SAVE TIME AND MONEY WITH THIS STATE-OF-THE-ART GUIDE TO THE LATEST, MOST ADVANCED DIAGNOSTIC EQUIPMENT AND TECHNIQUES
“Ed Sherman is one of America’s great teachers and communicators of marine technology.”--Tim Murphy, Executive Editor, Cruising World
Whether you are a marine electronics professional or a boatowner, Advanced Marine Electrics and Electronics Troubleshooting helps you understand the new, more powerful methods of troubleshooting marine electrical and electronic systems. A modern boat’s sophisticated installations and networked electronics can stretch the traditional diagnostic methods based on trouble lights and multimeters past their useful limits. This book will show you how to:
- Use microprocessor-based diagnostic tools and techniques from the automotive and communications sectors, adapted for boats for the first time
- Diagnose the most difficult AC and DC problems
- Protect communications and navigation electronics from interference and lightning
- Seek out and eliminate stray-current sources and galvanic corrosion
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About the Author
Ed Sherman is a regular contributor to Professional Boatbuilder and Cruising World and a senior staff writer for the American Boat & Yacht Council.
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Advanced Marine Electrics and Electronics Troubleshooting
A Manual for Boatowners and Marine Technicians
By Ed Sherman
The McGraw-Hill Companies, Inc.Copyright © 2007 Edwin R. Sherman
All rights reserved.
Marine Troubleshooting the Modern Way
Advanced Marine Electrics and Electronics Troubleshooting introduces the technician or boatowner to some new equipment for troubleshooting electrical systems. With this equipment, some of the traditional techniques used by marine electricians over the years can now be altered or vastly improved upon. The new gear provides more accurate information, and many of the traditional troubleshooting steps can be eliminated altogether. The microprocessors in these new devices simplify diagnoses that used to require multiple steps and painstaking labor.
Because much of the information in this book may be new to many readers, it seems prudent that we first look at some common problems related to electrical and electronic systems, and then move on to finding solutions to these problems. Rather than using the traditional tools of electrical troubleshooting, however, I will identify the new equipment and point you to the chapter that describes how the equipment is used.
My goal throughout this book is to elevate your skills to the next level in diagnostic work, using the latest in equipment and techniques. If you're a professional electrician, you will certainly need these skills as boats continue to evolve into increasingly more complex electrical/electronic marvels. And if you're the owner of a sophisticated boat, learning to use this equipment will greatly simplify your life when it comes to diagnosing a problem quickly and with minimal electrical expertise. The equipment really does most of the detective work for you. Your part consists of understanding and applying the results generated by the gear, and I hope this book gives you much greater insight into that.
With only a few exceptions, all of the instruments discussed cost less than $500—some of them are less than $100 (and one is under $10!). For anyone who works on boats with complex electrical systems and lots of electronics, these costs can be easily and quickly justified by savings in time and increased effectiveness over old troubleshooting methods. As for the more expensive gear, even that can generate relatively quick payback for professionals, while some advanced amateurs who readily drop thousands of dollars on boat "toys" should have no trouble finding practical applications for these useful and highly capable tools.
To help you build your high-tech toolbox, I've placed Toolbox sidebars in every chapter describing an instrument. In them, I've listed some models and brands that have a good track record to give you a good place to start.
Throughout this book, I've included extensive descriptions of specific instruments to demonstrate the functionalities and basic operations for a class of equipment. My use of these instruments is not an endorsement for any particular brand. Instruments from other manufacturers may offer comparable or superior functionality to the ones I've used here. If you are considering the purchase of a specific piece of equipment, carefully weigh all factors: pricing, service, warranty terms, availability, and your specific needs for an instrument's functions and capabilities.
Caution: AC circuitry is dangerous! Extreme shock hazards exist. If you are not experienced and comfortable around AC equipment and troubleshooting, call in a specialist.
FINDING YOUR WAY
How is this book set up? I've divided it into two parts, each with specific goals.
Part 1, Electrical Systems Troubleshooting:
Identifies new methods for troubleshooting electrical circuits (including the engine starting and battery charging systems and the AC and DC distribution systems).
Introduces you to test instruments you may not have seen before, such as the time domain reflectometer, megohmmeter, and amp clamp, and explains their capabilities and applications.
Provides step-by-step instructions, with accompanying photos, on how to use these instruments and apply the results.
Explains the importance of grounding systems from the multiple perspectives of equipment functionality, shock prevention, corrosion minimization, and lightning protection.
Part 2, Marine Electronics Installation and Troubleshooting:
Addresses the relationship between the electrical system and marine electronics.
Looks at numerous installation factors that influence the functionality of electronic equipment, and tells you how to anticipate and avoid problems before you cut holes and run wires.
Gives special attention to antennas and coaxial cable, as they are critical to the proper functioning of many types of equipment.
Introduces the cutting edge of onboard wiring—networked systems—to give you a taste of what to expect in the near future.
Let's begin, then, with a discussion of the types of electrical circuits on modern boats, and how to troubleshoot the modern way.
ELECTRICS VERSUS ELECTRONICS
Today's typical modern boat, whether power or sail, has the potential for carrying a wide variety of circuits and equipment:
AC-supplied battery chargers
bilge pumps and blowers
bow or stern thrusters
electric galley (stove and oven)
electric head sanitation system
engine-driven charging circuit
engine starter circuit
lighting, including navigation lights and general illumination
navigation and communications electronics
refrigeration and air-conditioning system
shore-power transformers (isolation transformers) and AC generators
All of these devices can be divided into two broad categories: electrical systems, which include such things as basic shore-power service or the navigation light circuit on your boat; and electronics, which we can generally categorize as circuits that distribute data, such as between a GPS receiver and an autopilot.
The common characteristics of these devices are that they all have a power source, either AC or DC, as well as a path for the electrical current to flow. And inevitably, at some point during their service life, they will need to be repaired, upgraded, or replaced.
Beyond these, few factors apply across all of the devices, so it is convenient to organize them into the categories listed below:
1 Electrical systems
high-amperage motor circuits
low-amperage motor circuits
AC resistive loads (heating elements)
battery chargers and inverters
AC power sources
Using these categories, I've created flowcharts to identify some common problems, the equipment or instrument to use to troubleshoot those problems, and the general step-by-step testing procedures. (Each test instrument walks you through the process via on-screen prompts, so I won't repeat all those steps here.) I've also included, for comparison, the old method of troubleshooting, so you can see the greater efficiency and effectiveness of the new method. Finally, each flowchart gives you a quick reference to the chapter that offers more detailed information on the instrument's use and application.
Flowcharts: Electrical Systems
High-Amperage Motor Circuits
The first category consists of motor circuits with high current draws. These are really dual circuits, with a low-amperage control circuit side to activate a relay or solenoid, which then activates the high-amperage side to run the motor. Examples include:
The troubleshooting procedure is summarized in the flowchart on page 4.
Low-Amperage Motor Circuits
This category includes AC and DC motor circuits of low current draw (relative to the high-amperage motors above):
refrigeration systems (AC or DC)
electric heads and macerator pumps
Unlike the circuits for high-amperage motors, low-amperage motor circuits typically do not have a control side and a high-current side, and they are usually fed directly by a DC power supply (although refrigeration systems may be powered by AC or DC, or both).
Typical problems with this category of circuits include the following:
No operation when the switch is activated.
Abnormally slow motor operation.
Frequent tripping of an overcurrent protection device (such as a circuit breaker or fuse).
The troubleshooting procedure is summarized in the flowcharts on pages 4 and 5.
The Engine-Driven Alternator
The engine-driven alternator is a unique device—both in its electrical properties and in its function—so it is treated separately.
We'll assume the mechanical side of the alternator is in good order, the drive belts are tight, and the alternator is securely mounted to the engine. The flowcharts also assume that the problem is new, and that previously all was well with the charging system. There are several symptom sets related to alternators that need to be considered:
1 Undercharging will be manifested as poor battery performance.
2 Overcharging will show up as either a foul odor in the battery compartment, or swelling of the battery cases or low electrolyte levels (if the problem is of long standing). With sealed batteries, of course, this cannot be checked, nor can you replenish levels. If a cell of a sealed battery gasses itself dry, the situation becomes dangerous. The cell can short itself out, and an arc inside the battery can cause an explosion.
3 Electronic "noise" emitted from the alternator may interfere with the performance of other electronic equipment on board the boat.
The troubleshooting procedure is summarized in the flowcharts on page 6.
This category includes all lighting circuits, both AC and DC, with their different power supply considerations:
Light circuits are simple. All you need is power supplied from a source and a good return path to ground. The primary concerns are of course electrical continuity and sufficient voltage throughout the circuit, especially in the case of navigation lights, which are governed by both U.S. Coast Guard regulations and American Boat and Yacht Council (ABYC) standards. The equipment can be very basic (e.g., a multimeter) or extremely sophisticated (e.g., a time domain reflectometer, or TDR). I now use a TDR almost exclusively for this sort of work.
The troubleshooting procedure is summarized in the flowcharts on page 7.
Here I've grouped the engine instrumentation and related gauges as follows:
oil pressure gauge
These devices need battery power to function, but they often work on a variable ground principle from a sending unit, or in the case of tachometers, also receive a signal from the engine. So in effect, they have two sides to their circuits: the instrument power side, and the sending unit input side.
The troubleshooting procedure is summarized in the flowcharts on pages 7 and 8.
AC Resistive Loads
This category covers AC-powered resistive loads; i.e., heating elements. These include:
electric ranges and ovens
electric space heaters
These devices have high current draws and can develop problems over time. You can save a great deal of troubleshooting time by using the diagnostic equipment discussed in this book.
The troubleshooting procedure is summarized in the flowcharts on pages 8 and 9.
Battery Chargers and Inverters
AC-supplied battery chargers, inverters, and inverter chargers have both AC and DC circuitry in the same case. They also have both AC and DC outputs or inputs. The test equipment required will be dictated by whether the problem is on the DC or AC side.
The troubleshooting procedure is summarized in the flowcharts on pages 9–11.
AC Power Sources
AC power sources consist of shore-power isolation transformers and AC generators, both of which are AC current producers. The transformer is a point of distribution on board the boat; it is supplied by the shore-power feed but electrically isolated from it. Because the tools of choice here are the full arsenal of AC diagnostic tools already mentioned, no flowchart is presented.
Check amperage and voltage outputs: use the SureTest tool (Chapter 4).
Diagnose waveform and harmonics issues: use an oscilloscope (Chapter 7); if a problem is intermittent, use an oscilloscope/laptop combination to track and record data (Chapter 8).
For safety reasons, routinely use a Yokogawa or similar clamp-on leak tester (Chapter 10).
Flowcharts: Electronic Devices
Here we'll cover circuits serving electronic equipment, such as audiovisual, navigation, and communications devices:
communications equipment—VHF and SSB radios
computer or laptop
fishfinders and chartplotters
navigational equipment—GPS and radar
televisions and DVD players
weather monitoring equipment
This category is a bit more complicated than electrical systems because it includes both AC- and DC-powered gear, with slightly different considerations for each. As with all devices, the first step is to confirm the integrity of the power source at the device. In the case of these circuits, that means voltage, whether it's 120 VAC (volts of alternating current) or 12 or 24 VDC (volts of direct current). In many cases, however, you may need to take additional steps.
The troubleshooting procedure for navigation and communications equipment is summarized in the flowcharts on pages 11 and 12. For troubleshooting audio and video systems powered by AC current, see the bottom flowchart on page 12.
BASIC TROUBLESHOOTING STEPS
Over the years, I've taught troubleshooting in dozens of classrooms and seminars. While the equipment necessary to solve more complicated problems has become more sophisticated, the basic processes haven't changed. Problem solving is not always easy, and to be done properly and efficiently, several steps must be taken in logical order:
1 Verify the problem. Does the complaint represent a genuine problem? Or is the solution really awareness or education?
2 Gather information. Get the complaint directly, not thirdhand. Determine the exact symptoms and the conditions under which the problem occurs. Get a timeline—is this a new problem, or has it been going on for awhile? Get as much history about the boat as possible.
Try to determine the order in which symptoms developed.
3 Determine probable causes. Perform a thorough visual inspection, and repair obvious problems before diving into lengthy testing procedures. Have the appropriate service manual or wiring diagrams available if at all possible (unfortunately, this is often not possible). Think about subsystems and ancillary components that could contribute to or cause the problem.
4 Narrow the list of causes. Use the history and symptom conditions to narrow down the list of probable causes. If more than one symptom exists, are there common causes? Avoid preconceived ideas. Follow test procedures step by step, skipping none.
5 Test all subsystems. Test the most likely cause first. Follow any manufacturer-recommended procedures.
Following these logical steps to troubleshooting may seem like the medical history a doctor gathers when trying to figure out what ails you, and for good reason: the method works. Used in combination with the best, most capable equipment, this method will definitely increase your odds for success. Now let's get started!
Excerpted from Advanced Marine Electrics and Electronics Troubleshooting by Ed Sherman. Copyright © 2007 by Edwin R. Sherman. Excerpted by permission of The McGraw-Hill Companies, Inc..
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