Quoted from VDrums2112:
Exactly... I'm pretty sure those LEDs need a consistent 5 to 6 volts or they won't even try to light up. Am I wrong?
Post edited by VDrums2112 : Typos, mispellings, improper grammer... You name it!
Not exactly. An LED has its own internal voltage that it wants/needs to light up. A Red LED, might be as low as 1.2 volts. A number of the larger LEDs along with most of the whites and blues typically require 3.4V. Some as much as 4.9VDC.
The voltage rating of the "replacement" LED is all about what they have done to deal with the extra voltage (6.3V - 3.4V = 2.9V). In its simplest form, that is a resistor put in line with one lead of the LED. But you also need to know the maximum current draw of the LED. That typically ranges from 20 milliamps to 70 milliamps. (0.070 A). So, you might find a 75 or 100 ohm resistor in series with the 6V LED.
But, 6.3 VAC is not 6.3VDC. Which is what all the above is based on. 6.3VAC GI power is continually changing polarity and going up and down from 0 volts (think Sine Wave). So the LED does not recieve 6.3 V all of the time unless it is a specially designed replacement.
So, if the LED only contains a single resistor and used on AC, it will only be lit half the time and be flashing 60 times a second. This is the strobe light effect many of us complain about. It may not be noticeable when looking directly at the LEDs, but you will see its effect as your eyes track the moving ball across the playfield.
If the LED actually contains a Bridge rectifier (or 4 diodes) to convert AC to DC, then you get more brightness but it is still strobing 120 times a second.
If they add a capacitor to smooth the pulsating DC into filtered DC, you get a contantly lit LED. You also get the possible benefit of LED slightly ramping up to full brightness when first turned on, and fading out when turned off.
This is why there are all sorts of different standard and premium, non ghosting, reduced strobing etc. etc. LEDs being sold for the Pinball Market.
Another problem I have seen by using LEDs in an EM game is what I believe to be caused by induced current. If you see an EM where someone has replaced all the lamps in the backglass with LEDs, you can see various non-lit LEDs flash very briefly when various things are happening in the game (like scoring etc.) Unlike an Incandescent bulb, LEDs can light extremely fast, and, as described above, can light with very low voltage and current. When a wire has to pass current, it actually creates a small magnetic field around it. The more current it passes, the greater the magnetic field. If you lay another wire parrallel to the first wire, the current in the first wire will induce voltage in the second (The basic principle of how an air transformer works). So, by turning on a coil in a EMs head you induce voltage in the lamp wires (like Ball in Play, match lights, Game Over) which are laying parrallel to them in the wire loom. And you get faint little random flashes of light in some, if not all of the feature lamps. This may not be very noticeable down at the PF, and also not by the person playing the game (except maybe during bonus collect). But its easy to see by on-lookers.