New Dimensions in Digital Sound Technology
Digital Sound Decoder Installation Notes
This application note describes the installation of a DSD-090LC Digital Sound Decoder into a Bachmann 2-6-6-2 Locomotive. All of
the components are installed inside the tender. No major mechanical modiﬁcations are needed and the entire installation should
only take a few hours.
A 1” speaker is installed under the coal load. The
sound decoder is wired to a standard 8-pin NMRA
connector and plugs into the “DCC ready” connector
in the tender.
Bill of Materials
Stock No. Description
821102 DSD-090LC Digital Sound Decoder
810054 1” Speaker
810119 1” Speaker Gasket (Pack of 4)
810012 Two-pin Microconnector
810037 Heat-Shrink Tubing
810123 NMRA-type 8-Pin Header (pack of 4)
Tools You Will Need ■ Wire Strippers
■ Miniature Screwdriver Set ■ 25W Solder Iron
■ X-acto Knife with #11 Blade ■ Rosin Core Solder
■ 1-1/2” x 3” x 0.040” Styrene Sheet ■ Heat gun
■ Flat Black Paint ■ Tweezers
■ RTV or Silicone Sealant ■ Double-sided Foam Tape
■ 1/4” Drill ■ Pin Vise or Electric Drill
■ 7/8” Forstner Bit or Spade Bit ■ #65 Drill Bit
■ Miniature Files Photo 1
■ Wire Cutters
1. Remove the tender shell by unscrewing the small phillips head
screw on the bottom frame center, near the back of the front truck
(Photo 1). Set this screw aside. Slide the front of the tender shell
forward until you can slide the two tabs at the back of the tender
out of their slots.
2. The coal load is a separate piece that can be removed by sliding a
knife blade under the back of the load and then gently prying the
plastic part loose (Photo 2).
3. With your X-acto knife, cut out a piece of 0.040" sheet styrene that
measures 0.60" x 0.25". Paint this a ﬂat black and glue over the
opening at the bottom of the coal bunker using Gluing the template to the sheet styrene ﬁrst
RTV. Photo 3 shows test-ﬁtting the piece of makes the measuring and cutting easier. Use
styrene before painting. the spade bit to drill the large 7/8” hole (Photo
5). If you do not have access to a Forstner or
spade bit, you can drill several smaller holes
and trim the excess away with a hobby knife.
4. Drill a 1/4" hole in the back of the coal bunker
for the speaker wires and connector. (Photo4) Cut and trim the outer edges. Test ﬁt the plate
Since this piece of plastic is simply glued in in the tender. File the rear edge at a slight
place, it is a good idea to make a small pilot angle to match the back of the bunker for a
hole ﬁrst so as not to 'snag' the plastic. Drill perfect ﬁt.
from the bottom of the tender shell to avoid
the screw boss. 6. Cut approximately 2.75" from each of the
purple wires on the DSD-090LC. This should
leave roughly an inch of wire still attached to
the decoder. Strip 1/8" of insulation from both
ends of the two 2.75" lengths of wire. Tin the
ends and set aside.
7. Trim the leads of the 33 uF, 16V bipolar
capacitor to 1/2” (Photo 6).
5. Create a speaker mounting plate from 0.040”
styrene using the template provided.
Speaker Plate - 0.040" Styrene
8. Solder one of the 2.75” purple wires you cut
in Step 6 to one lead of the capacitor. Solder
the other capacitor lead to one of the speaker
terminals, putting a small piece of tape under
0.36" the connection to insulate it from the back of
0.66" the speaker.
9. Solder the other length of purple wire to the
other speaker terminal. Slide a piece of shrink
tubing over your connections and shrink with a
heat gun, being careful not to point directly at
10. Solder one speaker wire to the solder terminal
of the male Microconnector (Photo 9). Solder
the other speaker wire to the remaining male
Microconnector terminal. Slide heat shrink
tubing over both connections and shrink with
the heat gun.
14. Strip and tin the remaining length of purple
wire still attached to the DSD-090LC. Slide a
piece of shrink tubing over each piece.
15. Solder of these purple wires to the solder
terminal of the female Microconnector. Solder
the purple speaker wire to the remaining
female Microconnector terminal. Slide the heat
Photo 8 shrink tubing over both connections and shrink
with the heat gun, being careful not the heat the
11. Peel the backing off of one side of the self- decoder itself.
adhesive speaker gasket with a pair of tweezers.
Line up the gasket with the rim of the speaker 16. Following the diagram below, solder the
and press into place. Peel off the remaining remaining decoder wires to the 8-pin
backing from the gasket. Line the speaker up connector. Since you will not be using either
with the hole cut in the center of the speaker the brown or yellow wires for this installation,
plate and press into place with the speaker trim these wires back to about an inch and tape
terminals oriented toward the tab as shown in the ends to the side of the DSD so they will not
Photo 9. short to anything.
Solder wires to ‘cup’ side
of 8-pin connector
Motor Right (Orange) Right Rail (Red)
Rear Light (Yellow) Function Common (Blue)
Not Used Headlight (White)
Left Rail (Black) Motor Left Gray
NOTE: If you wish to use a cam to synchronize the
exhaust or use the DSD-090's lighting effects, do
12. Slide the two-pin speaker connector through not cut the yellow or brown wires! The yellow wire
the hole in the coal bunker that you drilled in can be used to hook up a tender backup light if
Step 4. you wish; connect one buld lead to the yellow wire
and other to the Blue, or Funtion Common wire.
13. Mount the speaker assembly in the coal The brown wire connects to your cam.) Insulate
bunker as shown in Photo 10. Run a bead of your connections.
RTV around the edges of the mounting plate
being careful not to get any on the face of the 17. Remove the dummy plug on the Bachmann
speaker. Set aside to let the RTV dry. PCB and plug the 8-pin connector into the
exposed socket. The red wire should line up 17. CV Programming
with the 8 marked on the Bachmann PCB. Most of the sounds from the DSD-090LC will
not need to be changed. The default address is
18. Mate the two-pin female connector on the 3. You may wish to change the address of the
DSD-090 to the two-pin male connector decoder by changing CV1 (see your command
coming through the hole in the coal bunker. station manual for instructions).
15. Attach the DSD-090LC to the tender roof, on You may wish to make adjustments to the
the opposite side of the tender from the 8-pin Auto Exhaust Chuff Rate (if you have not
connector, with Velcro or foam tape (Photo11). installed a cam). Auto-Exhaust automatically
generates an exhaust chuff rate proportional to
the throttle setting. Since every locomotive is
different, CV 116 is used to match up the Auto
Exhaust rate to the locomotive speed and may
be loaded with any value between 0 and 127.
Higher values will yield higher chuff rates for a
given throttle setting. A typical synchronization
rate may be computed as:
CV Value = 115.9 X ———
16. Before you reassemble the locomotive, inspect where SPD is the locomotive’s top speed in
your work for mis-wires, shorts, broken or scale miles-per-hour at full throttle and DIA is
nicked wires. the locomotive’s driver wheel diameter in scale
17. Before replacing the coal load insert in the
top of the tender shell, drill some small holes If you don’t know your locomotive’s top speed,
in the 'coal' with a #65 drill. Space your holes you can also estimate it and still get pretty
approximately 1/4" apart and drill 30-80 holes good results. A good rule of thumb is to use 45
at random angles so they will not be visible. MPH for freight locomotives and 70 MPH for
Replace the coal load in the tender shell. passenger engines.
17. Replace the tender shell. Be careful that the Here are some suggestions for CV settings to
wires are not caught between the tender shell get you on track.
and the frame. Replace the screw you removed
in step one. Complete the connection between CV 2 Start Voltage 20
the locomotive and the tender by plugging in CV 112 Articulated Exhaust 129
the two small orange connectors. CV 116 Chuff Rate 34
CV 115 Whistle Selection 1, 2 or 3
18. Put the locomotive and tender on the
programming track and check for shorts.
The LC Series Owner’s Manual Software
Release 2.00 is available for download at our
web site (www.soundtraxx.com/dcc/docs.
html). This manual will give you additional
information regarding CV set up and
customizing the decoder for your operations.