RP lighting question - fried circuit?

[BP125V]

Hello,

I have been using RP for several years now and doing my own hardwire installs and LED upgrades without any issues.  However, for some strange reason, I just completed an install on a HO Bowser SD40-2 and forgot to install a few of the resistors on some of the new LEDs.  Headlights worked and then when I turned on the ditch lights they, and the headlight blinked and now none of the lights work. However, loco runs fine and sound still works.

Does anyone know how the lighting circuit works in the LM-3S?  By that I mean is it one circuit that I potentially fried and now none of the lights will work?  I had wired with the 9 pin yellow, white, green, and 6 pin green and purple.

Thank you,
Bill

[Espeelark]

Its possible that you fried just the LED's because of the absence of the resistors. As a trouble-shooting step, I would suggest replacing the LED's (or at least one of them) first and see if that fixes the problem.

[G8B4Life]

It can't hurt to try and replace the LEDs as Espeelark suggested (or just remove the ones that didn't have resistors) and see if the lighting then works again. Ideally, as in an ideal circuit the LEDs that had the resistors should have been protected by those resistors and should still work if the common (+ blue wire) has not been damaged. Without knowing how Ring does protection, if any, on the LM it could be possible that you've killed whatever's supplying the common in that very brief overcurrent moment between when you turned on the LEDs without resistors and when the LEDs went out.

As for how the outputs work, they are switched ground, with the common (+v) always present on whatever you've got hooked up to the outputs. I imagine there is only one source supplying this so if you've killed this source then that's it no more outputs (unless you put in your own external bridge rectifier and hook it up to the blue wire  ).

- Tim

[gregeusa]

What about just testing the LEDs in place first?