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A common saying is, “Current takes the path of least resistance.” This is a misleading half-truth. The real truth is that electrons (“current”) takes ALL VALID PATHS simultaneously. A valid path is one that is NOT OPEN and has a complete, uninterrupted path from the power supply, through the load, and then back to the same power supply. This is why you can have parallel circuits, each with different loads of different resistance, and electrons from the power supply will go through ALL the parallel loads. The AMOUNT of electrons that goes through each load is inversely related to the resistance (really, impedance) of the loads. Loads with lower impedance will allow more electrons through.
As Susan mentioned, shunts are a special case. A SHUNT across a load DOES NOT create parallel circuits. The shunt is a path of 0 resistance (functionally speaking– ignoring the minuscule wire resistance) therefore 100% of the electrons will go through the shunt instead of the load.
is it possible to elaborate here as well?
Every circuit has to return to its source. Think about the return path for the spark circuit. What component allows the spark current to return to the “source” (ie., spark module).
Its my understanding that ions only are present with the flame.
This topic is about Module 7, Unit 3. Your question pertains to Module 7, Unit 4. Your question is amply explained in the video for Module 7, Unit 4. Please review. If still confused, please start a new topic.
September 21, 2023 at 7:30 am in reply to: Module 2 unit 4 User Interface Controls In Laundry Appliances #25308In Frigidaire terminology, yes. The middle terminals are just the part of the circuit being connected to either the top or bottom terminals to make different circuits. You’ll see this readily on the schematic.
September 18, 2023 at 9:59 am in reply to: Module 2 unit 4 User Interface Controls In Laundry Appliances #25302Good question. You would need the schematic to answer this, which I didn’t include in this video. However, this video from the Core course does show reading the the schematic in conjunction with the timer chart.
The short answer is that the middle row of contacts is from the circuit that is being switched to either the top row or the bottom row, depending on where the timer is in the cycle. But watch the above video for a more detailed explanation.
Question; would you be able to do the same testing at the board and come up with the same results or do you want to go to the actual load itself and test?
Absolutely you could (and usually should) do this exact testing from the board. The schematic shows you the wires connecting from the motor to the board. Simply follow those lines from the motor back to the board. Note the pin connections where the lines connect to the board. Those points become your test points exactly as if you were at the motor itself. Why does this work? Because when you have a wire connecting two points, the two points that are connected become EEPS– Electrically equivalent points. In other words, what you do at one end is the same as if you were doing it at the other end. This is the power of EEPS and reading schematics.
The reason I tested the motor this way was first for a demonstration. And second, because in this particular case, the refrigerator could not be pulled out from its cubby without the great peril to the floor. And the customer was already super anxious about scratching her high dollar floor.
Also, what was the initial customer complaint for the service call discussed here?
The original customer complaint was a revving noise from the fresh food compartment. This revving sound was a result of the evaporator fan motor RPMs increasing rapidly, then decreasing rapidly, then increasing rapidly, then decreasing rapidly and on, and on it, would do this throughout the day and drive her insane. I explain this later in the video. Because of the potential floor damage liability, it was very desirable in this situation to diagnose the problem without rolling the refrigerator out.
Hi Ray. I don’t have a video showing troubleshooting BLDC motors from the board. But this would be exactly like troubleshooting it at the motor itself. The only difference is that you’re using the schematic to follow the wires from the BLDC motor to the board so you can identify the pins where you’re place your probes.
For example, in this video, I’m demonstrating the voltages into and out of a BLDC evaporator fan motor that’s already removed from the refrigerator. In this particular case– GE FDBM– it was actually easier and less risky to test the voltages at the motor itself because the board was in back and pulling the fridge out risked scratching the expensive maple floor which the customer was very anxious about. The exact same tests could be run from the board by simply using the schematic to follow the lines from the motor to the board to find your test points.
If we get moisture in the sealed system we get the restriction near the end of the cap tube and it cycles on and off.
This was actually the case with some GE models several years back. Moisture was introduced into the system at the factory. It would manifest in such a way that ice would form at the capillary tube where it entered the evaporator and then form an ice plug. This would cause the evaporator to warm up which after a while would melt the ice plug and then restart the flow of refrigerant and the refrigeration process. This, in fact, is the dynamics of moisture in a sealed system.
2) Will the filter dryer need to be changed after the removal of the moisture? since if the filter dryer has to be changed and we have to do sealed system repair then it is better to open and recharge the sealed system instead of using the heat gun.
The fact that moisture was present in the system in enough concentration to cause a problem means, de facto, that the filter dryer was not able to handle the moisture. The filter dryer may have been saturated with moisture and unable to handle any additional. That additional moisture would have been circulated in the system wreaking havoc.
In such cases, you will want to certainly replace the filter dryer, but also pull a deep vacuum on the system to ensure that you have evaporated all of the residual moisture in the system. Then recharge the system, by weight, according to the manufacturer’s specifications on the model number tag.
Glad to help!
Your analogy is flawed. A refrigeration system with a running compressor does not have the “lid” effect because the compressor is continually “sucking” vapor to maintain a low pressure (and, consequently, temperature).
Some conditions such as higher heat loads (warm food placed inside, extended door opening, high ambient temperature, etc.) will cause the total system pressure to increase or decrease but this is normal thermodynamics in a sealed system, not the result of intermittent restrictions.
Now as I read the question – you are measuring in a live voltage test between the common terminal and the NO terminal of a switch during a live voltage test of a 12 V DC circuit.
Correct!
You should measure 12 volts because it is similar to measuring between the ground switch and the L1 of a socket.
Ground is simply referred to as “Ground” not a “ground switch.” And this is a DC circuit, so no L1. Doing the measurement described in the quiz question would be similar to measuring voltage across any open on a circuit. Whether the open is caused by an open switch or a broken conductor doesn’t matter. You’ll have voltage (assuming it’s plugging in as in the question scenario) but not current because electrons need a complete circuit to move.
Measuring from COM to NO on a switch that is in its normal state (meaning not actuated), you will measure the supply voltage because COM to NO is open in this condition.
I’m guessing “micro switch” means the circuit can be closed and carry current even when this particular small switch is open?
No, this is not true. Microswitch just refers to the style of switch shown in the lesson. They’re used all over the place in appliances. If the circuit connects to the switch by the COM and NO contacts, then this means the switch must be actuated for COM to NO to be closed (because NO is normally open, but closes when actuated). If this is not clear, let me know.
You may also want to watch this workshop recording that goes into loads and switches: https://appliantology.org/topic/72423-voltage-voltage-drop-loads-switches-jumpers-cheaters/
July 19, 2023 at 8:40 am in reply to: Internet connected Appliances making appliance repair opportunities obsolete? #25195Hi Ted,
In that webinar, I was relaying what I’ve heard manufacturer executives say at appliance service meetings. These are executive mucky-muck types. They are non-technical people who talk big and dream big without much basis in the reality of the technology. Think about service mode and fault codes on most appliances today. They claim to point techs to the defective load but in reality they rarely do that accurately. The tech still has to verify the fault code with electrical measurements and usually go on to identify the real problem. The actual problem could turnout to be a broken wire harness or some other defective load or switch. If they can’t get the fault codes to be 100% accurate 100% of the time, then there is zero possibility for them to identify and repair the correct problem remotely. Just because big wig executives say they want something does not mean it’s possible not or even ever.
Software and AI do not have the ability to think through a problem and are utterly reliant on the accuracy of the fault codes to fix the problem. This may work 10% of the time but will never be a 100% reliable solution to repair the problem.
Troubleshooting is a very human and analog skill. It is the irreplaceable skill. Too much physicality and sensory stuff going on: seeing the problem, reading the schematic, planning a troubleshooting strategy, hearing strange noises, etc. Machines cannot do this.
PCMs who are dispatched to replace a specific part (Whirlpool’s vision) are a very replaceable and interchangeable commodity. Real technicians who know how to troubleshoot the way we teach, will be irreplaceable.
@Moby- After you click the link, you have to then click the purple “Download” button to download the PDF.
PTC Positive Temperature or thermal Coefficient
Resistance decrease and temperature decreasesCould you give a time stamp in the webinar video where you heard this?
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