Master Samurai Tech’s Big Three Troubleshooting Secrets

Even in the digital age, the ‘old-school’ approaches still apply

By Sam Brown, Master Samurai Tech/

It’s tough for appliance techs today.

Our biggest competition is from cheap replacement machines. The proliferation of pricey electronic boards in appliances (and their uncertain procurement these days) means that if you can’t do a quick 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-school” troubleshooting techniques that we old timers learned way back. And guess what: these same 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. These three troubleshooting secrets are foundational principles that will always apply to any electric circuit, no matter how many control boards the appliance has.

If you understand just these three principles, I guarantee you can successfully troubleshoot any appliance electrical problem:

  1. The distinction between voltage and voltage drop
  2. How loads and switches function in circuits
  3. 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 voltmeter is showing you when you make a measurement. For example, in this video where I demonstrate 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 simply 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 diagnosis based on what your meter is showing you. It will almost always allow you to avoid unnecessary disassembly and to 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,” as 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 that 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 encounter only 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 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, meaning you’ll have to spend some time learning the basic principles, which we teach in the Core Appliance Repair Training course at Master Samurai Tech.

We are not teaching anything new, pointy-headed or academic. At Master Samurai Tech and in the many webinar recordings at Appliantology, we teach the same principles of electricity and circuitry that technicians have been learning for 50 years or more.

Believe it or not, we’ve had guys try to “agree to disagree” with us about basic electrical principles, as if it’s a political discussion on Facebook. No, we’re talking settled science and physics: proven, repeatable, and taught the same way all around the world, because electricity works the same way everywhere. The facts will be the same, whether you learn them in the Navy, any physics or engineering course or at Master Samurai Tech.

We’ve spent more than 20 years helping techs online, so we know where a trainee’s pain points are, and we’ve figured out what you need to know and how to communicate it most effectively.

We teach the real thing. If you want your techs to understand how circuits really work and how to troubleshoot, check out the Core Appliance Repair Training course at Master Samurai Tech, and be sure to use your BrandSource discount coupon for 15% off your enrollment.

Sam Brown is “Professor of Appliance Repair Mastery” at BrandSource partner (MST), an online training academy for appliance repair personnel, and is the administrator of its sister tech support site, For more information, email Sam at or call (603) 290-5516.

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