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
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
Here's the situation: the tech has a Maytag dishwasher with no lights, no life, no nothin'.
With a multimeter on LoZ, the tech has already checked the following with reference to ground. Here are his findings that he reported:
Seeing that there was a solid 120 volts to the board and no operation, the tech concluded (with the aid of a few ohm checks across the control board) that the board was the culprit. He replaced it, and...
Still nada.
How could such a seeming slam-dunk
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.
In our latest workshop webinar, we cultivated the much-desired skill of troubleshooting appliances with multiple control boards. Topics included:
Using the schematic to form your troubleshooting strategy
Identifying inputs and outputs
Making meaningful measurements and understanding what their results mean
...and much more!
Want to learn this stuff for yourself? The full webinar recording is available right now to premium tech members of Appliantology. Click b
We had a great webinar this past Sunday all about troubleshooting a Thermador wall oven with a cooling fan that wouldn't run. Lots of vital tech know-how covered in this one, like how to structure your troubleshooting flow, identify loads and switches on schematics, and perform useful and meaningful tests that will lead you to the correct solution.
In this short excerpt from the recording of that webinar, we talk about using the schematic to identify EEPs for your testing -- no unnecessary
Say you're working on the cooktop of a Frigidaire gas range, and after chasing some wires, you find that this component is in the circuit, right after the power comes in from the outlet:
The label calls it a "signal transformer", but what is the point of this device, exactly? Well, as with most circuit mysteries, the schematic will give us some more insight...
How odd -- a transformer that, seemingly, doesn't do anything. You have 120 VAC going to the primary, and 120 VAC c
Ever looked at a timing chart and been mystified by how to decipher it? Or maybe you're looking at the schematic, and you can't make heads or tails of which switch is supposed to be closed when during a cycle.
If timer charts have ever given you trouble, then this is the video for you. In less than 10 minutes, we'll show you how to read a timer chart, correlating it with the actual steps of the cycle, and then identifying how it relates to the state of the switches on the schematic. Give it
Here at Appliantology, our primary mission is to support appliance repair techs in performing prediagnosis: the method of performing as much troubleshooting as you possibly can before setting foot in the customer’s home. Prediagnosis is the biggest factor in increasing FCC (First Call Complete) rates, and the higher the FCC rate, the higher your company's profitability.
So how exactly does one prediagnose, and how does Appliantology help with that? Well, let's walk through the journey of an
There are many standard items a CSR should collect from the customer (name, address, contact information, type of appliance, etc.), but I'd like to focus on the key features of a good service ticket that may be overlooked by some. If you make sure to follow these tips, you'll set your techs up for the easiest prediagnosis and best service calls possible.
1. Collect a valid model number
A model number is essential for a tech's prediangosis. Without it, he cannot get the correct in
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
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
When you're working on an appliance that's DOA (no lights, no response from the UI), your first troubleshooting priority is to identify where the power supply is missing.
Is it just the UI that's not getting power? Or is the main control board not getting power? Is there even power at the outlet it's plugged into?
These are the questions you need to answer before anything else, and you're going to answer these questions by taking measurements with your meter. However, there are right a
You can't get around it -- you've got to understand at least the basics of thermodynamics to troubleshoot sealed system problems.
Let's say you're working on a two-compressor R134a refrigerator -- completely separate sealed systems for the freezer and the fresh food compartment. Two evaporators, two compressors... you get the idea. You're experiencing an issue where the FF is always too cold. Say, 20F or so. All the other components seem to be in spec, so you put a gauge on the low side of
Ghost voltage is a term that you'll hear used in tech circles, and often incorrectly. Ghost voltage is the name of a very specific phenomenon, but I've seen it used variously to refer to failing under load, high resistance connections, and even simple open circuits. What does it really mean?
What we call ghost voltage is transient, seemingly sourceless voltage. It does, of course, have a source. You know how when current flows through a conductor, it produces a magnetic field? Well that mag
If you cracked open a freezer and saw the defrost drain looking like this, what would be your immediate reaction?
Do you see what the problem is? Take a closer look...
Have you figured it out? The deal with this defrost drain is...
There is no problem. This is a clear, perfectly normal-looking defrost drain. You can see a little evidence of some water pooling and freezing, but the amount is well within acceptable limits. Based on a visual inspection, there is no issue
When it comes time to perform the repair and install a new part, the last thing you want is a surprise throwing a wrench in your plans. All the unexpected twists and turns should have already been dealt with during your troubleshooting. Ideally, performing the repair itself should just mean doing as little disassembly as possible, installing the new part, and collecting your repair fee.
While there will always be unforeseen problems every now and then, there are a couple rules of thumb to a
To follow along with this blog post, you should go ahead and download the refrigerant slider app called "Ref Tools" to your smartphone (don't worry, it's free!). It's the one developed by Danfoss. I'm going to be referencing a few features of that app as I explain some properties of refrigerant, so go ahead and familiarize yourself with it. It's a great tool to have on hand regardless, since it lets you painlessly calculate superheat and subcooling in sealed systems.
Got it? Good. What I wa
You're probably familiar with the term "split-phase motor", but do you actually know what it means? That's exactly what we'll dive into in this post.
The whole trick with motors on single-phase, standard household power is how to get them going from a dead stop. Once the rotor is spinning, it'll keep going happily as long as power is applied to the motor winding. But without a little engineering, single-phase power won't get a motor spinning -- it'll just hum and twitch in place.
The t
Team Samurai has been training appliance techs at the Master Samurai Tech Academy for over 6 years now, and helping out repairmen on the web for far longer. Mr. Appliance has already used our online training for 4 years to make their techs the best they can be. Now, BrandSource has teamed up with us, too!
BrandSource is a non-profit buying group for independent retailers of furniture, mattresses, electronics, and, of course, appliances. They help the little guys by negotiating better prices
Ever wondered what the inside of a gas dryer valve looks like? And what's the purpose of having two separate valves in one component? What about those mysterious "safety" and "booster" coils?
All of these questions are answered in this short excerpt from one of our many in-depth technical training webinar recordings. Give it a watch and, if you want to see more, click here to watch the full recording. This and dozens hours more of technical education are available only to our premium member
See if you can identify two things on this Samsung dishwasher schematic:
1. Where does the control board receive line and neutral?
2. Where do the sub-control boards get their DC power supply?
The answer to the first question can be found easily enough, if you have a little schematic reading experience. But it's a bit trickier for those who don't have as much practice.
For one thing, line and neutral aren't explicitly labeled. Just wire colors are given, but fortunately
We techs should always be looking to sharpen our repair skills, and one of the best ways to do that is to learn from each other's experiences.
In this excerpt from a longer webinar, the Samurai walks through a Bosch dishwasher no heat problem that he encountered, working through his thought process and schematic analysis step by step. Watch it and learn a thing or two!
Want to watch the full webinar recording? Click below -- viewable only by premium members.
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
How you go about your troubleshooting makes all the difference between whether you're a Parts-Changing Monkey or a real appliance repair technician. While parts-changers rely on pattern recognition and rote memorization of "if this problem, then that part", a real tech uses analytical troubleshooting techniques and understanding of the technology involved to get to the right problem every time.
That's exactly what this excerpt from one of our technical training webinar recordings demonstrat
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