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I am in the process of replacing the controller for a jenn-air oven. Ever curious as I am, I was poking around the wiring for all the sensors and elements, tracing them out, and learning their function. Then I came to this, and I have no idea what to make of it: image of a one-quarter inch headphone jack image showing the location of a headphone jack inside an oven

It is a 1/4" phone jack. INSIDE the oven. I am puzzled. Is there an option that uses this method to connect? Is some engineer at Jenn-Air trolling me? The connection on the controller PCB for this device is labeled "MT"... and the jack was (of course) empty. What is it for? Why is it there?

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    @jsotola 1/4" TS/TRS are in fact historically and still called "phone" jacks — their original use was in telephone switchboards. A "phono" jack, for connecting a phonograph, would be an RCA jack, instead. – Kevin Reid Nov 21 '20 at 14:15
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    @KevinReid aren't phone jacks the things you plug telephones into? Those 1/4" TS/TRS sockets are headphone jacks. (I'm not an audiophile, but when I read "Why is there a phone jack in my oven?", I expected to see an RJ11 socket.) – RonJohn Nov 21 '20 at 16:20
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    @RonJohn The term originates from the days of manual switchboards where humans plugged cables together to connect calls, using TS connectors. The modular (RJ11, etc) jack came long after that. – Kevin Reid Nov 21 '20 at 16:32
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    @RonJohn The usage persists to this day when discussing electronic components (e.g. if you shop for them, that's the category name.) I'm not saying it's the best word to use in all contexts, only that it's not a typo. – Kevin Reid Nov 21 '20 at 16:51
  • The goal is not pedantic correctness, but understandability. It doesn't matter if it's a typo; the title should be descriptive to the broadest reasonable audience. – Reid Nov 29 '20 at 20:04
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That type of connector is commonly used as a socket for a temperature probe that can be inserted into the food (usually meat) to measure its internal temperature instead of the air temperature in the oven.

I imagine the labeling “MT” you saw probably stands for “meat thermometer”.

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    Exactly correct. Typically, you can set the oven to "Roast" setting and enter a temperature and it will warn you when the probe/meat temp reaches the setpoint. – Jimmy Fix-it Nov 21 '20 at 15:47
  • Correct answer. I have one like this in my oven, and it came with a temperature probe. – Tom Nov 22 '20 at 18:55
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Temperature probe connection, indeed. Go look up the manual for your oven, or look around the junk drawer in your kitchen for the matching temperature probe.

Temperature probe image form genuinereplacementparts.com, no endorsement implied.

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    It could potentially be an accessory you have to buy separately. – Davidw Nov 22 '20 at 23:50
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    How come the plastic coating on the wire doesn't melt? It doesn't look particularly heat resistant. – Karl Nov 23 '20 at 0:26
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    Trust me, it's heat resistant. A lot of that stuff had plastic components formed out of Bakelite, back in the day — rated to well over 500°F, for the sort of durations it'd be exposed to heat while cooking meat in an oven. Er, well, not the wire coating, which you mentioned. But There are plenty of heat-resistant possibilities. It could even be Actual Rubber™. Silicone rubber can go to 200° C indefinitely, which is more than hot enough to cook a roast. – FeRD Nov 23 '20 at 4:30
  • Odd that the OP's jack socket has two poles, whereas the plug in this pic has three? – Tim Nov 23 '20 at 14:08
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    The handle part is probably Bakelite or related. The cable insulation could be fiberglass, Teflon, or silicone rubber off the top of my head, and there are likely other suitable materials. @Tim - the third connection is the nut screwed to the chassis. – Ecnerwal Nov 23 '20 at 14:09

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