MES 30 model 20071914 over heating

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FrankB12

Newbie
Original poster
Feb 2, 2024
4
0
My MES 30 has worked flawlessly for years till the last time I tried to use it. It turned a 9lb pork butt into charred in 3 hrs. Was set at 275 but when I opened it to check on progress, I know my fault for not checking temp when added more wood chips, but had been automatic for years, I saw the state of the meat and checked temp it was registering at 300. As it was for an event, I had to put the wings in at that time as well, so for the entire cooking process of the wings I would turn off when it hit temp and turn back on when the temp was too low.

Troubleshooting steps so far:
1 - Cleaned the meat probe and the temp sensor on back of unit thoroughly - Ran unit set at 150 and within 20 minutes was up to 300 again. Actually not sure what the temperature was actually, had not put the over thermometer in yet
2. - Ordered a new control unit from Amazon, Masterbuilt said it was out of warranty and just gave me their parts list order link. The controllers for electric units on their site didn't list my model as an option for replacement. When set to 150 with oven thermometer inside on the rack it was up to 300 on controller and over 300 on thermometer within 25 minutes.

What can I do to get it to work correctly again?
 
It sounds like the internal thermometer is on the fritz. I'd say it was open, but an open condition might cause it to shut off. So it might just be giving a faulty reading. But I am also guessing the readout on the display is working, doesn't mean its correct but you can compare by putting your external probe near its internal one.

The only time I've had issue with my mes40 is when the chips had caught fire for one reason or another, spiking the temp. I've caught it quick enough to open the door and dump the chips and start over though. This sounds like something different.

The best suggestion would be to convert it with a PID controller (I've heard of this but never done it). You would basically be bypassing all of masterbuilts electronics and turning the element on/off yourself with other electronics.

I can't imagine the element to be at fault...it either works or it doesn't imo.
 
It sounds like the internal thermometer is on the fritz. I'd say it was open, but an open condition might cause it to shut off. So it might just be giving a faulty reading. But I am also guessing the readout on the display is working, doesn't mean its correct but you can compare by putting your external probe near its internal one.

The only time I've had issue with my mes40 is when the chips had caught fire for one reason or another, spiking the temp. I've caught it quick enough to open the door and dump the chips and start over though. This sounds like something different.

The best suggestion would be to convert it with a PID controller (I've heard of this but never done it). You would basically be bypassing all of masterbuilts electronics and turning the element on/off yourself with other electronics.

I can't imagine the element to be at fault...it either works or it doesn't imo.
What model Auber PID would be best for my unit?
 
My MES 30 has worked flawlessly for years till the last time I tried to use it. It turned a 9lb pork butt into charred in 3 hrs. Was set at 275 but when I opened it to check on progress, I know my fault for not checking temp when added more wood chips, but had been automatic for years, I saw the state of the meat and checked temp it was registering at 300. As it was for an event, I had to put the wings in at that time as well, so for the entire cooking process of the wings I would turn off when it hit temp and turn back on when the temp was too low.

Troubleshooting steps so far:
1 - Cleaned the meat probe and the temp sensor on back of unit thoroughly - Ran unit set at 150 and within 20 minutes was up to 300 again. Actually not sure what the temperature was actually, had not put the over thermometer in yet
2. - Ordered a new control unit from Amazon, Masterbuilt said it was out of warranty and just gave me their parts list order link. The controllers for electric units on their site didn't list my model as an option for replacement. When set to 150 with oven thermometer inside on the rack it was up to 300 on controller and over 300 on thermometer within 25 minutes.

What can I do to get it to work correctly again?
Hi there and welcome!

My bet is that the circuit board is failing (installed in riveted shut compartment on the under-side of the MES).
I believe the relay (a switch) is permanently stuck in the "On" position.
This switch cuts On to feed power to the heating element and Off to stop feeding power.
What you describe sounds like no matter the temp you set, it heats up to 300F or so.

What will happen at this point is that it will get a good bit over 300F and the safety limit switch will then cut the power to the smoker until it cools off enough for the switch to return to the normal position to let power flow again. Meanwhile Relay at the circuit board is still stuck in full blown ON position.

When this kind of issue occurs you are basically out of standard repair options because it seems that since the pandemic that it's impossible to get replacement circuit boards.

The good news is you can fix and IMPROVE your MES by doing the simple rewire and slapping a PID controller on it.

The rewire is simple as in you cut the ends off 3 wires and wirenut the ends to make 2 whole wires. This will then allow the MES plug to feed power to the heating element while keeping the safety limit switch in the mix.

Now you take the PID controller plug it into the wall outlet and drop the PID temp probe down the vent and clip it to the underside of the lowest smoker rack so it can read the smoker temp.
You plug the MES plug into the PID controller.
Punch in the set temp to the PID controller and it will cut power on/off to the smoker until it hits and holds the temp dead on or within 1-3 degrees of the set temp!!!


This is more than a repair. This will make your smoker perform better than a $1,000 electric smoker unit and 50x better than any new stock smoker that Masterbuilt makes. I always say it's like turning a golf cart into a Ferrari. So understand this is like making a whole new smoker better than anything you've had!


Here is detailed info on the rewire for using a PID controller and I hope all this info helps :D
 
So I followed the instructions and connected the #1 & #3 wires as well as the #2 & #4 wires. When I tried plugging into the Auber PID device I purchased it immediately blew the fuse in the Auber. I then plugged it directly into the wall and tripped the 15 amp circuit breaker. Could there be something else wrong with the smoker causing this issue?
 
Frank,
So sorry you are going thru such issues with your MES. Another method is to bypass all of the smoker's original wiring by re-wire an extra power cord directly to the heating element. You then plug the other end of this new power cord into the Auber. Did this to my MES40 and never looked back.

Just another idea to consider.

Craig
 
Last edited:
So I followed the instructions and connected the #1 & #3 wires as well as the #2 & #4 wires. When I tried plugging into the Auber PID device I purchased it immediately blew the fuse in the Auber. I then plugged it directly into the wall and tripped the 15 amp circuit breaker. Could there be something else wrong with the smoker causing this issue?
Hi Frank,

Lets confirm your wiring 1st and any pictures would be helpful.

In short a smooth wire should be connected with a braided wire. Never 2 smooths together or 2 braided wires together. Also these should be the 16 gauge wires not the little thinner wires.

Next, if you have a Multimeter with the continuity setting, you can check and make sure things are wired properly going from the plug to the heating element.
In short, now that have rewired you would unhook the wires from the heating element.
Then with one multimeter lead connected to a flat plug prong you then use the other lead and touch both unhooked connectors (one at a time) that go to the heating element. The multimeter should beep if it finds continuity from the prong to a connector. If not beeps then the wiring is wrong OR there is a break in continuity/wiring somewhere in the MES.
Do this to confirm that each flat plug prong has continuity to a single wire connector that goes to the element.
Again you will need to unhook the connectors from the heating element to do this properly.

Finally, was your outlet and breaker a GFCI one? My GFCI trips now as well but my regular outlet works fine. I believe my element has some tiny non-visible cracks in the insulation that causes it to trip my GFCI outlet/breaker.

This is a solvable situation and before you blow any more fuses on the Auber, we can get this sorted out on the MES 1st (having it just heat up on an outlet without a controller for testing). Then when the MES is sorted, the Auber should have no issues unless you got a dud :)
 
Hi Frank,

Lets confirm your wiring 1st and any pictures would be helpful.

In short a smooth wire should be connected with a braided wire. Never 2 smooths together or 2 braided wires together. Also these should be the 16 gauge wires not the little thinner wires.

Next, if you have a Multimeter with the continuity setting, you can check and make sure things are wired properly going from the plug to the heating element.
In short, now that have rewired you would unhook the wires from the heating element.
Then with one multimeter lead connected to a flat plug prong you then use the other lead and touch both unhooked connectors (one at a time) that go to the heating element. The multimeter should beep if it finds continuity from the prong to a connector. If not beeps then the wiring is wrong OR there is a break in continuity/wiring somewhere in the MES.
Do this to confirm that each flat plug prong has continuity to a single wire connector that goes to the element.
Again you will need to unhook the connectors from the heating element to do this properly.

Finally, was your outlet and breaker a GFCI one? My GFCI trips now as well but my regular outlet works fine. I believe my element has some tiny non-visible cracks in the insulation that causes it to trip my GFCI outlet/breaker.

This is a solvable situation and before you blow any more fuses on the Auber, we can get this sorted out on the MES 1st (having it just heat up on an outlet without a controller for testing). Then when the MES is sorted, the Auber should have no issues unless you got a dud :)
 

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From what I can see in the pics it does look like smooth to braided in both cases.

The multimeter continuity check may shed some light on things.
Also when unhooking those wires from the heating element, ensure the ground wire is nice and secure as well (likely braided yellow wire with green diamonds on it).
 
Measure the resistance from the hot to the neutral blades of the power plug. Also, measure the resistance from the hot blade of the plug (the smaller blade) to the cabinet (a metal screw or rivet will do.) With these two values we should be able tell what is going on.
 
Ohm on the highest setting from blade to blade on the power cord and see continuity and nothing from each blade to the ground prong. The back of the cabinet see continuity from plug ground prong only to cabinet. Direct connection wire to the element with the ground attached to one of the access element screws and tighten will isolate the element and see if it shorts to ground, tripping the breaker which is what cmayna cmayna mentioned. This is a great backup cord for tallbm tallbm simple rewire and to isolate the element to find a short and to just run the Mes without their circuitry. Just have an alarm from your independent pit therm to alert if temps are not 145-290 or whatever your alert range is since an independent power cord takes the safety snap disk out of the circuit, which is what primarily makes owners dump their Mes to the trash, being the hidden link to bypass or replace.
 
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