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.

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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

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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

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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

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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.

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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.