MTHTrains MTH SD-70 User manual

R
ELECTRIC TRAINS
MTH SD-70 MAC DIESEL ENGINE
OPERATING INSTRUCTIONS
Thank you for purchasing the MTH Electric Trains SD-70 MAC diesel
locomotive. This ¼” scale reproduction of the famous SD-70 MAC
locomotive measures over 18” in length and weighs almost 6 pounds.
Despite its scale size, the locomotive is capable of operating on O-31 3-rail
track with any compatible AC transformer, (see page 34 for a complete list
of compatible transformers and wiring instructions) and is completely
compatible with most other 3-rail locomotives, rolling stock and
accessories.
The locomotive is equipped with several deluxe features that are simple
and fun to operate. Each feature is described among the following pages
which should be read before the engine is operated. For those of you who
can’t wait to get started, the Quick Start Operating Instructions, found on
page 3, should be read so that you understand the basics of the operating
system. Those features marked for 2 and 3-rail engines are available in
both types of engines. Features not marked as such are only available in the
3-rail version.

2
MTH SD-70 MAC Diesel Operating Manual
Table Of Contents
QUICK START - BASIC OPERATION(All 3-Rail Models) 3
PROTOSMOKE™ UNIT OPERATION 4
PROTOSOUNDS® OPERATING INSTRUCTIONS 5
ProtoSound® DCRU® Reverse Unit Operation (All 3-Rail Models) 5
Horn Operation 6
Bell Operation 6
ProtoCoupler Operation 7
Cab Chatter Sounds 8
Squeaking Brake Sounds 8
Tips On Using The Squeaking Brake Sounds 9
Freight Yard Sounds (FYS) 10
Activating and Triggering Freight Yard Sounds 10
Tips On Using FYS Features 15
Self-Recharging Battery Backup System 16
Replacing The ProtoSound® Battery 16
ProtoSound® Volume Adjustment 17
USING “RESET" TO PROGRAM PROTOSOUNDS® 18
Entering RESET Options 18
Setting The Engine Volume 19
Programming For A Separate Bell Button Controller 20
Programming For Squeaking Brake Operation 20
Programming For Horn In Neutral Operation 21
Programming For ProtoCoupler Operation 22
Programming For FYS Operation 23
Activating Remote Lockout Control 23
Programming For Cab Chatter Sounds 24
ResettingAll ProtoSound® Options To Factory Default 24
REVERSE UNIT LOCK-OUT OPERATION 25
Locking The Engine Into Forward or Reverse 25
Unlocking The Engine 25
Locking The Engine Into Neutral 25
OIL & LUBRICATION INSTRUCTIONS 27
TRACTION TIRE REPLACEMENT INSTRUCTIONS 28
LIGHT BULB REMOVAL & REPLACEMENT 29
TROUBLE SHOOTING PROTOSOUND® PROBLEMS 30
ProtoSound® RESET Feature Chart 33
Transformer Wiring Chart 34
SERVICE AND WARRANTY INFORMATION 35
HOW TO GET SERVICE 35
LIMITED ONE YEAR WARRANTY 35

3
MTH SD-70 MAC Diesel Operating Manual
QUICK START - BASIC OPERATION
The MTH SD-70 MAC contains state-of-the art electronics with several
built-in automatic features for incredibly realistic operation. Despite these
advanced features, the SD-70 MAC is easy to operate with any compatible
standard AC transformer (see the compatibility chart on page 34). All
models are equipped with an operating smoke system that should be primed
with smoke fluid before operating. Adding 20 - 25 drops of fluid through
the smoke stack should be sufficient. If you choose to not prime the units
with fluid,turn the smoke unit switch located under the trailing truck to
the OFF position. (See Figure 1) This will prevent any damage from
occurring to the smoke unit when running the engine without a primed
smoke unit. For more information see the section on page 4 on Smoke Unit
operation.
The SD-70 MAC model is controlled
by a ProtoSound® DCRU® electronic
reverse unit. The reverse unit operates
in the same manner that all reverse units
function by using forward, neutral and
reverse states that are entered each time
the throttle is turned on and off or by
using the transformer direction switch (if
so equipped).
The reverse unit is designed to ignore
dirty track, dead spots on switches
or minor short circuits without
disrupting the engine operation,
even at slow, prototypical speeds.
Once the engine is placed ont the
track, the transformer throttle can be
advanced. You will see that only the engine’s lights come on and two dings
from the sound system will chime followed by the air compressor pump
sounds. The engine does not run. This is known as the RESET state and is
explained in more detail beginning on Page 5. The ProtoSound® DCRU®
will not power the motor until the throttle is turned OFF and then ON again.
At this point, the engine will now function just like any other electronic or
mechanical E-unit.
Smoke Unit
ON/OFF Switch
Figure 1: Locating The Smoke Unit Switch
RESET
Neutral
Reverse
Neutral
Forward
Figure 2: ProtoSound® DCRU® Cycle Phases

4
MTH SD-70 MAC Diesel Operating Manual
PROTOSMOKE™ UNIT OPERATION
(2 and 3-Rail)
The SD-70 MAC contains a self-powered smoke unit that outputs a steady stream of smoke
through the smoke stack on the roof of the engine. The ON/OFF switch located next to the
trailing truck must be in the ON position in order for the smoke unit to function. See Fig. 1 on
page 3.
The smoke unit is essentially a small heating element and wick which soaks up and then
cooks" a mineral oil-based fluid that omits a harmless smoke. The smoke is then forced out
of the stack via a small electric fan which runs at a constant speed. However, the smoke
intensity can be varied by increasing the transformer voltage setting. The higher the setting,
the more intense the smoke output.
For best results, we recommend that you add 20 - 25 drops of ProtoSmoke, Seuthe, LGB or
LVTS fluid before you run the engine. If you dont choose to add the fluid, then the smoke
unit switch should be turned off. Failure to either add the fluid or turn the switch off could
lead to damage to the smoke unit heating element and or wicking. Add the fluid through the
smoke stack hole. After adding the fluid, gently blow into the stack to eliminate any air
bubbles. Do not overfill the unit as overfilling can cause the fluid to leak out and coat the
interior engine components. When the smoke output begins to diminish while running the
engine, an additional 20-25 drops of smoke fluid should be added or the smoke unit switch
should be turned off. When storing the engine for long periods of time, you may want to add at
least 20 drops of fluid to keep the wick soaked with fluid and prevent it from drying out. After
removing the engine from storage, it is advisable to add another 25 drops of fluid, letting the
wick soak up the fluid for 15 minutes prior to operation.
SMOKE UNIT MAINTENANCE (2 and 3-Rail)
CAUTION: Operating the engine without smoke fluid and with the smoke unit switch in the
ON position can damage your smoke unit wick, causing the wick to become hard, blackened
and unabsorbant around the heating element. When this
occurs, it may be difficult for the wick to soak up the
smoke fluid resulting in poor or no smoke output. If
that occurs, we recommend that you inspect and/or
replace the wick taking care to not run the engine
without fluid in the future. You can inspect the wick to
see if it needs replacement by removing the smoke unit
inspection cover from the body as seen in Fig.2. After
removing the chassis and inspection cover screws lift
the inspection plate away and inspect the wick. If the
wick is darkly discolored and hard, it should be
replaced.
Smoke Unit
Circuit Board
Mounting Screws
Smoke Unit Frame
Mounting Screws
Figure 2: Inspecting The Smoke Unit

5
MTH SD-70 MAC Diesel Operating Manual
PROTOSOUNDS® INSTRUCTIONS
The MTH ProtoSound® digital sound and train control system provides
the operator with unprecedented realistic operation on your model railroad.
In addition to actual diesel engine, CD-equivalent 16-bit digital sounds,
you get the following features:
*
Built-In ProtoSound® DCRU® Reverse Unit * Authentic Diesel Horn Sound*
Authentic Diesel Bell Sound* Squeaking Brake Sound* Freight Yard Sounds*
Operating Remote Controlled ProtoCoupler™* Self-Recharging Battery Back-
Up System With Automatic Battery Shut-Off* Remotely Controlled Reverse Unit
Lock-Out* Remotely Adjustable Diesel Engine Volume* Authentic Cab Chatter
Neutral Sounds* Authentic Diesel Engine Startup & Shutdown Sounds *
Each feature is described among the following pages. Though the system
is easy to use, we encourage you to read the instructions thoroughly.
PROTOSOUND® DCRU® REVERSE UNIT
As mentioned in the Basic Operating section, the engine is controlled by a
DCRU® reverse unit that contains the standard forward-neutral-reverse
states found on most reverse units. However, as described earlier, when
power is first applied to the track, the reverse unit begins in RESET or what
seems like a neutral state. Power must be interrupted again to get the
locomotive to enter the forward state. It is this first RESET state that gives
ProtoSound® its unique, remote controlled functions. The system will enter
RESET whenever power to the track is off for three or more seconds.
NEUTRAL will be referred to as the state between Forward and Reverse.
ProtoSounds® is equipped with a microprocessor, that, depending on the
amount of memory it is allotted, allows the user to utilize several remotely
activated functions. In the simplest terms, ProtoSounds® has its own
“Computer" controlling these functions. In fact, the power of this
microprocessor is the same as that of a 286 desktop computer! In order to
access many of these remotely controlled functions, the user must be in the
RESET state to do so. RESET is entered anytime power to the locomotive
has been off for more than 3 to 5 seconds. When the engine first enters
RESET, the microprocessor initiates a system check to determine if the
system, transformer and engine are operating correctly. This takes
approximately 2.2 seconds during which you will hear the engine’s startup
sounds begin. In order for ProtoSounds® to properly initiate the system
check, do not advance the transformer throttle past 10 volts when you first

6
MTH SD-70 MAC Diesel Operating Manual
enter RESET, wait for the diesel startup sounds to begin and then slowly
turn the transformer throttle to the off position and then back on again to
enter the forward phase. Interrupting the power too quickly may cause the
system to re-enter RESET (signaled by two dings of the bell). Should this
happen, wait longer before interrupting the power to enter the Forward
phase.
ProtoSounds® comes with several programmable functions, including
remote Diesel Engine Volume Adjustment, Separate Bell Button Operation
(pre-programmed at the factory), Horn In Neutral Operation,
ProtoCoupler™ On/Off Control, Squeaking Brakes and Passenger Station
or Freight Yard Proto-Effects. Each of these features are described in more
detail later. You will notice that when in RESET, your engine will not
respond to the whistle button with a horn blast or continuous bell ringing.
In fact, when in RESET and the whistle button is depressed, only one single
bell chime will be heard each time the whistle button is pressed. If you
don’t want to configure or change your locomotive using any of these
programmable features, simply leave RESET and wait 2.2 seconds before
interrupting the power to put the engine in forward. After you leave
RESET, your engine will operate normally in all the direction states of
forward, neutral and reverse. Remember though, once power is turned off
for more than 3 seconds, the next time power is applied to the track, your
engine will be back in RESET.
HORN OPERATION
Your SD-70 MAC ProtoSound®-equipped engine is equipped with a
digital recording of a diesel horn. The horn sound can be activated anytime
the engine is in forward or reverse by pressing the whistle button on your
transformer. The horn will continue to blow as long as the whistle button is
depressed. The horn will not function in RESET and must be configured
through a RESET option to allow the whistle to work when the engine is in
neutral. See page 21 for information on horn programming in the Using
RESET To Program ProtoSounds® section of this manual.
BELL OPERATION
Your SD-70 MAC ProtoSound®-equipped engine is equipped with a
digital recording of an actual diesel engine bell. The bell can be turned on
or off with any separate bell button, like the Lionel® Railsounds® No. 5906
Bell Button, by simply pushing the button. If you don’t have a separate

7
MTH SD-70 MAC Diesel Operating Manual
bell button, the bell can be controlled through your transformer’s whistle
button whenever the engine is in NEUTRAL. The bell will never ring
continuously in RESET (Remember NEUTRAL is the state between
Forward and Reverse). Once the bell is turned on, it will continue to ring
when the engine is cycled into forward or reverse until you press the bell
button or re-enter NEUTRAL and turn the bell off with the whistle button.
In fact, because of ProtoSounds® state-of-the-art design, the
microprocessor remembers its last command. Therefore, unless you turn
the bell off before you quit running your train, the next time you run the
engine, the bell will come on. No matter whether you come back an hour
later or a year later, the bell will begin chiming once the engine enters one
of the three directional states.
To turn the bell on using the transformer’s whistle button, turn on power to
the track and cycle the engine into NEUTRAL. Turn the throttle to 8 volts
or less (any higher voltage will arm the ProtoCoupler™) and press the
whistle button. The bell should begin chiming. To turn the bell off, press
the whistle button again. If you want to keep the bell on while running the
engine, simply interrupt the power with the transformer throttle or the
transformer directional switch and enter forward or reverse.
PROTO-COUPLER™ OPERATION
Your SD-70 MAC ProtoSound®-equipped locomotive is equipped with
two coil-wound ProtoCouplers™ for remote uncoupling action. Because
the ProtoCoupler™ is controlled through ProtoSounds® microprocessor, it
doesn’t require an uncoupling track section or modification to your layout
to function. The three simple steps below are required to operate the
coupler.
1. Put your engine in NEUTRAL and turn the throttle all the way up.
2. Press the transformer whistle button to “Arm" the coupler. (You
will hear a “Clank").
3. After arming the coupler, press the whistle button again to open
the coupler.
When the knuckle fires open
you will hear the buzzing of the
coil energizing and the sound of
HH
Ca-Clunk
Cha-Chussshhh
Put Engine In Neutral
At Full Power
Press & Release
The Whistle Button
Press & Release
The Whistle Button
Listen For The
Ca-Clunk Sound
See The Coupler Open
And Listen For The
Cha-Chusshh Sound

8
MTH SD-70 MAC Diesel Operating Manual
the air lines coming apart. It can best be described as a CHA-CHUSHHH
sound. The coupler doesn’t have to be fired in NEUTRAL. Once the
coupler is armed it can be fired in Forward, Neutral or Reverse. However,
you may find that the coupler
doesn’t open when firing the
coupler at high speeds. Reduce
the voltage setting on your
transformer if this occurs and
run your engine at a slower
speed before firing the coupler.
If the coupler continues to open
erratically, try lubricating the
knuckle with light oil as
indicated in Fig. 3.
For multiple heading purposes, only one of the two ProtoCouplers™ will
function at any one time. Use the coupler direction switch as shown in
Figure 3 on page 17 to select either the front or rear coupler. Simply slide
the switch toward the direction of the coupler you want to make active.
NEUTRAL-ACTIVATED CAB CHATTER SOUNDS
Your engine is equipped with four dispatacher-to-engineer “Cab Chatter”
radio transmissions that occur every 2 to 30 seconds. Each sequence will
play at random intervals to eliminate repetition. While the sounds are
selected to play randomly by the microprocessor, there is no guarantee that
you won’t hear the same message repeated twice or more times.
SQUEAKING BRAKE SOUNDS
ProtoSound® equipped engines feature the ability to play the sound of
squeaking brakes whenever your engine slows in speed. There are two
settings for activating the squeaking brake sounds. The default setting
allows the brake sounds to play while the engine is in forward or reverse
and the transformer throttle is lowered from a high setting to a low setting
(14 volts to 8 volts or less). The
second setting requires that a bell
button be used to “arm” the
brake feature and is explained in
more detail in the “Activating
Freight Yard Sounds” section
Lubricate
Coupler
Knuckle
Figure 3: Lubricating The ProtoCouplers
Squeeek
Throttle Down From
High Voltage To Low
Listen For The
Squeaking Brake Sounds

9
MTH SD-70 MAC Diesel Operating Manual
found later in this manual. The sound itself is a stored record on the
ProtoSounds® software chip and will always play the same brake sound for
the same three second length each time the voltage is reduced from high to
low. Some practice may be required to synchronize the playing of the brake
sounds with the movement of the engine. It is not uncommon for the engine
to stop before the brake sound is completed. Operators will find that by
coordinating the movement of the throttle setting from 8 volts to off will
allow the engine to maintain its movement while the brake sounds play.
Note: The brake sounds will not be heard if the transformer throttle is not
set above 14 volts and/or not reduced below 8 volts.
TIPS ON USING THE SQUEAKING BRAKE FEATURE
Because the squeaking brake feature always plays for approximately 3
seconds, it is possible that the brake sounds will play longer or shorter than
what visually seems prototypical. You will find that by practicing with the
brake feature, you can quickly determine how quickly to throttle down and
what speeds and voltage settings give you the most prototypical braking effect.
Typical users will find the feature to be a very realistic way to simulate the
sound of an engine slowing down for curves, crossings or coming to a stop at a
station, side track or switch yard. As mentioned above, you will find that
initially your engine may continue to play the brake sounds once your engine
comes to a stop or that the sounds stop prematurely before the engine comes to
a complete halt. For example, if you simply run the engine and turn the throttle
off quickly, the brake sounds will likely continue playing even though the
engine has come to a complete stop. This annoying effect can be eliminated by
simply practicing with the brake feature. In no time, you will quickly learn
how to feather" the throttle to keep the engine moving while the brake sounds
play and then turning the throttle off just as the sounds stop. Remember that
once you stop the engine, you should turn the throttle to the off position if you
dont want to activate the Freight Yard Sounds feature described later in this
manual.
The ProtoSound® squeaking brake feature also has the ability to simulate the
squeal of wheel flanges when your train enters a curve at high speeds. The
same brake squeaking sound plays, but you dont need to reduce the
transformer throttle to activate the squeaking sounds. To play the squeaking
sounds as wheel flange sounds, trigger the brake feature using either method 1
or 2 above. Once triggered set the transformer throttle setting at 14 volts or
higher. As your engine enters a curve (or anywhere on the layout) quickly
flick" your transformer whistle button about half way. This flicking" action
causes the transformer to release a short DC signal that ProtoSounds® reads as
an indicator to activate the brake sounds. The engine wont slow down even
though the sounds play. This simulates the wheel flange squeal of a train
traveling through a turn too quickly.
Note: Consistent activation of the wheel flange squealing is determined by the
condition of your transformers whistle button rectifier disc. Older rectifier
discs may need to be replaced in order to play squealing sounds.

10
MTH SD-70 MAC Diesel Operating Manual
FREIGHT YARD SOUNDS (FYS)
ProtoSounds® comes equipped with operator controlled Freight Yard
Sounds, hereby referred to as FYS. This easy to use feature plays digitally
reproduced freight yard sounds whenever your engine stops on your layout
and is parked in the Neutral position. No additional wires or modifications
are needed on your layout to enjoy these amazing sound effects. The
sounds themselves are randomly generated and randomly “shuffled” on the
ProtoSounds® software chip. This gives the system the ability to produce
different sounds in a different order each time FYS is enabled. These
different sounds are heard each time you cycle the transformer throttle from
ON to OFF in the same manner that you would cycle the throttle to enter the
various states of Forward, Neutral and Reverse. The entire FYS sequence is
designed to simulate the arrival, loading or unloading and departure of a
freight train in a freight yard. Each sequence is described in more detail in
the following sections.
USING FREIGHT YARD SOUNDS
Your ProtoSound® equipped engine features an operator controlled freight
yard sound set. Once activated, this easy-to-use feature plays the sound of
freight yard activitities whenever the operator parks the engine in the
neutral position.
ARMING THE FREIGHT YARD FEATURE
Before FYS can be heard, ProtoSound® must be told to activate the
feature the next time the engine enters the neutral position. This can be
accomplished in one of two ways.
Option 1: If you are using a separate bell button controller to ring your
bell (like the Lionel® Railsounds® number 5906 bell activation button),
you can activate the feature by pressing and holding down the bell button
for three or more
seconds (it doesn’t
matter if you are in
Forward, Neutral or
Reverse). You will hear
the bell chiming turn on
and if you listen
Ding, Ding
Psshhee
Put Engine In Neutral,
Forward or Reverse
Press & Hold
The Railsounds® Bell Button
For 3 Seconds
Listen For The
Start Of The Bell Sound
Listen For The
Air Release Sound
After 3 Seconds

11
MTH SD-70 MAC Diesel Operating Manual
carefully, you should hear an air release sound after three seconds have
passed. At this time you can release the bell button. (Note: because the air
release sound may be difficult to hear, we recommend that you count out a
full three seconds before releasing the bell button.) The bell will continue
to chime, so if you want to turn off the bell ringing, simply press and release
the bell button a second time. If you were in Neutral when you triggered
the brake feature, interrupt the transformer throttle to enter either forward or
reverse and allow the engine to begin moving. (Note: the feature will only
be activated in the first direction state you enter after arming the feature
from the Neutral position. You cannot interrupt the power twice to enter
another direction state and still have the brake feature active.) Once your
engine begins moving, you can trigger the sounds to begin playing
whenever you enter Neutral.
Option 2: If you do not have a separate bell button on your layout, you
can still activate the feature with your transformer whistle button. To
activate the feature, turn on the transformer throttle and get your engine into
the Neutral position (not RESET). Once in Neutral, set the transformer
throttle at 8 volts or less and press and hold the whistle button or at least
three seconds. You will hear the bell chiming begin and if you listen
carefully, you should hear an air release sound after three seconds have
passed. At this time you can release the bell button. (Note: because the air
release sound may be difficult to hear, we recommend that you count out a
full three seconds before releasing the bell button.) The bell will continue
to chime, so if you want to turn off the bell ringing, simply press and release
the bell button a second
time. If you were in
Neutral when you triggered
the brake feature, interrupt
the transformer throttle to
enter either forward or
reverse and allow the
engine to begin moving.
(Note: the feature will only be activated in the first direction state you enter
after arming the feature from the Neutral position. You cannot interrupt the
power twice to enter another direction state and still have the brake feature
active.) Once your engine begins moving, you can trigger the sounds to
begin playing whenever you enter Neutral.
Ding, Ding
Psshhee
Put Engine In Neutral
At Low Power
Press & Hold
The Whistle Button
For 3 Seconds
Listen For The
Start Of The Bell Sound
Listen For The
Air Release Sound
After 3 Seconds
H

12
MTH SD-70 MAC Diesel Operating Manual
ACTIVATING THE FREIGHT YARD SOUNDS
Before FYS can be heard, the feature must be armed as described on the
proceeding pages. Once armed, activating the FYS effects is accomplished
by simply interrupting the transformer throttle and parking the engine in the
Neutral position with track power remaining on. Remember, power to the
track must remain on while the engine sits in Neutral in order for the FYS
effects to operate.
At this point ProtoSounds® has taken over control of your engine and
disabled the bell and whistle buttons from responding to any futher operator
input. In addition, ProtoSounds® has reconfigured the way the reverse unit
functions by disabling the Reverse state during operation of the FYS
effects. This forces the engine to leave your freight yard in the same
direction that it arrived in. The following operator controlled “events”
control FYS’s actions and sound effects.
Event 1 (Forward) While the locomotive is running in forward (or
reverse) FYS is activated by the operator pushing and holding the bell
button down for three or more seconds. The locomotive bell begins
chiming and can be left on or turned off without disabling FYS.
Event 2 (Neural Before Reverse) The operator now interrupts the
transformer throttle to stop the engine and put it into Neutral. If the throttle
setting was at 14 volts or higher , ProtoSounds® will play the sound of
squeaking brake sounds as the engine comes to a halt.
A. Upon stopping of the engine, the operator must immediately turn
the throttle back on to keep the engine in the Neutral position. If the
bell was not turned off after activating
FYS, it now turns off automatically.
Note: Failure to turn the throttle back
on within 3 seconds of leaving the
Forward phase will disable FYS and
shutdown ProtoSounds®. The next time
you turn power back on your engine will
be in the RESET position. See page 5 for more information on
RESET.
Put Engine In Neutral
At Low Power

13
MTH SD-70 MAC Diesel Operating Manual
B. After entering Neutral, ProtoSounds® will immediately play an
air release sound followed approximately 2 seconds later by a man
whistling and a freight car door sliding
open. Immediately following the man’s
whistle, the sound of freight car doors can
be heard opening, followed by the sounds
of freight loading and unloading. At this
point various freight yard sounds can be
heard including the loading/unloading
operation, engine sounds, yardman
“slang”, and additional freight car door
sounds.
Event 3: (Reverse) The operator now interrupts the transformer throttle
again to enter the next reverse unit phase; reverse. In an effort to enhance
realism, FYS has disabled the reverse
phase so that it doesn’t power the motors
causing the engine to move backward.
Upon entering reverse, FYS confirms to
the operator that it has entered the reverse
phase by immediately playing a highlight
sound best described as a rumbling sound.
You may have to go through the entire
FYS sequence several times before you can
clearly identify this sound. After the rumbling highlight is played, the
freight yard sounds heard in Event 2 continue to play randomly.
Event 4: (Neutral Before Forward) The operator now interrupts the
transformer throttle again to enter the next reverse unit phase, neutral before
forward. FYS confirms to the operator that it has entered the neutral before
forward phase by emitting two quick air release sounds. This is followed
approximately two seconds later by a man
whistling and continued freight yard
loading and unloading sounds.
Listen For Air Release Sound
And Cab Chatter Message
Psshhhee
Listen For Engine
Rumbling Sound
Rummmbllle
Interrupt Throttle To
Enter The Next Phase
Listen For 2
Air Release Sounds
Psshee, Psshhee
Interrupt Throttle To
Enter The Next Phase

14
MTH SD-70 MAC Diesel Operating Manual
Event 5: (Forward) The operator now interrupts the transformer throttle
again to enter the next reverse unit phase; Forward. FYS confirms to the
operator that it has entered the Forward phase by playing the sound of the
freight car door closing. Within 2 seconds of the door closing, the
locomotive bell begins chiming. After
approximately 8 chimes of the bell, the
engine begins moving in the forward phase
with the bell continuing to ring another 8
chimes before automatically turning off.
Once the bell turns off, the operator regains
control of the transformer whistle and bell
buttons and can ring the bell or blow the
whistle as usual.
Note: When entering the Forward phase of FYS, it is important to set the transformer
throttle at a high enough setting that will allow the engine to begin moving once FYS
automatically activates the motors. Otherwise the engine will just sit still until you increase
the transformer throttle setting on the transformer. However, dont set the throttle setting too
high or the engine will go racing away faster than you might expect.
TIPS ON USING FYS FEATURES
FYS is a unique feature of ProtoSounds® that is completely controlled by the
operator. You decide how, when or if you want to utilize the feature. By
reviewing the following tips, you should find solutions or suggestions to the
various operating scenarios you might encounter when using FYS.
Tip #1: You can escape the FYS sequence by interrupting the transformer
throttle before the man whistles in Event 2 (neutral before reverse).
Tip #2: You can terminate FYS at anytime by turning the transformer
throttle Off for 15 seconds.
Tip #3: You do not have to be in the Forward phase to utilize FYS. For
example, if you activate the FYS feature while in Reverse and interrupt the
throttle to enter Neutral, you will be entering Neutral Before Forward rather
than Neutral Before Reverse as defined in Event 2 above. Consequently, the
Forward phase will be rendered inactive by ProtoSounds® instead of the
Reverse phase as explained in Event 3. This will allow your train to leave the
yard in the same reverse direction that it arrived in.
Listen For The Sound
Of Box Door Closing
Clunnkkk
Interrupt Throttle To
Enter The Next Phase

15
MTH SD-70 MAC Diesel Operating Manual
Tip #4: You can utilize FYS even if you are double-heading with another
engine regardless of whether the second engine is equipped with an FYS
programmed ProtoSound® module. If the second engine isnt equipped with
FYS, the only thing to remember is that you not turn up the transformer throttle
very high when entering the Reverse phase found in Event 3. If the throttle is
set too high, then the second locomotive will begin vibrating on the track as its
motors will be turning in the reverse state since they cannot be disabled
automatically like FYS equipped engines. If your second engine is equipped
with FYS, you may want to disable it when used in double-headed operations.
To disable FYS, see the section on programming for squeaking brakes and FYS
operation on page 23 of this manual.
Tip #5: It is not necessary for the squeaking brake sounds to be heard to play
the FYS sounds. for example, the brake sounds wont be heard if the high
voltage setting is below 13 volts when the power is interrupted to enter the
Neutral state.
Tip #6: You can leave any of the event states at any time after entering the
state by simply interrupting the transformer throttle. Any sound effects
programmed to play in that event will simply not occur. The only exception is
Event 2 and Event 5. In Event 2, interrupting the throttle has no effect on FYS
until after the man whistles and the freight car doors have opened. In Event 5,
you cannot interrupt FYS until after the engine begins to move. Interrupting
the throttle before the engine begins to move has no affect on the locomotives
operation.

16
MTH SD-70 MAC Diesel Operating Manual
SELF-RECHARGING BATTERY BACKUP
ProtoSounds® state-of-the-art design includes a self-recharging battery
backup system for improved performance at any speed. The battery ensures
that power to the sound system will remain on during directional changes,
setting RESET options or when travelling over dirty track and switches.
The self-recharging battery backup system is automatically turned on or off
whenever track power is turned on or are off. There no switches needed to
enjoy the benefits of the automatic battery backup system.
ProtoSounds® contains a warning alarm if the battery backup system fails
to automatically disengage when track power is turned off. Should the
backup system fail, you will hear a repeating whistle blast indicating this
has occurred. Should this happen, unplug the battery from the
ProtoSound® module (to prevent the battery from being run down) and
contact MTH for instructions on returning the tender for repair.
REPLACING THE PROTOSOUND® BATTERY
The ProtoSound® battery (located in the tender body, is a special NiCad
7-cell, 8.4v battery - NOT the 6-cell, 7.2v battery found in most
convenience stores. The 6-cell NiCad is NOT recommended for use with
ProtoSound® applications. The battery is continually charged from the
track when power is applied and should last for up to five years. In
addition, the NiCad battery is a dry battery and should not leak or cause any
damage to your locomotive during its lifetiem.
If you notice that the sounds seem distorted or garbled at low voltages or
become silent when power from the transformer is shut off, the battery may
be going bad. Before replacing the battery, you should put the engine in
NEUTRAL and leave the transformer throttle set at about 12 volts for 15
minutes. This should temporarily recharge the battery. If the garbled or
distorted sounds are reduced, then your battery charge has worn down. You
can give your battery a full charge by leaving the engine ON in the
NEUTRAL position for 18 hours. (Make sure the smoke unit switch is in
the OFF position to prevent harm to the smoke unit wicking).
If you need to replace the battery, replacement ProtoSound® batteries are
available from MTH ProtoSound® Electronics at 9693-A Gerwig Lane,
Columbia, MD 21046. A standard 9v alkaline battery can be substituted as

17
MTH SD-70 MAC Diesel Operating Manual
a temporary fix, but since alkaline batteries can’t take a charge, it will
eventually wear down. Regardless, it should give you a week to a couple of
months use while you wait for your replacement ProtoSound® battery to
arrive.
PROTOSOUND® VOLUME ADJUSTMENT
Your ProtoSound® system has two types of volume adjustment. A
manual turn knob on the bottom of the chassis (See Fig. 4 below) allows
you to control all the sounds in the system and a remote control “RESET"
option (Option # 6), allows you to control the volume level of the engine
sounds remotely from the transformer. Turning the volume adjustment
knob clockwise will increase the volume and counterclockwise will lower
the volume of all sounds; bell, horn, engine sounds, Cab Chatter, etc. For
information on operating the RESET volume adjustment option, see the
section entitled “Programming ProtoSound RESET Options” on the
following pages.
ProtoSound® Manual
Volume Adjustment
Figure 4: Adjusting The ProtoSound® Volume and selecting
the ProtoCoupler
ProtoCoupler™
Selector Switch

18
MTH SD-70 MAC Diesel Operating Manual
USING “RESET" TO PROGRAM
PROTOSOUNDS®
As mentioned earlier, there are several programmable options in each
ProtoSound®-equipped engine that can be remotely set from any
compatible standard AC transformer equipped with a whistle button. For a
list of compatible transformers, see the chart on page 34. This hands-off
approach gives you unprecedented control of your railroad empire’s motive
power never before seen in model railroading. Each programmable feature
can be accessed whenever your engine is in the RESET state as described
earlier on page 5. By following the instructions below you will find the
programming easy and straight forward.
ENTERING RESET OPTIONS
ProtoSound® is equipped with a few programmable features that are
accessed in the RESET state by moving the transformer throttle up and
down between full voltage and low voltage (6 to 8 volts) without shutting
the transformer off completely. Each time this is done you advance, one
feature at a time, through the available options. An air-release sound is
heard each time the throttle is advanced. In addition, there are special
sounds to tell you what RESET position you are in.
For example, if you want to select Feature 2, you put the engine in
RESET, and move the throttle up and down from full throttle to low two
times. After the second advance, you will hear two “clinks" indicating that
the computer is now in Feature 2. Advance the throttle again and you will
hear three “clinks" for Feature 3. Advance it two more times and you will
hear a “clank" indicating
that you are now in
Feature 5. Advance the
throttle two more times
and you will hear a
“clank" and two “clinks"
indicating Feature 7. ((5
throttle advancements = 1
clank) + (2 throttle
advancements = 2 clinks)). “Clank + “Clink" + “Clink" = Feature 7. You
can advance the throttle as quickly as you like (though you may not hear the
air-release sounds) and the computer will still remember the number of
Clink, Clink
Clank, Clink
In RESET Mode
Move The Throttle
Up & Down From
High Voltage To Low
2 Times
Advance The Throttle
Up & Down From
High Voltage To Low
4 More Times
Listen For The
2 Clink Sounds
Listen For 1 Clank
And 1 Clink Sounds

19
MTH SD-70 MAC Diesel Operating Manual
times the throttle is advanced by playing back the number of “Clinks" and
“Clanks" to confirm the feature you’ve selected.
SETTING THE ENGINE VOLUME
Of all the sounds that come with each ProtoSound®-equipped locomotive,
the one most often turned down is that of the engine volume because it is
the one sound normally heard whenever the engine is running and is what
usually can become tiresome to the ear over prolonged running sessions.
The volume adjustment is controlled through RESET Feature 6.
To access the feature, advance the transformer throttle to put the engine in
RESET. Move the throttle up and down, as described on page 18, 6 times.
After you hear the “clank" and “clink" indicating that you are in Feature 6,
press the whistle button to select the engine volume level you desire.
Pushing the whistle button once will give you full volume, which is the
factory setting. Pushing the whistle button a second time will give you 50%
volume, pushing it a third time will give you 25% volume and pushing it a
fourth time will give you no sound. The microprocessor will immediately
play the sound level each time the whistle button is pushed so that you can
decide if it is acceptable. You can recycle through the four choices by
simply continuing to
press the whistle button.
Once you have decided
on the appropriate
volume level, turn the
transformer throttle off
and on again or press
the transformer direction switch to lock in your selection. The volume
adjustment will remain set at the level you have chosen until you change it
again. Regardless of the engine volume setting, the horn, bell, compressor
and Cab Chatter sounds will function normally. In fact because only the
engine volume is affected by selections in Feature 6, when you select 0
volume, you can still hear the horn, bell and Cab Chatter sounds when the
engine is running or in neutral.
Clank, Clink
In RESET Mode
Move The Throttle
Up & Down From
High Voltage To Low
6 Times
Listen For 1 Clank
And 1 Clink Sounds
Push The Whistle Button
Until You Reach The
Setting You Desire
Interrupt The Throttle
To “Lock-In”
The Volume Setting
H

20
MTH SD-70 MAC Diesel Operating Manual
PROGRAMMING FOR A SEPARATE BELL BUTTON
CONTROLLER
To operate ProtoSounds® with
a separate bell button controller,
like the Lionel® No. 5906 bell
button, you will need to wire up
the controller to your
transformer and track as shown
in Fig. 5. Once the button is
wired, ProtoSounds® comes
preprogrammed to allow you to
operate the bell by simply
pushing the bell button once.
To turn the bell off, push the
button again. If the bell doesn’t’t function when you press the button, you
may need to re-program ProtoSounds® to operate with a separate bell
button controller. To do this enter RESET and go to Feature 20. (See the
section Using RESET To Program ProtoSounds®on page 18.) Once in
Feature 20, press the whistle button and wait for the module to sound a bell
ding(s). Continue
pushing the whistle
button until the module
plays back two dings
(signifying that the
module has been
programmed for a bell
button). Simply turn the
throttle off and then on again to “Lock-In" the new setting. To reset the
computer to its original factory (default) setting (no separate bell button
operation), repeat the above procedure but keep pushing the whistle button
until the computer only responds with one bell ding.
PROGRAMMING FOR SQUEAKING BRAKE
OPERATION
ProtoSounds® can be programmed for squeaking brake operation in three
different manners; (1)Squeaking brakes can be activated by bell button
control, (2)they can be programmed for continuous operation subject to
throttle changes or (3)they can be programmed to be turned off. The default
setting is (2) Squeaking brakes are activated for full-time operation as
described on page 8. To change the default setting, enter RESET and go to
Power Terminal
Wire (black)
Center Rail
Wire (red)
Outside Track
Wire (ground)
Figure 5: Wiring Up A Bell Button
Clank, Clank, Clank,
Clank, Clank
In RESET Mode
Move The Throttle
Up & Down From
High Voltage To Low
20 Times
Listen For 5 Clank
And 0 Clink Sounds
Push The Whistle Button
Until You Hear 2 Dings
Interrupt The Throttle
To “Lock-In”
The Bell Button Setting
H