How to Troubleshoot the Humminbird 100 Depth Finder

How to Troubleshoot the Humminbird 100 Depth Finder
The Humminbird 100 series of fish finders uses sonar waves to transmit information on the water depth below the boat. With these sonar waves, you get imaging of schools of fish under the boat, submerged logs or hazards, and water depth. This information is valuable as it lets you fish in productive areas and avoid underwater hazards. If your 100 series Humminbird fish finder is not functioning properly, there are a variety of ways to troubleshoot the device.


Difficulty: Moderate

Step 1
Check the power cord attachment at the screen display unit and make sure it is attached properly if your unit does not power up when the "On" button is pressed. Go to the boat battery and makes sure you have the red connection wire attached to the battery's red/positive terminal and your black wire attached to the black/negative terminal. Check the fuse box for faulty fuses if the unit still does not power on.
Step 2
Press "On" and check that the default display is the "Normal" screen. If it is not, check the transducer and transducer cable. Verify that the transducer cable is correctly attached to the display unit. The cable is a black round cable with a plug at the end. Make sure the plug is fastened into the display unit. Replace the transducer if it is damaged or has exposed wires. Check the transducer cable for frays, exposed wires or damage. Replace if damaged.
Step 3
Confirm that your battery is 20 volt if your unit displays screen changes or flickers when the boat is at high speed. The display unit must be attached to a 20-volt power source or it will malfunction.
Step 4
Move the transducer to a new location under the boat if the bottom reading drops out of view on the display screen when the boat is in motion. The transducer needs to be completely underwater and away from the engine and prop. Adjust the location accordingly if your depth readings are affected at higher speeds.
Step 5
Turn off the boat engine if your display screen shows electronic noise in the form of random pixels. Turn off all electrical devices, including an electric trolling motor, and then one by one, turn them back on until you locate the source of the electronic display noise.

Article Written By Eric Cedric

A former Alaskan of 20 years, Eric Cedric now resides in California. He's published in "Outside" and "Backpacker" and has written a book on life in small-town Alaska, "North by Southeast." Cedric was a professional mountain guide and backcountry expedition leader for 18 years. He worked in Russia, Iceland, Greece, Turkey and Belize. Cedric attended Syracuse University and is a private pilot.

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