Forum Replies Created
-
AuthorPosts
-
I have difficulty in finding the jumper wire from H1 to the hot light in the ‘wiring diagram’.
The reason you’re having difficulty is because wiring diagrams are terrible for tracing and understanding circuits. This is because of a key difference between schematics and wiring diagrams.
Schematics are an abstract representation of the circuit which show it “as electrons see it”. In other words, it represents each circuit as straightforwardly as possible, disregarding physical realities like molex connectors.
Wiring diagrams are representations of how the circuits exist physically, showing how all the wires tag off of different loads and go through various connectors. This makes it very hard to trace a circuit through a wiring diagram, because that’s not their purpose.
As techs, we almost always use the schematic. That’s the document that’s actually useful for us when it comes to understanding circuits, troubleshooting, and identifying test points. The only situation when you’d want to use a wiring diagram is if you’re tracking down a broken wire or failed harness connector, which is much rarer.
So basically, you should just stick to the schematic. The wiring diagram will only confuse you if you try to use it to understand a circuit.
It all comes down to how many amps are in the circuit you’re jumping. Different gauges of wire have different ampacity ratings — that is, they have a spec for how much current they can carry before overheating. This page explains ampacity and has a nice chart to demonstrate.
For the amount of current in the AC circuits we work with, 12 gauge wire is a safe bet. The only situation where you might want to have a different wire gauge on hand is if you’re jumping something in a low-voltage DC circuit. Much lower amps in these, and often the connectors are itty-bitty, making it hard to get a 12 gauge jumper in there. For these, 18 gauge works well.
Hello Susan,
Thank you for the reply, I was just looking at that schematic and since this is the first time I’ve seen anything like this, I am a little confused on the lines I see where the schematic lists Active and Fixed like your example 16/13/15 but am I to understand the Active number box has a line which goes across the entire page that line is referring to 16 on Cam 8 then does Fixed 13 begin at 6 min. under the Pump box and end at 4 min?
If so then thank you for clarifying if not…
Sounds like you’ve basically got it, but I’ll clarify a bit more. We’ll take the row you gave as an example — the one for “pump” and “low motor”. Don’t worry about those “fixed” and “active” labels. All you need to focus on is the numbers of the contacts, because that’s what’s telling you which switches are closed when during the cycle.
For example, moving to the right along the timer chart, you’ll see that the boxes in the “pump” row are filled in during the pump part of the cycle (naturally). That means that, during that part of the cycle, the timer closes the switch that connects T16 to T13. You can double check that on the schematic. If you look, you’ll see at the section marked 8, the cam number, there’s a switch that can be closed in one of two ways. If it closes one way, T16 and T13 become electrically equivalent. If it closes the other way, T16 and T15 become electrically equivalent. That second one is for running the motor on low speed, as the timer chart says.
Does that make sense?
If the dielectric barrier in the capacitor breaks down and the capacitor shorts, then it would cause issues. The motor would run, at least for a bit, but there would now be voltage drop across the start winding even after the PTC has gone open. This causes excessive current draw and will probably blow the motor’s overload protector.
April 24, 2023 at 1:42 pm in reply to: Troubleshooting Freezing in Fresh Food Compartments, Mod2, Unit4 #24982I don’t believe we have a video showing that exact procedure, but it’s really not any more complicated than what you just stated. You situate the head of the thermistor in a glass of ice water, and then you go to the harness connector on the control board and put your meter probes on the two pins for the thermistor. The way you identify the pins is by using the schematic. That will show you which pin numbers correspond to that thermistor.
Hello MST, in the 3rd video what cause the 30amp fuse to open? I’m assuming it was a loose connection in one of the terminals.
Remember what a loose connection causes: higher resistance. And the more resistance you have, the less current will move through the circuit. So a loose connection would not cause the excessive amps to open a fuse.
Far more often than not, these safety fuses trip for no reason (simply due to age), and that’s what happened in that video. Once you replace the fuse, everything almost always works just fine.
It is a general purpose and pretty reliable test. Hall sensors all work the same way, and they don’t usually go out of calibration — in fact, a lot of Hall sensor problems are due to a break in the wire harness rather than an issue with the sensor itself.
The test would be done while the washer is not running. The machine could be plugged in or not — that part doesn’t matter, so long as the motor is not being powered. Which should be obvious, since you’re spinning it by hand as part of this test.
And of course, you should go to the documentation for the model you’re working on first. They may provide a more specific test routine for their implementation of the Hall sensor.
There’s a blog post at Appliantology with more information about Hall sensors if you would like to learn more: click here to check it out.
Just wondering how is the Convection Fan Motor (letter ‘A”) relay turned on if this fan motor is not running?
The circle marked “A” isn’t the convection fan relay — it’s the convection fan motor itself. That’s our load of interest. The relay is the switch that supplies voltage to the convection fan. What we want to find out with our voltage test is if that relay is closing and supply the convection motor with voltage.
The measurement points that you gave would only tell you if the entire appliance has a valid line and neutral. Where could you do a test that would be more specifically focused on the convection fan motor’s power supply?
When you make a voltage test, you need to ensure that the circuit you are testing is supplied with power. Otherwise, it’s not a live test.
So yes, in your drain pump example, you would want to active a drain cycle or activate the drain pump in test mode.
If you pay attention to the name of each thermal control and think about their function, you’ll get an idea of its intended purpose in the circuit.
The operating thermostat, as its name suggests, opens and closes during normal operation to moderate temperature. It’s the intended way for temperature to be regulated in a normally functioning dryer. The hi-limit, on the other hand, is there to put an upper limit on how hot the machine can get during a cycle for safety reasons. So one is expected to open and close during operation and the other is not.
The thermal cut-off is also there for safety, either as the “last line of defense”, which would be when it goes open at its functioning temperature, or as an indicator that there is a chronic problem with the dryer, which would be when it goes open due to cumulative hours at its holding temperature.
As for the temperature selector, it’s just an infinite switch, like the kind you use to control the stovetop burners of a range. If you look at the circuit with that in mind, you should see how the temperature selector allows the user to adjust the drying temperature.
Hi. I got this one wrong. I chose 8.49 VAC. I have an 18v battery from my cordless drill. I put my meter on it. When testing with the DC setting, I get 17.4 volts. When I switch the leads I get -17.4v.
When I switch the meter to the AC setting, I get 38.3, and if I swap the leads, the negative sign pops up, and it shows 0 on the meter. Please advise.
That question is assuming you’re doing this measurement on a standard copper-top battery, like a Duracell. If you measure AC across a battery like that, you will read 0.
A battery for a drill is going to be different and more complex. Those contain circuitry with load-sensing capabilities, and that circuitry can cause weird AC readings like what you’re describing.
The video in module 7 unit 4 covers this very directly — is that the one you’ve been reviewing? Once of the first slides covers the path the spark current takes.
but i dont get why arent they old plain bimetals.
That’s the thing — they are plain old bimetals. A bimetal is a bimetal — they all work the same way. These bimetals just have itty bitty heaters attached to them so that, in cycles when those bias heaters are activated, the bimetal goes open. This is desirable on low heat cycles, like the delicates cycle. But these bimetals will also open in response to heat from the main heater coils, as we discussed in the video.
These aren’t weird and different technology — just a clever adaptation of a regular old bimetal and a regular old heating element.
The table shown was for illustrative purposes — to show the difference between functioning and holding temperatures. For whatever reason, the manufacturers did not include temperatures in certain spots. We work with the specs we’re given.
The cycling thermostat is only one part of the equation. A number of other issues could cause a thermal fuse to open, such as a grounded heating element or clogged vent. Any situation that causes excessive heat buildup can cause or contribute to a thermal fuse opening.
We didn’t cover those because that wasn’t the focus of the lesson. Again, be careful not to get led off on rabbit trails. These are real-world schematics, so they contain lots of different elements, and we’re not going to cover every single thing shown on a schematic in a single lesson.
However, I will say this: the bias heater’s function is pretty self-explanatory when you consider a) how bimetals work, and b) during which cycles the bias heater is activated (see the timer chart). You should be able to figure out for yourself the purpose of the bias heater with the information shown on the tech sheet.
-
AuthorPosts
