# Oh no... grinder explosion...



## chinery (Apr 14, 2014)

I am still in shock! I just cleaned out my Mahlkonig Vario the way I always do... run some grindz through, run some coffee through, take the top burr off, brush everything I can see, put it back, and switch it back on... but this time: BANG.

Loud noise, flash of light, and smell of smoke. The grinder was still running (at least it was making noise) so I immediately hit the stop button. I unplugged it from the wall, and recovered enough to remove the top burr again and note that there is nothing visible at that level -- whatever happened was inside.

The case seems to have deformed too. It is bursting at the sides which I'm pretty sure it wasn't doing before.

Don't know what to do now, too scared to try turning it on again. I guess something has happened to the belt. I really can't afford to buy a new grinder right now so I'm feeling like I might be pretty screwed.


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## DavecUK (Aug 6, 2013)

I wish people would stop buying these grinders...perhaps then the company would make them better. Sounds like the motor has a problem, I have read of a few failing. You could alsways see if Malkhonieg will do something from a goodwill perspective, as I assume it's out of warranty.


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## The Systemic Kid (Nov 23, 2012)

chinery said:


> Don't know what to do now, too scared to try turning it on again. I guess something has happened to the belt. I really can't afford to buy a new grinder right now so I'm feeling like I might be pretty screwed.


Can you put up some pictures? Take the casing off and have a look inside. It might be the powerboard which is reasonably easy to replace if that is the problem. Suggest you contact Baratza USA - they are extremely helpful and might be able to point you to what exactly the problem is.


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## Dylan (Dec 5, 2011)

Did it trip your mains or blow the fuse in the plug?


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## chinery (Apr 14, 2014)

I've contacted the shop I bought it from because I think they have a contact at Mahlkonig, but after I've spoken to them I'll take it apart and have a look. After watching some videos online (helpfully provided by Baratza USA as you mention!) the idea of fixing it is much less daunting. The motor kept spinning after the bang, so hopefully neither that or the circuit board is damaged? If it is the belt or pulley it looks easy enough to replace.



DavecUK said:


> I wish people would stop buying these grinders...perhaps then the company would make them better.


Hard to argue with you. I love how compact it is, genuinely feels designed for home use. But I have and would continue to advise people buy something second hand which is a bit more "industrial" if they have the space.

Thanks for the advice, will keep you posted.


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## chinery (Apr 14, 2014)

D_Evans said:


> Did it trip your mains or blow the fuse in the plug?


Nope, it keeped spinning until I hit the stop button. It still turns on and lights up, but I haven't tried running the motor. I didn't even notice a difference in noise so I want to say the burr was still spinning too (but hard to say given it was very surprising and my main concern was turning it off.)


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## Dylan (Dec 5, 2011)

I was just trying to imagine what could have created such a bang without a mains short, but that would tripped the mains or blown the fuse.

I hope you get it fixed, I had a mains short (loose wire) when modding my SJ, and that gave a big bang with lots of smoke, but the grinder was completely undamaged and just needed a new fuse.


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## The Systemic Kid (Nov 23, 2012)

Does the motor run still? If so, does it run at slow RPM when plugged in without you pressing the start button?


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## chinery (Apr 14, 2014)

D_Evans said:


> I was just trying to imagine what could have created such a bang without a mains short, but that would tripped the mains or blown the fuse.
> 
> I hope you get it fixed, I had a mains short (loose wire) when modding my SJ, and that gave a big bang with lots of smoke, but the grinder was completely undamaged and just needed a new fuse.


Yeah I'm a little confused by that too. I can hear loose coffee inside the casing so I think that must be the culprit of whatever it is.

Thanks! Watch this space...


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## chinery (Apr 14, 2014)

The Systemic Kid said:


> Does the motor run still? If so, does it run at slow RPM when plugged in without you pressing the start button?


The motor ran seemingly fine for a few seconds before I switched it off, but I haven't tried starting it again since. It doesn't run at all when plugged and idling (but never has).


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## NickR (Jul 1, 2011)

I would think the starter capacitor has exploded. If it was rotating at the time of the failure it would continue to work. I doubt that it will work now. Starter capacitors are cheap and easy to fit, you may not even need a soldering iron.


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## chinery (Apr 14, 2014)

That's interesting Nick, is there a way I could check without turning it on?

I have an update, I got bored of waiting for a response from the shop so I opened the case (also realised I could do so without it being obvious). Everything on the inside looked fine to my untrained eye.









However I have noticed that the distance between the bottom and top burr is way too big. About the size of a coffee bean or bigger. It is like something that was "holding up" the bottom burr has given way (I am not sure whether such a thing exists). Changing the setting from coarse to fine still makes a very slight difference in the height of the burr, but the gap is big even on the finest setting.









Any thoughts?


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## froggystyle (Oct 30, 2013)

The flux capacitor looks shot to me!


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## MrShades (Jul 29, 2009)

The gap that you can see there MUST be big... as that's how the beans get in... so I would hope that it's as big as a bean or bigger!

The gap tapers towards the outer edges of the burrs - where the ground coffee exits - and that's where the gap matters and is what sets the grind.

Check this photo of another Vario from a quick Google image search:










I'm with NickR and I think a cap will have blown somewhere, either starter cap or perhaps a smoothing cap. Would be a big bang and smoke but otherwise would probably run. Try starting it, briefly, and see what happens. If it doesn't start then it's probably the starter cap, but with zero load it may start anyway.

Edited to add:

Try looking at this post on Coffeegeek that shows the Vario PCB. See the small cylindrical things with silver tops, they're the capacitors - and you may well find, if you can access your PCB, that either one of them has blown to pieces - or (more usually) looks like a small grenade has gone off inside and the top is bowed outwards and not flat. Anyway, if you can access and see the PCB then check all the components, as they shouldn't be burnt or in pieces. Using your nose often helps, as you can still smell the "blown electronic component" smell when you get close to it!

http://coffeegeek.com/forums/espresso/grinders/545547#545547


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## froggystyle (Oct 30, 2013)

Stick it on an extension cable and put it outside, then turn it on via the switch on the plug socket, if it goes boom then its outdoors!


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## chinery (Apr 14, 2014)

Huh! My stupidity for not checking a simple google image search then. Or for paying enough attention to the grinder before. Apologies for the idiocy.

Froggy your advice is invaluable.

I'll give it a go and see what happens then!


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## froggystyle (Oct 30, 2013)

Dont sue me if it burns your house down though...

I have no cash!


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## The Systemic Kid (Nov 23, 2012)

To access the powerboard, you will need to remove the motor. To do that, you will need an offset Phillips screwdriver. They are either side of the cam belt at the top.


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## mean_beanmachine (Aug 5, 2014)

Our company fix kit if you get stuck? The parts aren't that expensive you will be able to fix it so I wouldn't worry. ??. I wouldn't try fixing things a component level unless you know what you are doing. Also if the board has gone it is likely caused by another component so fixing the board won't help if when you restart the damaged component just blows the board again. I'd check components first for continuity then look to the board.


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## mean_beanmachine (Aug 5, 2014)

Do you have a multimeter?


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## chinery (Apr 14, 2014)

Okay, so I tried running the motor for 0.1 seconds, it ran fine. Rinse, repeat... tried increasing the time, no problem. It was running without any noticeable issue. So I put some coffee in, (it has been set to the coarsest setting this whole time) and it still worked. I tried running it and trying to make it finer. The motor started chugging way too early on the range. If you don't know, they suggest calibrating the Vario by ear, as in this video https://www.youtube.com/watch?v=_xYw6MVi40E. So I turned it to the coarse end via the allen key, but I had to go all the way until it wasn't actually changing any more to make it sound the way it does in the video. Tried grinding, and no surprise, it came out far too coarse. I tried slowly turning the allen key towards the fine end, and the motor didn't chug for quite a few turns. When it sounded about right (as per the video) I gave it another try, and at the finest setting the coffee was really fine, powdery. So, all well, I guess.

So what gives? Should I just go back to using it until something goes wrong?

If it was a capacitor that blew, is it possible that it would still seem to be working fine?

Thanks mean_beanmachine, I do have a multimeter, but if it turns out to be something fiddly and it's not too expensive then I will certainly call on you!


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## MrShades (Jul 29, 2009)

Yes, it's possible. Capacitors are used for all sorts of practical reasons: within an AC motor device (like a grinder) they CAN :

- provide an extra 'store' of power that can be used in addition to the normal power through the PSU to help with the startup peak power demand as the motor starts (hence startup cap) or the extra power drawn when or if the motor jams

- be used simply as filters to stop the motor producing RF interference

- others can be used as inherent standard components as part of a 240V->12V power-supply board, for example.

Either of the first two types could fail and the grinder would probably still run (certainly, if it's a filter cap that has gone then you'll notice no difference in grinder performance at all - but it might affect an FM radio that you place near it!).


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## aaronb (Nov 16, 2012)

If you are willing to get to the circuit board you can easily see if its a blown cap as the top will be a big bump instead of flat, or the entire thing will be scorched.

Caps are cheap and easy to fit, get a good brand though as some of the really dirt cheap ones will just blow again straight away.


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## chinery (Apr 14, 2014)

Okay, I will see if I can inspect the board. I'll try to do it without removing the motor, but if I have to that doesn't look too difficult either.

I'm sure this thread must seem extremely melodramatic but I can't tell you how relieved I am that I may not have totalled my £320 toy that I can in no way afford to replace. So thank you everyone for the advice!


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## aaronb (Nov 16, 2012)

How old is it anyway?

Sale of Goods Act specifies it must be fit for purpose, certainly within the first 6 months the retailer is obliged to repair / refund / replace as long as it hasn't been misused, after 6 months you may have to prove to them that it hasnt been misused.

Many retailers (including big names) will try and ignore this and send you direct to the manufacturer, but you have a contract with the retailer and they are responsible under SOGA whether they like it or not.


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## chinery (Apr 14, 2014)

Unfortunately I think it's about 16 months old now. But I'm still in touch with the guy who sold me it, he's just been offline recently while they are in the mad panic leading up to their new shop opening. I'll speak to him in person next time I'm in the area.

At the moment though I'm not sure what I'll tell him. I've had a close look at the circuit board and I can't see any damage at all. I can see four capacitors and they all look fine, flat tops. There are no scorch marks on the board at all, it's hard to tell in the photo but by eye I can look around the motor from both sides and see the whole board. So unless there's another board hidden in a separate section I'm lost. I definitely didn't imagine it happening though! I can't believe that a big enough reaction to pop the casing out at the sides has left no visible evidence.

I've been using the Porlex but might switch back to using the Vario again and just see what happens. Thanks again for the advice from all you guys who understand how these machines actually work!


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## aaronb (Nov 16, 2012)

Those caps and the board do look fine, but I'd expect a much bigger cap somewhere if there is one for the starter.

How very odd!

Yeah as long as your sockets are wired up to a RCD I'd give it another go, power should just trip if there I a short circuit.

Actually could be worth emailing Baratza and telling them what happened anyway, they may have an explanation.


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## Dylan (Dec 5, 2011)

Here is my guess...

A bean or other something else shorted out the mains supply somewhere on the circuit board, causing a bang (maybe an exploding bean). The only thing going against this theory is that it didn't trip the mains.


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## chinery (Apr 14, 2014)

Luckily I have a standalone RCA plug adaptor so I set that up and tried using the grinder for a bit... the grinds were coming out extremely messily, and I'm not sure why except maybe it was just set too coarse. It was doing that after I had just run Grindz through, before I cleaned it out properly and before the bang, so it could be an early symptom or it could be unrelated.

But then I started smelling the burning smell... electronics burning, if you know what I mean. I decided to open the back up again, and this time run it while I had the casing off. I see sparks coming from the motor, and so I assume this is the problem area? Although this is where my ignorance could be failing me again and this could be totally normal.

Here's a video:






(you can put it in HD and in slow motion to get a better look)


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## Zakalwe (Oct 19, 2014)

It could be that the brushes are getting low?


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## 7493 (May 29, 2014)

From that video it could well be a capacitor that's the problem. Caps are often used to suppress this kind of sparking. (And radio interference.)


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## Dylan (Dec 5, 2011)

Im fairly sure that sparking is normal, you get it with drills sometimes.


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## DavecUK (Aug 6, 2013)

You could well have a bad winding, or shorted winding in the motor (which would make it get hot and smell). it may or may not run rough, have problems restarting in certain positions and will usually arc excessively. My initial post was a guess that the motor has gone bad...I think it may well have been correct.


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## aaronb (Nov 16, 2012)

Yeah, email Baratza telling them what happened and a link to the vid!


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## chinery (Apr 14, 2014)

Okay, thanks all. I have emailed Baratza with a plea for help, but the big 240V sticker is pretty obvious so I was upfront about it being a Mahlkonig version. Hopefully they still reply, as Mahlkonig don't seem remotely interested in supporting their customers going by the website (not a hint of instructions for DIY troubleshooting, just a list of how many ways you can void the warranty).


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## El carajillo (Mar 16, 2013)

I would agree with Dave c, with that arcing I would say there is a motor winding gone "kaput"


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## DavecUK (Aug 6, 2013)

I suppose one should quickly add, that in fairness, I don't think this is a "known problem" with these grinders. If indeed it is the motor, you have probably been fairly unlucky. Personally I don't like the grinder at all, but that's for different reasons and not for any motor issues.

I'd also say it's always better to stick to grinding only coffee and opening up the grinder to clean it (old school style)...don't think I should say any more.


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## The Systemic Kid (Nov 23, 2012)

Baratza do stock 240volt parts.


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## NickR (Jul 1, 2011)

Maybe the bang was a rogue element going through, such as a stone or nail. Have you looked at the burrs since the "explosion"


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## chinery (Apr 14, 2014)

DavecUK said:


> I suppose one should quickly add, that in fairness, I don't think this is a "known problem" with these grinders. If indeed it is the motor, you have probably been fairly unlucky. Personally I don't like the grinder at all, but that's for different reasons and not for any motor issues.
> 
> I'd also say it's always better to stick to grinding only coffee and opening up the grinder to clean it (old school style)...don't think I should say any more.


That is understandable, these things happen. I wonder if I would agree with you on the Vario's issues. I love the form factor and it's not too loud (but not super quiet either). But I've only recently started to learn how I was never really impressed with the grind quality.

You're probably right on the second point too... I only use Grindz because it is strongly recommended in the manual of the Vario and on the website. But I've never been totally satisfied with that either. Always seems to lead to me having to spend ages dialing in the grind again afterwards.



The Systemic Kid said:


> Baratza do stock 240volt parts.


Well that's good to know, they don't have them listed on their online store. Would probably be expensive to order in but I guess better than replacing the whole thing.



NickR said:


> Maybe the bang was a rogue element going through, such as a stone or nail. Have you looked at the burrs since the "explosion"


Yes the burrs look totally fine. thankfully.


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## DavecUK (Aug 6, 2013)

chinery said:


> That is understandable, these things happen. I wonder if I would agree with you on the Vario's issues. I love the form factor and it's not too loud (but not super quiet either). But I've only recently started to learn how I was never really impressed with the grind quality.
> 
> You're probably right on the second point too... I only use Grindz because it is strongly recommended in the manual of the Vario and on the website. But I've never been totally satisfied with that either. Always seems to lead to me having to spend ages dialing in the grind again afterwards.


I think if you looked dispassionately at the grinder, you would agree with many of my views on the Issues. Some are stated in the review done in April 2010 and have proven to be well justified, others (not in the review) have surfaced over time.

http://www.bellabarista.co.uk/pdf/compact-grinder-1-closerlook.pdf

As for the use of the grinder cleaning product, if you have to spend ages dialling it in again, that might give a few clues as to why I think it's better to open them up and clean them old school.


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## chinery (Apr 14, 2014)

You don't even have to ask me to look dispassionately, I agree with your review totally on an espresso grind, and I find it completely unsuitable for filter with the stock burrs. Plus, the claim that you can just switch between the two seamlessly, which partly sold me on the device, is laughably untrue.

The only impassioned opinion I'll give is that my girlfriend is happy for it to be in our kitchen, in fact she really likes it.


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## DavecUK (Aug 6, 2013)

chinery said:


> The only impassioned opinion I'll give is that my girlfriend is happy for it to be in our kitchen, in fact she really likes it.


Says it all really....


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## chinery (Apr 14, 2014)

DavecUK said:


> Says it all really....


What does it say?


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## DavecUK (Aug 6, 2013)

chinery said:


> What does it say?[/quote
> 
> Increasing WAF (or Girlfriend) is "usually" inversely proportional to the performance of a grinder.. in fact it may even be the case that this ratio is even larger once you are married!


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## chinery (Apr 14, 2014)

Ha, well maybe. I am glad someone is putting out these sorts of products though. The home market is really poorly targeted and I can see why.

As an update, Baratza have sent me a friendly reply saying that it's an extremely odd problem since the machine is still running. They said the sparks are probably normal, and to take a look at the power board without the motor. I've replied with photos so we'll see what happens.


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## DavecUK (Aug 6, 2013)

chinery said:


> Ha, well maybe. I am glad someone is putting out these sorts of products though. The home market is really poorly targeted and I can see why.
> 
> As an update, Baratza have sent me a friendly reply saying that it's an extremely odd problem since the machine is still running. They said the sparks are probably normal, and to take a look at the power board without the motor. I've replied with photos so we'll see what happens.


The problem is what people are willing to pay for a grinder....

As for the advice they have given you, it's quite simple. You think when you run the motor, it smells hot....run the motor till you get the smeell, quickly unplug grinder and use fingers to find out where its getting hot...first port of call the motor.


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## chinery (Apr 14, 2014)

Latest update:

Baratza have been super helpful despite me being very upfront about my machine being made and distributed by Mahlkonig. I am really impressed.

I have taken the grinder apart further, removing the motor, and can safely say nothing on the circuit board looks damaged. The Baratza support guy, Pierce, said he had been discussing with his boss and could "only come up with hair-brained explanations". He said to just try using it.

When I thought I could smell burning again I decided to try Dave's advice and try to find where the grinder was getting hot. Unfortunately I missed the part about unplugging it, and got an electric shock when I touched the motor. The shock was minor and it was running on a RCD but it was pretty stupid. Still I wonder if that provides any diagnostic info. The grinder is also making a high pitched noise when it's on standby that it wasn't before. And changing the grind results in very odd noises compared to before:






In particular the fact that changing the micro arm makes the motor struggle more than the macro arm, and some just plain weird noises at different grind settings.

My fear is that any of this could have just been caused by taking the motor out and putting it back in (in particular the tension in the belt will be different so I wouldn't expect the sound to be identical).

Baratza haven't responded to my latest email in a few days but given their helpfulness I assume they're just delayed.

Knowing that this is a super odd situation, I'm not necessarily expecting any solutions here, this can just be to document. But as always appreciate any thoughts.


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## DavecUK (Aug 6, 2013)

chinery said:


> When I thought I could smell burning again I decided to try Dave's advice and try to find where the grinder was getting hot. Unfortunately I missed the part about unplugging it, and got an electric shock when I touched the motor. The shock was minor and it was running on a RCD but it was pretty stupid. Still I wonder if that provides any diagnostic info. The grinder is also making a high pitched noise when it's on standby that it wasn't before. And changing the grind results in very odd noises compared to before:


I just want to write nothing more.....


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## chinery (Apr 14, 2014)

DavecUK said:


> I just want to write nothing more.....


Okay...

I wonder if Baratza feel the same way.


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## Han (Jan 13, 2016)

Found this thread through a google search but had a similar issue with my vario grinder. Hadnt been used in a while, turned on without the been hopper even in place and loud bang and plenty of smoke. Took off back cover and can see a exploded capacitor right off.

Was still on after the explosion and had to pull from mains. Quite scary

Will recap the entire board as if one cap has failed the other cant be in great condition.


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## dc101 (May 20, 2016)

Surprised no one has mentioned the fact that working on the innards of an electrical appliance containing caps - even though it may be switched off - can be a risky business. Caps can hold their charge for a long time (that's their job) and a few hundred volts through one's chest is not in the least bit a pleasant experience!

I'd run a meter from + to ground and make sure the voltage is safe before 'testing' for hot spots with my hand!

Just to say....


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## mr_phillip (Jan 6, 2014)

Reviving this old topic to say that this exact thing just happened to me today. I cleaned my Vario with a brush and a can of air, put it back together, turned it on to test and BANG! The thing visibly jumped on the countertop, there was a smell of burnt rubber, and the casework had popped out at the sides (although nothing was broken). Interestingly our RCD didn't trip and the plug fuse didn't blow. I instantly pulled the plug out, but after I got myself together I plugged it in again to see what'd happen and, expecting it to be dead, was surprised when it went through the little boot up procedure just fine. I ran it for a second and again it seemed totally normal.

After finding this post I decided to open it up to look for any blown caps, but the electrics all look perfect and like I said both the internal and external fuses were fine, leading me to suspect a mechanical rather than electrical cause. I did notice a whole lot of course coffee chunks around the motor area though, and a big deposit stuck to the inside case right behind where the belt sits on the pulley. I've cleaned it all out now, but my best guess is that during cleaning a bean found it's way into the pulley/belt assembly, got trapped when I powered it on, then exploded forcefully as it lost the battle against the motor. I guess that seems the most likely explanation?

While I had the back off I ran it for a few seconds to check the motor, and saw only very light arcing - exactly what you'd expect from a brushed motor of this type (the brushes are in great shape too). I'm just curious if this has happened to anyone else?


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## Blue_Cafe (Jun 22, 2020)

Is coffee dust explosive like flour is?

If so, that's a concern!


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## mr_phillip (Jan 6, 2014)

I think it is yeah, although I don't think that's what happened in my case. I think it must've just been that the way the bean finally let go as it was caught between belt and pulley must've been violent enough to pop the plastic casework out of its clips, producing the loud bang. That's the only thing that makes sense to me.


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## Ozzyjohn (May 31, 2020)

https://www.ccohs.ca/oshanswers/chemicals/combustible_dust.html

Coffee dust is regarded as a combustible dust - dangerous hobby this coffee malarkey 😳

Regards,
John


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