Masterbuilt 40" element wiring issue. Please help.

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RHBertson

Newbie
Original poster
Mar 15, 2024
2
1
Hi everyone. Was using my smoker last week and the element stopped working. I figured that it needed a new element so I ordered one. Installed it today and the element is still not working. I tested for resistance the old one and the new one are fine. The controller works fine. Each wire on the element has 120 volts when the temp and time are set. Pretty sure they should not both read 120 volts. Any help would be appreciated.
Thanks!
 

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Although not about your problem, this thread has a lot of useful information relevant to your situation. https://www.smokingmeatforums.com/threads/mes-rewire-simple-guide-no-back-removal-needed.267069/

These units work by switching the neutral side of the element to the incoming line. When it is off, you will find 120V to ground on both sides of the element. When the element is heating, the neutral side will be 0V (or close to it.)

In decreasing order of probability:

1) Your overtemp switch has failed. This is the round disk you see on the back wall of your smoker, sometimes called the "rollout switch" because the same part is used in gas furnaces for that purpose. The switch disconnects the neutral wire if the temperature gets too high, and reconnects when the temperature falls. I believe newer units have a small access panel on the back side that can be removed, likely rivets drilled out, to facilitate changing it. Otherwise, you can remove the entire back panel by drilling rivets, or cut a smaller access panel as outlined in the thread I listed above.

2) The relay has failed. The relay switches the neutral wire to control the temperature in the smoker. The relay is a part of the relay and power supply board located in the compartment on the bottom of the smoker. It is accessed by drilling the rivets out of the access cover located there. Replacement boards may or may not be available for your particular unit.

3) The wiring connections to the overtemp switch have corroded and no longer make contact. This is possible, but based on how your connectors to the element look, it seems unlikely as they typically fail first.

4) The controller has failed. Even though you can set the time and temperature, it still has to be able to drive the relay. I would think this would be a rare occurrence.


So, what to do next....

I would drill the rivets on the bottom panel to gain access to the relay board. I would then prepare a short 14 or 12 gauge wire with male .250 quick disconnects on each end. Referring to the thread linked above, use the jumper to connect the two wires going to the relay, #2 and #3 in the photo. #1 and #4 are already connected by the board. The element and overtemp switch are are now connected directly to the power plug. Next, plug it in and see if the element starts warming up. If it doesn't warm up, the problem is the overtemp switch or the connections to it. If it does warm up, it is the relay or the controller. In this case, I would make sure the jumper is well insulated with electrical tape, screw or pop-rivet the cover back on and go buy a PID controller as you have already rewired your smoker to use one.
 
Holding off on my response as I'm not sure how the power exactly works once coming through the other end of the circuit board to the heating element.
I'd have to test the unhooked wire ends to confirm :D
 
Thanks everyone!
I had an extra controller that mounts to the top of my smoker. (Masterbuilt sent me one, when I first bought the smoker last year it was running about 20 degrees cooler than what the controller listed. The one they sent did not change that.) I swapped the controller out and no change.

I wont be able to check the overtemp switch, relay and wires until after we get back from our RV trip to Natural Bridge VA. next week.

Wanted to smoke a brisket to take with us!!!!
Looks like it be some ribeyes instead.

Thanks again for the quick replies!!!
I am learning a lot reading through all the posts.
 
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Thanks everyone!
I had an extra controller that mounts to the top of my smoker. (Masterbuilt sent me one, when I first bought the smoker last year it was running about 20 degrees cooler than what the controller listed. The one they sent did not change that.) I swapped the controller out and no change.

I wont be able to check the overtemp switch, relay and wires until after we get back from our RV trip to Natural Bridge VA. next week.

Wanted to smoke a brisket to take with us!!!!
Looks like it be some ribeyes instead.

Thanks again for the quick replies!!!
I am learning a lot reading through all the posts.
When I got a free mes 30 on marketplace and plugged it in and set temp and time I made sure to listen to the relay on the PCB to click. When it did the controller was doing it's job but no heat. I have a test power cord or back up for my PID controller if the OEM controller fails with lugs soldered to the neutral and hot and wrap the ground around one of the six element access screws to ground the chassis. Plugging that in isolated the element and heated so element is good for MES 30 at 18 ohms and Mes 40 at 12 ohms. If your smoker doesn't have an access to thermal safety switch I would make one with a dremel cut off wheel or similar because it will fail. I found the free smoker had burnt lugs off at the thermal safety to be the problem and bypassed with a wire nut. I did the same with the Mes 40 before it failed to get that off my mind and set the independent pit probe to a range 145-290 for an alert on all smokes I'm not nearby like mowing etc. You can get the recommended thermal safety switch replacement tallbm tallbm but I'm not sleeping during a long over night cook or very well just having that on my mind and still getting up to peek at it several times.
 
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