At one of our recent Live Dojo workshops, a tech shared an interesting problem he had encountered.
He was called out on a GE wall oven where the upper oven lights stayed on all the time, and the door lock wouldn't activate. He investigated further, discovering that when he opened and closed the lower oven door, he heard a relay click as the light turned on and off — but there was no such relay sound for the upper oven.
Presuming this meant a stuck relay on the control board, he went ah
Many appliance repair techs are intimidated when it comes to troubleshooting control boards. When we talk about "control boards," we're really talking about a single-board computer. After all, we are talking about computers here -- computers that just so happen to run appliances. Samsung is especially famous among techs for being “too electronic” or using too many control boards. Many techs will install a replacement control board from Samsung without running a single test, just to avoid the hea
How does a dryer dry without a vent? Why is there a sealed system in this dryer, just like what you would find in a refrigerator? How well does this model dry clothes compared to a conventional dryer?
All of those are questions we answer as we explore Whirlpool's hybrid heat pump dryer. In this thorough rundown of the machine's key systems and components, we cover topics such as:
The function of the sealed system in this heat pump dryer
How this dryer condenses moisture rathe
Reading timer charts may just seem like an old-skool skill for a bygone era of appliances, but there are still plenty of these old workhorses around that need troubleshooting. Plus, analyzing these circuits teaches you a lot of schematic mojo that is useful in all areas of appliance repair.
In our latest Live Dojo workshop, we worked through how to read this timer chart and schematic in harmony with each other. You can't understand the schematic without the timer chart, and vice versa. Topi
This microwave will run with the door open -- lucky for the customer, it also doesn't heat. But why is the turntable able to run with the door open? What do you do when a circuit doesn't work at all the way it's supposed to?
That's exactly what we discussed in our latest Live Dojo workshop.
Topics covered include:
Microwave door interlock switches
Turntable motor circuit analysis
Control board algorithms and relays
Theorizing a reasonable failure scenario
Timer charts may be for old-skool appliances with mechanical timers, but there are still plenty of old-skool appliances knocking around, so reading timer charts remains a vital troubleshooting skill.
That's exactly what we cover in this workshop: how to cohere the timer chart and the schematic, reading them in tandem. Kind of like they're dance partners in the Timer Chart Cha-Cha!
Topics covered in this workshop include:
How to decipher the rows and columns on a timer chart
When a control board doesn't seem to behave the way it's supposed to, does that mean it's always time to replace the board? How do you avoid the dreaded callbacks on service calls where you replaced the board because you had no idea what else to replace? Is there a way to reliably troubleshoot computer-controlled appliances and avoid guesswork when it comes to the control board?
Of course there is, and Team Samurai is going to show you how!
It all boils down to understanding how these
Got a fun exercise for you today: let's use our electrical and schematic know-how to figure out how a circuit works in a schematic that leaves out a lot of useful labelling.
The circuit we're interested in is the one labelled Door safety interlock.
Based on its name and its context within the schematic -- it gates Line to a number of loads elsewhere in the appliance -- this circuit contains the door switch and the door lock. But how exactly does it work? We can assume that the sw
When it comes to switches in appliances, it's hard to think of one more ubiquitous than the relay. It can be used with and without a control board, and it allows a small voltage to control a much larger voltage. But what exactly does that mean, and how do they do that? And what about triacs, the relay's solid-state cousin?
We cover both of these devices, including how they work and how to troubleshoot them, in detail in this excerpt from one of our recent Live Dojo workshops. Give it a watc
Ghost voltage has misled many a green tech during his troubleshooting. How are you supposed to interpret it when the VAC function of your meter tells you that you have 108 volts going to a load? Is your voltage supply bad? Or are you perhaps simply missing your Neutral?
That's where a loading meter comes to the rescue. By actually putting a load on a circuit, the loading meter shows if there really is the difference in voltage between those two points required for current to flow.
No N
Schematics and wiring diagrams -- two different kinds of service documents that seem similar, but actually serve completely different purposes. One of them is essential to any electrical troubleshooting and should be consulted on every service call, while the other has much more niche applications. But which is which, and how do you tell them apart?
That's what we explore in this workshop, which is an excerpt of the discussion from one of our latest Live Dojo workshops. In it, we go through
What are strip circuits and how do you read them? What purpose do they serve in troubleshooting? Are they better than normal schematics, worse, or just different?
That's what we explore in this workshop, which is an excerpt of the discussion from one of our latest Live Dojo workshops. Parallel to that, it also acts as something of a part 2 to our previous workshop on DC terminology. These schematics that we show have a number of esoteric and straight up confusing DC terminology, but don't w
Refrigeration is its own little world within appliance repair. The presence of a sealed system introduces all kinds of specific knowledge and skills you need to have to properly troubleshoot these machines, from thermodynamics to compressor technology to brazing. And that's not even mentioning the other systems, like airflow and control.
So how do you learn all this stuff? Well, if you want to troubleshoot refrigerators like a real tech, you'll need both brains-on and hands-on trainin
DC power in appliances works the same way no matter the manufacturer, but everyone has their own way they like to talk about it. And if you're not up on the lingo, you'll be left mystified by DC circuits in schematics.
You don't have to worry, though, because we explain all kinds of DC terminology in this latest workshop. From VDC to VCC, we cover everything you're likely to encounter in your troubleshooting travels through DC power, including:
Terms for DC voltage supplies
T
While all appliances use the same fundamental technology, their manufacturers often talk about them using different terms. Let's talk about DC power supplies and how not to get tripped up by the different terminology used there.
First off, the very basics. Just like in AC, any DC circuit needs two legs: the voltage supply, and the return. The return is called Ground in DC. Don't let that confuse you -- DC ground is NOT AC ground-- they are electrically distinct and separate. Ground is to DC
We had some fun in this Live Dojo Workshop! We went beyond the screen into the big, scary Real World and showed off live a few things about BLDC fan motors, including:
BLDC fan motor wire color conventions
Expected readings on PWM and RPM feedback lines
Simulating a PWM signal
Identifying failed speed sensor
...and more! Click below to watch the workshop recording -- viewable only by premium tech members.
If you're an Appliantology tech member and y
It's always the old-skool style circuits that have the most interesting electrical issues, isn't it?
In this workshop, we took a look at just one such machine. A missing neutral in the power supply doesn't have the effect that you would necessarily expect. For example, in this dryer, the timer motor runs on 240 VAC, but the drive motor runs on 120 VAC power. With a missing Neutral, the drive motor won't run, but the timer motor will. We go all into that, as well as the kind of troubleshooti
How are we as techs supposed to understand the specifications we see on a split-phase motor's label? What's the difference between a motor's output power and its input power, and which of those specs is given on the label? What do acronyms like FLA and LRA mean? All that and more covered in this short video on motor specifications.
This is just a short excerpt from the great technical discussions we have every other Saturday during our Live Dojo Workshops. If you're not joining us for these
Loading down is a failure scenario unique to DC power supplies, and if you don't know what to look for, it can leave you scratching your head and eating some expensive parts. How do you identify that you have a potential loading down scenario, and what steps can you take to verify that? That's exactly what we cover in this Master Samurai Tech Workshop.
Topics covered include:
How DC power supplies work
How they affect the board's operation
What loading down is and how
Why are microwaves so picky about the way they do their door switches? Are two different interlock switches really necessary? And what does the monitor switch even do, anyway? All these questions and more answered in this short instructional presentation.
Big props to Brother @Vance R for his explanation of these switches in this topic, which inspired us to make this video.
Topics covered include:
Schematic analysis of interlock switch circuits
Identifying if the schemat
What do you do when even the service manual can't be trusted?
In this video, we discuss how to deal with bad or missing information in all kinds of tech docs -- service manuals, tech sheets, schematics, you name it. Topics covered include:
Pin numbering discrepancies
Reconciling pinouts with schematics
Identifying power supplies
Recognizing incoherent specs
What are dummy directions?
..and more!
You can watch this one right now for free! We've
In this video, we give a comprehensive answer to this question: "Why is it that high ambient temps cause high side and low side pressures to rise?"
This simple question about one specific sealed system problem scenario is a great opportunity to take a deeper dive into how sealed systems work, how they're affected by their environment, and how an issue in one area of a sealed system has ramifications for every other area.
Topics covered include:
The temperature/pressure relation
Got a short and sweet one for you today. Here's the scenario:
You're troubleshooting an LG wall oven that doesn't heat. You've gone ahead and torn it down as much as you could to do an ohms measurement on the broil element (in spec) and the temperature sensor (also in spec). You confirmed that the unit was getting a good 240 VAC power supply. You wanted to test the bake element too, but you didn't have a second man with you, so you gave up on that idea. Instead, you just replaced the main c
Got a fun one for you today, pulled right from the annals of Appliantology. That's right -- a tech just like you encountered this whacky problem and figured it out.
Here's the weird scenario: several different loads aren't working on this Whirlpool-built Thermador refrigerator. The water and ice dispensers, the dispenser light, and the freezer light are all inop. Wow, four different loads all happened to fail at the same time! Crazy, right?
A lesser tech might have gone full PCM and st
By now, most of us are used to variable speed drive motor systems in appliances. The control board sends a PWM signal to an inverter, which tells the inverter how fast to run the BLDC motor.
While this is the type of inverter that's been used in appliances for years now, it's not the only kind of inverter out there. In fact, another type of inverter is starting to crop up in the appliance world, and it may very well become the norm for some applications. It's called a drop-in inverter, and
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