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
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
If you read my previous post about sealed system basics, you know that understanding the thermodynamic states of refrigerants (saturated, subcooled, and superheated) is essential to sealed system troubleshooting. In that post, I explained these states in terms of a simple pressure-temperature table. While that keeps things simple, it doesn't really give you a strong visual and mental model for how the refrigeration cycle works thermodynamically.
That's why we're going to spend this whole po
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
Ohm's law, meaning the set of simple equations that define the relationship between voltage, current, resistance, and power, is an essential tool for appliance techs. Not only is it the cornerstone of understanding electricity, but it's also an invaluable troubleshooting tool. This said, there are some loads to which the simple form of Ohm's law doesn't apply. The simple form of Ohm's Law only takes into account real resistance (ohms) but does not consider other ways that electron movement can b
The very first step in troubleshooting a broken appliance happens long before the tech sets foot in the customer's home. In fact, it can happen even before the tech knows about the service call. We're talking about formulating a problem statement.
What I mean by a problem statement is very specific. A valid problem statement answers these two questions: "What is the appliance not doing that it should be doing?" and/or "What is the appliance doing that it shouldn't be doing?" It doesn't go b
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. (
We’ve all been hearing about R600a refrigerant for years now, and the reality is that it’s no longer an innovation in the area of household refrigeration; it’s the new standard.
With the majority of new refrigerators now being R600a models, repair companies need to be ready to perform sealed system repairs on them. This raises a few questions for these companies: how is R600a different from R134a, and what do I need to service R600a refrigerators?
R600a (let's just call it R600 from he
Sealed system thermodynamics is a deep well, but fortunately, you only need to skim the surface to gain a functional understanding. And as techs, it's this functional understanding that we need to acquire in order to effectively troubleshoot.
To do that, we're going to cover the three central concepts to understanding a sealed system: saturation, subcooling, and superheat. Let's start with the one upon which the other two hinge: saturation.
In order to talk about what saturation is, we
Gas burners are a whole little microcosm within appliances with some interesting technology that we don't see much elsewhere. In this webinar recording, we cover how to troubleshoot various cooktop ignition systems, covering topics such as:
DSI systems
Single-point ignition
Reignition systems
Continual sparking after a flame is established
Applying the Ten-Step Tango to real-world problems
...and more!
Click below to check out this webinar record
In this two-part Master Samurai Tech webinar series, we explore the nuances of sealed system diagnostics. Specifically, we're covering the nitty-gritty of applying our understanding of sealed system thermodynamics to real-world sealed system failures, such as refrigerant leaks, overcharges, and inefficient compressors.
Sealed System Diagnostics, Part 1
Sealed System Diagnostics, Part 2
Topics covered in the first part include:
Sealed system temperatures and pressure
Come on a journey with me as we explore just how tangled your circuit analyses can get when you're confronted with conflicting information in a tech sheet.
Here's the Samsung washer schematic we're working with:
Nothing crazy here -- this is pretty standard stuff to see on a Samsung schematic. But when it gets weird is when you try to trace out the power supplies of various loads and board on the schematic with the help of the pinouts elsewhere in the same tech sheet.
Here'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
When it comes to troubleshooting BLDC motors and inverters, there's usually a standard strategy. You check the input to the inverter (a good 120 VAC power supply and a PWM signal from the main control) and you make sure the motor windings are in spec and all the same resistance. But what about measuring the output of the inverter?
This is certainly possible to do, and it can be a useful measurement, especially in hairier inverter troubleshooting scenarios. But before we get into that, let's
Imagine you're in this situation: you're trying to do some ohms testing on the heater of an LG electric dryer. You're reading 21 ohms across a single coil, and 42 ohms through both coils. But when you look at the spec on the schematic, you're seeing almost exactly half that:
Weird. Maybe the heater is out of spec, but that's a weird discrepancy. And it's bizarre that we're reading double the specs given.
Can we get a second opinion? You look elsewhere in the manual, and you find
Unlike when we first started Appliantology, the Internet is now full of appliance repair support resources. From Facebook groups to subreddits to Voxer and Telegram groups, you've got your pick of the litter when it comes to what flavor you'd like.
Are there advantages to using a private forum-based site like Appliantology over the social media plantations? You betcha: Privacy and Functionality
Feeding Big Brother
All the Big Tech social media sites have one thing in common: they
All appliance repair techs should understand the AC split-phase household electrical power supply that they deal with on a daily basis. But the fact is that most do not, and there's a lot of disinformation and "tech myths" out there about these power supplies. But they re easy to understand once you grasp a few fundamental concepts about electricity and split-phase voltage.
And that's exactly what we cover in this webinar recording!
Topics covered include:
How sine waves are us
We're taking a step back from our fancy electronics to the good ol' days of simple AC circuits. Well, I say "simple", and that is true -- but engineers back then had to pull out all the stops and do some pretty cool tricks to get the functionality they wanted. This means that, to really understand what's going on in these older circuits, you need to have a firm grasp of both AC circuits and the technology used.
In this webinar, we:
Work through 4 real-world dryer case studies that h
Want to really put your technical know-how to the test? Well, have we got the webinar for you!
This one covers a whole potpourri of circuit puzzles and troubleshooting scenarios, including:
Some pop quizzes about series and parallel circuits
Diodes, how they work, and the surprisingly tricky situations that can arise because of them
Loads in series, how they work, and what they look like in a real refrigerator schematic
A real world troubleshooting scenario invo
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
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
A lot of techs lose their heads when it comes to control boards. This leads to the classic PCM behavior of "throw a part at it and hope it works." But isn't there a better way of troubleshooting computer-controlled appliances?
Of course there is. With a concrete and logical troubleshooting plan like the Ten-Step Tango, you can troubleshoot any appliance with a control board with confidence. In fact, in many ways, a control board being present makes it easier to do your troubleshooting.
In this interactive webinar workshop, we explored an LG gas dryer issue that had stumped an Appliantology tech. We performed a forensic analysis on the troubleshoot to figure out how it could have been improved, and then we moved on to thoroughly examine the circuits and understand how they work.
This and our dozens of other technical training webinar recordings are only viewable by premium tech members at Appliantology.
Topics covered include...
DC and AC loads
Compute
What do you do when a seemingly simple problem stumps you? Well, it's times like that when it's essential to have a structured troubleshooting strategy like the Samurai's Ten-Step Tango.
What is the Ten-Step Tango and how do you use it? That's exactly what we're going to teach you all about in this webinar recording, using a real-life example from here at Appliantology: an LG electric wall oven that won't heat. Strange as it may seem for such a simple problem, most techs would troubleshoot
4 comments