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. Efficient and accurate troubleshooting leads to happy customers and good profits.
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!).
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 easy-to-use 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. Once you do, you'll be able to pull up a schematic for an appliance and read it as easily as you are reading this article and your troubleshooting mojo will go off the charts!
"This seems a bit 'sciencey' for appliance repair..."
We sometimes hear a bizarre criticism of our training - that it's too much into the science of electricity for what most appliance techs need. That would only be accurate if someone's idea of appliance repair is "parts changing". But we are training folks to be appliance repair technicians. A technician understands the basic technology he or she is working with deeply enough to be an effective troubleshooter, even on machines they've never worked on before.
And believe me - we are not going very deep into the world of electricity and circuits in our courses. The Samurai was trained by the US Navy to troubleshoot electronic circuitry that their pilots depended on, and has two engineering degrees. He knows how deep the rabbit hole goes. He also knows the portion of that information that he relied on when he began his appliance repair career to quickly become a slam-dunk troubleshooter, and that portion is what we teach.
Interestingly, the "old school" techs that we knew back in the day (before the internet) were often ex-military and approached appliance repair the same way we do.
But things have changed since then. In the more than 20 years that the Samurai has been helping techs online, he has seen where the pain points and knowledge gaps are, and has figured out what you need to know and how to communicate it most effectively to you.
You know what the biggest obstacle to becoming an ace tech is? Ego. Someone who has some years of experience under his belt and thinks there's nothing that he needs to learn from us. We've seen it too many times. Fortunately, we've also worked with plenty of techs who value success and profitability over false pride, who take our courses to become masters.
Your path to mastery
The Master Samurai Tech Academy offers structured courses of training in appliance repair. Begin with the Core course, which teaches the knowledge and skills that are fundamental to being a successful tech. It explains the Samurai's "secrets" in much more detail, along with quizzes and exams to help keep you accountable. Then continue on with our other courses to take a deeper dive into the technology specific to various types of appliances, and get more troubleshooting instruction and practice.