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
One of the first things you need when you start working on an appliance is the model number. Otherwise, unless there's a tech sheet with the machine, there's no way to find technical info on it. But what do you do when the model number tag has been damaged or removed? It's a rare occurrence, but one that can cause a major roadblock in a repair. Here's an example of one such situation:
As you can see, both the model and serial numbers are almost entirely illegible. Fortunately, there's
The general rule for dryer vent airflow is that, if the airflow feels like a breath (even a strong one), then you have a problem. This rule of thumb will serve you well a lot of the time, but sometimes a "calibrated palm" just isn't enough. Sometimes, you need to get an actual measurement of the airflow so that you can compare it to the specifications.
What you really want to know is the volumetric flow rate of the dryer exhaust. That is, how much air it's pushing out over a particular peri
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
There's a very common configuration of valves that are used in refrigerators with ice makers and dispensers -- so common that every tech should be very familiar with how it works and what terms are used to refer to it. You can't troubleshoot what you don't understand!
We'll use a GE refrigerator as our example, but this same system is used across almost all refrigerators with water supplies. Here's a snippet from a GE manual:
All this is saying is that you have three valves in th
Refrigeration can seem a bit like magic -- how does a little bit of refrigerant being pushed around in some metal tubes somehow chill a freezer down to 0 degrees F? Well, it's not magic -- it's just physics. But granted, it's an aspect of physics that we don't often interact with in our daily lives, and it can be a bit unintuitive at first.
It all has to do with how a material can absorb heat without actually getting hotter. How does this happen? That's what we explain in this excerpt from
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
Imagine you're out on a call, and you run into this:
As the picture says, the dryer runs like this. And even weirder, when you correct the wiring, it stops running.
Take a minute to think, then see if you can answer this pop quiz:
1. How does the dryer run in this configuration?
2. What's wrong about the wiring in this configuration?
3. Why does it stop working when you correct the wiring?
4. What one test could you do that would prove your hypothesis about th
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
I've seen a few guys around the forums ask the same question: are surge protectors (also called surge suppressors) safe to use on refrigerators?
Best I can figure, this question comes from folks mixing up surge protectors with AFCIs and GFCIs (you can click here to read about how those devices work). But it speaks to a general ignorance of how surge protectors work. Well, why don't we fix that?
The reason surge protectors exist is to block voltage spikes -- those are large spikes in th
Whether a control board in an appliance is simple or sophisticated, there's one trick it has to pull off: switching high AC voltage using low control voltage. They pull this off by using relays or triacs, devices that all of us are at least passingly familiar with.
But how do these very common control components work, exactly? And how is troubleshooting a relay different from troubleshooting a triac? That's what we'll look at today.
Relays: The older and simpler of these two devices, r
We've all changed countless ignitors in gas ovens, and any tech worth his salt knows that the definitive way to detect a failed ignitor is with a current measurement. But why does low current through the ignitor cause ignition to fail? Where does that current spec come from?
In this short excerpt from one of our many technical webinars, the Samurai explains the mechanism behind how these gas valves work. Not only will it give you a clear idea of the technology behind these common parts, but
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
Have you ever been robbed of a quick troubleshoot by ghost voltage? How about by an open neutral? Sounds like you need to start using a loading meter for ALL of your AC voltage measurements. Watch the video below to learn why, and find out some things you didn't know about circuits and electrical measurements along the way.
Want to see the full troubleshoot of this dryer, showcasing multiple ingenious voltage test locations that ensure for a fast and accurate diagnosis? Click here to watch
Most of you have probably heard about loading down before -- when one failed DC component causes a ripple effect that keeps other DC components from functioning properly until the failed component is removed. But what does that actually look like in practice? And how do you go about troubleshooting it?
To answer these questions, let's take a look at a straightforward, real-world example of loading down (taken straight from this topic at Appliantology).
@marshall450 ran into what seemed
Happy Thanksgiving from all of us on Team Samurai!
I'm thankful for a year of Appliantology members keeping each other sharp and preventing us all from devolving into turkey techs. It's due to this fine community that we're not the ones in the oven.. this time.
Here's to another great year!
Happy Thanksgiving to all the Appliantology Brethrens!
I'm thankful to be part of a community of such sharp techs who are always willing to help each other out. Here's hoping you're popping open a cold one with the family and enjoying the things that matter most.
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