The cabinet has a very nice and fancy marquee featuring back light graphics and active score board. The original game shows the top 5 scores, as well as your current score. Very impressive! However, that entire module was missing when I received the cab. All is not lost however
Here's the cool marquee but sadly, no illumination.
Here's what I'm dealing with. It's a basic board with no active components. There are tons of 7-segment LEDs which simply connect to a 50 pin header on the rear. I'll figure that out later. I'm sure I can drive them with the raspberry pi and the right interface. Right now it's the missing lights that I'm interested in. Most of the holders were in place when I received the cab but they take some sort of incandescent light bulb. I don't want the machine eating up expensive electricity, so replacing them as is wasn't an option. LEDs to the rescue.
Here's the dirty backside showing where to holders go in. I actually have most of them, but since LEDs rarely "burn out" I chose to just solder them directly, with the right resistor of course.
The extremely bright, and cheap LEDs I scored on ebay say 5V forward voltage and 20mA forward current. I wanted to power them with 12VDC for no real reason. I could use 5V as I'm powering the system with a standard computer power supply but I went with 12V. To not exceed 20mA, I'd need of course:
R = V / I = 12 VDC / 0.02 A = 600 ohm resistors. So I went with 680 ohm.
They were very bright so I went with that. I didn't believe the LEDs would drop 5 volts, but upon measuring they actually do. So the resistor is eating up 8 volts at just under 20 mA so 1/4 W rating resistors would do.
The extremely bright, and cheap LEDs I scored on ebay say 5V forward voltage and 20mA forward current. I wanted to power them with 12VDC for no real reason. I could use 5V as I'm powering the system with a standard computer power supply but I went with 12V. To not exceed 20mA, I'd need of course:
R = V / I = 12 VDC / 0.02 A = 600 ohm resistors. So I went with 680 ohm.
They were very bright so I went with that. I didn't believe the LEDs would drop 5 volts, but upon measuring they actually do. So the resistor is eating up 8 volts at just under 20 mA so 1/4 W rating resistors would do.
The 5mm diameter LEDs mounted to the resistors. I then installed them.
Pretty neat. You can move them around a bit with needle nose pliers to get them centred.
However it became clear why they didn't use LEDs in the initial design. Since LEDs are way more of a point source, the lights are very uneven even with diffusion by the marquee graphic. I tried cutting some card stock and fitting them in front of the LEDs, but behind the marquee graphic and the result is as expected.
The lighting is nice and even but way too dim now. I'll leave it for now, but what I plan to do is take some plexiglass and cut it size using the card stock as templates. Sanding plexiglass (with a mask on) produces a very non-see through piece of plastic that allows light to pass and should be a good diffusor. I did something similar with the main marquee on my Defender cabinet and that turned out nice.