# Replacing Circuit Board on MasterBuilt smoker



## bethanyhud (Jul 16, 2021)

Quick question. We were having issues with our smoker. Masterbuilt sent us a new circuit board and heating element. We took a pic before we pulled out the old circuit board.  This is the one. Notice the blue wire over the white one. The paperwork with the new board says to install with white over blue. Thoughts? I don’t want to ruin this new board


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## Wurstmeister (Jul 17, 2021)

First - Welcome to the Forum from South Carolina's Thoroughbred Country.  Your attachment didn't make the post.  But without that, there should be a lot of folks out there who understand your question and give you a response. IMHO:  Probably it's not an issue. _However_, if the new one fails and you _*didn't *_follow their instructions, then they might void the warranty?! 
John


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## normanaj (Jul 17, 2021)

The guy to talk to is 

 tallbm
 . Pretty sure he'll chime in shortly.


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## bethanyhud (Jul 17, 2021)

Wurstmeister said:


> First - Welcome to the Forum from South Carolina's Thoroughbred Country.  Your attachment didn't make the post.  But without that, there should be a lot of folks out there who understand your question and give you a response. IMHO:  Probably it's not an issue. _However_, if the new one fails and you _*didn't *_follow their instructions, then they might void the warranty?!
> John


Thank you!


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## bethanyhud (Jul 17, 2021)

Sorry…Here’s the pics
First is the way it was
Second is the paperwork
Third is new way it says to do


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## tallbm (Jul 17, 2021)

bethanyhud said:


> Quick question. We were having issues with our smoker. Masterbuilt sent us a new circuit board and heating element. We took a pic before we pulled out the old circuit board.  This is the one. Notice the blue wire over the white one. The paperwork with the new board says to install with white over blue. Thoughts? I don’t want to ruin this new board



Hi there and welcome!

First off, what is your smoker doing?

The circuit board and heating element are not common parts to simply fail or mess up on you.
It feels like 90% of the time failure to heat up is due to the crappy wire connectors Masterbilt uses at the heating element and at the safety rollout limit switch.  I swear they are made to only last 2 months before they corrode of burn off haha.
Also if the unit heats up and then stops heating at some point, same issue the connectors and/or the safety rollout limit switch has started overheating and melting down usually due to bad connectors. This switch stops the unit from overheating BUT if the switch itself is overheating because the connectors are bad then it switches off until it cools down thereby cutting off power to your whole smoker.


Masterbuilt rarely understands your actual issue and often just throws parts at you. 
We help guys fix their MES units all the time here as well as rewire them to use a much better 3rd party controller because the unit is too broke down as is or people simply want to upgrade the MES to become like an all new 100X better performing electric smoker (like going from a Golf Cart to a Cadillac) :)

I would hold off on changing the circuit board and *especially the heating element* until you tell us what the MES id doing. There are some MUCH simpler troubleshooting steps in areas that more commonly fail and are way simpler to fix. Changing to all hi temp connectors at the heating element safety rollout limit switch (if it has a panel) can be a 10 minute fix for $6.

I hope this info helps :)


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## Aaron Smithey (Sep 30, 2022)

Smoker is a MB20076718.  3 years old.  I am having the same issue.  I was smoking and my temp just started dropping out of the blue.  Then eventually would not heat up at all.  I purchased a new heat element.  Still won't heat up.  Control panel has power and functions properly.  Masterbuilt has told me I need to purchase a new power circuit board.  I popped the panel of the circuit board and it looks great.  No evidence of heat damage what so ever.  Can someone please fill me in on the "safety rollout limit switch"?  *(Edit: Found it. Easy access panel)* Where its located and if it is a universal type of switch or is there a proprietary on for my smoker? Thanks!!!

I can't find a power circuit board on line for my smoker.  MB tells me they are no longer available. 

I found this which is for my smoker.  I will try it..








						9907140015 - High Temperature Limiter Kit
					

High Temperature Limiter Kit for electric smokers. Part Number: 9907140015. Fits Models: MB20070115, MB20072115, MB20075118, MB20076118, MB20076718, MB20078319, MB25072215, MB26072415, MB71071115, MB71073315, 20070115, 20070215, 20070315, 20070415, 20070615, 20070816, 20071115, 20072115...




					www.masterbuilt.com
				




Masterbuilt told me a bad thermostat would not prevent the smoker from heating up.


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## tallbm (Sep 30, 2022)

Aaron Smithey said:


> Smoker is a MB20076718.  3 years old.  I am having the same issue.  I was smoking and my temp just started dropping out of the blue.  Then eventually would not heat up at all.  I purchased a new heat element.  Still won't heat up.  Control panel has power and functions properly.  Masterbuilt has told me I need to purchase a new power circuit board.  I popped the panel of the circuit board and it looks great.  No evidence of heat damage what so ever.  Can someone please fill me in on the "safety rollout limit switch"?  *(Edit: Found it. Easy access panel)* Where its located and if it is a universal type of switch or is there a proprietary on for my smoker? Thanks!!!
> 
> I can't find a power circuit board on line for my smoker.  MB tells me they are no longer available.
> 
> ...


Hi there and welcome!

Most likely what has happened is that your safety rollout limit switch has failed.  Yep the switch you provided the link to.

It is located here inside your smoker and is like the size of quarter:






If you are lucky you have a panel on the back of your smoker like the top one here labeled "Rollout Switch Panel":






Under the panel it will look like this to get to the switch:






If there is no panel then you can: 
1.) Cut a panel (I highly suggest this)
2.) Remove the back and get to it (way more complicated)

The part you want is a KSD301 150C degree switch.  These switches are pretty low quality and melt down all the time so having more than 1 is pretty much mandatory.  Here is a link to ceramic ones that should not fail as easily as the plastic ones like the one from the Masterbuilt site. IMPORTANT: Get this exact one!!!! There are 2 styles of switch that look the same but are not built the same and the other style will NOT work.  This is the proper style, is ceramic, and is 150C so buy something different at your own risk :)

If you don't have a panel just look on the inside and measure with a measuring tape from the ground  up to get an idea of where to make a cut.  The sheet metal on the back isn't too thick so if you drill a hole just through the metal and then use pointy tin shears/snips you can cut into it to access the switch cover box you see halfway up on the right hand side of this picture (again, don't remove the back, this pic is showing u the switch cover box):






That box unscrews from the 2 other screw heads you see on the inside of the smoker.

Once you get to everything and GENTLY replace the switch you can seal it all back up and cover with foil flue tape or high temp duct tape or whatever you want and then you now have access to it whenever you need.

Finally, I highly recommend you get some of these high temp 14-16AWG female spade connectors to replace the spade connectors that Masterbuilt uses.
The connectors Masterbuilt uses are pure trash and corrode away in no time so these will be a great improvement with you already in there.  In any case it is very likely the connector has already corroded away on top of the switch melting down.

Let me know if you have any questions and I hope this info helps :)


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## Aaron Smithey (Sep 30, 2022)

tallbm said:


> Hi there and welcome!
> 
> Most likely what has happened is that your safety rollout limit switch has failed.  Yep the switch you provided the link to.
> 
> ...


Thanks.  I pulled the cover off to reveal the switch.  From inside its compartment, it looks to be in great shape.  No melting or burnt terminals.  I will still replace it and see what happens.


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## dr k (Oct 1, 2022)

Aaron Smithey said:


> Thanks.  I pulled the cover off to reveal the switch.  From inside its compartment, it looks to be in great shape.  No melting or burnt terminals.  I will still replace it and see what happens.


Or if you get a male to male connector and bypass the switch or a jumper cord 16-14 guage and see if it's the safety switch.


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## Aaron Smithey (Oct 1, 2022)

Yeah.  I will make a jumper and test it.  Thanks.


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## tallbm (Oct 1, 2022)

Aaron Smithey said:


> Thanks.  I pulled the cover off to reveal the switch.  From inside its compartment, it looks to be in great shape.  No melting or burnt terminals.  I will still replace it and see what happens.


Yeah what drK said.  If you can bypass it for the moment and check if you still get the same behavior you can determine whether or not the switch is to blame.

Just be careful when you pull the connectors off and put them back on.  If you wiggle the tabs of the safety switch at all where they connect to the plastic back of the switch, it will melt down on you sooner rather than later.  They are cheap plastic junk ready to fail if you look at them wrong.  That is why I suggest the ceramic ones when possible... they should at least be a little less likely to melt down lol.


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## Aaron Smithey (Oct 1, 2022)

The jumper confirmed a bad limiter switch.  Burner started to get hot immediately. 

THANKS!!


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## tallbm (Oct 2, 2022)

Aaron Smithey said:


> The jumper confirmed a bad limiter switch.  Burner started to get hot immediately.
> 
> THANKS!!


Glad to hear you found the problem! 
The behavior described sounded like a bat safety limit rollout switch, glad you confirmed it.

Those things are cheap and melt down on a whim.  Being able to access it to easily repair, troubleshoot, etc. is basically a must on these units since the connectors and the switch are so cheap and wear out so fast.

Just be sure you delicately put the new switch and wiring back together.  If you wiggle the tabs at all where they connect to the back of the switch, it will fail on you in short order.
My technique was to sit in my living room and gently put the spade connectors on the switch tabs.  Then go outside and connect the wires to the spade connectors.
FINALLY, fasten the switch back in position.  This helped me keep from stressing those delicate switches.

I hope all this info helps :)


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