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!

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 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

Some things take time, like manufacturing a coffee roaster …

Popper is a coffee roaster

popper*, the coffee roaster was right on the verge of going into production.

… but one thing just wasn’t right. The factory had sent sample after sample, but the fan speed (and therefore the air flow) was not consistent. This impacted the potential batch size.

A late night video chat with the engineers in China made it clear to me though. They were testing under the principle that the roaster should not use the entire pre-programmed roast cycle of 7 minutes. They thought of 0 to 7 as a range so they were presupposing what I wanted was a 4 minute roast!

Well, a 4 minute roast is easy in a popper, but it’s rarely an ideal roast time. In fact, the whole idea of *popper is that the user can fluidly adjust roast time up or down on the fly. It’s a manual, low tech machine, unless you want to get in there with an arduino interface etc.

It’s a machine that rewards people who want to play around with the variables, so it’s simple to do a 7 minute roast just to first crack and add 2 or 3 minutes for development. You just have to be there and tend to your roast, make intuitive decisions and turn a knob. Simple.

(For me I actually feel the 7 minute pre-set roast time can work very well. For City roast I target 5:30 to hear the start of first crack, and the remaining 1:30 for further development. Remember, roast time is relative to the device and the type of thermal transfer. Higher air flow and more movement of the mass means more rapid levels of heat transfer via convection.)

Let’s call it February …

popper coffee roaster line art

Popper* will make coffee go pop, but probably pop corn too. And it is coming along nicely. No need to rush to get it made before Christmas, because it needs to do what it’s supposed to do. It’s going to be February I think.

The prototype samples were going well except in one regard: Each seemed to roast a little less than the previous. We ended up with a final sample straining to move 85 grams of fresh green coffee. No!

So we delayed production to balance out fan and heat and the roast chamber vents. I worked on the exit air vents thinking they were constricting flow … but it turned out it was the inlet air vents. And just minor tweaks made big changes in batch capacity.

But those changes impacted the heat curve too and, while I could roast 140 grams, too much heat was blowing by the coffee and out of the roaster. I couldn’t get darker roasts within a single cycle. (I could by adding time, but we need dark roasts to be in closer range).

So now, fingers crossed, last set of prototypes are on the way with new fan speed, and an additional set of roast chambers, 5 in all, to find the best combination.

I think this is it! What I want is a 120 gram target that makes use of the range of air and heat settings, allowing manual profiling with extended roast times, and full roast range.

And with that, I’m able to get some really striking profiles that don’t at all taste like fast popcorn popper air roasts. Low heat warm-up times, ramping up to first crack, and backing off to finish the roast with control. The 10 minute roast profile I did yesterday of Guji Uraga Hare Wato was really the best roast I have had of that coffee. Really fantastic, sweet and floral.

popper coffee roaster line art
popper coffee roaster line art