Installing a sound decoder - 3
uses, as you will need to know this later. The decoder must be
mounted far enough forward so the wires will not get caught in
any moving parts, and there must be enough room around the
motor for the cable to the tender and a couple other wires to
pass freely.
If the decoder will fit in the boiler, proceed to the next para-
graph – if it will not, it will be covered in the paragraph entitled
“Decoder in Tender.”
Lighting functions
First, decide on what lighting effects you want to use. Then we can
discuss the actual wiring and soldering in the next section after you
have all the components ready to hook up.
Most steam locos had a single headlight but some, like the SP
Daylight 4-8-4s and others, had a Mars light as well. In addition,
many people have also installed a golden white LED at the rear of
the firebox to simulate the flash of the oil burner flame, using the
“Firebox Flicker” option of the Tsunami. I have also wired in a few
classification lights on the front, as well as cab interior lights.
The Tsunami is a four-function decoder, meaning it has provi-
sion for a headlight and a backup light, plus two additional
lighting options using functions 5 and 6.
Determine which lighting you want and whether you want LEDs
or incandescent bulbs. Most steam loco headlights need to be
drilled for a bulb.
The small 1.5-volt bulb is the easiest to use, but it will need a
dropping resistor, since decoder lighting functions deliver 12
volts. A 1/16” drill works well for the 1.5 volt bulb and you may
need to drill the backup light as well.
CAUTION!
Drill slowly and gently, or you will rip the headlight
off its bracket!
TIP:
on any engine with two headlights, use the same lighting
for both of the lights, either LEDs or bulbs. An LED next to an
incandescent bulb looks odd and not prototypical. A white fire-
box LED can be placed at the rear/center of the firebox on oil-
burning engines, but after you determine the best spot for it, it
will be easier to mount it if it is wired first.
If your engine has interior cab detail and a full backhead, a light
mounted on the cab ceiling is easy to wire up, and looks cool
when the engine is standing still at night. We will cover the actual
wiring of the lights in the section, Soldering and Splicing Wires.
Loco/tender cable
You will need to determine a safe path for the cable to the ten-
der. This is a critical part of the job, and if not done properly,
can cause derailments and other weird problems!
In 99% of decoder installations, with the decoder in the engine
and a tender with a backup light, a four-wire cable will do the job
– you need two wires to the speaker, two wires to the backup
light. However, if the decoder must be mounted in the tender
or if space is at a premium, TCS makes a subminiature six-wire
“The decoder must be mounted far enough
forward so the wires will not get caught in
any moving parts.”
“An LED next to an incandescent bulb looks
odd and not prototypical.”
MRH-Dec 2013
