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 Fundamentals of 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 Fundamentals of Appliance Repair course. You'll learn this and much more in a comprehensive, self-paced, up-to-date, and affordable online training course.
Here's an excerpt of the full, 20-minute training video now available in the Fundamentals of Appliance Repair training course that shows how to use a schematic diagram and timing chart to troubleshoot a problem with a washer drain pump that would not operate. The drain pump itself was good and getting voltage. Turns out that the problem was an open neutral.
The full training video explains these important troubleshooting concepts in detail:
- how to break down a complicated schamatic and read it to solve the problem you’re working on,
- using timing charts to interpret timer switches on schematics,
- technical explanation of open neutrals,
- test methods for identifying an open neutral,
- power and loads.
Samurai Tech Academy Fundamentals students will find the full-length video in the Troubleshooting module of the Fundamentals of Appliance Repair training course.
The specific problems with this electric dryer were that it would run but not heat and the drum light stopped working, yet the motor still ran.
A couple of important concepts that are taught here at the Samurai Tech Academy are illustrated in this interesting and unusual service call that I had recently:
1) there can sometimes be an unusual situation that is causing what sounds like a typical problem, so you have to keep a holistic view of the entire appliance, its surroundings, and its inputs (i.e., electric or gas supply);
2) pre-diagnosing an appliance using the schematic diagram always makes the service call more efficient. I knew exactly what I needed to look at first which allowed me to zero in on the problem quickly rather than wasting time going down false trails. Huge benefit: I didn't spend unnecessary time disassembling the dryer.
Come with me now on a Journey of Total Appliance Enlightenment, and sharpen those schematic-reading skills along the way!
Learn appliance repair and become a certified tech right here at the Samurai Tech Academy.
If you have any questions about the Samurai Tech Academy that aren’t answered on our FAQ page, just contact us by phone or email.