I have a 36803 SOB Tm 34 (Köf) locomotive with an older decoder with dip switches for the address and pot rheostats for acceleration and braking delays. The old decoder stopped functioning correctly so am replacing it with an ESU LokSound 5 Micro decoder. The locomotive already has LED lighting for forward and reverse. I do not see resistors for the LED lighting as the lights are hidden from view. My concern is do I need to add resistors for the LED's or not - a very small amount of space exists within the locomotive.

I also have a 37591 SBB Ae 8/14 that I am upgrading to an ESU LokSound 5 decoder - replacing what I believe is a C90 decoder from Märklin. Same concern is do I need resistors for the existing LED lighting in the locomotive. Again I cannot see resistors already installed inside the locomotive as the lighting circuit boards are not visible and I am concerned about getting access to them.

Someone please respond regarding the need or not of resistors for the lighting of this locomotive with an ESU LokSound 5 Micro. From what I can tell there are 5 LEDs wired in parallel when in forward and when in reverse. Three white LEDs in direction of motion and 2 red LEDs on opposite side of direction of motion - this reverses with direction changes.

I did find a YouTube video on the Köf II conversion for this locomotive with this decoder, however as it was in German I did not understand what was being said, plus it did not appear that any resistors were added for the lighting.