Scott Brown

[Scott Brown]

What i meant was how did he locate the physical component of the dryer by using the schematic?

The schematic shows me the circuit as electrons see it. I identify my load of interest (LOI- “the thing that ain’t doing it’s thang”), locate that on the schematic, and it shows me the various switches that control the power supply to that LOI. To locate that LOI and its associated switches on the physical appliance, I would use:

– eyeballs (eg., there’s only one drive motor in a dryer, if I remove a panel and see the drive motor, as I show in one of the videos, I have located the physical component)
– photos in the service manual
– exploded parts diagrams

(those latter two are available at our sister site, Appliantology.org, and you have a complimentary 6-month membership there as part of your enrollment).

In a later unit, you will learn about various components used in appliances. Be patient and keep at it, you’ll get there. For now, I want you to focus on understanding the discipline and procedure of troubleshooting. That is the learning objective for this module.

[Scott Brown]

I neglected studying the difference between Voltage and Voltage Drop.

Have you watched that webinar recording yet? If not, you need to do that now.

The concept being illustrated is that voltage is always relative to some other point. There is no 120 volts “out there” somewhere– it always with reference to some other point. This is the takeaway point.

There are certain troubleshooting situations where it is more expedient to use something other than Neutral for a reference. This video demonstrates an example:

https://player.vimeo.com/video/237972064

[Scott Brown]

Scott said make it a good practice to use LOWz and in a video he said to use VAC???

I did that deliberately to see if anyone would notice. Good job! Do as I say, not as I do. 😉

And please elaborate when we have to use resistance testing as well. Thanks

As Sam told you in your other topic, use resistance when you have an ohm specification that you are testing for. For example, the schematic shows a spec on a drain pump motor as 14 ohms. How would you verify that the pump motor is in spec: continuity or resistance?

[Scott Brown]

You’re confused because you’re reading information from engineers. Engineers use “hole” movement instead of actual electron movement. This is due to a mistake originating with Benjamin Franklin. Even though later physics has proven that it’s electrons that move, the tradition was set and so continues to this day.

Holes move opposite to electrons. You end up with the same result as long as you are consistent.

Engineers developed the schematic symbols based on their backwards system and are still taught hole flow to this day. Everyone else, including physicists and technicians, are taught actual electron flow but we are stuck with the engineer’s backwards symbols. This is true for all semiconductors such as transistors and triacs.

I actually learned both electron flow in the Navy and then later hole flow at University of Georgia where I earned my engineering degree. You are learning electron flow exactly the way I was taught in the Navy and the way technicians all over the world are taught.

[Scott Brown]

A tech walks into a warm refrigerator service call– both compartments warm. The FIRST question he should be asking himself is this: “Is the compressor running?”

If the compressor is not running on a warm box service call, nothing else happens–the evap fans can blow all day long and the box still won’t get cold. It is the FIRST load you verify proper operation on for this type of call.

Let’s look at a typical workflow for a simple, split-phase compressor, single evap system with a mechanical cold control, like the one you used in your example:

1. I walk into the house, greet the customer, ask her not to open the fridge doors for me.
2. I stand in front of the fridge and listen (asking customer to turn off extraneous noises and shut up her yapping little dog).
3. I can hear a split-phase compressor running from the front of the fridge. You can, too, as you said. Great, I have just performed a partial but essential check of the refrigeration system– verify compressor is running– without moving the box or disassembling anything.
4. If I DO hear the compressor running, then I go on to shoot the compartment temps. While I have the doors open for the temp shoots, I listen for the evap fan, look for frost behind the louvers in the freezer back wall, check for unusual condensation or frost, and check the door gaskets and closing.
5. If I DO NOT hear the compressor running, then I’ve just verified that my load of interest is inop and this directs my troubleshooting to the controls and the compressor start device.

Now, let’s look at a typical workflow for a three-phase BLDC or linear compressor box. Knowing whether the box is single or dual evap informs me about what to listen for when I have the doors open for the temp shoot.

1. I walk into the house, greet the customer, ask her not to open the fridge doors for me.
2. I stand in front of the fridge and ask the customer to turn off extraneous noises and shut up her yapping little dog.
3. Since we CANNOT hear BLDC or linear compressors running from the front of the fridge, we know that we’ll be pulling the fridge out to verify that the compressor is running. I know this is the essential question to answer at this point but, while I’m in front of the fridge, I might as well…
4. … go on to shoot the compartment temps to verify the customer’s complaint. While I have the doors open for the temp shoots, I listen for the evap fan, look for frost behind the louvers in the freezer back wall, check for unusual condensation or frost, and check the door gaskets and closing. But note that I do this to accommodate the normal workflow when servicing this style of fridge, not because it makes troubleshooting sense. I do this in order to gather data that may be useful after getting the essential piece of troubleshooting info I need: Is the compressor running?
5. Now I pull the fridge out, go around back and see if the compressor is running. If the compressor IS NOT running, then I’ve just verified that my load of interest is inop and this directs my troubleshooting to the controls and the compressor start device.

That trick with tapping the cold control is great for older, simpler fridges. But, as Mrs. Samurai pointed out, the diagnostic info that prompted you to tap the cold control in the first place was because you did not hear the compressor running!

You are applying our system without even realizing it. You’re welcome. 🙂

[Scott Brown]

Hi James,

Had the customer set it upright for 24 hours *before* running the refrigerator for several days like this, that *may* have prevented the problem. However, depending on the particular tubing configuration, even this doesn’t guarantee that the oil will return to the compressor. In some configurations, once the oil leaves the compressor, some or most of it may remain in undesirable places such as the evap or condenser tubing.

Either way, in this case, the damage was already done. When a compressor runs this hot it only takes minutes to hours to permanently damage the bearings and valves inside the compressor. The buzzing noise was also evidence of internal damage already done. Too late for this one!

[Scott Brown]

Hi Phil,

Could you give me an approximate time stamp in the video to the explanation that you have a question about?

[Scott Brown]

“ok, I’ve replaced this, that, and this other part; which part should I try next?” Wow, that’s surprising that people who do this for a living are approaching it like that.

I know, I think the same thing– how are these guys comfortable making a living doing something they don’t understand? I think most of these guys who ask those kinds of questions have not clue that there’s an informed, analytical way of doing appliance repair that doesn’t rely on guesswork. They literally don’t know what they don’t know. They will always be the techs asking questions, never the ones answering them.

Speaking of asking questions, hope you can make it to the webinar this Friday. We’re going to review electric circuits using a Samsung dryer and GE oven as example. See this calendar event at Appliantology for details: https://appliantology.org/calendar/event/837-workshop-electric-circuits-review-with-samsung-dryer-and-ge-oven-case-studies-friday-march-29-430-pm-eastern/

[Scott Brown]

What you’re feeling is completely normal and will pass. Just hang on, keep studying and trust that it will click at some point.

Just a side note— I didn’t mean to imply that you were complaining. I was just relating a humorous story of my own struggles with learning this stuff to help you see that even I struggled with the basics. Everyone does. Anything worth learning requires real effort. But most people are lazy— sounds harsh but it’s true. (again, not referring to you at all— after all, you’re here making the effort to learn!) That’s why most appliance techs today do not understand basic electricity and circuits— takes too much effort. They’d rather just know “the answer” — which part to replace— and then move on to the next job.

Keep at it, keep studying and asking questions and you WILL get it!

[Scott Brown]

One more thought… you mentioned you were overwhelmed with the information at the end of the Samsung Dryer webinar. You can and should rewatch the sections that are difficult for you. It’s normal and expected that you re-watch some or all of the more technical videos in the course.

I remember in Navy A School, Basic Electricity, when I was complaining about how difficult it was to understand circuits, my beloved instructor, Petty Officer Second Class Crowe, told me in his distinctive Alabama drawl, “Brown, learnin ain’t for pussies.” I went back to work.

[Scott Brown]

Keep at it, it will click for you at some point.

Do you think watching me show this in a live webinar would help? I’m planning a webinar for this Friday afternoon and could include this as one of the topics.

[Scott Brown]

In this video, I show the phase difference between L1 and L2 at a household panel. Watch and see if it helps:

https://www.youtube.com/embed/vOh2OSJ44eE

 

[Scott Brown]

Sean, this is a great question and would be a good topic for a webinar where I could go walk everyone through the circuit. Let me know if you’d be interested in that. In the meantime, or maybe in lieu of a webinar, I have a video where I break down the circuit in these Samsung dryers and discuss troubleshooting strategies. Watch this video and let me know if you have any questions:

https://mastersamuraitech.com/webinar-recording-troubleshooting-samsung-electric-dryer-control-board-using-live-testing/

[Scott Brown]

I’m having trouble reading the schematic by myself.

Not to worry, this is normal. You’re learning the fundamental principles in the course and you will master them as you apply them to solving problems.

Now that I know what document you’re working with, I see that you’re using the training manual. This is okay to get familiar with then machine but for troubleshooting, you’ll usually want the Fast Track. I’e uploaded it to Appliantology for you:

https://appliantology.org/files/file/5749-samsung-dv42h-dryer-fast-track/

The schematics in both documents are good quality and not pixelated, which is what I thought you meant at first about “hard to read.” But it sounds like you mean that you’re having a hard time understanding how to use the schematic. Is that right?

I put the machine into self-diagnosis and it showed a code for the door switch.

If you’re getting a door switch error code, then your first move is to verify that the door switch is operating in spec.

The door switch does not connect to the heater and, based on the problem you described, I’m not sure why you’re interested in this… unless you’re troubleshooting a no-heat complaint.

You can see on the schematic that the heater receives power via a relay on the main board. The door switch supplies Neutral to the board two ways: directly and via the second centrifugal switch contacts on the motor.

Referring to the Ten Step Tango, the first step in troubleshooting is to have a clearly and succinctly stated problem description. This is also the step that most techs fail to do. Just read the topics in the tech forum at Appliantology– most of those guys utterly fail to give a succinct, clear and specific problem statement. Solving problems requires clear thinking. If a tech can’t clearly define the problem he needs to solve, how will he ever solve it?

Your problem statement answers these questions: What is the appliance doing that is SHOULD NOT be doing? What is the appliance NOT doing that it SHOULD be doing?

Post that and we’ll go from there.

[Scott Brown]

Oh man, at the risk of sounding really stupid, I don’t know what you mean or how to do it.

This is actually a great answer! Part of your fundamental skill set as a competent, professional tech is effectively using information tools to get the job done. Your comment let me know to give you some good tips for using Appliantology as the powerful appliance repair information tool that it is.

Watch this super short video on how to search for files at Appliantology:

https://www.youtube.com/embed/Ua7juYqZKkM

 

Then use your new-found File Finding Fu to find the download page for the fast track at Appliantology. Copy the address of that page in the address bar of your browser. For example, click here to see how I get the address to this page that we’re both conversing on. Past the link here in this topic so I can download the exact manual you have.

Another great thing to do is take the free Appliantology 101 course which you’ll see on your “My Courses” page, upper RH corner of your screen, click here to see a screenshot.

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