Susan Brown

[Susan Brown]

In the schematic the switch is closed so it changes the direction of the current right?

“Changes direction” isn’t the best way to think of it (it could get confused with the way that AC current changes directions), but you are getting at the right idea. The switch being closed creates a certain condition that affects the voltage drop of the loads.

[Susan Brown]

It sounds like you are guessing. You’ve gone from saying none of them get current, now two of them get current. Which two do, and which two don’t, and why?

[Susan Brown]

What makes you say they aren’t receiving current? The problem states that you have a good 120 VAC power supply.

[Susan Brown]

Jake – did you read what I wrote above? I moved your question to its own topic. This thread is on equivalent resistance of parallel circuits.

Here’s the link, but you can also just find it by looking at the list of topics in the Basic Electricity Forum.

https://my.mastersamuraitech.com/appliance-repair-course-support/student-forums/topic/voltage-drop-across-several-loads-in-series-parallel/

[Susan Brown]

There are 4 loads in that diagram (igniter, booster, main, safety).

For each one, tell me your current understanding of how they are laid out compared to the others – series or parallel – and if they are getting current going through them.

[Susan Brown]

Jake – I’m moving your question to a new topic, since you have tagged onto a post that’s unrelated to the question you asked.

[Susan Brown]

Glad to hear it!

[Susan Brown]

Hi JP,

No – the optional/bonus material is not on the Final.

[Susan Brown]

Hi JP,

Glad that was helpful! Thanks for letting us know.

Flow charts are a great visual representation of the troubleshooting process. However, each flowchart has to begin with a specific problem. In this case, it was “warm refrigerator.”

We created the Ten Step Tango Troubleshooting Procedure to be a more generic form of the troubleshooting process that can be applied to pretty much any situation. In other words, to help a tech develop his own mental flowchart of how to troubleshoot any issue in the most streamlined way possible.

That does take some practice, and in the Oven & Range course you will follow these steps for a number of real-world scenarios.

But – we’ll keep your comments in mind. It might be good to create a few more flowcharts if that would help students visualize the process.

[Susan Brown]

pouring out opposing electrical potentials in both directions away from its center.

Do not think of voltage as movement. Current is movement, not voltage.

I’m having a hard time understanding what you are asking in you hypothetical, partly because I think you are thinking of voltage as something that moves.

Also, the graphs that show the sign waves are a conceptual way of showing voltage over time, not a portrayal of what is physically happening in the wire.

What I found I had to do, when I was learning this stuff, is rewatch certain key videos to get the voltage and current stuff straight in my head.

[Susan Brown]

We’re glad you are working hard to figure things out!

We gave you some additional information in the other topic you started. Let me know if that helps to clear things up, or do you still have lingering questions about 240 power supply?

You wrote a lot above – let me know what questions are remaining in your mind.

[Susan Brown]

Hi Matt,

Thanks for enrolling, and thanks for communicating with us.

We’ve had a sprinkling of Chuck Norris jokes in the courses for 5 years now. The primary reason we include them is that a certain percentage of our students feel some intimidation with “school,” and especially having to take tests. Many people who go into appliance repair did not have a positive academic experience. So, we try to have a friendly, approachable tone in the courses, and use the jokes – which are some of the most universally-liked jokes around – to help them feel at ease.

As we often say – we are serious about excellent technical training, but like to have a little fun along the way.

Since you don’t care for them, I hope that you will just overlook them and focus on the other 99+% of the material in the courses. The majority of quizzes in the technical courses do not contain them – there happen to be a few extra in the Business course because there aren’t that many quiz questions that make sense to ask about the material, compared to our technical courses.

[Susan Brown]

I’ll try to give a short answer, and see if it helps.

The electrons all move in unison in the wire, towards the relatively more positive pole. And whatever the net voltage difference is will determine (along with the resistance in the circuit) the current flow. By “net voltage difference”, I mean the difference between the two ends (actually subtracting the numbers).

And remember with AC current, the electrons are moving back and forth rapidly in the wire, as the polarity (or polarities, in the case of 240vac) at the power supply change. It’s very violent!

When you have an L1-N scenario, the polarity of L1 is changing back and forth from +120 to -120, while the polarity of N stays the same. So the net voltage changes back and forth (rapidly) from +120 to -120. (The math: +120-0=+120vac, or -120-0=-120vac)

When you have L1-L2, the polarity of each end is switching from +120 to -120, but they are doing it oppositely from the other. In other words, when L1 is +120vac, L2 is -120vac. So the net result (what the electrons “feel”) is 240 vac (plus or minus). [+120-(-120)= +240vac; -120-(+120)= -240vac]

Also make sure you are keeping voltage and current distinct in your head. Current is the actual movement, or flow, of the electrons. Voltage is just the amount of “pressure” that causes them to move. That pressure comes from a difference in charge between the two ends of the circuit.

[Susan Brown]

Hi James,

You state it correctly. It’s very frustrating when faced with a situation like this, when you aren’t given enough specs to narrow the troubleshooting down to a specific board. You know the customer probably isn’t getting the best deal on a possible repair, through no fault of your own. But you can’t afford to buy multiple boards to then experiment with the one that will repair the machine. (And, it is conceivable that both boards could have been damaged by whatever event caused the failure.)

Fortunately, not all manufacturers do this, and we are hopeful that the ones who tend to (currently, Whirlpool comes to mind) will up their game. It’s not something to be overly concerned about, but to be on the lookout for.

[Susan Brown]

Hi Jay,

Good question!

We do mention safety at various places in the course, but I’ll summarize some safety tips for you here.

The number one way to increase safety is to understand electricity! So, learning the material in the Basic Electricity module as thoroughly as possible is your first step towards being safe on the job.

The second way is to apply common sense and be observant.

Pay attention to safety information in the service manual for the appliance you’ll be working on.

Disconnect power to the appliance before doing any disassembly or replacing parts.

Some measurements must be taken when power is connected. Reapply power for the test, and disconnect when you are done. During the test, make sure you are just touching your meter probes, and nothing else, to the test points.

We caution against wearing metal jewelry on your hands or wrists, and any metal neck chains should be secured or removed.

We show you how to use a voltage stick (or “sniffer”) to check for the presence of voltage in many of our videos. That’s a smart thing to do regularly.

For a more thorough description of safety procedures, see Part 1, Chapter 2 of the Kleinert reference book.

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