Popper Coffee Roaster Has No Heat?

The Fix Could Be Simple! A connector may have come loose.

In the last month we have seen a few Popper roasters where they start blowing cold – no heat. The function seems fine, the fan blows strong, but there is no heat.

This was something new, and when we looked at the first unit, the fix was so simple. One of the connectors that goes to the thermal switch on the side of the roast chamber had simply come off.

I am not sure why this would happen, but in each case the fix took less than 5 minutes. Most people might be interested in doing this themselves so here is what is needed:

  1. Get a small phillips head driver, number 0 or 1.
  2. Pop off the 4 rubber feet on the bottom of popper. See Image Below
  3. Loosen the screws under the rubber feet (I leave them very slightly in, as it makes reassembly faster)
  4. Remove the 2 screws on the bottom of popper along the front .See Image Below
  5. Ease the Popper shell off the base – there is a ribbon cable attached but you can wiggle the shell off without undoing it. Don’t yank on it!
  6. You will see the 2 wires going into the thermal switch on the side of the roast chamber, through the opening in the foam insulation shield. See Image Below
  7. Is one off? Loose? Slide back the silicone cover and reattach the connectors. Crimp them on securely with pliers.
  8. Note that sometimes the silicone boot is discolored or heat damaged, These aren’t really critical to the function, so I usually remove them altogether. See Image Below
  9. Reverse the steps to reassemble and you are done!

Replacement Motor Kit Update


Replacement motors are available at Sweet Maria’s now (June 2023)

Finally, the replacement motors for a DIY rebuild of the Popper coffee roaster are here. I created a video on Sweet Maria’s you tube, and there is more information, plus the link to get a kit, on the SM Coffee Library page. And here is where you get the motor kit for $5 .

Listed instructions from the Video Captions

If it’s helpful, here are the instructions listed out, as they are shown in the video. If there is extra clarification you need or a photo that would be helpful, please comment and we will try to add that.

1- remove the 4 rubber feet to reveal screws beneath.

2- remove the 2 larger front face screws with the No. 1 driver.

3- remove the 4 screws under the rubber feet to release the base from the body shroud.

4- separate base from shroud gently tilting at angle toward the  the ribbon wire

5- disconnect ribbon wire and put the body aside.

6 – remove thermal switch connectors and remove insulation jacket.

7 – remove 3 screws holding roast chamber assembly to base plate

8 – remove 3 machine screws holding white fan shroud to metal roast chamber.

9 – remove 3 ceramic spacers to prevent damaging them.

10 – pull the fan off the splined motor shaft 

11 – remove 2 small motor mount machine screws – motor is free now

12 – pinch the insulation above the spade connector to help release, while gently pulling side to side and upward. 

13 – apply the 2 strips as in the video, not covering any openings in motor casing

14 – insert motor back into white housing, lining up holes in motor with where the 2 mounting screws will go.

14a – (oops) reattach motor with 2 screws, and tighten while pushing motor in place from the back. Don’t overtighten…

15 – push fan down with firm even pressure. test that it moves smoothly

16 – replace ceramic spacers. (added: These are very important to hold fan and heat coil in proper position!)

17 – replace 3 machine screws holding metal chamber to white motor mount.

17a – (added: You will be connecting the red and black wires on the new motor back to the PCB board exactly as they came off; black wire on the lower connector, red wire on upper connector. If you reverse these the motor functions but cannot roast much coffee because (I am pretty sure) the fan will be spinning backwards!

18 – slide thermal jacket on and re attach connectors to thermal switch, pinching them on if they feel lose at all. (added: if they seem loose at all, crip them on a but with pliers. If they aren’t well connected, full power is not getting to the heat coil, and your roasts will take too long / bake.)

19 – Inverting popper, attach base to chamber with 3 screws.

20 – reconnect ribbon cable.

21 – Reseat the shroud on the base, keeping one hand in top hole of roaster to guide it. Don’t force it!

22 – Replace the 2 larger front screws and 4 screws under the rubber feet, and replace rubber feet.

23 – Test your work… hopefully that motor purrs at an even clip and you have 250+ roasts more…

Popper v.1 is on Clearance Sale

Popper Coffee Roaster Front Angle View

It’s a lower $79, but has a limited warranty period!

Popper is back on sale at Sweet Maria’s now on “clearance.” What is it about?

It’s probably best to repost some of the description and the Clearance FAQ posted on the SM site. It really answers all the questions… Here it is:

What do we mean by Popper V.1?

The first 2 manufacturing runs of the Popper are what we are calling “Popper V.1” as we prepare to do a 3rd run with modifications, which we are calling V.2 for now.

When is Popper V.2 coming?

Not for a long time actually, because final parts haven’t been approved at this writing (Feb 2023) and things are moving pretty slow. The target was production in July 2023, which would not have them here in USA until around September or October 2023. All that can change though. Manufacturing has been very slow generally.

Why offer a “clearance” on Popper V.1?

We wanted to grab people’s attention by calling it a clearance honestly. It’s not like there are a few units left. There are 1800 at this writing! We aren’t doing a “clearance” to get rid of them fast. We used the word to draw people’s attention to the fact we frame it as a roaster for light and medium roasts, and that there is a 30 day warranty against manufacturing defect. For more see in the next question…

What are the changes in the marketing of Popper at the lower clearance price?

We think Popper is a great roaster, have stress tested it for 180+ roasts and 40 lbs of coffee, and have confidence in its roast quality. We think our original marketing material, and thus the way people used it, put a lot of stress on the machine and led to issues with the fan motor. We didn’t anticipate that.
1. The main issues were roasting very dark, not allowing the machine to cool enough between roasts, and extending roasts a long time to get into dark roast ranges.
2. Machines we inspected that had fan motor failure often showed signs of misuse, repeated dark roasts, lack of chaff basket cleaning. And while our instructions read not to do these things, they didn’t make it clear the machine could fail if you repeatedly do them. So we changed the instructions.
3. We frame the Popper as a good machine for light and medium roasts. If you want dark roasts this isn’t right for you. Stovetop roasting is great for repeated dark roasts.
4. We state that you should start out roasting 85 gram batch size. You can likely increase that to a maximum of 100, if you have watched our video and see the coffee is rotating well.
5. We require 30 minute rest time to cool the machine between batches. This was never intended as a back-to-back roaster. It’s a small capacity machine, not one to produce pounds of coffee per week.
At our clearance price, the warranty is only 30 days from date of sale. If you buy it, please use it in that time frame to be sure it has no issues. We will absolutely replace a machine that fails or has a manufacturing defect in that time, after we receive it back for inspection at our warehouse.

How can I roast on the Popper and make the machine last?

Really, heed the instructions that come with it, don’t overload it with coffee by weighing out your batches, don’t roast dark, let it cool between roasts as instructed … We highly recommend using a digital scale to weigh out your batches so you get good results! We think using a wattmeter with the Popper is brilliant! It lets you know exactly what your heat setting is in watts, talking some of the guesswork out of getting consistent results.

How long should my V.1 Popper last if I follow the instructions and roast light-to-medium levels?

Our stress tests on V.1 Poppers are successful for 180 roasts of 85-100 grams, totalling about 42.5 pounds of coffee. (Meaning that it still works great at 180 roasts). We calculate that at 15 months of use roasting 3 batches per week. For $79 that seems like a pretty good deal.

What if I have a problem after the 30 day period?

Contact us at info@sweetmarias.com . We have some parts for the hood and chaff collector, and can assist on other issues. Please start using the machine though, when you receive it, so if you have an issue, we can back it up.
But to be clear, the warranty is only 30 days and only covers manufacturer defect, not errors in use. Hence the low clearance price. By buying it you are accepting those terms.
The warranty does not cover misuse and is not a warranty of customer satisfaction.
(FYI If you have a fan motor issue, and you have some tech skills (ie can fix an appliance), we are working on getting a good supply of the V.2 motor we intend to use, which we have tested as being able to handle higher heat levels than the V.1 motor. So you can potentially repair your Popper and do a lot more roasting on it! We hope to have the motors in stock by June 2023, and they will be inexpensive).

What will be the changes with the V.2 Popper when available?

Basically it will be a different motor with harder carbons. At this point that’s the only change, although we are looking into a different fan. We think Popper design matches it’s intention, a Popcorn popper with added controls. We just want it to be durable for the way people use it, and many people want to roast darker. Calling it V.1 and 2 makes it sound like a big upgrade, and it isn’t actually, but we don’t have any better idea to make the distinction. And “clearance” makes it sound like we only have a few and want to sell them really fast, which is also not the case. But it’s the best way we could think of to try to get people to slow down, and think before buying it.

Popper Roaster after Christmas

Popper is a coffee roaster

Delays delays until after the holidays

The latest update is that, unfortunately, we won’t have a supply of the Popper coffee roaster until after the holidays. We tried to get it here. But the priority in manufacturing and shipping favors big appliance brands. A small project is put last.

We are also looking on fan motor upgrade kits, which can bring a Popper back to life from the verge and/or extend its useful life. More details on that to come…

Out of Popper

Popper Coffee Roaster Control Knobs

It’s not easy to keep things in stock these days …

So you might have noticed the Popper coffee roaster is out of stock. We have some units in reserve to cover any issues / replacements, but don’t have any to sell.

It’s pretty easy to guess the reasons, but just to state the obvious … this big rats nest called the global manufacturing and logistics network is very hard for a small business to negotiate these days. Parts aren’t available and time lines keep changing.

We are taking this break to make any changes we need in components. The plan is really not to “upgrade” what we have, add function (which always adds cost). But instead to improve the durability and % of units that come off the line with a quality issue.

When you manufacture something the accepted rate of defect is 1.5%. That could be one of the many components, or the assembly itself. We actually came in way below that with assembly defects (and we replace any problem units promptly as our buyers will know). But we want to improve some components in terms of durability, specifically a better fan motor.

So that’s where Popper is at, and the focus of the project. Look for updates when we are in production again, which should be fairly soon.

In the meantime, Popper is 100% supported, so send any questions about operation or to report any issues!

Popper Coffee Roaster Side View
Popper Coffee Roaster Side View

Popper Coffee Roaster – What Does a Bad Fan Motor Sound Like?

Popper is a coffee roaster

We have had some issues with the Fan Motor in some units. Here’s how you know if it’s happening to yours!

We have had some issues with the fan motor failing to turn at a constant speed. It has cropped up in about 30 roasters (out of 1800 units or so!).

It seems to happen after 30-50 roasts or more, which is why our QC team didn’t catch it. This video demonstrates the sound of a good fan motor and a bad one, and tells you what to do to get roasting again!

If you’re Popper roaster starts sounding like the Defect Unit I show in this video, STOP using it though! And email info@sweetmarias.com for more…

Popper Fan Motor Problem – Good vs Bad

Popper Fan Knob Repair

Popper Fan Knob Repair DIY

Don’t be rough with that knob! We find people are twisting it past the stopping points: If the fan knob starts to feel like it is not “clicking” into position at Off, Low, or High, it might break soon…

If the fan knob is turned past the Off or the High position stops, it can break. When it breaks it spins freely on the post, so it can’t be used to turn the machine on or off, or change air speed.. Bummer.

This is caused by being handled too rough, turned too hard, especially when the user believes the range of the Fan knob is the same as the Heat knob, which turns in a 180 degree arc. It isn’t. The fan knob turns in a 90 degree range. But honestly this would be less of an issue if the way the knob grabbed the post was stronger. We will fix that in the next manufacturing run!

The good news is that it doesn’t damage the post that the knob attaches too, nor the function of the machine … just the knob itself.

The bad news is that the knob doesn’t just pull off the post from the front of the machine. It is “trapped” behind the front plastic panel. So you have to take the machine apart a bit to get at the knob. You can either get a used replacement knob from us , or even just opt to take it off and use the machine by turning the post directly. It also seems that other types of knobs will fit on this “half moon” shaped post. Get creative!

Also, getting at the knob isn’t hard, you just need one small screwdriver and the rest is pretty easy. I can do it in 5 minutes, but it probably took 15 minutes the first time to complete this repair. See below for the video version of this repair or follow this link to see on youtube directly

Video DIY Fan Knob Fix for Popper Coffee Roaster

Video Version: Popper Fan Knob Fix

Popper Deconstruction: Inside an Air Coffee Roaster

deconstructed popper coffee roasters

A very basic video about making and testing Popper, the air coffee roaster.

Here’s a video to show a few early versions of the machine, and some aspects I had to deal with in getting this project completed.

I don’t think this is a video of general interest so please don’t expect much, and the quality isn’t great. I was trying to move the camera phone around to show details and didn’t always do a great job. Ugh.

Also I need to make it clear that you shouldn’t do what I do here, because opening up the machine voids the warranty against manufacturer defect. I made the video to provide some background details only, and show how I test temperatures.

  • Some things I go over here are
  • A look at an early prototype
  • Location of the thermal cutout switch that protects Popper from overheating
  • When I have a unit that turns off before reaching dark roasts, how i move the thermal cutout switch upward to solve the issue.
  • How I use a thermometer to probe the bean mass
  • Show a bare version with probe locations for input air and bean temperatures
  • Deconstruct (partially) a Popper to show how it’s put together
  • Talk about the unit that easily roasted 140 grams, and why I couldn’t get it built that way 😢

PS – this is in my workshop space where I store the pallets of Popper, hence the motorbikes and cars and such.

Inside Popper Coffee Roaster

What’s in a Name? Not Much.

Popper roaster logo
Popper the Roaster Logo Name

So we had some clever names, and over time none of them seemed right. We ended up with a name which is okay, likely not the best. It’s not clever or funny, unless it’s funny in a bad way, like ha ha that’s dumb. But in the case I think it’s okay to be dumb.

I have product fatigue. I am tired of new versions of the same old thing. I am tired of being a consumer and tired of feeling duped. That likely will never end, I am a sucker and I supposed most people are, just at varying intensity levels. (?)

Anyway, you have to give something a name it can be called. You have to “market” it at least to the degree it is being “brought to the market” as a thing to sell, and it needs some name to distinguish it from all other things. We could just point and say “that thing” but it might be confusing.

So there’s this mental exhaustion I have brought on by nearly all shopping except just repetitive grocery type trips. And even those too …for example, walking down the beer aisle at your basic fancy store, and just being tired of all the labels trying to have “personality.” *

I know, ironic since we have a site (ie sweetmarias / coffeeshrub) with a bunch of choices and long reviews and exhaustive descriptors.

So yeah, Popper* and an explanation “popper is a coffee roaster.” I guess for me, 20+ years in home roasting business, there has been some dry (very very dry) humor in pointing at a popper and calling it a roaster. So I started to write popper-roaster, or air-popper-roaster, or air roaster, but appreciated that someone who had no context to understand what it refers to finds any title confusing.

So I guess Popper as a name just ropes in that confusion and claims it.

The other funny thing is the name is too common to be a trademark. Not that we are just saying “yeah, copy us, open source.” I feel like we own this project and put a lot of time and money into it. It’s not cheap for tooling and such in manufacturing.

At the same time, it’s a popper! We didn’t invent that. We weren’t the first people to roast coffee in an air-popper-roaster. We made a lot of small decisions that resulted in this thing, but it’s not that big a deal.

And as it sits it is not the ultimate coffee roaster. It just works well, costs less, is basic and easy to use, and (nudge nudge) it could be made more interesting as well by some clever people in the internet world.

We did our part. Here it is. Well, soon, like probably Oct-Nov 2020.

I can’t believe you read all this! – Thompson

* Things relate as subjects, people relate as objects. This is the basic notion of Commodity Fetishism. It’s the way, for example, cars have “Stance” or “Character” in advertising. And in the world, on the road, express the Taste, Character or Class of the owner. But the person themselves is mute, as an object.

Sumatra And Popper

Sumatra from Aceh area isn’t that low grown generally (1250 to 1800 meters) but can be tough to roast. It often gets a heavy, dark roast treatment that obscures the coffee to a point. Lighter roasting is more challenging.

Air roasters do a pretty good job with this. It’s hard to scorch coffee in an air roaster … provided you don’t overload it.

Currently we use a 3 barrel Probat for samples but when I have a single sample to check out, I’m using Popper lately.

Here is a 1450 meter Sumatra from Aceh (near Lake Takengon) roasted for cupping in Popper.

Lighter City roast from the popper for cupping and drinking!