Scott Brown

[Scott Brown]

Hi Marvin,

I use the Fluke 54-2 dual input digital thermometer for calibration: http://amzn.to/2xsd7Um

It’s expensive but my preference is to always buy the best when it comes to test equipment. If that’s not an option, there are other, less expensive alternatives. For example, if your DMM has a thermocouple into jack, you could just buy a K-type thermocouple, like this one, and use that. The disadvantage is that you’ll only get one temperature reading. Two simultaneous measurements can be very useful for tracking down uneven cooking complaints. But, admittedly, this is probably infrequent. You could probably buy a second, inexpensive DMM with a thermocouple jack and use that to get two temperature readings for those infrequent times when that is needed for diagnostics.

[Scott Brown]

If you’re taking about the 1/4″ and 3/16″ spade terminals, mostly yes. If you match the wire AWG and whether or not the terminal is insulated or insulated, you’ll usually be okay. You can buy sets of terminals in assorted sizes on Amazon.

For more info on electrical terminals, here’s a good information article from an engineer at Tycho: https://mastersamuraitech.com/wp-content/uploads/2017/09/Electrical-Terminals.pdf

[Scott Brown]

Hi Don,

Remember: a hypothesis is something specific that you can measure and prove or disprove. Something like “bad board” is not a hypothesis- that’s what we call a WAG (Wild A** Guess). 🙂

please reset CS5 troubleshooting hypothesis quiz.

For resets, please use the reset request form as explained in Orientation, Module 1, Unit 1. Here’s the direct link to the rest request form: https://my.mastersamuraitech.com/quiz-exam-reset-request/

[Scott Brown]

This is common problem with some Whirlpool/KA SxS models where the wire harness gets chewed up from normal door openings and closings. Depending on how extensive the damage is, I’ve had mixed success repairing the harness with splices. It is plausible that its so far gone that it would need a new door. If this is the case, I agree that a new refrigerator would be the way to go.

I don’t mind answering a few appliance-specific questions here but the these forums at Master Samurai Tech are focused on helping students with the course material. If you’re running service calls and need information or resources relating to those calls, this is exactly what Appliantology is for- supporting the professional appliance tech community in day-to-day service calls with troubleshooting help and technical literature.

[Scott Brown]

I’ve actually graduated from the Ryobi and now use this Bosch driver exclusively: http://amzn.to/2vCKmP6

It’s a little bit more money but vastly superior. These two drivers are not even in the same league.

I do still have a Ryobi impact driver that I use maybe twice a year.

[Scott Brown]

At about 14:50 on the video you are saying the switches are open – and the electrons are flowing thru them. I hate to be thick – but I’m not following the video. If the switches are open how can the electrons flow through them?

You’re not being thick at all, John– this is an excellent question. I used the term “open” deliberately to make sure you were paying attention. 😉

But seriously, you are correct: electrically, the IGBT semiconductor switches would be CLOSED to allow electrons to get pushed through. I was explaining the path the electrons take through the different switches during commutation. Poor choice of words.

I hope that clears it up for you. Let me know.

[Scott Brown]

If you have two loads in series, voltage will be dropped across the two loads will be proportional to the resistance of each load and the total circuit current. This is Ohms Law:

E=IxR

The sum of the voltage drops across the loads will add up to the supply voltage. This is Kirchoff’s Law.

If you remove one of the loads so now there is only one load in the circuit, the voltage dropped across that load will always equal the supply voltage. (Note – I’m not saying that the load fails open, in which case you’d have an open circuit and current would stop flowing, resulting in zero voltage drop. I’m just saying we remove a load and now there’s only one.)

Make sense?

[Scott Brown]

If a load is open you won’t get any current.

Correct!

Anyway if you measure 120 volt to a load if course with a “LOADING METER” and the load isn’t running there is no need to measure current ,you replace that load

Correct again! Well done!

I’m glad to see you have snatched the pebble from my hand. You have had the diligence and benefit of attending many of the Office Hours where I drill this concept in with various problem scenarios. Alas, many students are not as diligent as you so, for them, this question represents a paradigm shift and is a real teaching moment for them.

You are overthinking this particular problem and reading information into the question that is not there. The question does not mention using a loading meter, thus leaving it ambiguous. And deliberately so.

[Scott Brown]

do you mean line v is supplied to heater by black wire on line side of fuse ,or black wire coming from clutch motor?

The heater is a load. So one side will get Line voltage and the other side will get Neutral. The question is asking what color is the wire that supplies Line voltage to the heater.

[Scott Brown]

Ahh, so that explains why there are 2 tech sheets for the dryer: the 120 V is for the controls and the 240 V is for the heating elements. That definitely threw me for a loop.

I re-looked and you are correct– the other tech sheet (unrotated) is for a gas dryer, which runs off 120 VAC only. The tech sheet that’s oriented in landscape is for an electric dryer, which runs on both 120 and 240. Sorry for the confusion.

See you Monday!

[Scott Brown]

I read the tables for the error codes very carefully as you suggested. The dryer beeped 6 times, paused, and beeped 5 times. That corresponded to a “high Limit Thermostat trip count too high.” The table said to check for vent blockage. We looked in the vent and found rags. http://imgur.com/a/OiVvZ

Now that’s what I’m tawkin’ about! You took that tech sheet and service manual and ran with it- way to go, Idaho! I can tell already that you’re going to be a great tech. Seriously. I’m going to let you in on a little trade secret…

One of the biggest problems I see with techs today: they either don’t have the attention span or patience to simply take a few minutes and RTFM. Almost every day at Appliantology, I see experienced techs with years of experience who don’t do this and it always amazes me. If you do this one thing, you’ll be miles ahead of your competition.

Being successful at appliance repair really comes down to a four key skills:

1. knowing the basics (electricity, circuits, gas, technology, etc.) which you’re learning here at the Master Samurai Tech Academy
2. getting the tech sheet or service manual for the specific model you’re working on, which you can get at Appliantology.org
3. paying attention to details
4. doing business according to a system (pricing, delivering service, etc.) and doing what you tell your customers you’ll do

It really comes down to those four things. Most techs that I have met, even those with 20+ years of experience, absolutely fail at items 1 & 3. And because of that, even if they do item 2, it usually doesn’t do them any good because they don’t have the fundamental skills to know what how to interpret the technical information (except maybe disassembly– most techs are really good at parts changing- disassembling to replace a part- problem is, it’s usually the wrong part!). And they usually don’t take the time to read it anyway.

I can tell you already have item 3 dialed in and you’ll soon have item 1 so you’re already (or soon will be) better than most techs out there. Seriously- that’s the deplorable state of the appliance repair trade today and why there is such a demand for skilled techs. Good techs who know how to troubleshoot will always be in high demand and always have work.

Now as to your other questions (

– What do you notice right off the bat about the dryer “timer”?
– How does this inform your troubleshooting strategy? (hint: remember from the TST special notes about loads with algorithmically-controlled power supplies)
Maybe you can talk about this during this upcoming office hour.

If you’re definitely planning on being there, I’ll be glad to talk about it– that’s exactly why we do Office Hours!

But I can go ahead and tell you a couple things..

– What do you notice right off the bat about the dryer “timer”?
– How does this inform your troubleshooting strategy?

The intention here was to get you to look at the schematic and realize there this dryer doesn’t use a mechanical timer– it’s a computer board. So this affects how you’ll troubleshoot it. You did this by retrieving error codes which led you to the problem. When dealing with a computer board in an appliance, talking to that board to let it tell you what it “thinks” is wrong (via error codes) is Job One.

I can’t seem to find the dryer “timer” in the diagram. In the manual there are 2 schematics for the dryer — one for 240 and another for 120 V.

The other thing to keep in mind with technical literature is this: for the schematic, the tech sheet, not the service manual, is the go-to document. The service manual is good for disassembly, some theory of operation, and expanded explanations about service procedures such as entering diagnostic mode (talking to the computer).

With that in mind, look on the tech sheet and scroll to the end. You’ll see there are two dryer schematics but they are identical, they’re just in two different languages. I always use the English ones.

Also, note that an electric dryer uses both 120 and 240 VAC: 120 for the controls and 240 for the heating elements.

There’s another pair of schematics but they are for the washer part of the laundry center.

I also don’t know what you mean by TST special notes

This refers to the special precaution in your LOI circuit analysis when the power supply for your LOI is controlled by a microprocessor (computer) because that microprocessor is executing a software program and making algorithmic decisions about when to supply power to that load. So if the load is not getting power from a microprocessor, you can’t automatically assume the microprocessor has failed because it may be responding to some other sensor or input from the machine. We cover this in detail in the Advanced Troubleshooting course but that’s the main idea.

Spend some time watching the webinar recordings on the Webinar Recordings page- menu at the top of the page, mouse over SUPPORT and click WEBINAR RECORDINGS from the drop down menu. The one on Appliance Service Call Structures and Strategies would be a good one to start with.

Let me know if you’re planning on being at Office Hours on Monday and I’ll have your tech sheet ready to screen share.

[Scott Brown]

Hi John,

The specific “key dance” for entering service or diagnostic mode (called various things by different manufacturers) and for retrieving/decoding error codes varies widely from manufacturer to manufacturer and even model to model. The tech sheet and/or service manual for the specific model are the go-to documents for this information, which you can get at Appliantology.org.

Once you have the tech sheet or service manual, the only other skill needed is to actually read the manual. This may sound obvious but, incredibly, this is one of the biggest problems I see with techs today- they either don’t have the attention span or patience to simply take a few minutes and RTFM. Almost every day at Appliantology, I see even experienced techs who aren’t doing this and it always amazes me. If you do this one thing, you’ll be miles ahead of your competition. I’ve been doing appliance repair for almost 25 years and I still have to RTFM because there are always new models with new key dances coming out.

At the very least, you need to get the schematic anyway (Step 2 of the Ten Step Tango) which is usually part of the tech sheet that also has diagnostic entry and error code information on it.

We’re having an open Q&A at Office Hours this coming Monday and I’ve already had someone request that I review entering and using service mode on Samsung refrigerators and using the tech sheet to troubleshoot. If you’re planning on being there, we could cover an example dishwasher, too. Just let me know.

[Scott Brown]

According to my understanding, the answer could be different depending on in what state the appliance’s burner valve, for example, is in. Open or Closed.

If the solenoid valve is closed, the regulator is not regulating because there’s no gas flowing, as you correctly point out…

If the burner valve downstream was closed, with unregulated gas applied to the inlet of the regulator, no gas would be flowing.

In this condition, the regulator is not regulating anything so the entire question becomes moot.

The quiz question is predicated on the operation of the regulator. That means the regulator must be regulating. In order for this to happen, the solenoid must be open.

With no gas flowing, the regulator valve attached to the diaphragm would be closed.

This is not correct due to the spring tension on the diaphragm, as I explained in my previous reply.

The regulator does not turn off the supply of gas or allow it to flow (unless the pressure goes above the operating limit, as explained previously). Turning on or off the gas supply is the job of the gas valve. The job of the gas regulator is to control the pressure at which that gas is supplied.

It simply makes no sense to analyze the operation of a regulator when it’s not actually regulating because it’s not operating. In other words, you’re asking the wrong question.

Re-think the quiz question in the context of regulator operation.

Here’s a webinar recording on dryer gas valve operation that may give additional insight:

https://player.vimeo.com/video/237949606

[Scott Brown]

Hi John,

However, if the regulator is in a normal state with the valve closed,

Seems like you’re assuming the normal state of the regulator diaphragm plunger is closed. In reality, there is spring tension placed on the diaphragm to keep the plunger open at specific pressures, depending on the gas it is set up to use (natural gas or LP). So I’m not sure how you’re defining “normal.”

If the diaphragm plunger was all the way closed, as you suggest, this would be an un-normal situation because this means the gas supply pressure is well above the allowable pressure limit– enough the slam the diaphragm plunger closed. Very abnormal (and rare)! But, in this situation, further increases in supply pressure would only further push the diaphragm plunger tighter against the seal (in other words, it would not move since it’s already closed).

When a gas regulator is not connected to a gas supply, that this would also be un-normal because the regulator is not connected and being used as normally intended. In other words, it is not actively regulating anything!

[Scott Brown]

Here’s the actual service manual: 2015 Frigidaire Laundry Center Service Manual

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