Susan Brown

[Susan Brown]

Main coil igniter and booster 40 vd each due to being in series

There are several reasons this is not correct. For one thing, voltage drop is proportional to resistance, and we haven’t given you any information on the resistance of these loads. Second, if all 3 of these loads are getting current, this is a series-parallel circuit scenario, which would require some complicated calculations.

However – none of that is necessary. Big hint: One of these loads is not getting current.

The key is to recognize the function of the closed detector switch.

Do you have any ideas about that?

[Susan Brown]

Okay. If you haven’t, see the Appliantology 101 short course, specifically units 2 and 3.

[Susan Brown]

Hi Jacob,

Question #4 – What does an oven’s gas valve need in order to open and release gas?

From the unit:

The gas valve has a specification for how much current must flow through it in order for it to release gas into the burner. The ignitor’s resistance lowers the hotter it gets, letting more and more current through. Once it is hot enough to allow the current to reach the valve’s spec, the valve opens,

I bolded the pertinent parts – heat is involved, but not the key component.

• This reply was modified 7 months, 1 week ago by Susan Brown.

[Susan Brown]

Correct!

Now the next step is to figure out what is going on with the other 3 loads, if they are in series or parallel with each other.

The Main coil is wired in series with the Ignitor and Booster, which are in parallel with each other. Normally, when we have a series-parallel configuration, the voltage drops are impossible to determine unless we give you the resistances so you can do some calculations (like I show in one of the videos for Unit 5).

***But that closed detector switch changes things significantly, and allows us to know the voltage drops without needing to do any calculations.

Do you have any idea what that might be, or do you need another hint?

[Susan Brown]

That is not quite right.

Only loads in series will split voltage up (Kirchhoff’s Law)

The important thing to remember about parallel circuits is that they are independent circuits that happen to be tied together at the power supply. Other than that, what happens in one does not affect the other.

Also remember that if a circuit just has a single load in it, the voltage drop for that load will equal the source voltage.

So, for example, the Safety is in parallel with the other circuits in this scenario. It has full, independent access to L1 and N. What will its voltage drop be?

[Susan Brown]

Hi Kevin – have you activated your Appliantology membership yet? That is usually where we want students to post questions about specific repairs that they are working on. The Ask the Teacher Forums are mostly for questions directly about the course content or quizzes.

[Susan Brown]

Okay – you’re all set!

[Susan Brown]

I can reset the quiz for you so you can retake it – there’s always another chance! I assume you’d like me to do that?

[Susan Brown]

Hi Ronald,

The two answers that are not invasive and do not involve disassembly are:
Temperature
Amps

Measuring pressure is invasive and looking at the frost pattern requires disassembly.

Let me know if you have any other questions.

[Susan Brown]

Hi Dale –
I assume you are talking about the “Kleinert” book that we have some assignments from. See the Orientation module, unit 1, Preflight Checklist item 4.

Also see this topic here in the Forums:
https://my.mastersamuraitech.com/appliance-repair-course-support/student-forums/topic/link-for-the-pdf-textbook/

[Susan Brown]

Basically:
While the fridge is running, you would use the schematic to find the pin locations for the sensor so you could measure the voltage across it (DC voltage). You would need to know the specifications (from the service manual/tech sheet) so you would know how to interpret the number you get. Not all manufacturers give voltage drop specs.

[Susan Brown]

Hi Zachary,

When looking at schematics, it can sometimes be hard to see if a load is in series with other loads or in parallel. Some people are good at tracing the voltage lines out by just looking at them, but for some it’s helpful to think of it the way we describe – imagining that we are the load, and reaching out with each hand to touch Line and Neutral at the power supply (or L1 and L2 if it’s a 240v circuit). We will take the easiest route – if there is a shunt (often a closed switch), we will take that to avoid going through another load. It’s just a little visual trick to help us out.

As you get more into the Troubleshooting material, you’ll learn more about why it’s important to be able to see how a load is laid out in a circuit, relative to other loads in the appliance.

Does that help?

[Susan Brown]

The switches determine which route L1 takes.

[Susan Brown]

First, I always like to make sure we are looking at the correct light on the schematic, since there are several.

Any load that is supplied with L1 and L2 will run on 240v. L1 and N is 120v.

There are two ways that L1 can get to the light – that is what we are asking for in Question 2.
One of them is Through the light’s bimetal switch, as you say. The other has to do with that jumper wire (BK-J).

Did you see the explanation that showed up on the results of the quiz for this question?

When the surface element is first switched on, the light gets L1 through the L1 to H1 contacts of the infinite switch and the black jumper wire. This can be easy to miss because the two ends of the black jumper aren’t explicitly shown as being connected.

During the element’s operation, once it gets hot enough, the light’s bimetal switch closes, providing another path for L1. This means that even after the infinite switch is opened, turning the element off, the light stays lit until the element cools off enough for the light’s bimetal to open again.

[Susan Brown]

Check out this topic – does it help you see the answer?

https://my.mastersamuraitech.com/appliance-repair-course-support/student-forums/topic/mod-6-unit-7-quiz/

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