I have a DCC/Sound equipped locomotive that I purchased last year. The seller elected to cut the wiring harness between the locomotive and tender vice modify the foam in the box. I am looking to reconnect the wires. The locomotive is equipped with what I think is a TSU-750. The headlight and backup light were grain of wheat bulbs (really small). I have been able to determine which wire connects to which other wire, with two exceptions. The headlight wires.
Question:
Does the Soundtraxx decoder care which side of the lightbulb is the connected to the capacitor and which side is connected to the function output. My initial thought is no. Just want to confirm that before I bring a soldering iron near the locomotive.
I only want to do this once, and Im going to put micro plugs on the wires so I dont have to do this ever again.
No, a bulb does not care about the direction of the current.
Just make sure we are "not" talking about LEDs!
Reinhard
From a Google search.
https://www.google.com/search?q=soundtraxx+micro+tsunami+decoder&source=lnms&tbm=isch&sa=X&ved=0ahUKEwi5mPXSxdDZAhXo5YMKHQQyA-0Q_AUIDCgD&biw=1024&bih=655&dpr=1.25#imgrc=ZVN97JH1NL689M:
Edit. The SoundTraxx website has documents also.
There is a Yahoo DCC SoundTraxx DCC Group with many decoder documents you can join.
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.
Incandescent bulbs do noot care about polarity. The two wires should be the blue wire and the white wire. An LED DOES car - for an LED, the blue is the + side and the white would be the - side.
A resistor is required for the LED. It MIGHT be required for the incandescent bulb. It does not matter which side of the circuit the resistor is in, the blue or the white, but it's a good idea to be consistent throughout the installation. Resistors don't care which way they are connected either, so even if you could somehow determine which end is which, it doesn't matter.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
The past few years I have read that some put in a 1/2 watt, 22 ohm resistor to limit the surge current when turning on the light with bulbs. That is what usually shortens light bulb lives.
Make sure the bulbs are 12 volt and not 1.5 volt.
It's actually the decoder you are protecting, not the light bulb. When cold, incandescent bulbs have an inrush current that can exceed the rating of the function output. A bulb rated at 15ma at 12 volts will draw 15ma - but that's the steady state draw, once it's been turned on. Initial inrush can be much higher. The resistor helps reduce that so as not too overload the decoder, while adding minimal additional voltage drop when the bulb is warmed up.
The bulbs were already installed, I know nothing about them. They are very small, around the size of the ball part of a ballpoint pen in diameter. This isnt a new installation, or I would be concerned. As it is a resistor is installed in series with both the headlight and backup light.
The only wires that are really of concern are the ones to the motor. If the track pickups are reversed, it will be fine - unless there are also track pickups int he tender, in which case it will be a dead short. If the motor wires are reverse, it won't hurt anything, but the loco will run opposite the normal direction. Since the lights are incandescent bulbs, the polarity of those two wires won't matter.
Boggles my mind that someone would install a decoder like this, with no plug and socket connection between engine and tender. And then double down on the lack of common sense by not putting a simple slit in the foam for the wires to fit in and just cut them apart.
rrinkerBoggles my mind that someone would install a decoder like this, with no plug and socket connection between engine and tender. And then double down on the lack of common sense by not putting a simple slit in the foam for the wires to fit in and just cut them apart.
There were plug and sockets of sorts on some of the wires, on this and other locomotives. The original owner was deceased, and his club was unaware that this locomotive had plugs on some of the wires (the club handled the auction and layout dismantling for the family).
IIRC: The blue common wire is the positive. The function outputs are actually ground which complete the circuit. With LEDS the leg with the long lead is the +You can use 14v, 12V or 1.5V. Some people claim 12Volt bulbs will melted their housing. The 14v and 12v bulbs have a much longer lifetime than the 1.5V which requires a higher current to glow. Current heat is what kills the bulb.
Don - Specializing in layout DC->DCC conversions
Modeling C&O transition era and steel industries There's Nothing Like Big Steam!
DigitalGriffinSome people claim 12Volt bulbs will melted their housing.
Un-likely in this case, as the melting point of the housing material in question is 1652 degrees F....the solder on the other hand, has a bit lower melting point.
Thank you all for your responses.