How to wire Tomar color light LED signals?

[CSXDixieLine]

I have recently purchased several Tomar color light mast signals. Each signal has one head with three lights: red-yellow-green. The lights are LEDs. There are four wires coming out of the base of the signal: blue-red-yellow-green. The blue is the common anode (+), while the other wires are the cathodes (-) for each LED.

Where in the circuit do I place the current limiting resistor(s)? Tomar states that a 390 ohm resistor can be used for these LEDs, but their wiring diagram shows resistors on every wire, which I have never seen before. Do I place one resistor on the common cathode wire (blue wire) or one resistor on each of the anode wires (red-yellow-green wires)?

Thanks,
Jamie

[rrinker]

 If you are absolutely positively sure there is no way for more than 1 LED to be on at a time (this is logically true based on how a 3-light signal is SUPPOSED to operate - but wiring mistakes and logic errors in whatever method you are using to control the signal do occur), then 1 single resistor in the common MIGHT be fine.

 I say MIGHT because different color LEDs are not all the same brightness. At a given, safe current level for each of the LEDs, one may be much brighter than the other, and it doesn't look 'right' when in operation. So rather than use a single value resistor for all 3 LEDs, you can use 3 different ones to 'tune' the brightness. You can't mke the dimmest LED brighter, but you can use larger resistors on teh brighter LEDs to cut them down. Plus if each LED has its own resistor, a mistake that accidently turns on all three won't hurt anything.

                                     --Randy