It's tough for appliance techs today. Our biggest competition is from cheap replacement machines. The proliferation of pricey electronic boards in appliances means that if you can't quickly do a slam-dunk diagnosis, you are at risk of losing customers and your profitability.
Meanwhile, electrical troubleshooting is largely a lost science. What exactly have we lost? The Old Skool troubleshooting techniques that us old timers learned way back. And guess what: these same Old Skool troubleshooting skills still apply to modern, computer-controlled appliances! There's a good reason for that: because there is no other way to troubleshoot ANY electrical circuits in appliances. The Big 3 troubleshooting secrets I'm going to talk about in this post are foundational principles that will always apply to any electric circuit, no matter how many control boards the appliance has.
If you understand just three things, I guarantee you can successfully troubleshoot ANY appliance electrical problem:
- The distinction between voltage and voltage drop
- How loads and switches function in circuits
- How electrons move around a circuit
Let's take 'em one at a time:
Voltage vs. Voltage Drop
Understanding this distinction is key to correctly interpreting what your volt meter is showing you when you make a measurement. For example, in this video where I showed troubleshooting an inop evap fan in a jazz board refrigerator, the correct diagnosis entirely hinged on whether I understood the voltage measurement on my meter as voltage or voltage drop.
Voltage is just the difference in electrical potential between two points. It's called "potential" because voltage creates the potential for electrons to move. Electrons WILL move in response to this voltage difference, always seeking the relatively more positive voltage, IF there is a complete circuit between those two points and the power supply. Voltage is the prime mover in any circuit; it is the first cause for everything else that happens in that circuit.
Voltage Drop, on the other hand, is an effect produced when a voltage difference forces electrons through the resistance of a load. The supply voltage is said to be "dropped across the load." If there are loads in series, the supply voltage will drop across each load in direct proportion to the resistance of that load. The sum of the voltage drops will always add up to the voltage supply.
Understanding voltage vs. voltage drop is key to making the correct conclusion based on what your meter is showing you and you can almost always avoid unnecessary disassembly and do all your troubleshooting from a convenient location, such as at the timer or control board.
Loads and Switches
In appliance repair, we are troubleshooting very simple circuits: just loads and switches.
"Simple" used here is a technical term. It means that we don't deal with reactive circuits where voltage and current are out of phase with each other.
Yes - there's a very deep rabbit hole in electricity that involves reactive components like capacitors and inductors which have complex effects in the imaginary plane (I'm not making this up!) and we need to use the j-operator (also called the i-operator, same thing) to vectorially add the real and imaginary effects to get the total resultant.
Fortunately, in the circuits appliance techs troubleshoot, we are only dealing with real voltage and current. That's why the circuits we deal with are called "simple".
Even the circuit boards we deal with just function as software-controlled switches for various loads around the appliance with some data communications between boards. The software control doesn't change the fact that a switch is still just a switch and functions the same way in all electric circuits.
If you understand how loads and switches each function and work together to do useful work in appliances, you're a third of the way to troubleshooting mastery.
How Electrons Move Around a Circuit
A long time ago, the movement of electrons was given the unfortunate name "current". I say unfortunate because many techs take this to mean it moves like water. It does not. Electrons have nothing to do with water. Just forget about that whole silly analogy.
You need to understand what those electrons actually are and why they move the way they do in a circuit. This is all settled science and, for the types of circuits we work on, electron movement is completely described by simple Ohm's Law equations.
Electricity is neither visual (you can't see it) nor intuitive (you can't understand it or predict its behavior by intuition, gut feel, or beliefs). Electrons move in accordance with very specific rules (Ohm's Law) that you need to understand. So you have to spend some time learning the basic principles, which we teach in the Fundamentals of Appliance Repair course at Master Samurai Tech and also in the Webinar recordings here at Appliantology.
Your path to mastery
If you are motivated and disciplined, you don't even need to enroll in a training course at Master Samurai Tech. If you are a premium tech member here at Appliantology, just make it a habit to watch one webinar recording every weekend and ask me questions if you're confused about something. It's a killer deal! Not only do you get tech support and service manuals here at Appliantology, you get in-depth, high quality training taught by someone who knows his stuff like few others in the trade today.
However, many of us need (or prefer) a more structured course of training, broken down in more detail, along with quizzes and exams to help keep us accountable. If this is you, then enroll in our courses at the MST Academy (starting with Fundamentals).
We are not teaching anything new, or pointy-headed, or academic
At Master Samurai Tech and in the many webinar recordings here at Appliantology, I am teaching the same principles of electricity and circuits that technicians have been learning for 50 years or more.
Believe it or not, I've had guys try to "agree to disagree" with me about basic electrical concepts, as if it's a political discussion we're having on Facebook. No, we're talking settled science, physics, proven, repeatable, taught the same way all over the world because electricity works the same way all over the world. It will be taught the same way whether you learn it in the Navy, any physics or engineering courses, or at Master Samurai Tech.
How do I know this? Because I was trained on basic electricity and aviation electronics in the Navy and then troubleshot computer-controlled radar systems down to the failed component on electronics boards. I also have two engineering degrees, one a Masters, and am a licensed professional engineer in the state of New Hampshire. During my engineering career, I designed hazardous waste remediation systems and industrial ammonia refrigeration systems for large food plants. (If you're one of the morbidly curious, you can read my background here.) So I am not some hack at a keyboard pecking out inane ramblings on a website.
I am also not saying this to brag. I didn't discover all this on my own - I know what I know because I had some great teachers and I worked hard to learn what they were teaching because I knew it would help me be more successful.
I’ve also spent more than 20 years now helping other techs online, so I know where your pain points are, and I've figured out what you need to know and how to communicate it most effectively to you.
Unfortunately, with some guys this is like casting pearls to swine because they're so caught up in their own ego or blinded by envy that they can't be helped. They can't admit that they have knowledge gaps. It’s a pig-headed pride thing.
But if you are one of those techs who values your success over your ego, and you want to understand how circuits really work and how to troubleshoot, we teach you the real thing just as it is taught to real technicians at any legit institution around the world.