I tried googling before posting but didn't get any good results. My Williams widebody Pin (STTNG) has a driver 8 board. I want it are two diagnostic LEDs, 1 for 5V and 1 for 12V. the 5V is dead. I have 5V at the connector. The game plays fine. I had to work on the board as it blew the TIP102. I corrected the tieback creating it all in the back box. I replaced the bad TIP102. I fired up the game and the previous problem (burning coil, smoke, etc), did not reoccur. The 5VLED didn't light before I worked on the board and it doesn't like after I worked on the board. I replaced the board with a new board and that board shows the 5V light coming on.

so my question actually centers around the diagnostic LED. Are all the diagnostic LEDs of a certain type or are they dependent on the voltage they are reporting. In other words is the 12V LED only lighting up because it has 12V or is it Electrically a 3v led being told to light up because the circuit sees 12v.

If the answer is that all the diagnostic LEDs are identical in their make up then can I swap out what I think is a bad LED with a different one and see if the board lights up?

-Nac

I understand now. Thank you. So with that said, I am going to try and replace the led and see what happens.