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
Let's say you're on a call for a Whirlpool GI6FARXXY07 refrigerator. You notice that the evaporator fan isn't running, even when the unit isn't in defrost. "Simple enough," you think, and you disconnect the fan harness and check its resistance.
Wow -- 500 K-ohms! No way that's in spec. Gotta be a bad fan motor, right?
Before we get too hasty, let's step back for a moment and do what we should have done at the start -- look at the schematic. When we do that, we can pretty easily locate
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
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
Take a look at this LG gas dryer schematic, paying special attention to the circuit with the flame detector.
If you trace it out, it becomes a bit puzzling what that circuit is actually doing. The hi-limit thermostat, the safety thermostat, and the flame detector don’t appear to have any direct effect on the gas valve coils as you would find in other dryers. So what purpose do they serve?
This markup makes it all clear.
Unlike many circuits that use controls li
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
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:
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
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
Vent hoods are pretty simple appliances -- something you've probably surmised if you've ever looked at the schematic for one. Usually, all they have going on is a blower motor and a couple of lights. When it comes to troubleshooting a hood, there are just two technology-related concepts you need to be familiar with: venting specifications and how multi-speed motors work.
First, venting specs. As with any machine that produces exhaust as part of its operation, vent hoods have certain require
You open up the terminal block on a Bosch range, and you see this. What's wrong with this picture? (Hint: those of you who have watched this webinar recording should know what's up).
A few questions for you sharp Appliantology techs:
Will the machine run in this configuration?
Why is it not okay to leave the machine in this configuration?
Does this machine have a 3 or 4 wire power cord?
How would you correct this situation?
Let me know your answers
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
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
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
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. (
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
Here's our scenario: you're working on a Samsung WA50K8600AW washer that won't advance in the cycle. Error codes and test modes aren't telling you anything useful, and the control doesn't even seem to be trying to advance the cycle. You've checked the air tube connected to the pressure sensor, too, and everything is clear there.
What can you do here? Do you just call it a bad board and move on?
Let's see if there's a smarter test we can do on this one. What if we could test the signal
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
Join me on another short troubleshooting journey -- this one taken from a real tech's experience that he posted on Appliantology.
You're troubleshooting a Samsung dryer that won't start-- the control panel will let you select a cycle, but it won't actually run if you press the start button. But the real head-scratcher is that, despite not being able to start a cycle, the machine always runs when the door is closed.
Sounds tricky, but as you'll see, the troubleshoot is pretty simple if
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
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
We've got a toughie for you to figure out today. The tech in this scenario has been out on this dryer multiple times now, and the problem just won't go away. The heating element keeps going open, and the timer motor keeps stalling and not completing cycles. He's verified a good 240 VAC power supply to the timer and replaced both parts multiple times, but the problem keeps recurring every few months. What gives?
Let's board the train away from PCM-Land and use one of our foundational trouble
Here's the situation: our tech has a Whirlpool dishwasher that does everything normally, except the wash motor simply won't run.
He's done his due diligence and checked for voltage to the motor -- with a LoZ meter, even! -- and what he's finding is puzzling. It looks like the voltage is jumping around from 0 to 120 VAC erratically. What does this mean? Could it be a bad board?
As with all good troubleshoots, let's start with the schematic. Here's just the motor circuit:
Now,
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
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?
By Rhubarb Tau in Rhubarb Tau's Sloggy Vlog Blog Bog3 comments
2 comments