Let's look at a seemingly simple load that has more going on than you would think: a multi-speed hood fan in a microwave. The questions we want to answer are: how many speeds does this fan have and how does it achieve those speeds?
If you look at the spec block for the motor, the answer to the first question seems easy -- looks like it's a simple two-speed motor.
But when you look elsewhere in the tech sheet, you find this voltage table that seems to state you have four speeds. (
Ever wanted an in-depth explanation of how a split-phase motor gets going from a dead stop? Sure, most of us have a passing knowledge of what's going on. But do you really know what's happening on the electromagnetic level? What is this special "split-phase", anyway, and how do we quantify the way the magnetic fields interact?
These are exactly the questions we answer in this excerpt from one of our many full-length technical webinar recordings. Don't worry, we're not getting into any of th
In this short, easily-digestible technical workshop, we dive into some of the wacky things that can happen when a sloppy tech miswires a dryer terminal block. In fact, this dryer looks like it shouldn't be able to run -- the neutral wire isn't even connected! And yet it does run. How, you ask? That's exactly what you'll need to watch and find out.
This and our dozens of other technical training webinar recordings are only viewable by premium tech members at Appliantology.
Topics covere
Take a look at this motor circuit:
Three different windings? Triacs in the circuit? A "sense resistor"? What's going on here?
As it turns out, there's nothing really new or different happening here. In fact, all we're looking at is a standard split-phase motor with two different start windings. One is the start winding when the motor functions as a drain pump, and the other is for when the motor functions as a wash pump.
Here's what the circuit looks like when the drain wind
We've got an interesting one for you today -- take a look at the "IDI Motor" in this schematic:
That's the ice dispenser auger motor in this fridge, and there are a couple interesting things to figure out about it. First, what's the deal with its power supply? If you look at the label on the motor, you'll notice that it says:
So that's a 120 VDC motor. How does that work?
A quick look through the documentation tells us that this motor is designed to run in two differen
Here's a GE microwave schematic. There's a lot of typical microwave stuff going on here, but we're going to focus in on one component today: the monitor switch.
What exactly is this switch's purpose, and how does it affect the circuit?
The purpose of the monitor switch is to act as a safety to prevent the magnetron from being energized while the door is open. The door latch and switches in microwaves are designed so that, if everything is working correctly, the monitor switch sho
Let's crack out our schematic-reading skills and take a look at a seemingly straightforward washer lid lock circuit.
Notice that, while they give us labels for the pins, that's basically all we've got as far as specs or info about the control board's algorithm. So if we want to figure out how this circuit works during operation, we'll have to crack out some Circuit Fu™. That means using both our understanding of electricity and our understanding of the intended function of a lid lock
What would happen if you took a 240 VAC outlet and swapped the terminals around? What effects might that have on the machine that's plugged into it?
That might just sound like an interesting thought question, but it's an issue that more than one tech here at Appliantology has had to deal with. So let's pull out a schematic as an example and start drawing some lines!
By the way, the process I'm going to walk you through is something any tech should be able to do: puzzle out how a circui
Take a look at this schematic, paying particular attention to the two circled relays.
What the relays actually do is pretty simple -- they switch L2 to the left and right burners on the cooktop. But slightly more perplexing is the question of how the relays close when those burners are turned on. We see the row of four burner switches along the bottom of the schematic above, but how do those switches cause those DLB relays to close?
A quick recap on how relays work: a relay is an
We're going to take a dive into what exactly is going on electrically with the high-voltage circuit in a microwave. We'll use this specific schematic as an example, but these principles apply generally.
Don't worry about most of the schematic. All that matters to us right now is the high-voltage section -- the transformer on the right side of the schematic and everything to its right.
If you're not familiar with how magnetrons work (or even what they are), then this circuit
These aren't your grandma's ignition systems -- these are systems that use a DSI (Direct Spark Ignition) board, and that means you've got algorithms involved.
If you want to troubleshoot a DSI system, you need to understand this algorithm -- it's how the board thinks. Is the DSI board not sending any voltage to the electrodes? Well, it might just be in lockout mode after a failed ignition, meaning the problem lies elsewhere than the board. You can't troubleshoot a system if you don't know h
We encounter diodes in a variety of situations, such as in certain refrigerator water valve configurations. If you want to be able to properly troubleshoot these setups, you need to understand the underlying technology of diodes. How doe they affect the circuit around them? And how do you test them?
These are the questions that we answer for you in this short video introduction to diodes. In just 6 minutes, you'll learn about how they work and how to properly test them. Plus, you'll learn a
Whether you were aware of them or not, Hall effect sensors are everywhere. Any time you see a motor on an appliance with any kind of RPM feedback or speed signal, there's a Hall sensor on that motor. As with any ubiquitous appliance technology, it's important for us techs to know how they work. A deeper understanding of the technology means a deeper understanding of how to troubleshoot it.
So: what is a Hall sensor, and how does it work? These are semiconductor devices, so as with most elec
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
Here's a weird one for you: how does this dryer run with the neutral wire of the pigtail completely disconnected? To find out, watch this short, 7-minute excerpt from one of our many full-length technical training webinar recordings.
In this video, you'll learn the answer to questions like:
What is the difference between 3 and 4 wire dryer cords?
Why should neutral and ground be separated?
Why is the dryer able to run without neutral connected?
Give it a watch a
We've got a tricky one for you today: a Frigidaire-built Kenmore electric dryer that only runs on heat cycles. If you set it to a timed or auto dry, it runs just fine. But set it to air fluff, and you get nada -- no motor rotation, no nothin'. Sounds like a bad timer, right? That was our first thought, too. But like any good tech should, we covered all of our bases before jumping to conclusions, and what we found was much more interesting...
We'll start by analyzing the circuit of the motor
Inverter compressors can run really smoothly and quietly these days -- so quietly that it can be hard to tell if they're running at all, let alone if they're running properly. So if our ears and hands can't tell us what's up, what do we do to test these compressors?
Time to apply our brains and our meters: we're going to use the schematic and some simple electrical measurements with our ammeter and our multimeter to know if the compressor is running.
Step 1 is to use the schematic to
Reading schematics is an essential part of troubleshooting, but it's not always clear how to break down a circuit into understandable bits. Is there an easy rule of thumb for identifying what component does what and how to go about testing it?
In this excerpt from one of our many full-length technical training webinar recordings, you'll learn exactly that! In addition, we'll show you how to break down a seemingly tangled schematic and identify loads in series vs. loads in parallel -- all in
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
The temperature sensors used in ovens, which are devices called RTDs, don't vary too much between brands and models. There's something of an industry standard for RTD specs that you can generally rely on, even when you aren't given the specs explicitly.
However, Frigidaire has left a booby trap in the form of an RTD with unique specs in some of their ovens. What's more, this difference isn't even properly reflected in some of their tech sheets. They've got incorrect specs!
Want to know
"Ohms lie." It's become a popular phrase in the tech community, but what does it actually mean? Should you never do an ohms measurement? Are they completely worthless? Or is this phrase just another example of tech mythology?
The answer is more complicated than any of that. Let's run through a quick example to demonstrate. This is an old-skool Whirlpool gas dryer, just like they were cranking out left and right in the good old days.
Now, our scenario is a simple one: when we run
In this excerpt from one of the many technical training webinar recordings available to our members, we cover two tricky areas that have tripped up many a tech: deciphering an unclear schematic, and decoding a convoluted customer problem description. Both of these are essential skills for any tech, since if you mess up either of these steps, the entire rest of your troubleshooting will be thrown out of whack.
The troubleshooting framework that we're using in this video is our patented Ten-S
Some techs long for the "good old days" of mechanical controls, when troubleshooting appliances was supposedly simpler. But the universal use of electronic controls nowadays actually provides many troubleshooting benefits -- in particular in the form of error codes and diagnostic modes.
The purpose of error codes is for the control to tell you its best guess of what's wrong, based on the algorithms programmed into it by the engineers. Note that the engineers' best guess is sometimes a very
Special guest presenter Mark Williams will show you how easy it is to diagnose temperature problems in the newer electronically-controlled refrigerators and how to do it right the first time.
We'll show you examples from Samsung, LG, GE, Whirlpool, and Electrolux. You'll see that they all work the same way.
You'll also see how to accurately test thermistors from the computer control board and you’ll learn the difference between resistance and voltage drop when it comes to testing the
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
