Topic: Tech Talk

Why We Attend the Annual Service Training Institute

Posted on January 19, 2016 by - Academy Talk, Business Talk, Tech Talk

ASTI 2016Managing schedules (and time, in general) is a common problem, especially for people in service businesses, like ours. Everything tends to be emergency driven, and we feel pressure from the demands of customers and all the other aspects of running a business. The result of constant fire-fighting is burnout.

When we stop learning and creating, we stop growing and life becomes routine, tedious, and boring. We need to deliberately set aside time to do things that that help us grow. Recreation (literally, re-creation) is one form of this. But another equally important form is training and honing our craft, and experiencing those "Ah-hah!" moments when we gain a deeper understanding of the technology we work with every day.

It is vital that we MAKE the time for some big-picture work on our business. This is why annual training events, like ASTI, are so beneficial. Not only are you in a different physical location-- taken out of your regular work space-- but you're reuniting with old friends, meeting new Brethren in the Craft, and learning tons of cool new stuff, both business and technical.

With the Master Samurai Tech Academy, we have an additional reason for attending ASTI: to get the word out on the comprehensive, cost-effective appliance tech training that we offer online! We'll have a booth again and will be running an ASTI special, but also raffling off a free enrollment in our Fundamentals of Appliance Repair training course to anyone who stops by our booth for a visit.

Speaking of the MST Academy, a recent benefit we’ve added for our students is regular Office Hours live technical training webinars. I’ll usually have a special presentation on technical topics of particular interest to appliance techs. Some of the past topics we’ve talked about are:

  • Troubleshooting Strategies for Computer-Controlled Appliances
  • Digital Communications in Appliance Repair
  • Reading Tech Sheets and Schematics
  • Diodes and Rectification
  • Split-phase motors: theory of operation, types, and applications in appliances
  • Voltage and Voltage Drops in Electric Circuits
  • Techniques for Measuring Voltage without Getting Head-Faked by Open Neutrals and Ghost Voltages
  • Series and Parallel Circuits
  • Open Q&A on Student Coursework

I conduct these webinars using, the best service of its kind out there on the web today. I can pull up schematics and tech sheets for us to talk about and use the whiteboard app to whip out some sketches and talk through circuits.

Another big benefit of doing these weekly, live training webinars has been that we've gotten a real-time look into how, specifically, students are struggling to understand basic electricity, circuits, and schematics, and we’ll add additional videos and instructional material to the courses to address these trip points. This month alone (January 2016) we’ve added three new videos to the Fundamentals of Appliance Repair training course as a direct result of the Office Hours webinars! Here’s a 2-minute excerpt from a video we recently added to the Fundamentals course:


Do you know the answer?

We posted this clip on our Facebook page and got all kinds of different answers which confirms what we already knew: there’s lots of learnin’ to be done out there in the appliance tech community on basic circuits! And if you don’t know basic circuits, there’s just no way you can effectively use schematics to troubleshoot modern appliances.

Dynamic Doodle Dynamite! Another Powerful Tool For Teaching Circuits

Posted on January 14, 2016 by - Academy Talk, Tech Talk

Here's a 2-minute snippet from a recent Doodlecast video I made and added to the Fundamentals of Appliance Repair training course at the Master Samurai Tech Academy. The full video is 22 minutes and I explain current flows and voltage drops in parallel circuits using Ohm's Law.

I'm having fun making these Doodlecasts and we've found that they're a great way to explain basic electricity to appliance repair technicians!


If you are enrolled in the Fundamentals course, be sure to check out the full 22+ minute presentation in Module 3, Unit 4.

And to see even more of this kind of stuff, attend Office Hours, our weekly live webinars where I use presentation tools like this to explain all kinds of electrical and troubleshooting concepts.


Master Samurai Tech Schematic Lab Webinar 10-22-2015

Posted on October 24, 2015 by - Academy Talk, Tech Talk

Wow, what a great Schematic Lab Webinar we had. It was a Schlabinar!

It was our biggest turnout yet for a live webinar. This is a topic that serious students of appliantology can’t seem to get enough of, and I’m not surprised. As y’all know, I preach the virtues of pre-diagnosis, schematic reading, and troubleshooting. These are the premier technical skills we can possess as technicians. Interpreting the mystic scribblings that the manufacturers provide on their tech sheets requires quite a bit of background knowledge, such as understanding basic electricity, series and parallel circuits, and Ohm’s Law, not to mention collaboration with your Brethren in the Craft.

As with all skills, however, it gets easier with practice and knowledge, which was exactly the point of the Schlabinar. We pored over the actual tech sheets for 5 different appliances, using them as a springboard for diving deeper into the interpretation of these documents as well as their use in your troubleshooting.

If you missed it, or would like to review it again to fully absorb all of the info, you can watch the recording and download the tech sheets we reviewed here (NOTE: you must be enrolled as a student in the Samurai Tech Academy and logged in).

Loose Electrical Connections and Heat

Posted on October 23, 2015 by - Tech Talk

Burnt Electrical Splices in a Junction BoxLoose electrical connections cause multiple problems in appliances, heat being the most common one. We've all seen burnt wire nuts in a dishwasher power junction box or on a dryer heating element. But how does a loose connection produce heat?

Electrical connections need to be mechanically tight to ensure that the resistance across that connection is as low as possible, ideally 0 ohms. When a connection becomes either loose or corroded, it develops resistance. This resistance dissipates power in the form of heat when current flows through it. Even a resistance as low as 5 ohms can produce more than enough heat to burn up the connection and surrounding wires.

In this little video, I show you the effects of a loose connection in a circuit and we'll see how much heat, in watts, a typical loose connection produces. I'm also going to dispel a common myth that I hear, even from manufacturers: loose connections cause a circuit to draw more current. This is completely false and I'll prove it to you.



The Low Down on Loading Meters and DMMs

Posted on August 17, 2015 by - Tech Talk

Do you know the difference between a loading meter and a non-loading digital multimeter (DMM)? Both are critical troubleshooting tools for appliance repair and both belong in your tool bag. In this post, I'll explain the difference between these two types of meters and the situations when you would want to use each type of meter. Read, watch, and be illumined!


The Importance of Input Impedance

Most digital multimeters sold today are for testing electrical and electronic systems, such as those commonly found in appliance repair, and have high impedance input circuits, typically greater than one megohm (1 million ohms). Impedance is the term used to describe total circuit resistance which includes regular resistance, as well as resistance from reactive components such as capacitors and inductors.

Fun math fact you can use to impress the ladies: The symbol used for impedance in mathematical equations is Z. Total input impedance, Z, is the sum of resistance, R, plus capacitive reactance, Xc, plus inductive reactance, Xl.

Z = R + Xc + Xl

Once you know the total impedance, Z, you can treat it just like you would total resistance, R, in any of the Ohm's law equations.

The takeaway point here is that impedance is the term for all types of resistance in electric circuits.

A DMM’s high input impedance means that when it is placed across a circuit, it will have little impact on that circuit because it will draw hardly any current, not even measurable using common equipment. You want this for most voltage measurement applications, and it is especially important for sensitive electronics or control circuits. On these types of circuits, if you draw any measurable current with your meter, you could affect the circuit by inducing a failure mode known as "loading down,” and your measurements would be meaningless.

In contrast, other troubleshooting tools such as solenoid testers generally have low impedance input circuitry of around 10 K-ohms (10,000 ohms) or less, which means that they will draw some current when placed in a circuit. These are called loading meters because in drawing significant current they are, by definition, placing a load on the circuit being tested. While these meters aren't fooled by ghost voltages, they should only be used for testing power circuits or other circuits where the low impedance will not load down the circuit voltage or alter circuit performance. Their great strength, however, lies in the very fact that they aren't fooled by ghost voltages or open neutrals.

Ghost voltages and open neutrals are two of the major landmines waiting to trip you up while you're troubleshooting a tricky circuit on a service call. For this very reason, I always keep a loading meter in my tool bag.

I’ve encountered techs who don’t see the need for loading meters, but they learn real fast after they've wasted a lot of time or gotten their asses kicked on a service call chasing ghosts or open neutrals. If it hasn't happened to you yet, then this just means you have some fun learning experiences to look forward to!

Open neutrals are pretty self-explanatory – where the neutral side of a circuit is open either due to a break in the wire or high resistance (burnt, corroded, loose, etc.) connection. But let's talk more about those scary-sounding ghost voltages.

What are Ghost Voltages and Where are they Encountered?

Ghost voltages occur from having energized circuits and non-energized wiring (such as a “dead” wire that should be energized but has an open connection to either Line or Neutral) close together, such as in those wire harness bundles commonly found in all major appliances today. This can result in a buildup of static charge that a high-impedance meter (a DMM) will read as voltage if you place its leads between the open circuit and the neutral conductor. A low-impedance loading meter, on the other hand, will not be fooled by this ghost voltage because its high current draw will immediately discharge the static buildup.

Ghost voltages can sometimes be 80% of the actual Line voltage. Spooky! So in a 120 vac power circuit, ghost voltages will often be in the 75 to 95 vac range. In some of my videos, you'll hear me refer to these as "junk voltage." Same thing. If you don't recognize ghost or junk voltage when you see it, you'll end up wasting additional time on service calls chasing your tail and going down rabbit holes. Or worse, you'll get completely faked out and confused, unable to solve the problem.

Examples of common places you'll encounter ghost voltages in appliance repair situations are a wire with an open thermal fuse that’s near a live wire or an open neutral wire in a wire harness.

So hopefully you can see from what we’ve talked about that one of the desirable characteristics of a loading meter (also called a LoZ meter, by the way) is that it have as low an input impedance as possible or practical and, as a result, a high current draw.

With a DMM, on the other hand, you want as high an input impedance as you can afford so it draws hardly any current and thus doesn’t affect, or load down, the circuit being tested.

Now that you have a background on loading versus non-loading meters and low input versus high input impedances, let's watch a video showing a practical comparison of a couple of different types of meters. It gets really crazy as I use one meter to measure other meters. It’s Meter Mania!