I installed tsunami decoder in my sd70 mac and burned out some bulbs in the process not thinking I needed resistors. what is the mm of bulb that I need for this athearn gen model and what ohm resistors do I need to install with it or should I just replace with led's? Also can anyone explain exactly how to test my loco to see if the motor is isolated from the frame. I like the looks of the bulbs over the led's but how big of a pain it is to replace sd 70 lights leds might be more logical for the longevity. I am learning slowly and expensively how to work on my own trains. I figure it will save me in the long run knowing how to do all of these tasks. I have been great at frying decoders and burning up bulbs. Thanks
scott
If you are using the board replacement Tsunami decoders they have provisions for hooking up 1.5v bulbs without the need for additional resistors.
I have used Minitronics 1.5v replacement bulbs.
Good practice when installing decoders is to use a 1.5v battery to test your bulbs to see how bright they are before wiring in to the decoder and having flash bulbs.
Mike Tyl
If there are 2 wires going to the motor, it is isolated from the frame. The light bulbs should be 1.2MM size.Miniatronics sells these. The instructions that came with the decoder should tell you what resister to use. I think around 750 to 1,000 ohm 1/4 watt will work. If you get the Tsunami board style for Athearn units, they have the built in resisters for 1.5v bulbs. For the SD70MAC it should be part # 828052. Joe
What decoder did you use?
The decoders come with full instructions. I have the shrink wrapped and board type Tsunami and the instructions are very clear.
There are even some decoders with resistors for LED's but I do not think it is for your loco.
I am sure you know now, never, ever assume with DCC. There are many variables.
By the way, if you have a decoder with 1.5 volt connections. those will not work for LED's. Some have tried.
Some confuse LED's with light bulbs.
Below is a link you should look at,
http://www.members.optusnet.com.au/nswmn1/Lights_in_DCC.htm
A simple Google search or ask here, first would have been better. Many times I have found that a Google search got me an answer a lot quicker.
Rich
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.
The decoder I used was a board style tsunami type I believe the 710 style that is suited for the sd 70 series locos. I followed all the steps In the instructions assuming that the motor was isolated from the frame of the unit, it does have two wires red and grey that lead to the motor from the old decoder. and the bulbs that I used were factory bulbs so I know they are not led bulbs but I don't know if they are 12-14 volt bulbs how do I test that? I soldered everything nice and neatly and used heat shrink around all my connections. I hooked all the commons up to the 1.5volt area on the decoder including ditch lights. I guess I can't understand what went wrong. I sent the decoder back to soundtracks because it just wasn't working.