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Most Techs Wouldn't Troubleshoot this Door Switch the Right Way...


Son of Samurai

4,829 views

I want you to take a look at the door switch I've circled below. Think about it for a minute, then answer one question: what single test could you do to prove beyond a doubt whether or not that door switch is operating within spec?

Screenshot 2020-11-18 004610.png

There's no trickery going on here -- it's just a simple switch. But many techs will test it using a flawed, limited test that has a big chance of leading them to the wrong conclusion. And they'll do a bunch of unnecessary disassembly. Post your answer in the comments below!

Want to check your answer? Watch our in-depth technical webinar which covers this troubleshooting scenario and many other circuit puzzles, including:

- Some pop quizzes about series and parallel circuits

- Diodes, how they work, and the surprisingly tricky situations that can arise because of them

- Loads in series, how they work, and what they look like in a real refrigerator schematic

Click below to give it a watch! This webinar recording is only available to premium tech members at Appliantology and Master Samurai Tech Academy students and alumni. 

 

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18 Comments


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The dryer won't run if the door switch is open, so a good test to confirm the door switch is remaining open with the door closed, is to select a cycle, and try starting the dryer running. If it wont start, that confirms the door switch is remaining open. The motor circuit cannot be completed without a closed door switch.

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  • Team Samurai
Samurai Appliance Repair Man

Posted

34 minutes ago, Raynormensk said:

The dryer won't run if the door switch is open, so a good test to confirm the door switch is remaining open with the door closed, is to select a cycle, and try starting the dryer running. If it wont start, that confirms the door switch is remaining open. The motor circuit cannot be completed without a closed door switch.

Although all that’s true, you’ve not proven anything. This is just restating the original problem statement. You have not proven that the door switch is the problem and not the main board (which, BTW, the tech replaced with no joy). 

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  • Team Samurai
Samurai Appliance Repair Man

Posted

33 minutes ago, PlanB said:

I would measure the voltage from L1 and J3-2. 

There’s an even easier way that doesn’t require a meter. Hint: jumper wire. 

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Use a jumper wire to connect the orange to brown wire connection on the door switch?

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  • Team Samurai
Samurai Appliance Repair Man

Posted

3 minutes ago, JohnnyCage said:

Use a jumper wire to connect the orange to brown wire connection on the door switch?

You’re on the right track. While that would work, you would need to remove the front panel to install the jumper. There’s a more clever way to do it right from the control board and all you have to remove is the top panel. 

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Besides feeling the door switch with your hand and listening for the click; start the machine (or try to start it, move the timer and hit start) and do a voltage check on the board. Check J3-2 in respect to J2-3.

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  • Team Samurai
Samurai Appliance Repair Man

Posted

2 hours ago, JohnnyCage said:

Jump J2-3 to J3-2?

Yes! 

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MarcusF

Posted (edited)

Jumper J3-2 to J2-3. If the door switch is the problem this will turn off the "door open" light.

 

Is J2-3 just looking for the presence of 120V WRT to Neutral after the thermal limiter but before the door switch?

Edited by MarcusF
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  • Team Samurai
Samurai Appliance Repair Man

Posted

10 minutes ago, MarcusF said:

Is J2-3 just looking for the presence of 120V WRT to Neutral after the thermal limiter but before the door switch?

Yes, J2-3 is a sensing line like we’ve seen in the Samsung and LG dryers (and other appliances). Excellent!

Pop quiz: What’s the functional difference between J2-3 and J2-4? 

 

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41 minutes ago, Samurai Appliance Repair Man said:

Yes, J2-3 is a sensing line like we’ve seen in the Samsung and LG dryers (and other appliances). Excellent!

Pop quiz: What’s the functional difference between J2-3 and J2-4? 

 

It seems to me like J2-4 is the 120VAC power supply to the board while J2-3 is, like we established, a sensing line.

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  • Team Samurai
Samurai Appliance Repair Man

Posted

You got it, Toyota! 

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On 11/25/2020 at 2:46 PM, JohnnyCage said:

Jump J2-3 to J3-2?

If jumping the Door Switch doesn't work, we can assume the Outlet Thermal Limiter is open. So we could jump J2-4 to J3-2 to bypass both the Door and the Thermal Limiter... right?

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  • Team Samurai
Samurai Appliance Repair Man

Posted

7 hours ago, Slav said:

If jumping the Door Switch doesn't work, we can assume the Outlet Thermal Limiter is open.

Yes, but you probably wouldn't even need to assume. The fact that J2-3 is a sensing line for a computer means the computer's OS would likely be programmed to pick up the open on J2-3 and throw an error code. 

7 hours ago, Slav said:

So we could jump J2-4 to J3-2 to bypass both the Door and the Thermal Limiter... right?

Correctillia! 

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fillthebarman

Posted

I’ve jumped the motor relay to show that is bad a few times. 

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