MTHTrains GP38-2 DIESEL ENGINE User manual

R
ELECTRIC TRAINS
MTH GP38-2 DIESEL ENGINE
OPERATING INSTRUCTIONS
Thank you for purchasing the MTH Electric Trains GP38-2 diesel
locomotive. This ¼” scale reproduction of the famous GP38-2 locomotive
measures over 15” in length and weighs almost 5 pounds. Despite its scale
size, the locomotive is capable of operating on O-31 3-rail track with most
compatible AC transformer, (see page 31 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, theQuick Start Operating Instructions, found on page
3, should be read so that you understand the basics of the operating system.
Please note that some features are only found in the ProtoSound® equipped
engines and are marked as such.

2
MTH GP38-2 Operating Instructions
Table Of Contents
QUICK START - BASIC OPERATION(All 3-Rail Models) 3
PROTOSOUNDS ®OPERATINGINSTRUCTIONS 4
ProtoSound® DCRU® Reverse Unit Operation (All 3-Rail Models) 4
Horn Operation 5
Bell Operation 5
ProtoCoupler™ Operation 6
Cab Chatter Sounds 7
Squeaking Brake Sounds 7
Tips On Using The Squeaking Brake Sounds 8
Freight Yard Sounds (FYS) 9
Quick Overview On Activating and Triggering Freight Yard Sounds 9
Tips On Using FYS Features 14
Reverse Unit Lockout Control Functions 15
Locking The Engine Into Forward or Reverse 15
Unlocking The Engine 15
Self-Charging Battery Backup System 16
Replacing The ProtoSound® Battery 16
Manual ProtoSound® Volume Adjustment 17
USING “RESET" TO PROGRAM PROTOSOUNDS® 18
Entering RESET Options 18
Remotely Setting The Engine Volume 19
Programming For Squeaking Brake Operation 19
Programming For Horn In Neutral Operation 20
Programming For ProtoCoupler™ Operation 20
Turning Off Cab Chatter 21
Programming For FYS Operation 21
Activating Remote Lockout Control 22
Resetting All ProtoSound® Options To Factory Default 22
OIL & LUBRICATION INSTRUCTIONS 23
TRACTION TIRE REPLACEMENT INSTRUCTIONS 24
LIGHT BULB REMOVAL & REPLACEMENT 25
TROUBLE SHOOTING PROTOSOUND®PROBLEMS 26
ProtoSound® RESET Feature Chart 30
Transformer Wiring Chart 31
O-31 OPERATION 32
EXPLODED VIEW AND PARTS LISTS 33
SERVICE AND WARRANTY INFORMATION 36
HOW TO GET SERVICE 36
LIMITED ONE YEAR WARRANTY 36

3
MTH GP38-2 Operating Instructions
QUICK START - BASIC OPERATION
The MTH GP38-2 contains state-of-the art electronics with several built-in
automatic features for incredibly realistic operation. Despite these advanced
features, the GP38-2 is easy to operate with any compatible standard AC
transformer (see the compatibility chart on page 31).
The GP38-2 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 on 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 (see figure 1) 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.
RESET
Neutral
Reverse
Neutral
Forward
Figure 1: ProtoSound® DCRU® Cycle Phases

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MTH GP38-2 Operating Instructions
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:
1. ∗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-Charging 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

5
MTH GP38-2 Operating Instructions
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 Proto-Sound® equipped engine features a digital recording of a
diesel horn. The horn sound can be activated anytime the engine is in
forward or reverse by pressing the horn/whistle button on your transformer.
The horn will continue to blow as long as the horn/whistle button is
depressed. The horn will not function in RESET and must be configured
through a RESET option to allow the horn to work when the engine is in
neutral. See page 18 for information on horn programming in the Using
RESET To Program Proto-Sound® section of this manual
BELL OPERATION
Your Proto-Sound® equipped engine also features a digital recording of an
actual steam engine bell. The bell can be turned on or off by simply
pressing the Bell button on your transformer anytime the engine is in
forward, neutral or reverse. The bell will continue to ring until the bell

6
MTH GP38-2 Operating Instructions
button is depressed a second time. Note: The bell will not function in
RESET. .
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 GP38-2 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 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
H H
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

7
MTH GP38-2 Operating Instructions
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. 2.
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.
DIESEL CAB CHATTER SOUNDS
Whenever your diesel locomotive is parked in Neutral, randomly played
“Cab Chatter” sound effects will occur every 2 to 30 seconds. There are a
total of four of these Cab Chatter sequences that capture authentic radio
transmissions between dispatcher and engineer. They are designed to play
at random intervals to eliminate repetitive and boring sequences though
there is no guarantee that you won’t hear the same message repeated two or
more times.
SQUEAKING BRAKE SOUNDS
Proto-Sound® 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 sound itself is a stored recording on the
Proto-Sound® 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
Lubricate
Proto-Coupler®
Knuckle
Figure 2: Lubricating The ProtoCouplers
Throttle Down From
High Voltage To Low Listen For The
Squeaking Brake Sounds

8
MTH Centipede Operating Instructions
brake sound is completed. Operators will find that 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
Users will find the squeaking brake 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. However, you may find that your engine
continues to play the brake sounds once your engine comes to
a stop, or that the sounds stop 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 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.

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MTH GP38-2 Operating Instructions
Operating Proto-Sound Freight Yard
Sound EffectsFreight Yard Sounds (FYS)
Proto-Sound® is equipped with operator controlled Freight Yard Sounds,
referred to as FYS. The FYS sequence is designed to simulate the arrival,
unloading, loading and departure of a freight train in a freight yard. This
easy-to-use feature allows you to play digitally recorded sounds of
freight yard operations while your engine is parked in the Neutral State.
No additional wires or modifications are needed to enjoy these amazing
sound effects. The sounds themselves are randomly “shuffled” by the
Proto-Sound® computer. This gives the system the ability to play the
various sounds in a different order each time FYS is enabled.
Quick Overview- FYS Sounds
The following is a quick over view on how you can operate FYS.
The train on track moving Forward or Reverse direction.
BPress and Hold Bell Button For 3+
Seconds, Listen For a Horn Blast or
Air Release, then Remove your Finger
from the Button.
BPress Bell Button Again Quickly to
Stop Bell Chime.
Your train is now ready for you to play the FYS.

10
MTH GP38-2 Operating Instructions
d
Bell
Horn
Whistle
Direction
OR
To Play FYS, Stop Train Direction.
This Can Be Done by Pressing the
DIRECTION Button or Cycling the
Transformer Handle.
At This Time the Train Will Stop in
Neutral.
In a Few Seconds, A Man Whistling
Plays, Followed by a Background
Noise.
STOP
d
Bell
Horn
Whistle
Direction
OR Change/Press Direction- The Train Will
Remain In Neutral. It Will Continue to
Play More Background Noises.
d
Bell
Horn
Whistle
Direction
OR
Change/Press Direction- The Train Will Remain
In Neutral. You Will Hear a Double Air Release,
A Man Whistling Plays, More Background
Noises.
d
Bell
Horn
Whistle
Direction
OR
GO
Change/Press Direction- The Train Will Remain In
Neutral. You Will Hear Closing Doors, Horn Blast,
a Few Bell Chimes and Engine Departs in the
Direction the Engine First Stopped.
For more detailed FYS instructions, read the following.

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MTH GP38-2 Operating Instructions
Activating Freight Yard Sounds (FYS)- Detailed Instructions
Arming The Freight Yard Sounds Feature
Before the Freight Yard Sounds can be heard, the feature must be activated.
The feature can be activated in one of two ways:
Option 1: If you are using the Z-4000™ transformer, or any transformer
with a separate bell button controller, you can activate the feature by simply
pressing and holding the bell button for at least three seconds (it does not
matter if you are in forward, neutral or reverse). You will hear the bell turn
on and, after three seconds, you should hear a short horn blast or air release.
Once the horn blast or air release is heard, the bell button can be released.
The bell will continue
to chime, so if you want
to turn off the bell
ringing, simply press
and release the bell
button. If you were in
neutral, interrupt the
transformer throttle to
enter the next
directional state (either forward or reverse). (Note: the FYS will only play
in the first Neutral after it is armed. You cannot interrupt the power twice
to enter another direction and still have the FYS active.) You can now
trigger the sounds to begin playing when you next enter Neutral.
Option 2: If you do not have a Z-4000™ transformer or a separate bell
button available, you can activate the FYS using your transformer’s whistle
button control. To arm the FYS, turn on the transformer throttle and cycle
your engine into Neutral (not RESET). Once in neutral, set the transformer
throttle to 8 volts or less and press and hold the whistle button for at least
three seconds. You will hear the bell turn on and, after three seconds, you
should hear a short horn blast. Once the horn blast or air release is heard,
the whistle button can be
released. The bell will
continue to chime, so it you
want to turn off the bell
ringing, simply press and
release the whistle button.
Interrupt the transformer
Put Engine In Neutral,
Forward or Reverse
Press & Hold
The Railsounds® Bell Button
For 3 Seconds
Listen For The
StartOf TheBell Sound
Listen For The
Horn/Whistle
After 3 Seconds
Put Engine In Neutral
At Low Power
Press & Hold
The Horn/Whistle Button
For 3 Seconds
Listen For The
Start Of The Bell Sound
Listen For The
Horn/Whistle Blast
After 3 Seconds
H

12
MTH GP38-2 Operating Instructions
throttle to enter the next directional state (either forward or reverse). (Note:
the FYS will only play in the first Neutral after it is armed. You cannot
interrupt the power twice to enter another direction and still have the FYS
active.) You can now trigger the sounds to begin playing when you next
enter Neutral.
TRIGGERING FREIGHT YARD SOUNDS
Once the FYS feature has been activated, it will be played the next time the
engine enters neutral. At this point, Proto-Sound® will take over control of
your engine, disabling the bell and whistle button. In addition,
Proto-Sound® reconfigures the way the reverse unit functions during the
operation of the FYS feature. This forces the engine to leave your freight
yard in the same direction as it arrived. The following operator controlled
“Events” control the FYS’s actions and sounds. (Note: The direction states
shown assume the FYS is entered from forward. If entering the freight yard
in reverse, the direction states shown will be reversed.)
Event 1: Interrupt the transformer
throttle to cycle the engine from
forward into neutral. If the
throttle was at 14 volts or higher,
the squeaking brakes sound will
play. Once the engine is stopped,
the throttle must be turned on to keep it in the neutral
state. Note: Failure to turn the throttle back on within 3 seconds of
leaving forward will disable FYS and shutdown Proto-Sound®. The next
time power is turned on, the engine will be in the RESET position. See
page 19 for additional information on RESET. If the bell was not turned
off after arming FYS, it is now turned off automatically. After entering
neutral, Proto-Sound will immediately play a horn blast or an air release
sound, followed approximately 2 seconds later by a man whistling and a
freight car door sliding open. At this point, various freight yard sounds can
be heard, including loading and unloading operations, engine sounds,
yardman “slang,” and additional freight car door sounds.
Event 2: Interrupt the transformer throttle again to cycle the engine from
neutral into reverse. In order to have the engine leave the yard in the same
direction it entered Proto-Sound® disables the motors in this reverse state to
prevent the engine from running backwards. FYS confirms reverse is
entered by playing a sound highlight best described as a rumbling sound.
Put Engine In Neutral
At Low Power Listen For Air Release Sound
And Cab Chatter Message
EVENT 1

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MTH GP38-2 Operating Instructions
You may have to go through the entire
FYS sequence several times before you
clearly identify this sound. After the
rumbling highlight is played, the freight
yard sounds heard in Event 1 will continue
to play.
Event 3: Interrupt the transformer throttle
again to cycle the engine from reverse back
to neutral. FYS confirms that the engine is
now in neutral by sounding two quick air
releases. This is followed approximately
two seconds later by a man whistling and
continued freight yard loading and
unloading sounds.
Event 4: Interrupt the transformer throttle
again to complete the FYS feature and
cycle the engine into forward. FYS confirms it has entered forward by
playing the sound of the freight car door closing. Within two seconds, the
whistle will sound two short blasts (three if
entering reverse), and the bell will begin to
chime. After a few chimes of the bell, the
engine will begin moving in forward with
the bell continuing to ring. A few seconds
later, the bell will turn off, and the engine
will resume normal operation. Note: When
entering Event 4, it is important to set the
transformer throttle at a high enough
setting that the engine will begin to move
when the motors are activated. However, the throttle should not be too
high for the engine to maintain a safe operating speed.
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.
Listen For a
Horn Blast
Interrupt Throttle To
Enter The Next Phase
EVENT 3
Listen For Engine
Rumbling Sound
Interrupt Throttle To
Enter The Next Phase
EVENT 2
Listen For The Sound
Of Box Door Closing
Interrupt Throttle To
Enter The Next Phase
EVENT 4

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MTH GP38-2 Operating Instructions
TIPS ON USING FYS FEATURES
FYS is a unique feature of Proto-Sound® 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’s whistle plays in Stage 1 (neutral).
Tip#2: You can exit FYS at anytime by turning the transformer throttle Off for
15 seconds.
Tip#3: You do not have to be in Forward to utilize FYS. For example, if you
activate the FYS feature while in Reverse your train will leave the station/yard
in the same reverse direction that it arrived in.
Tip#4: You can use FYS even if you are double-heading with another engine
regardless of whether the second engine is equipped with an FYS programmed
Proto-Sound® module. If the second engine isn’t equipped with FYS, the only
thing to remember is not to turn up the transformer throttle very high when
entering Reverse in Stage 2. If the throttle is set too high, then the second
locomotive will begin vibrating on the track as its motors will be turning in
reverse. If your second engine is equipped with FYS, you may want to disable
the FYS when used in double-headed operations. To disable FYS, see the
section on programming RESET functions on page 26 of this manual.
Tip#5: You can leave any of the event stages at any time by simply
interrupting the transformer throttle. Any sound effects programmed to play in
that event will simply not occur. The only exceptions are Event 1 and Event 4.
In Event 1, interrupting the throttle has no effect on FYS until after the man’s
whistle has completed and the freight car doors have opened. In Event 4, you
cannot interrupt FYS until after the engine begins to move. Interrupting the
throttle before the engine begins to move has no effect on the locomotive’s
operation.

15
MTH GP38-2 Operating Instructions
Special Reverse Unit Options
Reverse Unit Lockout Operation
For operators who wish to lock their engine into a single direction,
Proto-Sound’s® unique design eliminates the need for a lock-out switch on
the locomotive. This will allow users to run the engine on layouts equipped
with block signals or stop stations that would normally cycle the engine
back into neutral. Note: The feature must be first turned on by accessing
RESET Feature 40 (See page 22).
Locking the Engine into Single Direction Operation
Cycle the transformer throttle so that your engine is operating in the
direction you wish to lock it in (forward, neutral or reverse). With the
throttle set to approximately 8 volts, press and hold the horn/whistle button.
While holding the horn/whistle button, turn the throttle OFF, then release
the horn/whistle button. After 2 seconds, you will hear a short whistle blast.
IMMEDIATELY turn the throttle back on. The engine is now locked, and
will continue in the previous direction whenever power is applied to the
track.
Unlocking the Engine
With the throttle set to approximately 8 volts, press and hold the
horn/whistle button. While holding the horn/whistle button, turn the throttle
OFF, then release the whistle button. After three seconds, a single bell will
be heard indicating that the engine is unlocked. When power is again
applied, the engine will enter RESET and perform as normal.
NOTE: When locking the engine in the Forward or Reverse positions, the
horn/whistle button will blow the horn/whistle. But when locking the engine
into the NEUTRAL position, the horn/whistle button may turn on or off
sounds of the bell. Remember, the horn/whistle doesn’t blow in NEUTRAL
(unless you programmed it to do so using Reset Feature 25 - see page 20
for details), only the bell rings.

16
MTH GP38-2 Operating Instructions
SELF-CHARGING BATTERY BACKUP
Proto-Sound® includes a self-charging battery backup system for improved
performance at any speed. The battery ensures that power to the sound
system will remain on during directional changes, while setting RESET
options or when traveling over spots of dirty track and switches. The
self-recharging battery backup system is automatically turned on or off.
There no switches needed to enjoy the benefits of the automatic battery
backup system.
Proto-Sound® 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 that
this has occurred. Should this happen, unplug the battery from the
Proto-Sound® module (to prevent the battery from being run down) and
contact MTH for instructions on returning the train for repair.
REPLACING THE PROTO-SOUND® BATTERY
The Proto-Sound® 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 battery is continually charged from the track when power is
applied above 10 volts 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 lifetime. The 6-cell NiCad is NOT
recommended for use with Proto-Sound® applications.
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 failing. 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 6 hours.
Note: When charging the battery in neutral, if your trains contains a
Smoke Unit should be turned OFF to prevent damage to the wick and the
heating elements.

17
MTH GP38-2 Operating Instructions
If you need to replace the battery, they are available from MTH
Proto-Sound® Electronics at 7020 Columbia Gateway Drive, Columbia, MD
21046-1532. A standard 9v alkaline battery can be substituted as a
temporary fix, but, since alkaline batteries can’t take a charge, it will
eventually wear down.
MANUALLY ADJUSTING THE PROTOSOUND® VOLUME
Your Proto-Sound® 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 chuff
sounds remotely from the transformer. Turning the volume adjustment knob
one direction will increase the volume. Turning it the opposite direction will
lower the volume of all sounds: bell, whistle, and enhanced neutral sounds.
For information on operating the RESET volume adjustment option, see the
section entitled “Programming Proto-Sound® RESET Options” on the
following pages.
Proto-Sound®
Volume Adjustment
Figure 3: Adjusting The ProtoSound® Volume and selecting the ProtoCoupler direction.
Proto-Coupler®
Selection Switch

18
MTH GP38-2 Operating Instructions
USING “RESET" TO PROGRAM
PROTOSOUNDS®
Proto-Sound® is equipped with several programmable features which are
accessed in the RESET state by moving the transformer throttle up and
down between full voltage and low voltage (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 and returned. In addition, there are
special sounds to tell you what RESET position you are in
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 times the
throttle is advanced by
playing back the number
of “Clinks" and “Clanks"
to confirm the feature
you’ve selected.
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 Centipede Operating Instructions
Remotely Adjusting The Engine Volume - Reset Feature 6 – (1
Clank, 1 Clink)
Reset Feature 6 allows you to change the volume setting of the chuff sounds
without affecting the volume of other sounds, such as whistle, bell,
enhanced neutral sounds, etc. To use, cycle to Reset 6 and press the
Whistle button. A single bell will play, and the chuff will begin at the
current volume. Each
time the Whistle button
is pressed, a bell will
sound and the volume
setting will cycle down
to the next level. The
levels available are
100%, 50%, 25%, and
0%. After 0%, pressing
the whistle button again will return the chuff to 100%. When the desired
level is reached, lock the changes by interrupting the throttle and cycling the
engine into forward
Programming For Squeaking Brake Operation-Reset Feature
45 –(9 Clanks, 0 Clinks)
Reset Feature 45 allows you to determine if and how the Squeaking Brakes
recording will be activated. To use, cycle to Reset 45 and press the Whistle
button. The engine will play a series of bells. This indicates the current
setting. Each time the Whistle is pressed, Proto-Sound® will cycle to the
next available setting and provide the appropriate bell indicator. The
settings for Reset 45 are 1
Bell = On Demand
(Enabled when FYS is
activated), 2 Bells =
Always On, 3 Bells = Off.
When the desired setting
is reached, lock the
changes by interrupting
the throttle and cycling the
engine into forward.
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 Horn/Whistle Button
Until You Reach The
Setting You Desire
Interrupt The Throttle
To “Lock-In”
The Volume Setting
H
In RESET Mode
Move The Throttle
Up & Down From
High Voltage To Low
45 Times
Listen For 9 Clank
And 0 Clink Sounds
Push The Horn/Whistle Button
Until You Hear The
Appropriate # Of Dings
Interrupt The Throttle
To “Lock-In”
The Brake Setting
H

20
MTH GP38-2 Operating Instructions
Programming For Horn In Neutral Operation- Reset Feature
25 -(5 Clanks)
Reset Feature 25 allows you to operate the Horn while the engine is in the
Neutral state. When ON, pressing the Horn/Whistle button while in
Neutral, with 10V AC or less on the track, will cause the Horn recording to
sound. To use, cycle to Reset 25 and press the Horn/Whistle button. The
engine will play a series of bells. This indicates the current setting. Each
time the Horn/Whistle button
is pressed, Proto-Sound® will
cycle to the next available
setting and provide the
appropriate bell indicator.
The settings for Reset 25 are
1 Bell = OFF, 2 Bells = ON.
When the desired setting is
reached, lock the changes by
interrupting the throttle and
cycling the engine into forward.
Programming For
Proto-Coupler®
Operation - Reset
Feature 10-(2 Clanks)
Reset 10 allows you to turn
the operation of the
Proto-Coupler® on or off.
When OFF, the coupler will
not arm or fire from Neutral.
To use, cycle to Reset 10
and press the Whistle button. The engine will play a series of bells. This
indicates the current setting. Each time the Whistle button is pressed,
Proto-Sound® will cycle to the next available setting and provide the
appropriate bell indicator. The settings for Reset 10 are 1 Bell = ON, 2
Bells = OFF. When the desired setting is reached, lock the changes by
interrupting the throttle and cycling the engine into forward.
In RESET Mode
Move The Throttle
Up & Down From
High Voltage To Low
25Times
Listen For 5 Clank
And 0 Clink Sounds
Push The Horn/Whistle Button
Until You Hear
2 Bell Dings
Interrupt The Throttle
To “Lock-In”
The Horn Setting
H
In RESET Mode
Move The Throttle
Up & Down From
High Voltage To Low
10Times
Listen For 2 Clank
And 0 Clink Sounds
Push The Horn/Whistle Button
Until You Hear
2 Bell Dings
Interrupt The Throttle
To “Lock-In”
The Coupler Setting
H