Susan Brown

[Susan Brown]

Are you clear on this answer now?

[Susan Brown]

You are correct!

[Susan Brown]

Hi Raja,
I can help step you through these. Please answer the questions in bold.

Question 5:
If you look at the J1 connector, what is the voltage supply to it? That is what will be available to the optional evaporator fan.

Question 14:

The hint for this question is:
Use the watts specification for the condenser fan motor to calculate its resistance.

Were you able to do this? What did you get?

The explanation that showed up after you took the quiz for the first time is:
There are 3 resistances in parallel here. The resistance of the condenser fan motor is *much* higher than the other two, and thus has little impact. The answer will be, basically, the equivalent resistance of the two compressor windings.

What are the specifications for the compressor windings?

[Susan Brown]

#3: yes, triacs and relays
#7, 12, 16, correct
#20: the answer is “Set the washer to fill and see if water comes into the drum.”
#21: the other answer is “Wiggy or solenoid voltage tester”

As for your question connected to #16 – remember that the drain pump and water valve are in series, so they will have the same current flowing through both of them (determined by the total resistance in the circuit). So, if the R of the water valve is much higher than the pump, very little voltage will be dropped across the pump, so it won’t have enough power to operate. Does that help?

[Susan Brown]

Hi Denis,

There are three answer choices on this question:
Yes
No
Probably, but it depends on the model

The text in the unit is:

The water supply from the home connects to a water inlet valve. When this valve receives voltage from the control, it allows water to enter the dishwasher tub. How long this valve is kept energized depends on the model, but it is usually under 2 minutes to get the specified amount of water in the tub.

So the answer we are looking for is that third choice.

Let me know if you have any other questions!

[Susan Brown]

Hi Joshua,

The reading across the element is looking for voltage *drop*, since we are measuring across a load. If current flows through a load, then it will create a voltage drop. Since we measure 0v, that confirms that no current is flowing in the circuit. In Figure 2, since we have deliberately disconnected the circuit (and current will not flow in an open circuit), we would not expect to measure any voltage across the load.

Does that help?

[Susan Brown]

My iPad is pretty old, so I don’t know much about the newer ones. Generally, we always get as much memory as we can afford. However, unless you are going to store a lot of video, you don’t need to max it out.

[Susan Brown]

Appliantology 101 is not required for Certification, so you are fine!

[Susan Brown]

We are referring to the second scenario in this paragraph:

After the agitation portion of the cycle has completed, the washer must drain the tub. This can be done two different ways, depending on the model. If the washer has a separate drain pump, the control sends voltage to the drain pump, which pumps the water out the drain hose. On some models, the main drive motor drives the pump by spinning in the opposite direction than it did during the agitation cycle.

[Susan Brown]

Hi Michael,

First, one small but important correction. Voltage does not flow – it is best thought of as being present. Current flows.

With the thermal fuse open, there is no current flowing, so the element is not doing any work or dropping any voltage across it.

If you measure from either side of the element wrt N, you would read 120v (coming from L1). You basically have a continuous wire from L1 at the power supply to the open fuse, with L1 present.

FYI – If you measured across the element, you would read 0v, because it would be like measuring across a wire.

(Note – this is just like Question 9 on the Midterm Exam!)

If you disconnect the wire on the right side of the element (between the element and the thermal fuse), then 120v would no longer be present when you measure from the now-disconnected wire wrt N, because L1 can’t jump over the open gap.

Does that make sense?

[Susan Brown]

Hi Jim – even better: we tracked down a copy of that tech sheet and posted it in the unit, right above the video, so you can download it.

[Susan Brown]

Okay, I’m glad it is working. Usually, when videos aren’t playing, it’s an isolated problem with the student’s system or connection.

[Susan Brown]

By the way – very good question to ask! It shows you’re really thinking about this stuff.

[Susan Brown]

Sorry about that! I must have read your question too quickly.

If the door switch were open, then neutral would not be present at the push to start switch, and we would not expect to get the readings that we did.

[Susan Brown]

Hi Jessica,

Great question – this is good material to think through.

When a switch is open, you expect to measure voltage (potential) across it. In a 120v circuit, there is “line” voltage on one side, coming from L1 in the power supply, and neutral on the other side, coming from N at the power supply. So when you measure the voltage from one side of the switch to the other, you measure 120v (the difference between L1 (120v) and N (0v)). It is “potential” because current is not flowing. We have the potential for current to flow, because voltage is present. We just need the circuit to close.

When a switch closes, it then allows current to pass through it, and it acts like a wire. A wire does not have a voltage difference across it. The switch is no longer open to create a voltage difference. The voltage difference will then occur across the load (or loads) in the circuit – we call this difference voltage *drop* (as opposed to potential). We’ll be talking more about voltage drop in Unit 8.

So when he presses the button and the voltage goes to 0v, he knows the switch closed as it should.

Does that make sense? Don’t worry too much if it isn’t 100% clear to you yet – we’ll keep working on these concepts. But let me know if you have follow up questions.

[Author]

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