Garmin GPSMAP 640 Manual

The Garmin GPSMAP 640 is a high-performance marine chartplotter featuring a 6-inch sunlight-readable color display, built-in worldwide basemap, preloaded BlueChart g2 coastal charts, support for various sonar modules, NMEA 2000 and 0183 connectivity, internal GPS receiver, microSD card slot for additional maps, and rugged, waterproof design. Below are key sections for safety, features, installation, setup, operation, and troubleshooting.

Features at a Glance

Key components: 6-inch color TFT display, Power/Data cable, Mounting hardware, Protective cover, Quick start manual.

Feature	Description
Display	6-inch diagonal, 480 x 640 pixels, sunlight readable, waterproof (IPX7)
GPS Receiver	High-sensitivity internal GPS with WAAS/EGNOS support
Charts	Preloaded BlueChart g2 coastal charts, worldwide basemap
Connectivity	NMEA 2000, NMEA 0183, microSD card slot
Sonar Support	Compatible with Garmin GSD series sounder modules
Power Input	10-32 V DC
Waypoints/Routes	3000 waypoints, 100 routes with 250 points each
Tracks	10,000 points, 20 saved tracks
Buttons	Page, Zoom In/Out, Power, Enter, Rocker key
Audio Alarms	Anchor drag, arrival, off-course, etc.

Installation

Unpack and inspect contents. Choose mounting location carefully.

1. Mount the bracket: Select a flat, sturdy surface on helm. Use provided template to mark holes.
2. Drill holes and secure bracket using stainless steel hardware (provided).
3. Route the power/data cable: Connect to unit, route to power source avoiding sharp edges.
4. Connect to power: Red wire to positive (+), black wire to negative (-) on 10-32V DC source.
5. Connect optional devices: Attach NMEA 2000 network, sonar module, or external antenna as needed.

WARNING! Ensure all power is OFF during installation. Use proper marine-grade wiring and fusing.

First-Time Setup

Power on unit; follow initial setup prompts.

1. Select language: Choose from available options (default ENGLISH).
2. Configure units: Set distance, speed, depth, and temperature units (nautical/statute).
3. Calibrate compass (if applicable): Follow on-screen instructions.
4. Acquire GPS signal: Place unit in open sky view; wait for satellite acquisition.
5. Set time: Choose automatic GPS time or set manually.
6. Configure alarms: Set default values for anchor drag, arrival, etc.

CAUTION! Ensure secure mounting before operating vessel.

Specifications

• Display Size: 6 inches diagonal.
• Display Resolution: 480 x 640 pixels VGA.
• Waterproof Rating: IPX7 (submersible 1 meter for 30 minutes).
• Power Supply: 10-32 V DC, 1.5 A max.
• GPS: High-sensitivity receiver, WAAS/EGNOS capable.
• Chart Storage: Internal memory, microSD card slot (supports up to 4 GB).
• Interfaces: NMEA 2000, NMEA 0183 (2 ports), microSD.
• Operating Temp: -15° to 70°C (5° to 158°F).
• Dimensions: 18.3 x 13.2 x 6.1 cm (7.2 x 5.2 x 2.4 in).

Controls and Settings

Access menus via Page button or touchscreen (if equipped). Front Panel: Power, Page, Zoom In/Out, Enter, Rocker key.

Main Pages: Navigation Map, Compass, Highway, Sonar, Active Route, Waypoint Manager.

Settings Menu: System (Language, Units, Time), Navigation (Routing, Alarms), Communications (NMEA Setup), Sonar (Frequency, Range), Display (Backlight, Contrast).

Quick Keys: Press and hold Page to customize page sequence. Use Rocker to navigate menus and move cursor.

Connecting Devices

NMEA 2000: Connect to backbone using appropriate T-connector. NMEA 0183: Connect to compatible devices (AIS, autopilot) using TX/RX wires. Sonar: Connect compatible GSD sounder module via network. External Antenna: Connect to optional GA 29 or similar GPS antenna.

1. Turn off all devices before connecting.
2. Refer to wiring diagrams in Appendix for pin assignments.
3. Secure all connections with waterproof heat-shrink or sealant.
4. Configure NMEA sentences in Communications menu to match connected devices.

Tip: Use marine-grade, tinned copper wire for all connections to prevent corrosion.

Using Navigation Features

Create and follow routes, mark waypoints, view charts.

1. Mark Waypoint: Press Enter twice at current location or use cursor to select point on map and press Mark.
2. Create Route: Go to Route Planner, select New, add waypoints in sequence, press Navigate.
3. Follow Route: Active route appears on Map page; use Compass or Highway page for steering guidance.
4. Edit Waypoint/Route: Select from Waypoint Manager or Route Planner to edit name, symbol, position.
5. Use Tracks: Enable track log to record path; save or navigate back along track.
6. Dock Mode: Zooms in for precise maneuvering at low speeds.
7. Man Overboard (MOB): Press and hold Enter to mark MOB position and begin navigation back.

WARNING! Always maintain situational awareness; use GPS as aid to navigation, not sole means.

Sonar and Fishfinding

When connected to compatible sounder module (e.g., GSD 22).

1. Select Sonar page from Page sequence.
2. Adjust frequency: Choose 50 kHz for deep water, 200 kHz for detail/shallow water.
3. Set range: Auto or manual depth range.
4. Adjust sensitivity: Increase to see weaker returns, decrease to reduce clutter.
5. Use A-scope: Real-time vertical display of water column.
6. View bottom contour and fish arches; identify bottom composition.

Note: Sonar performance depends on transducer installation and water conditions.

Care & Maintenance

Use soft, damp cloth with mild detergent to clean display and case. Rinse with fresh water after saltwater use.

CAUTION! Do not use harsh chemicals, abrasives, or high-pressure spray. Ensure connectors are clean and dry before reattaching.

Regulatory Information

FCC Compliance: This device complies with Part 15 of FCC rules. Operation subject to conditions: (1) not cause harmful interference, (2) accept any interference received. Industry Canada ICES-003 Compliance. Contains transmitter module FCC ID: IPH-XXXXXX. For support, visit www.garmin.com/support or contact Garmin Product Support.

Troubleshooting

Symptom	Possible Cause	Corrective Action
No power	Blown fuse, loose connection	Check fuse (3A); verify secure power connections at unit and source.
No GPS signal	Blocked view, antenna issue	Move to open area; check antenna connection; ensure no metal obstruction.
Display blank/dim	Backlight setting, power	Adjust backlight in Display settings; check voltage (min 10V DC).
NMEA devices not communicating	Incorrect wiring, settings	Verify wiring per manual; check NMEA sentence output/input settings.
Sonar not working	Module not connected, transducer	Ensure sounder module is powered and connected; check transducer installation.
Unit freezes	Software issue	Perform soft reset (disconnect power for 30 seconds). If persistent, contact support.

Reset: Disconnect power for full reset. System > Restore Defaults to reset settings.

Service: Contact Garmin Product Support or visit www.garmin.com for software updates and service.