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MES Digital 30" First Generation Controller Question

post #1 of 9
Thread Starter 

I'm smoking baby back ribs and using my new Maverick ET-733 for the first time.  My target temp for the MES is 235 degrees but the ET-733 shows the BBQ continually swinging from 225-246 back and forth. I never saw this before with any other therm I've used.

 

Does the MES digital controller swing like this to keep the heat at an average of 235 or is this a controller going bad? I've got the BBQ never the front of the 2nd rack near the door but I plan to move it to the rear when I remove the ribs to wrap them in foil for the next 2 hour cook.

post #2 of 9
Yes.
post #3 of 9
Quote:
Originally Posted by daRicksta View Post
 

I'm smoking baby back ribs and using my new Maverick ET-733 for the first time.  My target temp for the MES is 235 degrees but the ET-733 shows the BBQ continually swinging from 225-246 back and forth. I never saw this before with any other therm I've used.

 

Does the MES digital controller swing like this to keep the heat at an average of 235 or is this a controller going bad? 

 
The temperature swing most likely results from the on/off nature of the MES controller.
 
If you look at http://www.smokingmeatforums.com/t/151864/mes-40-model-20070512-temperature-problems the top graph shows this oscillation (first in my smoker, and then at the end in my oven.) If you scroll to the bottom of the thread, you'll see graph where the temperature varies by only a couple of degrees either side of the center line. This is the result of replacing the MES on/off controller with the Auber PID controller. 
 
It looks like you're swinging about 10 degrees either side of setpoint. If you integrate the temperature over time, you'll probably get a nominal value of about 235.
 
If you're curious, here's a thread on PID. http://www.smokingmeatforums.com/t/134526/what-is-a-pid
post #4 of 9
Thread Starter 
Quote:
Originally Posted by holyfeld View Post
 


First, I have to start using the term "setpoint" instead of target temp because that's more accurate. I looked at your mod of the controller and I guarantee you that if I did that same exact thing to my MES it would no longer be working. I have tools and I've a multimeter but after having it for about 5 years I really only know how to check if an alkaline battery is still good.

 

The DIY projects I hate the most and fear are electrical projects although I've gotten very good at replacing bad wall plugs, GFCI wall outlets, light switches, and outdoor house lights, including motion detector flood lights. But fooling around with any of the electronics of my MES scares me so many times I've thought I fixed something electrical or electronic only to have it fail to work again. I looked at your technical explanation of what you did and it reminded me why I took no hard science classes ever in college and only took an Electronics 101 class (which I aced) as a night class in jr. college when I decided to go back and learn something new.

 

While looking  at my ET-733 and looking at the temp swings I figured that the controller was maintaining an average of 235 degrees because the temp never went above or below a certain point in its swings. And the gorgeous ribs I pulled out after 6 hours proved that everything had been fine all along.

post #5 of 9
Quote:
Originally Posted by daRicksta View Post
 

I'm smoking baby back ribs and using my new Maverick ET-733 for the first time.  My target temp for the MES is 235 degrees but the ET-733 shows the BBQ continually swinging from 225-246 back and forth. I never saw this before with any other therm I've used.

 

Does the MES digital controller swing like this to keep the heat at an average of 235 or is this a controller going bad? I've got the BBQ never the front of the 2nd rack near the door but I plan to move it to the rear when I remove the ribs to wrap them in foil for the next 2 hour cook.

 

Mine does that when I make a big temp change, or when I start it up & run it all the way up in one move. After it settles down my swings are usually just a few degrees.

 

That's why if I want to smoke at 230*, I'll set it to about 220*. Then after it swings by 220* & stops at about 232*, I'll move my set point to 230*.  That eliminates a lot of the big swings.

 

 

Bear

post #6 of 9
Thread Starter 

 

This was posted by mistake. I don't know how to delete a post or if it can be deleted.

post #7 of 9
Thread Starter 
Quote:
Originally Posted by Bearcarver View Post
 

 

Mine does that when I make a big temp change, or when I start it up & run it all the way up in one move. After it settles down my swings are usually just a few degrees.

 

That's why if I want to smoke at 230*, I'll set it to about 220*. Then after it swings by 220* & stops at about 232*, I'll move my set point to 230*.  That eliminates a lot of the big swings.

 

 

Bear

This was the weird thing, Bear. I had the set point first set at about 225* for an target temp of 235* but according the my ET-733 it corresponded to about 232 then swung up to 250* then went down as low as 223*. I backed it down to 220* but the temp kept swinging up into about 240s and down to 220* (per the Maverick) or so I backed the therm down to 215* which made the low temp swing down to about 218*. I finally settled on about 220* on the MES and per the ET-733 the temp continued to swing between 225* to 246* all afternoon long. When I opened the door to relight the AMNPS or to remove the ribs to wrap or unwrap them, after the temp warmed up to the set point it continued its swing which, according to the ET-733 went from 11* above the set point to 10-12* below it. The MES therm used to stay at one temp but on the ribs smoke it never stopped at any one temp.

 

Per Todd's suggestion I'm going to clean both the MES back wall temp probe and the high limit switch.

post #8 of 9
Quote:
Originally Posted by daRicksta View Post
 

This was the weird thing, Bear. I had the set point first set at about 225* for an target temp of 235* but according the my ET-733 it corresponded to about 232 then swung up to 250* then went down as low as 223*. I backed it down to 220* but the temp kept swinging up into about 240s and down to 220* (per the Maverick) or so I backed the therm down to 215* which made the low temp swing down to about 218*. I finally settled on about 220* on the MES and per the ET-733 the temp continued to swing between 225* to 246* all afternoon long. When I opened the door to relight the AMNPS or to remove the ribs to wrap or unwrap them, after the temp warmed up to the set point it continued its swing which, according to the ET-733 went from 11* above the set point to 10-12* below it. The MES therm used to stay at one temp but on the ribs smoke it never stopped at any one temp.

 

Per Todd's suggestion I'm going to clean both the MES back wall temp probe and the high limit switch.

 

I just got a headache from all that swinging!!

 

Sounds like a good idea Todd gave you, I clean around my sensors now & then.

You can probably notice the clean ring around them in some of my pics.

 

Bear

post #9 of 9
Thread Starter 
Quote:
Originally Posted by geerock View Post

Yes.


Thanks!

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