Susan Brown

[Susan Brown]

Try recreating the scenario and calculations yourself on a piece of paper. That can help you think it through a little better. If at any point you feel there’s still something you’re not getting, feel free to follow up with more questions!

[Susan Brown]

Voltage drop is simply this: when current flows through a load, it will create a difference in voltage. In other words, if you put your meter probes on either side of a load while it is doing work, you will get a non-zero voltage measurement. We call this voltage drop, to distinguish it from generic voltage, which is simply the difference in electrical potential, or charge, and isn’t related to whether or not a load is doing work.

If there is just one load in a circuit, and current is flowing, the one load will drop all of the source voltage. (e.g, 120vac in an L1-N circuit). If there are two or more loads in series, then the sum of the voltage drops will equal the source voltage. The individual voltage dropped across each load would be proportional to the resistance of the load (E = IxR).

If you encounter a series circuit in an appliance, it was designed to be that way, so thinking in terms of “peak efficiency” of the load(s) doesn’t really make sense. Now, if you got an unintentional additional resistance in the circuit, due to a loose connection for example, then you could see that the loads wouldn’t perform as designed.

That’s your little intro to voltage drop. You’ll see more in Unit 8!

[Susan Brown]

Hi Shawn,

I took a look at the questions you missed. I’m glad you posted here so we can make sure you get a better understanding.

A couple of questions had to do with two light bulbs in series with each other, and asking what happens when one of the bulbs burns out.

I would recommend that you rewatch the beginning portion of the first video in this unit, and make sure you understand the behavior of current in a series circuit. Particularly – what happens when a load fails open? (like the burned out lightbulb)

As for voltage drop that is mentioned in a few questions and explanations, for now just remember this answer that you gave correctly: “The sum of the voltage drops across each load will equal the supply voltage.” You’ll learn a lot more about voltage drop in Unit 8. Once you’ve done that unit, come back to these questions and explanations and see if they make more sense.

[Susan Brown]

That’s correct!

There’s a longer explanation of why that is in this Forum thread, if you’d like to check it out:

https://my.mastersamuraitech.com/appliance-repair-course-support/student-forums/topic/equivalent-resistance-in-parallel-circuits/

[Susan Brown]

Hi Nate,

Question #7: The two main temperature sensing applications are:

We’re not asking for the names or types of the temperature sensing devices, but for their application – what they are used for in the appliance. We discuss this very early on in the video in that unit – a couple of slides in.

Question #11: A common place to find bimetal temperature sensors is ____.

I selected “inside oven cells for temperature measurement” because at 10 minutes into the 90 minute video, he said, “there is bi-metal inside the gas valve in top service ignition” so I was thinking it was related to the oven.

“Inside oven cells for temperature measurement” is not the same thing as inside the gas valve for ignition.

Can bi-metals measure temperature?

Around 9:40 he does say in old school fridges we can find bimetal, for overload protection, related to defrost.

Now you are getting somewhere!

[Susan Brown]

Hi Nate,
Sure – I’ve reset you.
A lot of students miss this question. We have ones like this here and there that require paying attention to wording or other details, like units. It’s good practice, since that’s something a technician needs to do!

By the way, if you should need a reset in the future, you can use the Quiz & Exam Reset Request form (it’s in the submenu under “Contact Us”. Here’s the direct link: https://my.mastersamuraitech.com/quiz-exam-reset-request/ ) rather than post here. it’s a bit more direct that way.

[Susan Brown]

And earlier in the class, I thought I learned that if you have current in a closed circuit, that the circuit will read “zero volts” if you check the voltage within the circuit. But if it’s open at some point in the circuit, then you’d read, say, 120 volts at the point where it’s open, because there’s the potential for current there.

Any properly-functioning circuit will have a load in it, and there will be voltage drop across the load that is equal to the source voltage. (If there are multiple loads in series, the voltage drop will divide up among them. See Mod. 3, unit 8, if you don’t remember this.)

If you measure along a wire with no load in between the probes, then you would measure 0 volts. But you will measure voltage if you put your probes on either side of a load (when current is flowing).

When you see us tracing Line (with red) and N (with blue), those lines will always be connected to a load. Otherwise, how does it switch from L1 to N?

[Susan Brown]

Hi Nate,

Putting your training to use in real life is part of the learning process. It definitely takes practice to get really good at making electrical measurements. But, you are building a strong foundation to grow from. You’ll also get more practice in our Oven & Range course and Advanced troubleshooting.

I’ll ask Sam if he can help you further with #5.

[Susan Brown]

Can you tell me which video and the time stamp where we discuss this?

[Susan Brown]

Hi Nate,

It looks like you already retook this quiz and got everything correct except #5.

Question #5: At what locations in this diagram would you make the test that you indicated above?

Answer: The explanation says “You’re checking to see if the noise filter is capable of putting out 120 V AC. Looking at the schematic, the output is at the points labelled L2 to N2.”

So I would test from L1 to L2?

The correct answer is given in the explanation – L2 to N2. If that doesn’t make sense, let me know and I’ll get more help for you!

[Susan Brown]

Hi Nate,

The timing chart tells you which timer switches are closed for the cycle and load of interest. You will then use that information on the schematic (which switches are open or closed) to trace out Line and N for the load of interest (in this case, the pump). The closed switches determine the paths.

Here’s an image that might help you to understand which contacts are where.

T17 is only present up to the switch node I circled and labeled T17. Same thing for T18. T16 comes up to the node labeled T16. If you look at the whole schematic again, you’ll then see that it goes down to Cam 8. With that in mind, hopefully you’ll understand why Scott drew the neutral line the way he did, based on the timing chart saying Cam 10 would connect 16 to 17, and Cam 8 would connect 13 to 16. Does that help?

[Susan Brown]

You’re welcome!

[Susan Brown]

Yes, you are allowed to do that, although it is good to push yourself to try to first answer a question from memory. But if you are stumped, looking at the course material during a quiz is fine. We’d rather you do that than simply guess at the answer!

If you do that, be sure you don’t navigate away from a quiz once you’ve started it. If you need to look in a different unit than the one the quiz is on, open it in a new tab or window.

Thanks for asking!

[Susan Brown]

Hi Art,

I’m not sure what you mean about getting the answer correct but not getting credit for it. I’ll send you an email – that’ll be an easier way to get this straightened out.

By the way, we encourage students to get 100% on as many quizzes as possible. We are quizzing you on important things to know for your job, and we give you two attempts to figure out the correct answers. The more you figure out now, the more profitable you’ll be in your work!

[Susan Brown]

Hi there! I’m always glad to see students thinking these things through.

Yes, we suspect that we’ll measure OL, but anytime we do an electrical measurement we want to know what the spec is and compare the measurements to that. The spec is what we expect. It’s a fine point, particularly in this scenario, but we like to have a consistent approach when it comes to interpreting measurements.

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