I have a Stern Star Trek LE that has no playfield LEDs lit up on it. All the LEDs are out. No inserts are lit up, no pop bumpers are lit up, nothing anywhere on the playfield. The system boots up, and plays normally, but it's dark. All fuses and voltages that can be tested on the CPU/Driver board, seem OK. The CPU board has some kind of serial communication that goes from J14 to a small node board. I replaced the cable with another straight through RJ12 cable, but no joy. Still no LEDs are lit.
The small node board looks like it has several LEDs on it (TX, RX, Stat/D1). None of these are lit up. It seems like the small node board should have LEDs lit up on it. Also, along the serial communication path, none of the red D21 LEDs on any of the LED control boards are lit up.
Any help is appreciated.

OK, I fixed my problem with no LEDs on the playfield of my Star Trek LE. The main LED control board #5, (p/n 520-6812-00) had a bad bridge rectifier (D36) on it, this boards supplies 5 volts to several other LED boards underneath the playfield (+5v and +3.3v). This is why none of the D21 red LEDs were turned on. I replaced the D36 bridge with a GBPC3504W, 400v, 35 Amp one I purchased from Newark.
That fixed the problem, all the GI LEDs now light up, and blink when they are supposed to. Sure is a pretty game when everything is working.
I tried to buy a replacement board, but no one had one, not Marco, Pinball Life, nor Stern, so I had to fix it. $15.00 vs $225.00 for a replacement board (if I could have gotten one).
Steve