Save yourself a bundle with these electronics troubleshooting tips
As is the case with most boat gear failures, electronic equipment problems always seem to crop up at the worst possible time. The multi-function display bites the dust when heading out for a day of fishing or the depth sounder blanks out while transiting some remote location during your annual cruise. Tech support is a wonderful thing, but self-reliance and the ability to recognize and fix simple problems are even better. Here are a few basic electronics troubleshooting tips to help bring your ailing electronics back online as quickly as possible.
Knowledge is Power
The first step in troubleshooting the system or piece of electronics gear is something you should have already done before the problem even arose: read the owner’s manual. A basic understanding of how the gear or system functions and is installed before you start troubleshooting is extremely helpful. It will assist you in recognizing and locating common problems. Most manuals will also have a basic troubleshooting section that helps point you in the right direction.
Start with the Basics
When a piece of electronics gear fails to turn on, start by checking the power connection at the unit for looseness or corrosion. If your DC power panel has a voltmeter installed, take a quick look to verify that it shows the correct voltage and that all required breakers are turned on. You wouldn’t be the first to realize a problem was actually caused by a battery switch or circuit breaker being in the “off” position.
For electronics that work intermittently or lose certain functions, check the remaining plugs or wire connections. These could also suffer from corrosion or may have loosened over time due to vibration. As odd as it may sound, sometimes problems can be corrected by simply disconnecting cable plugs and plugging them back in. The same is true for inline cable connections, which can loosen due to excessive movement or vibration if not secured or mounted properly. Trace the cable runs to see if there are any problems (breaks, damage, etc).
If a unit powers up but shows nothing on the display, start simple and check the display brightness and contrast settings. These settings often get adjusted on purpose (to preserve night vision, for example) or by accident to the point where the display is no longer visible under different lighting conditions.
Other control features can also generate what I like to call “operator induced anomalies.” If your radar fails to pick up targets, for example, verify you’re on the correct range setting and that the gain/sensitivity features are adjusted correctly.
When it comes to hardware problems, if you’ve verified all connections are tight and the problem still exists, it’s time to get all technical and break out the multimeter. Every boat should have one on board. You can buy a multimeter for as little as $6 at Harbor Freight. Stay away from pen lighttype voltage testers. They can tell you if there’s voltage, but not how much—a critical troubleshooting flaw as many electronics fail to operate if the voltage drops below a certain point.
To check the power to a piece of gear, turn the unit off and disconnect the power plug or access the terminal strip where power is connected. Then verify that battery switches and breakers are in the “on” position. Set the multimeter to DC volts and measure the voltage by connecting the meter’s negative probe to the equipment plug’s negative lead and positive probe to the positive lead. If you accidentally reverse the probes, the meter will simply display a negative reading.
A voltage reading of “0” indicates no power is reaching the unit (tripped breaker, blown fuse, loose connection, broken wire, etc). An item of note: if a fuse that blows multiple times when replaced, that should be considered a symptom rather than the problem itself. A low voltage reading indicates low battery voltage or, possibly, additional resistance in the line such as a corroded or faulty connection. Verify that the correct amount of power is leaving the breaker panel and if so, work your way toward the equipment in an effort to identify the problem. If not, then verify battery voltage is correct and proceed from there.
Consistency is King
Another thing to consider is how steady or consistent the voltage is during equipment operation. Some electronics draw more power during certain operations, such as your VHF radio when transmitting versus receiving. While you may have a full 12 volts at the power plug when the radio is disconnected or simply turned on, that voltage can drop well below a usable level when the radio is keyed to transmit. This is often due to a weak battery or possibly a corroded connection. Monitor your DC panel voltmeter (or use your voltmeter) while keying the radio to see if the voltage drops.
While standalone electronics will have their own dedicated power plug or source, newer electronic systems will likely be powered by a NMEA 2000 (N2K) trunk or backbone. If the system is installed correctly and was working previously, and you confirmed that the voltage supply is correct and that all plugs and connections are good, then the problem could be with the backbone itself. There are meters that allow you to test N2K backbones, but they’re pricey ($600 plus) and more than most occasional users are willing to spend. If you think the problem lies with the backbone, it’s likely time to call in a professional.
By Frank Lanier, Southern Boating December 2018