just close enough". That way, future failures are much less likely.

This company makes 555 bulb light boards for several classic Bally and Stern titles.
https://pinballreplacementparts.com/collections/all?page=1

Room for both types here I think. What the OP is doing is a good idea if the light doesn't spread out too much since it's eliminating the socket entirely - probably good to have a mix of both available.

Agree with pins4u on using a higher wattage resistor.
As a general guide, at least double the resistor wattage rating for what it's dissipating. Keep the resistor running cool.

BTW why don't you include the parallel resistor to get rid of the LED flickering on your first revision board? All you need to do is add a 470 ohm resistor across the two wire connection points. It's that simple. For flexibility also trace solder holes besides that resistor in case someone wanted to adjust the parallel resistance value using a through hole resistor.

Adding the load resistor may make things more complicated than it seems. There are a number of games that use lamp boards instead of discreet sockets, and then you'd have to mix and match your methods for handling the anti-flicker properties.

That and it also limits the locations these LED's can be used. They wouldn't be useful in non-bally/stern machines, nor would they be useable in GI locations if so desired.

Not saying it couldn't / shouldn't be done, just saying that there are a few other things to consider to make sure other issues aren't created in the process. To be quite honest.... I often wish that LED's of this style were available on the market, and I've considered doing something along these lines for my own games as well.

I wouldn't worry about diffusion at all, as I've used very similar RGB LED boards in my PROC project, and they look just fine.

-Hans

I would maximize the copper on both the anode and kathode of that LED.
There is no such thing as too much copper heatsinking when it comes to LEDs.

Just a suggestion, I would also include through holes for that parallel resistor if it's optional - not everyone is comfortable soldering surface mount parts:
The through holes cost you nothing to add and make it easier for some end users.
Position the holes however you see fit.

LED_PCB_mod.png

There are some cool lamp board conversions at that site, but if someone is going to make a lamp board to replace 30 sockets they should have put header pins on it and the buyer can get a couple female connector housings and pin the old wires to them.

Works for me

The only negative side effect in this case will be that the game will draw slightly more current from the feature lamp circuit when lots of playfield lamps are on. Worst case will probably be an extra amp of current, but you've already reduced current draw by a few amps switching from incandescent to LED anyway.
It will not introduce new problems, rather it might help lamp driver boards that have some lazy SCRs.

To complicate it more you could do the following - ignore me if I'm being overbearing:
Include a solder junction that connects/disconnects the surface mount parallel resistor. Add a solder blob over the junction to connect the R2 SMD resistor. Remove the solder blob to disconnect it.

LED_PCB_mod2a.png
LED_PCB_mod2b.png

Glad to see you took this advice.

Congrats on getting your first PCB design manufactured!