Sam Brown

[Sam Brown]

Three-phase power output requires three outputs — one for each phase. So yes, three pins. You would simply hook up the tester to all three pins and test that way.

[Sam Brown]

Hi Shawn,

I see where the confusion is coming from — we’re not talking about the solenoid becoming literally flakey — as in bits of it flaking off. We’re using flakey in the non-literal sense, meaning that the solenoid has become unreliable and started to fail.

Because metal expands and shifts slightly when you heat it up, if there are any micro-breaks in the solenoid coil, they can cause the solenoid to operate correctly at first, and then go open after it’s begun to heat due to the current flowing through it. This is called failing under load. Heating the coils with a hair dryer simulates this and lets you quickly see if this is the issue you’re facing.

So the test in question would be to first energize the solenoid, then heat it up with the hair dryer and see if it goes electrically open.

[Sam Brown]

Hi Shawn,

Using the schematic, you would first identify the pin on the main control that outputs the PWM signal. Then, you would simply measure that with your meter with respect to a valid DC ground. Note DC ground, not AC ground. That’s all there is to taking a frequency measurement.

[Sam Brown]

How is this test conducted? the tool has three leads so I’m gathering that this would be hooked up to the MCU or the motor but not sure.

You would simply hook it up to the output of the MCU while it’s trying to run the motor. That way, the tester can see if the MCU is putting out a valid three-phase power supply.

[Sam Brown]

Can a data communication line transmit data back and forth or only in one direction?

Yes, it can transmit data signals in both directions! Sometimes you will see more than one data line connecting boards, but often you do only have one. But that does not necessarily mean that only one board is doing the talking. In fact, you almost always have two-way communication happening in multi-bard configurations.

[Sam Brown]

“Cold” is a relative term. Refrigerant that has left the evaporator coils and is on its way to the compressor is generally around room temperature. But you’re right in that it is relatively cooler compared to after it goes through the compressor. By the time the refrigerant leaves the compressor, it will have heated up significantly compared to before it entered the compressor.

[Sam Brown]

Dryer vent pressures don’t vary too much from brand to brand, so yes, the tester should work regardless of the brand.

[Sam Brown]

As shown in the diagram, L1 is being removed from the heater. We’re not talking about unplugging the entire appliance — just removing the L1 spade from the heating element.

The reason for doing this is to isolate L1 and L2 from each other in order. This is because, if both are connected to the heater, whichever line isn’t missing (in this case L1) will feed through the heater to the L2 side of the circuit, making it impossible to distinguish which is actually missing. However, once you have one of the lines disconnected, the lines are completely isolated from each other, so you can tell which one reads 120 volts wrt neutral (meaning that it’s present) and which one reads 0 volts wrt neutral (meaning that it’s missing).

Once you’ve identified which line isn’t making it to the heating element, that’s when you would proceed with your troubleshooting to find out why that line is missing. For example, it could be missing at the wall outlet, or there could be an open elsewhere in the circuit.

[Sam Brown]

Great question, Troy — the explanation in the Kleinert book is badly worded and confusing. That’s why we don’t recommend it as a textbook and only as a reference.

This image has a better explanation of what’s going on. This type of circuit configuration is called a voltage divider, and the CPU essentially acts as a voltmeter, with one “lead” connected to ground, and the other connected to the hot side of the thermistor. That’s how the CPU detects the voltage drop across the thermistor.

[Sam Brown]

Hi Brian,

Sorry for the delay in getting back to you — you’re basically spot-on. The only correction I have is to this statement:

If it was working correctly you would read 0 v because the voltage is dropped across the evaporator fan.

The reason you read 0 VAC across the contacts at the Jazz board is because the switch is closed. A closed switch should have no voltage difference across it — it acts just like a section of wire.

Let me know if you have any more questions.

[Sam Brown]

Hi Davon,

That lid switch is very confusingly drawn, and it’s a situation where you have to use your knowledge of how circuits have to work in order to puzzle out what’s going on. I’ve explained how it works in more detail in this post: https://my.mastersamuraitech.com/appliance-repair-course-support/student-forums/topic/mod-3-unit-1/

[Sam Brown]

Whether or not it would spin at all would depend on the programming of your specific board’s algorithm. But yes, in general, the Hall effect sensor would be something to check when you have a machine that’s failing to get through load sense.

[Sam Brown]

Thanks for your feedback! We hear you loud and clear, and we’ve actually just added some more in-depth material on top-loader drive assemblies, using a Whirlpool VWM as an example. That’s available right now in the unit on top-load drive systems.

[Sam Brown]

There are a few different ways that manufacturers can implement load sensing in both front-loaders and top-loaders. They always do so using surrogate parameters — that means that, rather than actually measuring the weight of the clothes, they instead measure another variable from which the computer board can approximate the weight of the clothes.

The most common way of doing this is by energizing the motor briefly, then letting it come to rest and timing how long it takes to spin down. More clothes will cause the drum to spin down more quickly, which tells the control board approximately what weight of clothes to accommodate.

Make sense?

[Sam Brown]

Good Deal,? Is the filter dryer the same thing as the heat exchanger

Not at all — they are two completely different sections of the sealed system that serve different purposes.

The filter dryer does just what it sounds like. It both filters solids and grit from the refrigerant and removes moisture from the system.

The heat exchanger, on the other hand, is just a section where the capillary tube going to the evaporator is bonded with the suction tube coming from the evaporator. The idea here is to remove heat from the capillary and transfer it to the suction tube to improve the efficiency of the system.

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