Operations Manual
TABLE OF CONTENTS
INSTALLATION PREPARATION . . . . . . . . . . . . . . . . . . . . . . . 2
Parts Supplied . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Installation Overview . . . . . . . . . . . . . . . . . . . . . . . . . 2
Alternative Transducers and Mounting Methods. . . . . . 4
Transducer Exchange . . . . . . . . . . . . . . . . . . . . . . . . . 5
USING THE 250DX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
How Sonar Works . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Simulator Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 7
What You See On Screen . . . . . . . . . . . . . . . . . . . . . . 8
Control Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Menu Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
ADVANCED FEATURES . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Using Diagnostic . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
MAINTENANCE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Customer Support . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
REV 10822E
INSTALLATION PREPARATION
PARTS SUPPLIED
PARTS SUPPLIED
Before installing your 250DX, please ensure the following parts are
included in the box:
• 250DX fishfinder
• Transducer with 6m (20') of cable and mounting hardware kit
• Mounting system and mounting hardware kit
• 6m (20') power cable
• Publications kit
If any of these items is missing, contact your local distributor .
ACCESSORIES
Humminbird offers a wide assortment of accessories that complement and
expand the capability of your new 250DX. These accessories are designed
with the same high standards and are backed by the same one-year
warranty. The Humminbird Accessory catalog included with your unit
contains descriptions of the many accessories available and ordering
information. All Humminbird accessories are available through your full-
service Humminbird dealer or factory direct through our number listed in
the Customer Support section.
INSTALLATION OVERVIEW
The 250DX consists of two primary components to install: the control head
and the transducer.
The control head contains the sonar transmit and receive circuitry, as well
as the user controls and display. It should be installed in a location that
provides access to the controls and visibility while in use. The control head
mounts on a quick disconnect mounting system that swivels and tilts
providing flexibility for viewing from almost anywhere on the boat.
The transducer converts electrical energy from the transmitter into
mechanical pulses or sound waves. The transducer also receives the
reflected sound waves and converts them back into electrical signals for
2
INSTALLATION PREPARATION
INSTALLATION OVERVIEW
display on the control head. It should be installed in contact with the
surface of the water in an area that has smooth water flow - usually on the
transom of the boat. There are several mounting options for the
transducer. Review the following section to determine the method that
works for you and your boat.
Determining How to Mount the Transducer
The 250DX includes a model XT-6-20
transducer. This transducer can be
mounted on the transom of the boat,
or bonded to the inside of a fiberglass
hull boat.
The transom installation, which is the
most widely used, places the transducer
on the outside of the boat hull. This
technique produces the least signal loss,
and provides a way to adjust the
transducer after installation. The
mounting hardware included is designed
to protect both the boat and the
Transom Mounted Transducer
transducer should the boat strike debris
in the water or when trailering.
As an alternative to transom
mounting, it is possible on many
fiberglass-hulled boats to glue the
transducer on the inside of the boat
hull. Since fiberglass has similar sonar
characteristics as water, the sonar
signal can pass through the boat hull
with minimal loss. The hull of the
boat must be single layer
construction (not double-hulled).
Also, any air trapped in the
lamination of the fiberglass would
prevent the sonar signal from passing
through.
Inside the Hull Mounted Transducer
3
INSTALLATION PREPARATION
ALTERNATE TRANSDUCERS AND MOUNTING METHODS
Inside the hull installations require no holes be drilled into the boat and
through experimentation, high-speed operation comparable to transom
mounting can be achieved. Two part, slow cure epoxy is required to glue
the transducer in place.
ALTERNATE TRANSDUCERS AND MOUNTING METHODS
The 250DX comes with everything necessary for installation and operation
on most boats. However, there are several situations which may require a
different type of transducer. Inboard boats, wood or metal hulls, and sail
boats create unique transducer mounting needs. Alternate transducers and
mounting methods are detailed below.
Portable Mounting
The standard transducer can be adapted for
portable installations using part number MHX-
PT2. This accessory adapts your transducer to a
suction cup mount for temporary installation on
the boat hull or other surface.
Trolling Motor Mounting
The standard transducer can also be adapted to
mount on most trolling motors using part
number AD-STM-7. This accessory includes a
bracket and hose clamp that allows mounting
the transducer to the body of most trolling
motors.
Thru-Hull Mounting
Thru-hull transducers install through a hole
drilled in the hull of the boat. Larger boats or
boats with inboard motors create turbulence
that make transom mounting ineffective. Also,
hulls that are very thick or are double layered, or
made from materials such as wood or metal,
4
INSTALLATION PREPARATION
TRANSDUCER EXCHANGE
(which do not conduct sonar signals) make inside the hull mounting
inadvisable.
Thru-hull mounting may require the use of a fairing block to level the
transducer with the waterline. Also, since special tools and knowledge may
be required to perform this type of installation it is best to refer to a
qualified marine technician.
TRANSDUCER EXCHANGE
Other transducers are available as replacements for the standard
transducer. You may exchange your new and unassembled transducer for
another type by returning it to the address listed in Customer Support.
Some transducers may have additional costs. Refer to the Accessory cata-
log or call Customer Support for information.
BEGINNING INSTALLATION
Now that you have determined the transducer mounting method, you can
begin installation of the 250DX. The fold out installation guide included
provides detailed step by step instructions for installation of the control
head and transducer. For transom mount transducer installations, you will
need the mounting template at the front of this manual.
In addition to the parts included you need the following for installation
and operation:
• A powered hand drill and various drill bits
• Phillips and flat-head screw drivers
• A ruler or measuring tape
• Pen or pencil
• 12 volt power source (your boat’s battery)
• A 1-amp fuse
• A fuse holder (if you are wiring directly to the boat’s battery)
• Silicone sealant (for sealing drilled holes)
• 2-part, slow-cure epoxy (for inside the hull transducer installations)
5
USING THE 250DX
HOW SONAR WORKS
HOW SONAR WORKS
Your Humminbird unit uses sonar to
locate and define underwater objects,
define the bottom terrain, as well as
determine distance.
Sonar technology is based on sound
waves. Your Humminbird unit sends
out a sound wave signal. With this
signal it determines distance by
measuring the time between the
transmission of the sound wave and
when the sound wave is reflected off
an object. Your Humminbird uses the
reflected signal to interpret location,
size and composition of an object.
Sonar is very fast. A sound wave can travel from the surface to a depth of
240' (70m) and back again in less than ¹⁄₄ of a second. It is unlikely that
your boat can "outrun" this sonar signal.
The 250DX is a dual frequency, dual beam unit, and generates two distinct
sonar signals - one narrow, one wide. Each signal is optimized for a
particular purpose. First, the center beam transmits at a frequency of 200
kHz in a 20 degree (narrow) symmetrical pattern for greater depth
capability and excellent detail. Information from this center beam is used to
draw the graphic representation of the bottom on the display.
Second, the wide beam transmits at a frequency of 83 kHz in a 53 degree
(wide) symmetrical pattern for greater area of coverage. Information from
the wide beam is used to accurately detect the presence and location of
fish. A wide beam has a large area of coverage but limited resolution of
detail. A narrow beam has excellent detail, but within a limited area
of coverage.
The combination of the two beams and dual frequencies provides the
combination of a large area of coverage and a high level of detail.
6
USING THE 250DX
SIMULATOR OPERATION
Actual depth capability depends on factors such as bottom hardness, water
conditions, and transducer installation. Units will typically read to deeper
depths in fresh water than in salt water.
SIMULATOR OPERATION
The 250DX contains a simulator that allows
you to use the unit as if you are on the water.
The simulator is invaluable for learning how
to operate the 250DX.
There are two ways to start the simulator. If
the unit is powered off, press and hold the
POWER button for approximately three
seconds until you hear a continuous chirp.
The simulator can also be started by selecting the Simulator option on the
start-up screen after you power-up the unit. When this screen is shown,
simply press the DOWN ARROW until “Simulator” is highlighted. When the
screen times out, the unit will be in simulator mode.
When in simulator operation, the 250DX responds to control inputs as if it
is in actual operation, so feel free to experiment, or to customize the unit
for your particular operation.
To exit Simulator mode, power the unit off.
When in simulator mode, the word “simulator” occasionally
scrolls across the display indicating the information on-screen is
not real sonar data.
FEATURE MEMORY
If your 250DX is installed with a transducer connected, any changes you
make to the set-up or User Options (see Control Functions) while in
Simulator are retained in the unit’s memory. This allows you to use
simulator to experiment with the various set-up options, and retain your
selected settings for normal operation.
7
USING THE 250DX
WHAT YOU SEE ON-SCREEN
If you are using the 250DX in Simulator when no transducer is connected,
any selected options are lost when the unit is powered off. The 250DX will
return to Factory Settings, or options selected when last used with a
transducer, if no transducer is connected.
IMPORTANT: A transducer must be connected to the 250DX in
order to retain user settings selected when in simulator mode. If
no transducer is detected, the unit defaults to pre-selected
options when powered off.
Figure A
What You See On-Screen
Your 250DX uses a 128 V x 64 H matrix
FSTN LCD display. This display provides
outstanding viewability in all light
conditions over a wide range of
temperatures.
At initial power-up, the 250DX uses
settings that were set at the factory.
After initial use, the 250DX will
remember the settings you enter.
There are several elements on-screen
that are common to all modes of
operation.
Temperature/Speed. The initial screen layout takes one of two basic forms
depending on whether the optional Temp/Speed accessory is installed. Figure
A shows the default view when the Temp/Speed accessory is installed. Figure B
shows the default view when the Temp/Speed accessory is not installed.
Depth. The digital depth number shows the water depth directly beneath the
transducer location.
Depth Range. The depth range is shown to the right of the screen. The upper
number is 0 indicating the surface of the water. The lower number is one of
the nine depth ranges available that best match the depth of the water. As the
8
USING THE 250DX
WHAT YOU SEE ON-SCREEN
Bottom Depiction
Zero Line
depth of the water changes, the range
changes as necessary in order to retain
a bottom representation on-screen.
When in Auto mode, the horizontal
line at the top of the screen is the
“zero line,” representing the surface
of the water. Occasionally there is a
gap in this line. This gap indicates the
unit is updating the display even if
the bottom is not visible on-screen,
or if the bottom information is not
changing.
New sonar information appears on
the right side of the graphic area of
the display and moves to the left as
new information is displayed. The
Water Depth
Depth Range
Figure B
250DX automatically selects the appropriate depth range to show the
depth of water beneath the transducer. This range is selected so the
bottom representation is typically shown about ²⁄₃ down the display.
Bottom. The graphic depiction of the
Surface Clutter
Rocky Bottom
bottom provides an effective tool for
understanding the composition of
the bottom. If the bottom is hard and
smooth, the bottom depiction is
narrow and dense. If the bottom is
soft mud or sand, the depiction will
be thick and less dense. This indicates
much of the signal is absorbed by the
soft bottom. If the bottom is rocky or
rugged in composition, the depiction
is of varying density and textured in
appearance.
Wave action also affects the bottom
depiction. The information drawn is a
Soft Bottom
Hard Bottom
9
USING THE 250DX
WHAT YOU SEE ON SCREEN
distance measurement, so if the boat is moving up and down over flat
bottom, the bottom depiction often appears in regular variations that match
wave timing.
Structure. Structure is defined as any object physically attached to the
bottom. The sonar configuration of the 250DX is optimized to give the most
accurate depiction of bottom structure possible. Grass, trees, stumps,
wrecks or other debris are accurately displayed, however the depiction of
these objects varies with boat speed and direction. The best way to learn to
interpret structure is to operate the 250DX over a variety of known
conditions and experiment with user functions to best represent those
conditions on-screen.
Surface Clutter. Surface clutter is the layer of water near the surface that
is rich in algae and other growth, and often is aerated by wind or wave
action. This area of water interferes with sonar transmission and often
appears on-screen as regular clusters of individual dots near the “0” line.
Thermoclines. Thermoclines are sharp
Thermocline Second Return
differences in water temperature.
These are easily identified by the
continuous nature of the return.
Second Returns. When a sonar signal
is reflected off the bottom back to the
transducer, there is often enough
energy left in the signal to be reflected
off the surface of the water back to the
bottom a second time. Second returns
appear as a slightly weaker bottom
representation exactly twice the depth
of the primary bottom return. The
second return is most likely to occur in
shallow water and in areas of relatively
hard bottom.
Fish ID. The 250DX uses advanced signal processing to further evaluate any
sonar return between the surface and the bottom. For instance, a small
school of bait fish usually appears as a dense cluster of individual dots. If the
10
USING THE 250DX
CONTROL FUNCTIONS
Fish in Wide Beam
return meets certain additional criteria, a
fish symbol will be assigned. There are
three different size fish symbols used to
indicate the intensity of the sonar return.
While signal intensity is a good indicator
of relative fish size, different species of
fish have different sonar characteristics,
so it is not always possible to distinguish
fish size between varying species. The
signal intensity is "normalized" for
depth so that a small fish close to the
boat does not appear as a large fish
symbol.
ID+ adds an additional piece of
information to help the user locate fish.
On selected fish symbols, the digital
ID+ Fish Depth
Fish in Narrow Beam
depth of the designated fish is drawn to help locate the fish vertically. This
is especially helpful in setting bait depths or for downrigger operation.
The fish symbols indicate the sonar beam the fish is detected in. This
gives you a reliable indicator of side to side location of the fish relative to
the boat. Fish symbols that are hollow are detected in the wide beam and
are around the boat. Solid fish symbols represent fish detected in the
narrow beam and are directly under the boat.
CONTROL FUNCTIONS
The 250DX uses a simple five button keypad for all user
input. Press any button and an audible “chirp” confirms
the control input. If a button has no function or is
inappropriate for the situation, an audible “error” is
heard. The unit sounds multiple chirps.
Power. The Power button powers the 250DX up for
normal operation. When the unit is on, POWER turns
the unit off. POWER can also be used to go directly into
Simulator mode. To enter simulator, with the unit
11
USING THE 250DX
CONTROL FUNCTIONS
powered off, press and hold POWER for several seconds until a continuous
chirp is heard.
Light. LIGHT controls the unit’s display backlight. With the unit powered
on, press LIGHT once to turn the backlight on “high.” Press LIGHT a second
time to turn the backlight on “low,” and a third time turns the backlight
off. The backlight is very effective for low-light and nighttime operation.
When the backlight is on, the 250DX will consume more power than with
the backlight off. This is important when using the 250DX in a portable
configuration powered by a separate battery, or when powering the unit
from a trolling motor battery.
When powering the unit from a battery such as in portable applications,
you can prolong the battery life by using the backlight at a minimum.
The three lower buttons, MENU, UP ARROW, and DOWN ARROW work
together to control the 250DX menu-controlled user functions.
Menu. MENU displays a menu on-screen
for adjustment. In normal operation,
Menu Heading
pressing MENU repeatedly cycles through
all available menu headings. When a
menu heading displays, the full menu
appears after a short pause. A menu remains on-screen for several seconds,
and can be adjusted by using the ARROW keys. If no adjustment is made
in the allotted time, the menu disappears. If you want the menu to remain
on-screen longer press and hold MENU—the menu will remain on-screen
indefinitely. Once you release the menu button, the screen will time out.
Once a menu times out, it is still considered the active menu. Press MENU
to bring up the last menu used.
Arrow Keys. The UP ARROW and DOWN ARROW make adjustments to
menu functions. On the left side of every menu there are UP ARROW and
DOWN ARROW symbols. The symbols indicate which ARROW button has
a function in a particular situation. Either one or both ARROW buttons can
be used to adjust the menu function. A hollow ARROW symbol means the
corresponding ARROW button has no function. Pressing that button will
result in no adjustment and the “error” audible will be heard. A solid
ARROW symbol means the corresponding ARROW button can be used to
12
USING THE 250DX
CONTROL FUNCTIONS
affect the menu adjustment.
The ARROW buttons often can be used
when no menu is on-screen. In these
situations, pressing the ARROW button
affects the function of the active (last-
used) menu. This is a short-cut to menu
operation. The menu appears on-screen while the adjustment is made and
times out. A frequently used menu can be adjusted very quickly using this
technique.
After an adjustment is made to a menu function, the menu times out after
a few seconds and the unit returns to normal operation.
Menu Layout. All menus use the same basic layout. The heading at the
top describes the menu function. The UP ARROW and DOWN ARROW
symbols to the left of the menu indicate which buttons are available for
adjustment. In menus that have several possible settings, a range of
adjustment indicator shows the total range available and the current
setting.
Within the menu are the options available. The selected option or current
setting is highlighted in the black box. If no adjustment is made, this is the
selected setting. Press an ARROW button while the menu is displayed to
select another option.
Several of the menus are multi-step. In some situations if an adjustment is
made, additional options become available for further adjustment.
Examples of these multi-step menus are Depth Range, Depth Alarm and
Zoom. See the detailed description of each function for further
explanation.
Heading
Up Arrow Option
Arrow Symbols
Selected Setting
Down Arrow Option
Range of Adjustment Indicator
13
USING THE 250DX
MENU FUNCTIONS
Menu Functions
Sensitivity. The Sensitivity function controls the
sensitivity of the sonar receiver. The 250DX
automatically adjusts the level of receiver sensi-
tivity based on a number of factors including
the depth of the water and the level of noise
present. Noise can be caused by other electronic devices, engines, trolling
motors, propeller cavitation and hydrodynamic flow among others.
The user has the option of adjusting the Sensitivity higher or lower based on
personal preference. You can select one of 11 sensitivity settings from -5 to +5.
A setting of 0 (factory setting) has no effect on the automatic sensitivity control.
Increasing the sensitivity (+1 through +5) enables the unit to display the informa-
tion from progressively smaller sonar returns. By decreasing the sensitivity bias (-
1 through -5), the unit effectively filters small sonar returns.
In murky or muddy water, it is often helpful to reduce the sensitivity. This
prevents the display from being cluttered with sonar returns from debris or sus-
pended particles. In very clear or very deep water, it may be helpful to increase
the sensitivity since even the smallest sonar return may be of interest to the user.
To adjust Sensitivity, press MENU
High(+) Sensitivity Low(-) Sensitivity
repeatedly until the Sensitivity heading is
displayed. When the Sensitivity menu
appears, use the UP ARROW to increase
the sensitivity, or the DOWN ARROW to
reduce sensitivity. To sequence through
the available settings, press and hold
either ARROW button. Release the button
at the setting you want to change.
After an adjustment is made, the menu
disappears and the new sensitivity setting
is in affect. If additional time is needed to
study a menu, press and hold the MENU
button and the menu will remain on-
screen indefinitely. If you need to make an
additional adjustment, press the UP
ARROW or DOWN ARROW button.
Sensitivity at “0”
14
USING THE 250DX
MENU FUNCTIONS
Depth Range. The Depth Range function
controls the vertical distance displayed on
the graphic area of the display. There are
nine depth ranges available. The top of the
range is always 0, or the surface of the
water. Ranges of 0–15', 0–30', 0–60',
0–120', 0–180', 0–240', 0–360', 0–480',
and 0–600' are available. In the metric version, ranges of 0–5, 0–10, 0–20,
0–40, 0–60, 0–80, 0–110, 0–150, and 0–185 metres are available.The
range that positions the bottom depiction closest to the bottom of the
screen, will best utilize the available display resolution.
The 250DX automatically adjusts the depth range depending on the depth
of the water. The unit tries to maintain the bottom depiction about ²⁄₃
down the total range (for example, in 20' (6m) of water, the 0-30' (0-10m)
range would be selected). This provides the best display resolution and
therefore the best target separation possible.
The Depth Range can be adjusted
manually. Press MENU repeatedly until the
Depth Range menu is visible. Two options
are available: Auto and Manual.
The manual setting enables you to adjust
the current depth range setting. The unit
no longer adjusts the Depth Range to the
most appropriate range for bottom
display. Often, the bottom may not be visible on-screen. The digital depth
readout always determines the depth of the bottom, even if it is not visible
on-screen.
Using manual Depth Range control, you
can view sonar information from the area
near the surface in great detail.
15
USING THE 250DX
MENU FUNCTIONS
To return to automatic Depth Range
control, press the MENU button until
the Depth Range menu appears on-
screen and use the UP ARROW to
select AUTO.
Zoom. Zoom is similar to Depth Range
because it controls the range of information
displayed on screen. Zoom, however,
allows selection of ranges beneath the
surface so any area of water between the
surface and the bottom can be enlarged to
provide more detailed information. By using
the full display to show a small area of
coverage, the effective display resolution is
increased, and the unit’s ability to separate
close targets is enhanced.
Depth Range
There are four Zoom ranges available: 2m (7¹⁄₂'),
5m (15'), 10m (30'), and 20m (60'). These
ranges are not directly user controlled but are
instead dependent on the current depth range.
In shallow water, when the 5m (15') or 10m
(30') range is in use, the Zoom range is 2m
(7¹⁄₂'). If the 20m (60') or 40m (120' ) range is in
use, the Zoom range is 5m (15'), if a 60-
150m (180'-480') depth range is in use, the
Zoom range is 10m (30'), and if the 185m
(600') range is in use, the Zoom range is
20m (60').
Upper Zoom Limit
The Zoom range is shown on the left side
of the screen and full range information is
shown on the right side of the display.
Zoom can either operate automatically, in
which the Zoom range is constantly
adjusted to show the bottom, or manually,
in which the user controls the location of
the Zoom range.
16
Lower Zoom Limit
USING THE 250DX
MENU FUNCTIONS
Automatic Zoom is especially helpful when looking for structure or bottom
detail. The Automatic Zoom keeps the bottom in view even in quickly changing
terrain, but is most useful in flatter areas without considerable depth variation.
Manual Zoom provides detailed information of any area from the surface to the
bottom. In manual Zoom, the Zoom range does not move as the terrain
changes.
When the range is shown in the menu, the upper
number represents the top of the current Zoom
range. The lower number represents the bottom of
the Zoom range. Use the UP and DOWN ARROW
buttons to move this range. The upper number can
never be less than 0 (the surface of the water), and
the lower number can never be greater than the
active depth range. The difference between the
two numbers (the Zoom range) is preset and
determined by the active depth range.
Once manual Zoom is selected, the display
appears the same as in Auto Zoom, but the zoom
range does not change automatically.
To disable Zoom, press the MENU button until the
Zoom menu is on-screen. Use the UP ARROW to
highlight Off, and let the menu time out.
When the unit is powered off, the Zoom menu
returns to Zoom Off.
Depth Alarm. The 250DX contains an audible
alarm to warn you of shallow water depths. The
alarm is adjustable to depths of 1m (3') to 30m
(99'). When the alarm is enabled, an audible
alarm sounds if the water beneath the boat is
equal to or less than the selected alarm depth.
The alarm sounds continuously for about five
seconds, and then intermittently to remind you
that you are still in shallow water.
17
USING THE 250DX
MENU FUNCTIONS
Fish Alarm. The Fish Alarm alerts you to the
presence of fish, or other targets not connected to
the bottom. The Fish Alarm has three different
settings that correspond to the three different size
fish symbols shown on-screen.
The default setting is “OFF.” With the “Large fish
only” setting, the 250DX alarms on only those
targets that are represented by the large fish
symbols. The 250DX can be set to alarm on only
large and medium fish, or set to alarm on all fish.
Once the Fish Alarm is enabled, the 250DX emits an
audible beep when the selected size fish symbol
appears on-screen.
Set for large fish only
Set for large and medium fish
Set for all fish
Triplog. Triplog provides a running log of
information based on input from the Temp/Speed
sensor.
Since Triplog requires information from the
Temp/Speed sensor to operate, if this sensor
is not detected by the 250DX, the Triplog menu will not appear as
an option.
Triplog provides seven pieces of information: the current digital depth, water
surface temperature, current boat speed, the distance traveled since the 250DX
was powered up or reset, the average speed, the total time elapsed since
power-up or reset, and the input voltage from your boat’s electrical system.
The time, speed and distance calculations are useful for tracking your progress
on a trip. The input voltage is useful for determining the condition of the
charging system of the boat. When used in a portable application or whenever
18
USING THE 250DX
MENU FUNCTIONS
the 250DX is operated from a battery
source, the voltage number can be used to
determine battery life. The 250DX will
operate at voltages from 10 to 20 VDC.
Voltages in excess of 20 or less than 10
VDC cause the unit to power off.
Options. The Options Menu is a series of
linked menu functions used initially to set
your preferences. Once your preferences
are selected, it is unlikely these functions
need to be accessed during the normal
operation of the product.
The Options menu works differently
than other menu functions in that all of the
options must be cycled through in order to
return to normal operation. There are thirteen
Option menus: Contrast, Display Speed,
Battery Alarm, Bottom Black, Fish ID, Numeral
Size, Diagnostic, Units, Languages, Speed
Offset, Depth Offset, Filter and Reset.
Contrast. The Contrast function allows the
user to control the level of contrast of the
LCD display. The 250DX will automatically
adjust the display contrast to compensate for
changing ambient temperatures; however,
some situations may occur where manual
adjustment will provide a higher level of contrast.
Eleven contrast settings, +5 to -5, are
possible. The display contrast will change as
the adjustment is made so the optimum level
of contrast can be achieved. Use the ARROW
buttons to highlight the desired selection.
The 250DX will reset to the factory setting
when the unit is powered off.
19
USING THE 250DX
MENU FUNCTIONS
Display Speed. Display Speed controls
the rate at which the graphic information
moves across the display. There are 5
possible speeds; the fastest rate (5) is the
factory setting. Keep in mind that the
closer the update rate matches your boat
speed, the more accurate is the graphic
depiction of the terrain beneath your boat.
Use the UP and DOWN ARROWS to select the desired update rate. The
Display Speed setting is remembered when the unit is powered off.
Battery Alarm. The Battery Alarm
Option allows you to select the voltage
level at which the Battery Alarm
activates.
At the Battery Alarm menu (under
options), you will note that the default
setting is OFF. Push the DOWN ARROW
BUTTON to select the feature ON. Push the DOWN ARROW BUTTON again
to move into the ADJUST BATTERY ALARM setting. Using the UP and
DOWN ARROW BUTTONS, select a voltage between 9.0 and 12.0.
When the voltage drops below your selected voltage, an audible alarm will
sound, and a battery alarm icon will be displayed on screen with current
voltage level.
Bottom Black. There are two selections
available: OFF and ON. The factory setting
is OFF. With this setting, the 250DX
displays the bottom using Structure ID.
This allows you to determine the texture
and relative hardness of the bottom.
Selecting Bottom Black “ON” causes the
unit to blacken in the display below the bottom. This gives the user easiest
recognition of the bottom location, even from a great distance.
The 250DX remembers the Bottom Black setting when powered off.
20
USING THE 250DX
MENU FUNCTIONS
Fish ID. There are three selections available:
Bottom Black View
OFF, ID+ ON, and ADJUST. The factory
setting is ID+ ON. With Fish ID OFF, sonar
returns are displayed as “raw” information.
There is no interpretation made by the unit.
Selecting ID OFF also disables the fish alarm.
ID+ ON enables the 250DX to interpret
the raw sonar data and, using a variety
of techniques, depict appropriate target
returns as one of three different size fish
symbols. Further identification shows
whether the fish is in the wide or narrow
beam. The 250DX also displays the
depth beneath the surface with the
corresponding fish symbol.
Selecting Adjust and making incremental changes
enhances the fishfinder’s ability to identify sonar
returns as fish symbols.
Increasing the value to a number greater than zero
shows more fish symbols on-screen. In this case
smaller sonar returns will be depicted as fish
symbols. This is useful for identifying many smaller
sonar returns (such as baitfish) as fish symbols.
Decreasing the value to a number less than zero shows
fewer fish symbols on-screen. In this case smaller sonar
returns are disregarded. This is useful for eliminating
many small sonar returns
Raw Sonar
ID+ On
when seeking larger species
of fish.
The 250DX remembers this selection even when
the unit is powered off.
21
USING THE 250DX
MENU FUNCTIONS
Numeral Size. Two options are available:
BIG and SMALL. The factory setting is BIG.
With this setting, the digital depth and
speed and temp numerals are drawn large
enough to be read from across the boat.
The big numerals occupy space on the
display that could be used for the graphics
area. Hence, the small numerals option. With small numerals selected, a
greater amount of the display area is available for the graphic view. This
effectively increases the display resolution of the unit.
Numeral Size settings are remembered when
powered off.
Diagnostic. Two options are available: HIDE and
SHOW. The factory setting is HIDE. Selecting SHOW
brings up the Diagnostic screen. See the Using
Diagnostic section for more information.
Units. The Units function allows the user to
select the units of measurement for the depth
and speed readout. Metres/KTS, (metres/nautical
miles per hour), Metres/KPH (metres/kilometres
per hour), FEET/MPH (feet/statute miles per hour)
and FEET/KTS (feet/nautical miles per hour), are
available.The 250TX remembers this selection
even when the unit is powered off.
Languages. The language menu displays
one of two sets of languages. Language set
A includes: English, French, Italian, German,
Norwegian, Swedish, Spanish, and Finnish.
Language Set B provides Hungarian, Danish,
Polish, Portuguese, Dutch and English. To
select your language, push the UP or Down
Arrow Buttons to scroll through the list.
22
USING THE 250DX
MENU FUNCTIONS
Speed Offset. The Speed Offset option allows the
user to compensate for differences in hull design, and
its effect on the accuracy of the speed measurement.
If there is a discrepancy between the indicated speed
and another speed measurement device on the boat,
the speed measurement can be varied to improve
accuracy. Remember, the speed paddle wheel
measures speed through the water, not speed over ground.
Speed offset is remembered after power is disconnected.
Depth Offset. The Depth Offset allows the user to
select the point on the boat from which the depth
measurement is made. Selecting a positive value adds
distance to the measurement. If the transducer is
mounted 3 feet beneath the waterline, a positive 3
will show the correct depth from the surface of the
water.
Another frequent use of depth offset is to show the depth beneath the
deepest point of the hull. A negative value equal to the distance from the
transducer location and the deepest point of the hull will have the same
effect as mounting the transducer at the deepest point.
Depth offset is remembered after power is disconnected.
Filter. Filter provides an advanced level of control
over the amount of detail visible on-screen and the
sensitivity of the unit. You can choose the setting(s)
that works best for your style of use.
With Filter set to OFF, the 250DX displays increased
detail, showing more thermoclines, structure, fish and even your bait when it falls
within the sonar cone. However, this extreme sensitivity requires you to optimize the
installation of your unit and transducer so that “noise” generated by a moving boat
is not picked up by the fishfinder.
With Filter set to ON, excessive clutter often caused by interference from other
fishfinders, your boat‘s engine, or from noise generated by the hull at high speeds
is reduced in the display. This provides a cleaner image on the display in most cases.
With the Filter menu on screen, use the arrow keys to select the setting for your
boat. When finished, press MENU to display the sonar screen.
23
ADVANCED FEATURES
USING DIAGNOSTIC
Reset. With the many User Options available to
customize the 250DX, it is easy to configure the unit
in such a way that it is detrimental to a particular
use. By using the Reset function, all variable or user-
controlled features (except Filter) of the 250DX are
returned to the factory settings.
The Reset function is an important first step in troubleshooting problems to
ensure that a user selected setting is not the cause for the perceived
problem.
USING THE DIAGNOSTIC FEATURE
The 250DX contains a powerful diagnostic tool that can aid in determining
the cause of a problem.
To use the Diagnostic feature, select the Diagnostic feature on the start-up
menu on the initial screen. Diagnostic can also be accessed through the
Options menu.
Self Test. Initially, the 250DX will perform a self-test.
This test confirms the operation of all internal circuitry.
At the conclusion of the test, one of two messages will
appear. PASSED indicates the internal test discovered
no failures, FAILED indicates a significant internal
problem was discovered and the unit requires factory
service. A code number appears that tells repair
personnel where the problem is.
Transducer Connection. The first connection tested is
Transducer input. If a transducer is detected, the
message CONNECTED appears. If a series of dashed
lines is shown, no transducer is connected or there is
a problem with the transducer or cable.
If you are using multiple transducers, switch between
transducers to confirm the connections for each.
24
MAINTENANCE
MAINTENANCE
Boat Speed/Water Temperature Connection. Other connections tested
include the boat speed and surface water temperature sensors. These
accessory sensors can be purchased independently or together as a single
sensor (see the Humminbird Accessories catalog). If the sensors are
connected and working properly, a “connected” message appears.
The speed input feature only works when the boat is in motion as the
paddle wheel on the speed sensor must rotate to be detected.
Voltage Input. Another connection tested is the voltage input, and is
especially helpful in diagnosing input voltage problems. The current input
voltage is displayed. If voltage fluctuations or power supply in excess of 20
VDC or less than 10 VDC is suspected, use the diagnostic screen to confirm
input voltage. Often, small outboard motors do not effectively regulate
voltage when operated at high engine speeds.
Use Diagnostic while running the boat at high speeds to show the voltage
gain. Also, if you are using the 250DX in portable configuration or from the
trolling motor battery, Diagnostic can be used to evaluate the health of the
battery by showing the current voltage.
Total Time. The total time category indicates the total time the unit has
been in use since shipped from the factory. It is normal for some hours to
appear in the total time when the unit is new due to factory testing. While
this is often of interest to the user, it is primarily a diagnostic tool for the
repair technician should the unit need service.
MAINTENANCE
Your 250DX is designed to provide years of trouble free operation with
virtually no maintenance. Follow these simple procedures to ensure your
250DX continues to deliver top performance.
• If the unit comes into contact with salt spray, simply wipe the affected
surfaces with a cloth dampened in fresh water. Do not use a chemical
glass cleaner on the lens. Chemicals in the solution may cause cracking in
the lens of the unit.
• When cleaning the LCD protective lens, use a chamois and non-abrasive,
25
MAINTENANCE
TROUBLESHOOTING
mild cleaner. Do not wipe while dirt or grease is on the lens. Be careful to
avoid scratching the lens.
• If your boat remains in the water for long periods of time, algae and
other marine growth can reduce the effectiveness of the transducer.
Periodically clean the face of the transducer with liquid detergent.
Pivoting the transducer up in the bracket may allow better access for
inspection or cleaning.
• If your boat remains out of the water for a long period of time, it may
take some time to wet the transducer when returned to the water. Small
air bubbles can cling to the surface of the transducer and interfere with
proper operation. These bubbles dissipate with time, or you can wipe
the face of the transducer with your fingers after the transducer is in
the water.
• Never leave the 250DX in a closed car or trunk—the extremely high
temperatures generated in hot weather can damage the electronics.
TROUBLESHOOTING
Do not attempt to repair the 250DX yourself. There are no user serviceable parts
inside, and special tools and techniques are required for reassembly to ensure
the waterproof integrity of the housing. Repairs should be performed only by
authorized Humminbird technicians.
Many requests for repair received by Humminbird involve units that do not
actually need repair. These units are returned “no problem found.” If you have
a problem with your 250DX, use the following troubleshooting guide before
calling Customer Support or sending your unit in for repair. The 250DX contains
several tools that can aid in determining if there is a problem and how to isolate
and repair the problem in many cases.
1. Nothing happens when I turn the unit on.
Check the power cable connection at both ends. Be sure the cable is connected
correctly to a reliable power source—red lead to positive, black lead to negative
or ground. Ensure the power available at the mount is between 10 and 20 VDC.
26
MAINTENANCE
TROUBLESHOOTING
If the unit is wired through a fuse panel, ensure the panel is powered. Often
accessory fuse panels are controlled by a separate switch or the ignition switch.
Also, often a fuse can appear to be good when in fact is not. Check the fuse
with a tester or replace it with a fuse known to be good.
Check the power connection to the 250DX. It is possible to force the power
cable connector into the cable holder incorrectly. If the connector is reversed, the
unit will not work. Examine the contacts on the back of the unit to ensure there
is no corrosion. Finally, ensure the unit is firmly seated on the mount. The
electrical contacts are not made until the unit is fully seated.
Ensure the metal cable retainer is properly installed in the mount. If not, the
power connected may push out when the unit is put on the mount.
2. There is no transducer detected.
The 250DX has the ability to detect and identify that a transducer is connected.
If, at power up, a message indicates “transducer not connected,” only simulator
operation is possible. First, ensure that an appropriate transducer connector is
positioned correctly in the connector holder, and that the unit is fully seated on
the mount. The 250DX will work with the standard tri-beam transducer.
Second, inspect the transducer cable from end to end for breaks, kinks, or cuts
in the outer casing of the cable. Also ensure the transducer is fully submerged
in water. If the transducer is connected to the unit through a switch, temporarily
connect it directly to the unit and try again. If none of these items identifies an
obvious problem, the transducer itself is probably the problem. Be sure to in-
clude the transducer if returning the unit for repair.
3. There is no bottom reading visible on the display.
There are a number of possible causes for this condition. If the loss of bottom
information occurs only at high boat speeds, the transducer needs adjusting. If
the digital depth readout is working but there is no bottom visible on-screen, it
is possible the depth range has been adjusted manually to a range lower than
what is needed to display the bottom. Also, in very deep water, it may be
necessary to manually increase the sensitivity setting to maintain a graphic
depiction of the bottom.
27
MAINTENANCE
TROUBLESHOOTING
If you are using a transducer switch to connect two transducers to the 250DX,
ensure the switch is in the correct position to connect a transducer that is in
water. (If a trolling motor transducer is selected and the trolling motor is out of
water, no sonar information appears.)
If none of the above solve the problem, inspect the transducer cable from end
to end for breaks, kinks, or cuts in the outer casing of the cable. If the transducer
is connected to the unit through a switch, temporarily connect it directly to the
unit and try again. If none of these items identifies an obvious problem, the
transducer itself may be the problem. Be sure to include the transducer if
returning the unit for repair.
4. When in very shallow water, I get gaps in the bottom reading and
inconsistent digital depth indication.
The 250DX will work reliably in water 1m (3') or deeper. The depth is measured
from the transducer, not necessarily from the surface.
5. The unit comes on before I press POWER, and won’t turn off.
Check the transducer cable—if the outer jacket of the cable has been cut and
the cable is in contact with bare metal, you need to repair the cut with electrical
tape. If there is no problem with the cable, disconnect the transducer from the
unit and see if the problem is corrected, to confirm the source of the problem.
6. I get gaps in the reading at high speeds.
Your transducer needs adjusting. If the transducer is transom-mounted, there
are two adjustments available to you—height, and running angle. Make small
adjustments and run the boat at high speeds to determine the effect. It may take
several tries to optimize high speed operation. This can also be a result of air or
turbulence in the transducer location caused by rivets, ribs, etc.
28
MAINTENANCE
TROUBLESHOOTING
7. My unit loses power at high speeds.
Your 250DX has over-voltage protection that turns the unit off when input
voltage exceeds 20 VDC. Some outboard motors do not effectively regulate the
power output of the engine’s alternator and can produce voltage in excess of 20
volts when running at high RPMs. The 250DX displays input voltage in the
Diagnostic screen. Use this readout to determine if the voltage exceeds 20 VDC.
8. The screen begins to fade out. Images are not as sharp as normal.
Check the input voltage using Diagnostic. The 250DX will not operate on input
voltages below 10 VDC.
9. The display shows many black dots at high speeds and high
sensitivity settings.
You are seeing noise or interference caused by one of several sources.
Noise can be caused by other electronic devices. Turn off any nearby
electronics and see if the problem goes away. Noise can also be caused by
the engine. If engine noise is causing the interference, the problem will
intensify at higher RPMs. Increase the engine speed with the boat
stationary to isolate this cause. Propeller cavitation can appear as noise on-
screen. If the transducer is mounted too close to the propeller, the
turbulence generated can interfere with the sonar signal. Ensure that the
transducer is mounted at least 15" (38cm) from the prop.
29
MAINTENANCE
CUSTOMER SUPPORT
CUSTOMER SUPPORT
If you have any problems or questions with your Humminbird unit, contact
your local distributor.
Humminbird
Service Department
108 Maple Lane
Eufaula, AL 36027
USA
30
SPECIFICATIONS
Operating Frequency . . . . . . . . . . . . . . . . . . . . .200 kHz and 83 kHz
Power Output . . . . . . . . . . . . . . . . . . . . . . . . . . . .250 Watts (RMS)
2000 Watts (Peak to Peak)
Area of Coverage . . . . . . . . . . . . . . . . . . . . .Narrow: 20° at -10 db
Wide: 53° at -10 db
Power Requirement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12 VDC
Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .FSTN LCD
LCD Matrix . . . . . . . . . . . . . . . . . . . . . . . . . . . .128 V x 64 H Pixels
Viewing Area . . . . . . . . . . . . . . . . . . . . . . . . . . .2.90" V x 2.35" H
(7.3cm V x 5.97cm H)
Mounting . . . . . . . . . . . . . . . . . . . . . . . . .Quick Disconnect Mount
Unit Size . . . . . . . . . . . . . . . . . . . . . . . . . .6³⁄₄"H x 6¹⁄₄"W x 4¹⁄₄"D
(17.1cm H x 15.9 cm W x 10.5 cm D)
Transducer (Standard) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . XT-6-20
Transducer Cable Length . . . . . . . . . . . . . . . . . . . . . . .20' (6 metres)
Depth Ranges . . . .15', 30', 60', 120', 180', 240', 360', 480', & 600'
(5, 10, 20, 40, 60, 80, 110, 150 & 185 metres)
Zoom Ranges . . . . . . . . . . . . . . . . . . . . . . . . . .7¹⁄₂', 15', 30', & 60'
(2, 5, 10 & 20 metres)
31
Use with XT series Transducers
P/N 530975-2
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