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"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
Anytime you work on a refrigerator with a control board, you've got multiple NTC thermistors in play. With how ubiquitous these devices are, it's important to know them inside and out -- especially how to test them. That's why we've made a webinar all about NTC thermistor technology for your viewing pleasure!
In this short excerpt from one of our many technical training webinars, we cover topics like:
What is an NTC thermistor used for and where will you find them?
Here's a puzzling scenario on a Samsung refrigerator: the ice dispenser door keeps opening and closing nonstop.
When you encounter a weird problem like this, it's easy to lose your head and just start throwing parts at the machine and hoping one of them will fix it. But it's always important to keep our fundamental troubleshooting principles firmly in mind. In this particular case, troubleshooting is made even more difficult by Samsung providing us with a very low-resolution schematic -- bu
Everything runs on circuit boards these days, and wherever there are circuit boards, there are semiconductors. But what are semiconductors, exactly? How are they made, and what do they do?
These are exactly the questions we'll answer for you right now in this excerpt from one of our many on-demand technical training webinar recordings. In it, you'll learn the answer to questions like:
What are semiconductors?
What are they made of?
What is "doping" in semiconductors?
The technical side of the service call is generally what gets the spotlight, but what you do before, after, and during the call is just as important to your profitability -- and I'm not just talking about soft skills. The way you organize your thought process and go about your troubleshoot is vital to service call success. And that's exactly what we talk about in this short excerpt from one of our many technical training webinar recordings.
Topics covered include:
How to run a servi
Both of the big Korean manufacturers -- LG and Samsung -- have a little trick that they like to use in their schematics. While I think they do it to keep the lines from becoming too much of a tangled mess, it can sometimes be a bit unclear for the uninitiated. Here's an example of an LG refrigerator schematic:
The whole picture is a bit much, but notice all those bubbles popping up around the schematic? Let's pick one of those and focus in on it. Here's one coming off the sub PCB:
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
Here's a scenario taken right from the trials and tribulations of an Appliantology tech: you're troubleshooting a no heat complaint on a GE electric dryer. You start your troubleshooting with the heating circuit, and your findings are puzzling: there are 120 volts on either side of the heater with respect to neutral, but when you do a voltage reading across the heater, you get some weird amount like 80 volts. What gives?
There are a couple of things going on here, and one is easily remedied
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
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
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
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
Long gone are the days when we techs had any excuse to be scared by names like LG or Samsung. Through information tools like Appliantology, we have access to all the technical docs we need to service these models. And anyone who has spent time examining the schematics and service manuals for Samsung appliances knows that there's nothing weird or proprietary going on here -- maybe a bit of Korenglish here and there, but how electricity works and the fundamental technology used in all appliances i
I just got back from this year's ASTI a few days ago -- a somewhat unique one, styled as "ASTI Lite". While the conference was shorter than usual, I still had a great time meeting many of the fine techs who hang out here at Appliantology and/or train with us at Master Samurai Tech. Looking forward to seeing all of you again at the next ASTI this January!
When I wasn't putting faces to Appliantology usernames, I was attending the training classes put on by various manufacturers. Ever mindful
While we don't like to rely on ohms testing as appliance technicians, those tests have their place -- such as if you want to verify that a compressor's windings are in spec. But if you want to do an ohms test on a split-phase compressor's windings, you'll need to identify which of the three terminals on the compressor's casing corresponds to which winding.
To do so, you have to have a little bit of knowledge about how split-phase compressor windings are arranged, and what their specificatio
We're all familiar with how thermistors work: their resistance varies with temperature, which in turn varies the voltage drop across them. The control board then reads that voltage drop and determines the sensed temperature based on that.
But those with a bit of basic electricity knowledge might scratch their heads a bit if they think about this. Thermistors are almost always drawn on schematics such that they aren't in series with anything else -- it gets its 5 VDC supply and DC ground dir
Ever wondered how L1 and L2 in a 240 VAC circuit have a voltage difference of 240 VAC? Or what people mean when they say that L1 and L2 are 180 degrees out of phase? And what exactly do we mean when we say "voltage difference" anyway?
We cover all these topics in this short 6-minute excerpt from one of our many in-depth technical webinar recordings. If you've ever been mystified by the inner workings of standard, split-phase household power, look no further! Give this a watch and be enlight
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
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
You're investigating a refrigerator that's not cooling properly, and you see the following bits of evidence:
Two questions for you to answer:
What (if anything) does the rime ice on the evaporator tell you?
The source of the problem with this refrigerator is present in one of these photos. What is it?
Let us know your answers in the comments, and we'll let you know if you're right!
Want to troubleshoot refrigeration problems like this (and much m
Specs are essential for troubleshooting. After all, to test a hypothesis, you need to make electrical tests, and to make electrical tests, you need to know what your expected readings are. However, manufacturers don't always give you everything written out. What do you do if you need to make an amp measurement, but the manufacturer only gives you watts? That's exactly the question we're going to answer in this excerpt from one of our many in-depth technical webinar recordings.
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
Jazz boards are a classic common-fail item in Whirlpool refrigerators, so important to know the right way to go about troubleshooting them. The good news is that they operate on the same principles that all control boards do, so if you know your basic electricity and troubleshooting principles, making big money off of these is a snap.
This is exactly the kind of stuff we teach in our Core Appliance Repair Training Course over at the Master Samurai Tech Academy. If you want a taste of that g
We techs rely on accurate technical documentation to do our jobs. You can't make a troubleshooting plan or make meaningful electrical measurements without a good schematic. But what do you do when your technical info contradicts itself?
Let's take a look at this Whirlpool refrigerator, specifically focusing on the evaporator fan. Here it is on the schematic, marked up for your viewing pleasure:
Looks like a standard 120 VAC fan motor. But now, let's take a look at some of the wri
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