# A newbie's technical review and mods to a Masterbuilt MES smoker



## LenShustek (Nov 13, 2020)

We are new to the world of food smokers, so my wife strongly suggested
that a budget of only $200 would be appropriate. I chose the Masterbuilt
MES 130B electric, which was $184 from Amazon and was delivered for free
in two days.

My bottom line: it works ok. We've made some great meals with it. But as
an engineer I have a few quibbles, some of which I can have fun fixing.
Forgive me if this is all obvious to you experienced smokers.

(1) Opening the door every 30-60 minutes to check the internal food
temperature really disrupts the cooking.

(2) The chips are heated in a small tray over the heating element, so
when the thermostat turns off the heater to let the temperature
gradually come down, smoke generation diminishes and then stops until
the heater turns on again.

(3) The smoker has a large thermal mass, so their simple thermostat-like
control ("heater off when the temperature goes above the set point, on
when it goes below") results in huge overshoot and undershoot, by 10-15
degrees in each direction, with a cycle time of about 15 minutes.

(4) The display is all but unreadable in sunlight.

Being a tinkerer, I can't resist thinking about causes and fixes for
each of these:

(1) Problem solved by using an Enzoo 4-probe temperature sensor with
thin wires that can go past the gasket on the door. No need to build
anything here.

(2) Problem solved by putting a couple of small 100W heating elements
(wired in series, so 50W power dissipation) in the bottom of the chip
tray, and turning them on periodically whenever the main heating element
is off. To do that I tapped into their 4-wire controller cable (ground,
5VDC power, heater on, and temperature sense) and connected a little
circuit with a small solid-state relay that controls power to the
additional heating elements. For design details and photos see
https://github.com/LenShustek/smoker_mods. It seems to work well. 
Lots of smoke almost all the time.

(3) One common solution to feedback control for an inertial system is a
PID controller, which I see many of you recommend as an add-on, wired
into the 120 VAC heater power. Did Masterbuilt's engineer not understand
PID? Maybe not; I looked at what is in their controller: a Zilog S3
8-bit processor that has only 4K of program memory, 208 bytes of
registers, and no other read/write memory. It would be a challenge to
implement a PID algorithm with that chip, in addition to what it's doing
now. So why did they choose that chip? Because it's cheap: in quantities
of 1000 it costs only 31 cents!

(4) The story is similar for the display: their 4-digit 7-segment LED
costs less than 40 cents. Something that works well in sunlight would
cost a lot more.

I'm thinking about four possible solutions to the temperature control
problem (3). All would be compatible with the chip tray heater.

(a) Discard the Masterbuilt controller and design my own. I'd use an
Arduino-like processor good enough to implement a PID algorithm, and
include an e-paper display visible in bright light, which also solves
problem (4). I'm guessing the the parts bought new would cost about $50,
but I have most of them already. No changes to the smoker's 120V wiring
would be needed, since it just replaces the stock controller and plugs
into the existing 4-wire cable coming out of the hole in the top. It
would use the same temperature sensor, which incidentally isn't a
thermocouple; it's an NTC (negative temperature coefficient) thermistor
with a resistance of about 50K ohms at room temperature. (The advantage
of a thermistor is that there is no reference junction temperature to
deal with; the disadvantage is you have to correct for its
non-linearity.)

I wouldn't be entirely plowing new ground; here are two guys who
experimented with building a Masterbuilt replacement controller:
https://github.com/meyercm/masterbuilt_controller
https://github.com/rshields9093/SmokerMC

(b) Discard the Masterbuilt controller and use the inexpensive Japanese
Berne Rex-C100 PID unit with a new thermocouple, and a big solid state
relay with heatsink connected into the 120 VAC wiring of the unit.
Others have posted about doing this. At least with the MES 130B that
won't require drilling out rivets, as it apparently did with older
models, because there is a screwed-on access plate in the back.

(c) Discard the Masterbuilt controller and use the Rex-C100, but with a
little interface circuit that controls the "heater on" signal that the
original controller provided. That means no big relay, and no mucking
around with the AC wiring inside the unit; just plug in the 4-wire
connector that originally plugged into their controller.

(d) See if I can reprogram the CPU in their controller and shoehorn in a
PID algorithm. (I've been writing software for 50+ years and am pretty
good at space optimization.) The CPU's memory is rewriteable without
removing it from the board by using a auxiliary programmer that connect
with 5 wires, and the Zilog S3 development tools (assembler, etc.) are
available to anyone for free. It would be great if I discover that
Masterbuilt didn't set the "hide program" bit, so I can read out and
disassemble their program as a starting point. The advantage of this
approach: no new hardware is needed. The disadvantage:
reverse-engineering machine-language software is hard.

Comments? I'll let you know which path I go down, if any.


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## smokerjim (Nov 13, 2020)

not sure if your redoing your smoker or building a space shuttle, i only have a high school diploma so i just added a amnps tray with the mailbox mod and a inkbird wireless thermometer to mine but good luck on your build!


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## uncle eddie (Nov 13, 2020)

Good luck with your tinkering and builds...if something works well be sure to post the mod with lots of pic's!

Some FYI's from a long time MES40 user.

Some peeps fill the water pan with sand wrapped in foil.  It becomes a large hot mass (eventually) so if you do open the smoker it warms up more quickly.  I just wrap mine with foil an use it as a drip pan.
Be sure to open the top vent all the way.  I am on my second MES40 and this works well.  It helps to cycle the heating element a bit.  I use the chip tube for short smokes (like under 2 hours)
Look into an AMNPS (A-Maze-N Pellet Smoker) - available on Amazon.  This works great and I doubt you will use the chip tube very often going forward..


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## joenationwide (Nov 13, 2020)

Hey Len, I'm new to the forum myself, but have had my MES 30 for about 5 years.  The LEDs started to go out so it became hard to use.  So I bought the Auber WSD-1500H-W WIFI smoker controller.  It might have been overkill, but I can use it on any future electric smoker.  

If you could build a cheap PID controller there would be a lot of people interested I'm sure.   Even one that isn't programmable, but basic.  Right now the cheapest turn key option is either $119 for the 1200W max version, or $149 for the 1800W max version.  

Another tip is to look into the "mailbox mod", this brings the smoke generation outside the MES so it is much easier to control.  You simply pipe in the smoke through the chip loader hole in the side of the MES.  You can get a pellet tube or the AMNPS maze which uses pellets and can smoke non stop for up to 12 hours.   

Can't wait to see what you come up with!


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## MJB05615 (Nov 13, 2020)

Welcome from Ga Len.  What you are doing sounds fascinating.  Hope you'll share some pictures when done if all goes well.  It's way over my head tech wise.  I have an MES 40 gen 1 about 7 years old, switched to Auber PID almost a year ago and it's made my smoking much better by a longshot.


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## chopsaw (Nov 13, 2020)

LenShustek said:


> Did Masterbuilt's engineer not understand
> PID? Maybe not;


Not for $184 . 
Welcome , have fun , enjoy .


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## tallbm (Nov 13, 2020)

LenShustek said:


> We are new to the world of food smokers, so my wife strongly suggested
> that a budget of only $200 would be appropriate. I chose the Masterbuilt
> MES 130B electric, which was $184 from Amazon and was delivered for free
> in two days.
> ...



Hi there and welcome!

There are solutions/fixes for your 1-4 problems that exist but are not as much "tinkering" fun as your proposed solutions.  I'll go over the "lesser tinkering" solutions:

*Less Tinkering Solutions*

A wireless dual probe thermometer (or more probes, I prefer minimum of 4, I use 6).  You have the broadcast unit with the probes on top of the smoker and you close the door on the wires (what I do) or run them down the vent.
Benefits:   A number of good units out there.  These units can easily broadcast 300ft with no issues.  Units have alarms, often high and low alarms.  Many probes are a good thing!  You can also take the unit inside for cooking stuff in the oven like a turkey (though I prefer to smoke it vs oven roast it).  With so many probes you can measure both meat and smoker rack temps since temp is uneven across racks and on different racks so lots of data to see about meat and heat in your smoker!

As others have mentioned the A-Maze-N Pellet Smoker (AMNPS) tray is not freaking awesome! 
Benefits: Was designed to produce PERFECT Thin Blue Smoke (TBS) for up to 12 hours so no fussing with it!  Buy a 40lb bag of pellets and watch it last forever so that's great.  You separate smoke generation from heat generation so you don't propagate issues from one domain into the other especially if you build a Mailbox Mod to use with the AMNPS.  Finally, with a mailbox mod you can cold smoke and reduce or eliminate the amount of heat the pellets generate into the smoker which is important in hotter climate states like TX where we dont get many low temp days where we can truly cold smoke.

You guessed that a PID controller would help and you are right!  The wide temp cycle swing was very likely intentional to be able to smolder the wooden chips to make smoke.  If you have a stead temp like a PID provides then at some point the heating element is never on long enough or hot enough to smolder chips, it only maintains heat of the smoker. 
So a common approach here is to make or buy a PID, and cut the existing MES controller and electronics out of the loop by drilling out the rivets on the bottom panel, clipping 4 wire ends and splicing to make 2 wires. Now the MES plug feeds power directly to the heating element. So building or buying a PID + SSR + plug outlet + plug makes for a super simple and efficient controller for the smoker.
You plug the new PID controller into the wall, the MES into the PID controller (outlet), and throw the PID temp probe into the smoker (I feed mine down the vent) or fix it to the smoker body. My PID temp probe has an alligator clip end so can move it around and get the most accurate readings :)
A PID solution + AMNPS eliminates temp swings so now u can do bacon and sausage without fear of melting out the fat AND you now have a set and forget carefree smoking and smoke generation setup that you dont have to fool with for a minimum of 12 hours!


PID units like the ones you mention generally display much stronger than the crappy MES controller so problem solved there.  Also you can add/build a sun cover easily and if you want wifi or blue tooth u just look on your phone or computer for that info :)

*Your Very Tinkerish Ideas:*

Now with all of that out of the way for you to digest.  I TOTALLY understand and like where you are at with all the tinkering options.  I think some are more feasible and some are probably more effort than they are worth, mainly the work done on the heating element for smoldering chips.  The chip solution you have is cool though!


For solving your problem #3, which solves #4 as well:

I like your option B as its simply building a PID to drive the smoker much like us PID guys are doing today and as mentioned above we have ways to elegantly do that and you can incorporate your solution for #2 as you like since u are running additional elements for heating chips. 

Your option C may work but that depends if the heat on/off signal is "pulsing" and hammering the existing onboard MES relay.  I think they use a relay vs and SSR (could be wrong) so you would wear out their relay unless you somehow managed the signal to avoid wearing out the relay.  To me doing extra work to avoid wearing out the MES relay is a poor option since the whole purpose is to let the PID control the temp the best way it seems fit not worry about an improper component being in the mix.  It seems better to me to support the PID temp control behavior with a proper switch so everything does it's job properly.

Option D, I'm not personally a fan of.  If stranded on a dessert island with nothing but time, then no problem.  But it seems like a mountain of problems that must be solved where the inability to solve one of any of them makes the whole approach fall apart and become a waste of time.


Now for option A.  You can do something like this for sure and it may be more easy to piggy back of this guy's work using the Raspberry PI platform.  https://github.com/CapnBry/HeaterMeter

He has all the code there including Auduino stuff and this project is working.  I know I use a HeaterMeater PID to run my MES :D
You still could write your algorithm rather than use his because his PID algorithm is based on running a blower fan.  I use an SSR and after a good amount of tuning I figured out values that work with his algorithm that hold my smoker within 1-3F smoker temps (mostly within 1F). 
It would be nice to see an electric smoker option for the HeaterMeater based on use of an SSR supported by a friendlier algorithm for an electric smoker.  I have my PID settings that work with the existing algorithm and SSR if you ever need them.

One thing to know when u go down this route is that there are a LOT of failure points.  My wifi has failed and I've tried 2 different dongles for wifi so it's a hardware failure for sure now. 
The probe jacks allow you to plug in too far or too short, you have to get it just right or things don't read.
The networking and wifi aspect can be touchy even when it does work.
I had to use a stronger power plug or it would encounter power spikes it couldnt support and reboot.
Just so many moving pieces here! 
If/when my HeaterMeter completley dies I will buy an Auber PID wifi unit since I have more than met my tinkering quota molding the HeaterMeter to work for my MES usage.  Using 6 probes of wireless thermometers, AMNPS + Maiblox mod, I just really need a PID to control temp and I can RELIABLY and confidently perform and monitor my smoking with alarms and precision :)

So building a PID like in option B that is a dumb and simple unit would make life so much easier but it's less tinkering if you really want to tinker.

Anyhow, cool ideas and lots of room for tinkering.


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## cmayna (Nov 13, 2020)

joenationwide said:


> Hey Len, I'm new to the forum myself, but have had my MES 30 for about 5 years.  The LEDs started to go out so it became hard to use.  So I bought the Auber WSD-1500H-W WIFI smoker controller.  It might have been overkill, but I can use it on any future electric smoker.
> 
> If you could build a cheap PID controller there would be a lot of people interested I'm sure.   Even one that isn't programmable, but basic.  Right now the cheapest turn key option is either $119 for the 1200W max version, or $149 for the 1800W max version.
> 
> ...


Exactly !!

Auber PID controller and the mailbox mod.   Makes using a MES 30/40 smoker so much easier.


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## LenShustek (Nov 14, 2020)

Thanks, folks, for the comments and encouragement. (Especially tallbm, who seems to be a tinkerer after my own heart.)


uncle eddie said:


> ...if something works well be sure to post the mod with lots of pic's!


There are some photos of my first project (the chip tray heater) in a directory of that Github repository: https://github.com/LenShustek/smoker_mods/tree/master/chipheater/photos
It's public and you don't need to sign in, so just click on the names of the photos.


joenationwide said:


> If you could build a cheap PID controller there would be a lot of people interested I'm sure. ...Right now the cheapest turn key option is either $119 ...


How about less than $20? 
Here's what I'm thinking, which is basically my option (c) above:
 - Buy the great Rex-C100 PID controller plus thermocouple from this guy: https://www.ebay.com/itm/PID-REX-C1...-Thermocouple-Heat-Sink-TBB-BS40/124224762139. Choose the "2PCS SET" for $17.89 with free shipping.
- Add three resistors and one zener diode (less than $1),  and wire it to replace the Masterbuilt controller
I'm experimenting with it now, and it seems to be working.






Tallbm, you are right that the Masterbuilt smoker uses an electromagnetic relay and not a solid-state relay, so it shouldn't be turned off and on as frequently. But there are plenty of parameters in the Rex-C100 that can help with that. I started by changing the "proportioning cycle" from the default of 2 seconds to 15 seconds, and that slowed down its action by a lot.  It makes the temperature control a little looser, but it is still way better than what the Masterbuilt controller does.

More experimentation is needed before I declare this a win. Has anyone used the "autotune" procedure in these PID controllers, or otherwise changed the PID values to match the thermal characteristics of these smokers?


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## tallbm (Nov 14, 2020)

LenShustek said:


> Thanks, folks, for the comments and encouragement. (Especially tallbm, who seems to be a tinkerer after my own heart.)
> 
> There are some photos of my first project (the chip tray heater) in a directory of that Github repository: https://github.com/LenShustek/smoker_mods/tree/master/chipheater/photos
> It's public and you don't need to sign in, so just click on the names of the photos.
> ...



Thanks, and yeah I like to tinker some when I get the time haha :D
I checked out your github picks it looks like a cool little project and neat solution hahaha :)

It's cool seeing your option C in action there.  
I've done autotune with the Auber PID plug and play controllers like 2 different units and they seemed to be ok.  I've also fooled around with the PID values to get tighter control as well.
A number of people here have done auto tune or tweaked PID values with various Auber PID units and everyone who uses a PID loves them!

I have not fooled with the Rex-C100 so can't tell you anything about tuning with either autotune or individual tunings.  All these PID's have different algorithms so I'm pretty sure our Auber values wont help much :)

If you could get that figured out in a nice neat concise package that would be so cool!


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## barryvabeach (Nov 14, 2020)

I don't have the Rex,  but have a Mypin  for my Masterbuilt and a Twidec that I use on a countertop oven.  I have used autotune on both, and they seem to work okay.  I am no expert but understand that when using Autotune, you want the smoker to be similar to how you will use it in cooking,  since I often do 8 to 10 pound pork shoulders,  I put in a pan with 9 pounds of water when I did the autotune.


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## Jonok (Nov 14, 2020)

Bought several Rex’s for less than$20 each.  Have two working on my 7000w cabinet smoker with a separate 500 w smoke generator.  Two pole contractors cost less tnan$20, and 240v 3500w sauna elements that will fit in 40 inch masterbuiuts can be had for $40.
I’ve now got two more badass smokers for less than $100 each.


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## LenShustek (Nov 29, 2020)

Ok, I chose option(c): a replacement controller using the REX C-100 PID unit, connected to the smoker with a small interface printed circuit board I built. It works great: the temperature stays within a degree or two of the setpoint. We smoked a fantastic turkey for Thanksgiving!
The parts cost about $25, and there's no need to break open the box and change any of the 120V wiring. The PC board also optionally interfaces with the chip tray heater I described earlier, which keeps the smoke going when the main heater is off. 
Details and photos are in the attached file, and on Github at https://github.com/LenShustek/smoker_mods. 
I have a dozen extra PC boards (the total was only $4.90 from China), so send me a private message if you really want one.  I might even solder the components for you if that's not something you're comfortable doing. But this is definitely a DIY project, not a kit.


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## tallbm (Nov 30, 2020)

LenShustek said:


> Ok, I chose option(c): a replacement controller using the REX C-100 PID unit, connected to the smoker with a small interface printed circuit board I built. It works great: the temperature stays within a degree or two of the setpoint. We smoked a fantastic turkey for Thanksgiving!
> The parts cost about $25, and there's no need to break open the box and change any of the 120V wiring. The PC board also optionally interfaces with the chip tray heater I described earlier, which keeps the smoke going when the main heater is off.
> Details and photos are in the attached file, and on Github at https://github.com/LenShustek/smoker_mods.
> I have a dozen extra PC boards (the total was only $4.90 from China), so send me a private message if you really want one.  I might even solder the components for you if that's not something you're comfortable doing. But this is definitely a DIY project, not a kit.



Wow Len that is way too cool!

What are the specs on the resistors and the diode?
I didn't see those mentioned.

Also if you a have a list with specs of the other components soldered onto the PC board and their specs, that would be cool too in case I ever want to do this. 
I'm not one that has ever done anything with a PC Board before or any real hardware circuitry but I have a novice level of understanding when it comes to this stuff so the if you have that info it would help :)

Also, a quick question I think was brought up in a thread a long time ago. 
Couldn't someone buy an appropriate resistor and plug the ends into the MES 4 wire controller cable connector to force the Relay to always be switched "on" so that when the MES is plugged in, it would blindly feed power to the element with no control whatsoever? (like the rewire blindly feeds power but this would be with the relay in the mix instead of rewired around)

Can you explain what is needed to do this?  I ask out of curiosity and because you are muuuuch more knowledgeable about this stuff than I am and can probably clear it up in like a quick explanation.

I have a buddy who is about to get into meat smoking and if we can find him a cheap used MES I would like to tinker and try the "resister(s) in the MES connector" route with a cheap PID and SSR build... you have bit me with the tinkering bug to do this, it's all your fault :P


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## LenShustek (Nov 30, 2020)

tallbm said:


> What are the specs on the resistors and the diode? I didn't see those mentioned.
> Also if you a have a list with specs of the other components soldered onto the PC board and their specs, that would be cool too in case I ever want to do this.


Good point. I added a parts list file to the Github repository.








						smoker_mods/PCB_parts_list.txt at master · LenShustek/smoker_mods
					

Modifications to the Masterbuilt MES 130B food smoker - smoker_mods/PCB_parts_list.txt at master · LenShustek/smoker_mods




					github.com
				





tallbm said:


> Also, a quick question I think was brought up in a thread a long time ago.
> Couldn't someone buy an appropriate resistor and plug the ends into the MES 4 wire controller cable connector to force the Relay to always be switched "on" so that when the MES is plugged in, it would blindly feed power to the element with no control whatsoever?


Yes, that's easy. Just plug a 1K ohm 1/4 watt resistor between the "power" and "heat" contacts of the MES 4-wire cable coming from the smoker. Those are the two outside pins on the connector.
But beware that it will keep heating until one of three things happen: (1) you stop it, (2) the internal overheat sensor kicks in (I don't know what temperature it is set for), or (3) it starts a fire, or starts to melt, or otherwise blows up. Be careful!


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## barryvabeach (Dec 1, 2020)

Len,  great work.  Very much admire your expertise.


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## tallbm (Dec 1, 2020)

LenShustek said:


> Good point. I added a parts list file to the Github repository.
> 
> 
> 
> ...



Thanks for the reply and adding the parts list info to github!

Hahaha that makes total sense to put the resistor between the power and the signal pin.  
It was on the edge of my mind but I couldn't clear it up at 1am that morning when I asked.
It's good you explained the 1,2,3 of the MES behavior if this resist is shoved there into the connector.  That is what I am aiming for then it will be a simple PID build with an SSR and never having to open the MES at all.

The use case for this would be for anyone who doesn't want to or physically cant be messing with the MES to do the simple rewire... and for me to tinker with to see how well this works :)


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