Happened to discover today that, in some Fastrack lighted bumpers, the polarity of the LEDs is more or less random.
Why do I care?
Hint: Lionchief RTR set
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Well, you don't as Lionel also chose to not protect the LED against reverse polarity, they just use a resistor. 
Consider yourself lucky that they light at all! 
gunrunnerjohn posted:Well, you don't as Lionel also chose to not protect the LED against reverse polarity, they just use a resistor.
Interesting that you should mention that. I have been testing some LEDs recently and find that many current generic red LEDs don't go into reverse breakdown until well above 100 volts. I also have plenty of old red LEDs that clearly show the expected 5 - 7 volt range or so.
Not recommending that anybody ignore the published data for any given part, but is this an industry wide improvement or are my new generic LEDs really "specials?"
Regarding the Fastrack lighted bumpers, in our politically correct environment those are now called a "sub-optimal design." In all regards. Unfortunately, they look pretty good.
Mine actually work a lot better with actual wire from the LED down to the track connections.
I don't know about your 100 volt LED's, but all the current specifications still say around 5-7 volts. Here's the Kingbright I use on a board, typical specification...
