Installing a sound decoder - 2
handling and even wrapping the engine in plastic sheeting such
as Saran Wrap while working on it, any paint job should with-
stand installing a decoder with minimal touch-up.
(B)
Open-frame motors are not suitable for use with a decoder
– they arc too much at the brushes and usually draw too much
power. If your engine has an open-frame motor, replace it with
a good can motor.
I have had excellent results with the Alliance “Helix-Humper”
motors, and have also used them in my own engines with
decoders, but there are plenty of others on the market to
choose from. Just be sure to do a “stall current test” to make
sure it does not draw more current than the decoder can han-
dle. You can do this on the bench using a multimeter with a
regular power pack before you install it the motor your engine,
as described in the decoder instructions.
(C)
It helps if the tender comes apart! Surprisingly, there are
many Vanderbilt tenders out there that are completely sol-
dered together, and “breaking into them” can mean resorting
to brutal measures. I have had to cut large holes in the bot-
tom of one-piece Vanderbilt tenders to install a decoder and
speaker, and this tested my metal-working skills to the limit.
(D)
Lastly, your engine must be tested on analog DC power
before starting the decoder install. Clean all the wheels and
make sure it runs smoothly and quietly, with no binds, stalling
or shorts. It is much easier to troubleshoot an engine on analog
power than it is with the decoder installed, so give it a thor-
ough checkout before you begin the decoder installation, and
correct any problems that come up.
When items A through D have passed muster, we are ready to
begin the preliminary work of:
(1)
deciding where to mount the decoder,
(2)
what lighting functions we want, and
(3)
where to run the cable to the tender.
This is a good time to check the available space inside the
boiler for the decoder. If there is a boiler weight inside, remove
the smoke box front by prying it off, then the screw holding the
weight in, and drop it out the front.
By setting the engine upside down and looking into the front of
the boiler while shining a light down into the firebox area, you
should be able to see how much room you have.
Begin by removing the boiler from the frame, usually with
one screw through the bottom of the cylinder saddle and two
screws at the back or underside of the cab.
With the boiler removed, if the engine has a constant-lighting
unit for the headlight, remove it. Then make sure one side of
the headlight bulb is not “grounded” to the boiler—both leads
must be electrically isolated before connecting to the decoder.
Normally there is a wire running from the draw bar to one side
of the motor, so cut that wire but note which motor terminal it
“Open-frame motors are not suitable for use
with a decoder – they arc too much at the
brushes and usually draw too much power.”
“Surprisingly, there are many Vanderbilt ten-
ders out there that are completely soldered
together, and 'breaking into them' can mean
resorting to brutal measures.”
MRH-Dec 2013
