I will start off by saying that this mod will void your warranty and could well... smoke your smoker.
I am cooking a 19lb turkey in a couple hours and as this is the first time the wife has allowed me to smoke the turkey, I needed to do my homework. Sure, the LiLi market and restaurant is within walking distance, but who wants it to come to that really.
It was obvious early on that the MES30 wasn't going to cut it for a start to finish cook due to its 275* limitation. I would either need to smoke it early on the MES and transfer it inside or come up with some way of getting the internal temp of the MES to 325-350*.
So of course the MES which has served me well for a year now was drug off the patio and into the workshop.
Drill in hand, I started removing rivets for the back cover and was able to get to the wiring for the temp sensor. The temp sensor in my model is near the top third of the back wall on the right hand side as you look into the smoker. On the new MES, it's right in the middle. Don't get it confused with the thermal switch that is near the bottom third on the left. The temp probe is a probe that sticks out from the back wall about 3/4". This is where I focused my efforts.
With wire cutters, ohmmeter and thermometer in hand, I cut the wires running to the probe and checked the resistance. If I remember it was about 25kohm at 80*f. I reconnected the wires and fired up the smoker full blast and let it get to 275 (275 actually means 286 on my smoker, you have checked yours right) Once the temp stabilized I turned off the smoker, disconnected the wires from the probe and started noting the resistance vs temp. Short story is that a 1k ohm resistor in series of the temp probe would allow the computer to think the temp reading was about 75 degrees lower than the actual temp inside the smoker. This means that I can set the smoker to 255* and the actual temp inside is 325*.
I obviously didn't want this temp mod permanent, that would be a pain in the a, right? So I ran a new wire down the back of the smoker through the same hole the factory wiring comes through. I soldered and heat shrunk one of the probe leads back together and spliced in my new wiring to the other lead. Inside the control panel I added a switch and my 1k resistor and wired it so when the switch is on, the 1k resistor is in series and when switched off is removed from the circuit. This way the set temp can be 'right' or 'low'
Now then, just how low is low? Well I haven't done a great deal of research on that yet, I can tell you it's not linear which stinks. But for me, a set temp of 255* will bring the smoker temp to a stable 325*. I'll probably end up graphing a chart laminate and attach it to the side of the trusty MES.
I did run the smoker at about 350* for an extended 3.5 hours yesterday and sure the outside is warmer than it is at 275*, but it didn't have a meltdown. YMMV. If you decide to do this, be smart about it, don't test your work in your living room, in your garage or on your back porch. Run your extended test away from your house so if your MES decides to go Apollo it doesn't harm anyone or anything.