Susan Brown

[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.

[Susan Brown]

You are correct! I reset you.

[Susan Brown]

I think you have figured it out since you posted this – but just to make sure, did you see the explanation for this question?

Since the light stays on when the jumper is disconnected, the light must be getting L1 from some other source. Thus, we can conclude that H1 to L1 is not the problem.

[Susan Brown]

The only dopes are the ones who don’t ask questions when they are unsure of an answer!

“Step-by-step troubleshooting instructions” are not included on a tech sheet, although I’m sure many poorly-trained techs wish they were. There may be various amounts of guidance, but they do expect the tech to have a basic level of troubleshooting ability. Instead of that item, you should have chosen “the schematic”.

[Susan Brown]

Of your three answers for outputs, this one is wrong: “Motor speed feedback signal”

Outputs from a main control board are most often something to do with “power supply”

• This reply was modified 7 months, 4 weeks ago by Susan Brown.

[Susan Brown]

Hi Lukas,

Did you see this topic already?
https://my.mastersamuraitech.com/appliance-repair-course-support/student-forums/topic/module-5-unit-5-2/

[Susan Brown]

You have a membership at Appliantology – you can post in the Tech Forums, even if it is your own machine.

[Susan Brown]

It does take some time and practice, but you are on your way!

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