Dryer Schematic Quiz - Click for Larger View (opens in a new window)
1. Which timer cycle is the schematic showing?
Looking at the timing chart, we see that the cycles on this dryer fall into two main groups: auto and timed. The big distinction between the two is timer contacts TM-OR (timed dry cycles) and TM-WB (auto dry cycles). Since the schematic shows that the TM-OR contacts are made, then we know we're in a timed dry cycle. Checking the state of the other contacts listed in the timing, we see that the schematic shows them all as open. Therefore, we know that this dryer schematic is showing the dryer at the End-of-Cycle. Which also helps answer the next question...
2. Is the motor shown running or not?
We know from the forgoing analysis that the dryer is shown at end-of-cycle, so the motor is not running. But you can also tell by looking at the centrifugal switch contacts on the motor. They are shown in the retracted state meaning the motor is stopped.
3. Why won't the timer advance in Auto Dry cycle when the operating thermostat is closed?
In Auto Dry, the timer chart shows timer contacts TM-WB are made. With this in mind, trace L1 to the timer motor. L1 comes through timer contacts BK-BU to one side of the timer. L1 also comes through timer contacts BK-R, through the thermal cutoff, operating thermostat, and high limit to one side of the heater. But it also branches off through the resistor and timer contacts TM-WB to the other side of the timer. Since both sides of the timer have L1, the voltage difference across the timer is zero and the timer motor does not run.
Still confused? I explain and demystify circuits, reading schematics, troubleshooting with schematics, motors, and all the other basic skills that every appliance tech should have in our Core Appliance Repair Training course. Complete our free Sample course and get a discount off your tuition.
Training is THE hot topic in the appliance repair trade these days. Experienced techs want to up their troubleshooting game and keep up with the newer models, and many new folks are looking for training in a skilled trade so they can get a job or start a business. Manufacturers and multi-truck operations have an ongoing virtual manhunt for skilled appliance repair techs. But they just don't exist because new technicians are not entering the trade at the same rate as old servicers are retiring.
Here are some important questions you should ask about any technician training program you are considering investing your time and money in.
Is the material up-to-date, especially regarding computerized control boards?
Are the courses self-paced?
Is the educational style engaging and varied?
Is there a sequential order of instruction?
Are there quizzes or other forms of evaluation to make sure you are learning the concepts?
Is there a way to ask questions during the course as well as down the road?
Do you learn key troubleshooting skills using tech sheets and schematics?
Does the school offer a meaningful certification from a verifiable master in the trade?
How can you tell if the school you are considering is up-to-date? Besides asking for the production date of the materials used in the class, you can ask questions such as:
- Do you teach using schematics to troubleshoot an appliance? - Do you teach the technology used in current front-load washers and refrigerators, such as inverter-driven variable-speed motors?
And how do you choose between the various styles of appliance repair school that are out there? There are four basic types—
1. online training courses 2. in-person training schools 3. DVD and manual sets 4. correspondence courses
— and each has their strengths and weaknesses. The newest kid on the block, online training courses, was the format we found to be superior when we decided to create our training academy.
The Master Samurai Tech Academy Advantage...
vs. In-person training
Among the many advantages that the online Master Samurai Tech Academy has over in-person group training is that the MSTA allows students to go as fast or slow as they like, since the courses are self-paced. If a student needs more time to master a topic, they can go back and redo the lesson as much they want. The MSTA can be done whenever, wherever, no matter if you’re on the move or working from your house. In-person training obviously doesn't have such flexibility, and all the information has to be crammed into a very short period of time, making material retention difficult. Also, there are travel costs and time taken out from productive work days to attend the in-person training.
vs. DVDs and Manual sets
The online format allows us to keep the Master Samurai Tech Academy courses current and up to date with the latest technologies used in today’s appliances and doesn't flood our students with costly textbooks or DVDs, which can quickly get outdated. No one wants to pay for manuals or other materials that are so out of date that they're not even useful.
Many DVD-based programs do not have a specific sequence of instruction or testing, leaving it up to the student to figure it out. On the other hand, all the courses at the MSTA are carefully structured and organized to promote learning and material absorption.
Each course is broken up into small, digestible units, which are themselves made up of individual lessons. Our multimedia lessons use videos, text, diagrams, and audio to give an immersive, varied learning experience to help students better grasp the material. The lessons all end in quizzes so students can test and apply what they just learned and to further aid in retaining the information and determine any topics that need further review.
vs. Correspondence Courses
Some training courses out there still use only written materials and rely on instructor grading of materials. The STA’s online format allows for dynamic, up-to-date instruction and automatic grading of quizzes, so you determine your own pace.
If a student has questions, I’ve got answers, and the online Student Forums are where that happens. It’s like a class discussion, but time-independent!
Cutting-edge Education from an Expert
As you can see by checking out my YouTube channel, I enjoy showing others how to hone their craft.
I’ve also realized something that needs to be emphasized in the appliance repair community: that being an excellent technician requires more than disassembly and parts-changing skills. You need a fundamental understanding of the electrical and mechanical workings of each machine, as well as the ability to use the technical information for any appliance (such as the schematic diagram) to formulate a troubleshooting strategy.
This is critically important if you want to deal with today’s modern appliances with confidence and profitably. I know that this is a weakness with many techs out there, which is why I put so much emphasis on teaching this skill in the Academy courses.
There are loads of resources online that tell you all you need to know about disassembly and parts-changing. These resources are either free or nearly free. You don’t need to pay for a course on this.
Spend your training money where it really counts on a program that will teach you to be a troubleshooting master. That’s exactly what we offer at the Master Samurai Tech Academy at MasterSamuraiTech.com.
Start by noting the power supply. It’s called out as L1 to N. So we know that the power supply to this circuit is 120 VAC.
Ignore the thickness of the lines in the drawing; it doesn’t mean anything.
Since the ignitor is glowing, we know that 1) we have a valid power supply, and 2) current is flowing, so there will be a voltage drop across the ignitor (the load) and work is being done (producing heat).
Next, we note that the ignitor, booster, and safety are all in parallel with each other. From the Core Appliance Repair Training course, we know that the voltage in each parallel circuit is equal to the supply, in other words, 120 VAC in each leg. That’s just the way circuits work.
“But what about the voltage drop across the main coil— doesn’t that subtract from the voltage available to drop across the ignitor and booster?”
Ah, Grasshoppah, let’s look at that voltage drop across the main coil. Notice that the detector is closed. As such, it is shunting the current around the main coil because current will take the path of least resistance. Since there is no current flow through the main coil, the voltage drop across the main coil is effectively zero.
Also, the refrigerator is plugged in, the doors close properly, and the condenser coil is clean.
What's the next thing to check?
Bad control board, right? Nope. What's your next guess?
Check the defrost system, right? Nyet, tovarish!
This is an easy one IF you understand how refrigerators work. We reveal all the troubleshooting secrets for refrigerators in the Samurai Tech Academy's Refrigerator Troubleshooting and Repair Training Course. From the simple to the fancy, from single evaporator units to fridges with two or more evaporators, from split-phase, single-speed compressors to inverter-driven, variable speed compressors, our Refrigerator course is the most comprehensive, up-to-date, and affordable training course out there.
If you're looking to get into the appliance repair trade or to brush up your skills if you're already in the trade, your search for an appliance repair school is over. Enter the Dragon.
Oh, BTW, the answer to the quiz is to see if the compressor is running. 🙂
Bonus question: How do you check the compressor operation? To be continued...
Do you know what "electrically equivalent points" are? Do you know how to recognize them on the schematic? Most importantly, do you know how to use them to avoid needlessly tearing down an appliance just so you can check a component?
In this expedition into appliance repair transcendence, Samurai Appliance Repair Man reveals more tricks and techniques for using the schematic to troubleshoot an electric dryer with no heat. Watch how I identify electrically equivalent points on the schematic and use them to diagnose the problem with the dryer with minimal disassembly. This is a simple example showing how using the schematic can save you time, aggravation, liability, and even personal injury. The principles illustrated here can be applied to any and all appliances IF you know how to read and use the schematic diagram.
The two criteria for electrically equivalent points are: 1. There is no measurable voltage difference between them and 2. They are in electrical continuity with each other.
A simple example of electrically equivalent points are two points along the same unbroken wire.
If this seems mysterious to you, then check out our appliance repair training courses. You'll learn this and much more in a comprehensive, self-paced, up-to-date, and affordable online training course.