12 May, 2008

Krups GVX2 Coffee Grinder

Over the weekend the several month old Krups burr grinder stopped working. I spent a few minutes checking that all of the hoppers were tight and the safety switches were engaged. It looked like the safety sensor on the whole bean hopper was a little farther down than it should have been and after playing with it a little it fell into the grinder housing. Due to time constraints I was forced to drink the pre-ground Caribou Guatemala that was sitting in our cupboard. While drinking I checked the warranty and found out that this grinder carries a one year warranty from Krups, but then it has to be sent to a Krups repair center...

Tonight Joe and I decided that the need for coffee and the inability to find an affordable NSF certified replacement coffee grinder was reason enough to fix this thing. I figured this was a simple safety switch, I can hear the mechanical switch click when the ground hopper is inserted.

If you decide to follow along through the pictures and do this with your own grinder be aware that we are in no way responsible for you electrocuting yourself, breaking your grinder, starting a fire or anything else that might happen as a result of you reading or following this. If you want it fixed send it in to Krups for warranty work or get a new one.



Figure 1: Grinder that does not work because the safety switch for the top cover is no longer triggered by the plastic lid.

After removing the top lid, ground hopper, and keystone (turn right just like the arrow says) you can turn the grinder on its side with the grind selector facing you. If you have somehow not unplugged the grinder now would be an excellent time to do so. This selector is probably the most difficult piece to remove and is easy to break. Using a very thin screwdriver push the silver tabs in toward the center of the selector. Three of these tabs can be found evenly spaced around the selector, one about 45 degrees to the right and left of the selector point and another 180 degrees around from the point. While pressing these tabs down pull firmly up on the selector knob and continue around the tabs until the entire selector knob slides out.


Figure 2: Here is the selector knob after being removed, notice one of the tabs on the lower edge. Watch out for the spring and plastic nub which are used to simulate the clicking selector motion and possibly help keep the grind setting from changing during grinding.


Figure 3: Remove the outer plastic housing of the grinder by sliding it over the entire grinder, it is secured by four stealth plastic tabs. Apply firm pressure to the inside of the grinder where the ground hopper usually sits (note where my left thumb is). While doing this pry using a thin flat head screwdriver at the space between the inside and outside housing. You can identify the location of the tabs by the manufacturing marks on the edge of the housing.


Figure 4: Continue to work your way around the grinder (here I am on tab #2) until the outside housing is free of the tabs. Then simply slide the outside housing up and off the grinder.


Figure 5: With the housing off the PCB and brushed metal housing will lift slightly and fall forward. Notice the sensor for the top lid is visible on this picture. The screws were not properly tightened and the switch had slipped to the side causing the plastic cylinder which triggers the safety to fall through and not activate the switch. Remove the two screws holding this in place and set the safety assembly aside.


Figure 6: Two screws can be found holding the whole bean hopper and funnel shaped keystone housing in place. Remove these and lift the bean hopper off, joe took this opportunity to wash this piece.


Figure 7: A nice view of the AC motor which powers the Krups grinder, this grinder performs pretty well for our purposes but is obviously direct drive with no gearing involved. I have heard of other complain about jamming in this grinder but I have never experienced this.


Figure 8: With the whole bean hopper removed, turn the cup selector knob to its upright setting (about 6 cups) and the bushed metal plate should easily slide over the selector knob.


Figure 9: I had planned to remove the safety from the upper lid so two cuts and the switch is out of the picture. First attempt tin and solder the two wires together (remember your shrink tube) using my cold heat iron. This thing is possibly the most useless solder iron I own and it only seems to work for lighting up large solder pads on a PCB. A fun waste of time while waiting for my real solder iron to heat up...


Figure 10: Tin the ends of the two wires after stripping back about 1/8 of an inch of insulation. Tinning is the process of heating the wire and allowing it to absorb a small amount of solder. After tinning heat and place both ends together in such a fashion that the stripped and tinned parts are side by side and form a continuous wire with overlap. See ASCII Figure 11 below since I forgot to take a picture.

Figure 11:

=======-----
.......-----=======
Ignore the dots, blogger and I are not getting along on this right now...

Ensure you have a strong solder joint with complete contact between the wires the length of the stripped and tinned area. Slide your shrink tube over the joint and apply heat to shrink.


Figure 12: A somewhat poor picture to end with but the wire has been bundled with the others and it is time to reassemble the grinder.

Proceed to re-attach the whole bean hopper and secure it with two screws. Place the PCB inside the two notches on the top of the bushed metal plate and slide the entire assembly onto the grinder carefully fitting the PCB and plastic key of the cup selector into their respective slots. The brushed metal plate and whole bean hopper should be quite sturdy and secure at this point if all was reassembled correctly. Check that no wires are hanging in the way of the motor or in the way of the external plastic housing sliding over the grinder. Carefully insert the spring and plastic nub for the grind selector into their cylinder and slide the external housing over the grinder. The external housing should slide on easily and snap securely into its final position. Turn the square grind selector shaft to its farthest clockwise position and snap the grind selector knob back into place set to the Coarsest setting.

Fixed and look at that there is no need for that pesky plastic top to be in exactly the right position anymore!

What does a coffee grinder have to do with things "On The Back Side"? We drink a lot of coffee on the back side (Kenya AA and Caribou Fireside) and we are quite picky about how we drink it. This could be the biggest threat late night cuts ever faced.

49 comments:

jhgarstang said...

Joe - your repair guide was spot on and my dead grinder is back in business - many thanks! I found the grinder control knob very tight on its spindle and impossible to pull out at the same time as holding in the three latches. I solved this by inserting a small piece of card behind each latch to hold it in as I released them. When all three were packed out in this way, the knob levered out easily using two screwdrivers.

Danny said...

Thanks for this guide. Fixed my GVX2 grinder's broken power button. Cheap plastic bit connecting it had snapped after a couple of years of light use. Super glued on for the time being.

Peter said...

Thanks - this was a big help on getting mine apart. I did break the tabs on the grinder knob in Fig 2 but it does not seem to matter, goes back on and work fine without the tabs or spring.

jn said...

I had the same problem as Danny - plastic tab on the power button snapped. My fix was also the same as Danny's, except I also cut out a square from an dead credit-card, and super-glued it to the tab (drilled a hole through it so the screw would fit) for some structural reinforcement.

Thanks for the guide, and especially the pictures - they helped much more than other repair websites that had disassemble instructions for this grinder.

Puff said...

I have problems with almost everything you described. The plastic power pad went out years ago (but I could turn it on by using the "inner button"). The lid and the bottom safety switchs have to be in the correct position. The lid switch was broken yesterday. Thanks for this blog, I could find the way to open the case and now two safety switchs are short wound. Except the missing plastic power button, the machine is working like new. :>

Chuck said...

You are awesome! My initial problem was the hopper safety switch support was broken. So I cut out the switch and connected the 2 wires. Now I get the blue light for the on/off switch but still no grind. The thermal fuse looks intact. Guess I may have burnt out the motor, but I thought the thermal switch prevented that. Again, thanks for the post.

Gerald said...

Thanks for the guide! My problem was exactly the same (loose top sensor). I've had the grinder over 4 years so wasn't as concerned if the repair didn't work, but luckily it all worked out.
The control knob was a bit difficult, but I want to note that the tabs are metal, so once they are pushed in toward the center, they stay. I feared that they were plastic so would need constant pressure to hold in, and would be breakable.
I just pushed the tabs back out before reinserting at the end.

Fitz said...

Thank for this! My grinder worked flawlessly for several years and finally just stopped the other day. I was stumped, but determined to fix it. This blog had all the answers - much appreciated.

Anonymous said...

I was about to hit mine with a hammer before I read this blog. Great play by play and pics help too. I found that after prying the four tabs apart on the bottom that sticking toothpicks in beside them allowed the outer housing to slide off easier. The power knob is a pathetic design. I am now like "PUFF" and use the inner button but tied the lid safety wires so I am back in business.

Anonymous said...

Great play by play! I found that after prying the tabs apart that sticking 4 toothpicks in beside the tabs allowed the outer housing to slide off easier. The on/off switch is a pathetic design and I am now like "PUFF" and use the inner button but have bypassed the lid safety so I am back in business and didn't have to fork out another $100. Thanks!

John A said...

So would it be possible to bypass the electronics and install a simple on-off toggle switch to control the grinder? KISS approach?

jl said...
This comment has been removed by the author.
jl said...

thanks for the guide. i think mine had a burnt resistor(guessing by the scorch marks on the PCB, didn't test). I connected the AC power directly to the motor. It works now, sort of.

Ari said...

Thanks! That sure did the trick.

I ran across a few issues which might help others. First, yes indeed, that coarse/fine knob is tricky. The tabs that you need to push in are part of the knob and you don't need to push them in too much. Like others mention, you'll probably find it easier to have three screwdrivers (or toothpicks) or something.

The four tabs for removing the exterior case are on the bottom of the unit. You'll see the manufacturer's signs if you look.

The faux metal front face has two tabs that snap into the bean housing. I broke one off but it didn't seem to make a difference.

Lastly, I didn't use solder - I just stripped the wires, twisted them together and put some electrical tape on. I'm 100% sure about this but I usually don't use solder when you can just twist and tape (or use those twist on caps but that's more for heavy duty electrical work).

Again, thanks. If it wasn't for you, I'd probably be out a grinder.

And just in case you're reading this - how did you know how to take out the grind selector (with those three tabs)? Brilliant!

julencin2000 said...

Thanks for this dissasembly guide, I've been able to fix (by now) my grinder.

Leon said...

Many thanks for the excellent repair guide. Works like a dream now.

Michael Judd said...

Hi,

I found your post very helpful in disassembling my Coffee Grinder in a way that I could put it back together.

In my case, the button arm was broken and I was able to mend it by supergluing the piece back together and then reinforcing it by supergluing a piece of beer can around the arm.

Here are the photos:
link 1 and link 2

It seems to work better now than it ever did, as the button has an additional stiffness.

Steps to fix the "t" arm
I cut open a beer can, and cut a piece in a rectangle shape slightly bigger than the "t" bar. After gluing the arm together, and allow it to set, I then glued the rectangle to the back of the "t" rm. (nb: I'm calling the back the face that is away from the front of the button when installed)
I then cut the rectangle under the "t" arms and wrapped this around the stalk of the "t" overlapping in the front and gluing the flaps in place.
I then trimmed the additional beer can from the top of the "t" and punched a hole through the middle of the "t" intersection so as to make way for reassembly with a screw.
From there - I just reversed the directions for dissembly and the machine is as good as new.

Thanks again for the video and I hope some people can restore their unit back to full working order with the "beer can splint".

Mike Groys said...

Your guide rocks! Was really pushing off fixing the flaky safety switch because didn't want to break the case...

Thanks!

pav loves blogs said...

Pav (of Edinburgh)
Thanks for this EXCELLENT maintenance guide (better than Krups' own..) Broken on-off push-button was my problem.

Rather than repair the "T"arm (ridiculously weak..) I cut a paperclip into a "U" shape inserted the top ends into two small holes drilled in the button body, & trapped the bottom of the "u" behind the original T crossbar with the screw. It works!

Ground coffee at last... AAAH, the relief!!
Thanks once more

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Sasha Anferov said...

Thank you so much for this maintenance guide! Your advice is much appreciated- I spent hours trying to pry open the bottom plastic with force before I saw your method.

steve carville said...

Thankyou for this. Soldering on the PCB was my problem. A quick once over with the iron fixed it!

mlessa1@mac.com said...

Joe, thanks a lot, I was able to repair the power switch based on your guide.

Dave Cooper said...

Great guide thanks. I was able fix the power switch that had sheared at its screw fix position. I superglued back together and reinforced by adding a thin oversized washer between the switch and screw. Take care when detaching the top lid sensor (attached by 2 screws with serrated washers) as the black plastic cylinder can fall out easily. Gave it a really good clean too and now as good as new!

Eric said...

Just wanted to add my thanks too for this excellent guide. I bought a used GVX2 with a broken power button. What a silly design! I superglued it and reinforced it with a piece of credit card. I almost lost the black pin that activates the lid safety switch, and I ultimately did lose the spring for the grind control knob. Still, it is working well and I'm grateful to get it working again.

mikeola said...

Hi, great disassembly write-up that I may have to use, but I'm hoping you or a visitor has a better suggestion for me. I can't for the life of me get the "removable" grinder part out, and it is badly in need of cleaning (currently everything comes out coarse regardless of setting). I think I'm supposed to just twist it in the direction of the "unlock" arrow, then lift it out. But I can't get it to unlock, and I'm twisting so hard that I'm on the verge of breaking the vertical Y handle. Am I doing something wrong? Only other thing I can think of is to follow these disassembly instruction and hope that I can gain access to a better position from which to twist harder without breaking.

Eric said...

Mine was really tight at first. I tried a few times without much luck, but I think it finally budged when I held onto the grind knob (they are mechanically linked). Might be worth a try.

yflyer said...

Very nice writeup, thank you. If you don't want to mess with trying to repair the switch button, they are available online for $5.

http://www.smallappliance.com/product.asp?pid=15169&cam=GA_B_krups&sid=18956&mid=15&gid=18961&prdCls=P&pfor=2832&shopBy=Brand

DrJ said...

Thanks so much! I've managed to disassemble mine without breaking anything!

I've used mine for 8 years now. Good buy I'd say. Nevertheless it started to grind to coarse after a time. I've added 3 0,5mm washers to the top grinding part and fastened screws holding motor in place and now it grinds perfectly.

Also as a side note, DeLonghi grinders seem to be exactly the same hardware in different casing.

Reimer said...

My seems to have a burned resistor, the one which is located in a small window in the PCB. The value is unreadable, all colors are grey... Anyone knows the value? My PCB is "M521-502 REV.D"

seglea said...

Great guide, thank you. I went for the new start button option - the part number is SS-192581, put that and Krups into Google and you'll quickly find a supplier who will mail to you. Now, can anyone tell me where the red 1cm washer I've got left over should have gone?

Per said...

@Reimer: Mine is a Rev. C but maybe the resistor is the same. I don't know which resistor you need so I posted a picture of my Rev.C PCB at http://imgur.com/tl3jr0j

Per said...

Thanks for the disassembly guide. Probably would have trashed the course/fine knob without it.

I managed to get into my grinder and rotate the coarse/fine shaft a bit to allow a more corse grind for Prezzo coffee. I know that some people adjust it the other way for espresso.

I don't understand why there is almost no difference between the most coarse and the finest setting on these grinders. The scale should have been a bit steeper.

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PerP said...

Thanks for the guide. I would probably have trashed the grinder without it.

IDP said...

Hugely helpful. Thanks for documenting the info so carefully.

Unknown said...

Much thanks. Minehad both the start button and top safety switch button alignment problems. All fixed. Thank you so much

Danto N said...

Yeahhhh so easy when so well explained !
thanks !!

Joel said...

Adding to the chorus of thanks...living overseas with an imported Krups. I was ready to just replace it with a rotary grinder, but you got me up and running.

Jesse Livermore said...

Thank you for your guide.
Like others who've commented here, our problem was the power button.
The power button and the the detents for the timer knob are a single piece of plastic, the connecting section of which is a thin strip of plastic. Pressing the power button depresses a microswitch by means of a small protrusion on the back of power button. Poorly designed to act as a hinge, the plastic will inevitably break.
I just removed the power button altogether and simply press the microswitch with my little finger. Not the best solution, but it works. Probably best to keep one's finger dry though :)

Davidjohn said...

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Angelo Rudic said...

I bought my grinder in February 2007, so it's almost 10 years old , [I Taped the date on a little bit of paper underneath the grinder ), and it has been giving me grief for probably the last 4 years or so. It grinds beautifully - I just love it ...(when it works), the little micro switch on top would get dirty with coffee debris and wouldn't work so I had to clean it with a small brush, and then I noticed the main power switch started to be loose and it was very flaky as to whether or not it would engage. It had to press it "just so". I tried to figure out how to take it apart so I could replace the switch or put a toggle switch in it for the longest time but couldn't figure it out until I found your blog.
I bypassed the microswitch by soldering the two wires together and as many other posters here have experienced, the cheap little plastic connection that proved to be a huge weak spot in the power switch design was my issue as well. So I rigged up a little "splint" out of a tin can lid, drilled a 1/8" hole through one side of it to coincide with the hole in the plastic piece that allows a small screw through it to keep it in place; then I mixed up a tiny batch of J-B Weld Epoxy and glued the tin metal splint on the back of the 2 broken pieces, tying it together like a cast. Plus having a hole drilled in the new metal will give ithe whole piece extra strength when I screw it back in. ( many thanks to one of the posters previous to me that gave me the idea )! So I just have to wait until the epoxy hardens to put it all back together.
Thanks to the owner of this blog!,

Andreas Ullrich said...

Your hints on how to open the housing were tremendously helpful. Thank you so much.
Best
Andreas
Vienna, Austria

Max Edgar said...

Awesome job, my on/off switch broke and fell inside the machine. Fixed in under 20 mins with this guide. Thanks.

Mick C said...

Very good instructions my coffee grinder started playing up a few day ago starting and stopping after a few seconds
Instructions helped me to open the unit after checking the safety switches I temporary bypassed them and carefully turned it on, it started and just noticed some small sparks coming from a soldered joint on the printed circuit board,
After isolating the power closer inspection revealed a loose connection onto the PCB at the yellow capacitor joint a quick soldered joint an test corrected the fault. I can now look forward to my coffee in the morning

Thank you

Bryant Yudhistira said...

My grinder still able to turn on the light button. But the motor could not start. When i release the button, the light will turn off. Any advise? Thanks

Unknown said...

Thanks man! Your post saved my grinder. I couldn't figure out how to open it but your instructions made it easy. The on/off switch plastic bit broke off and I glued it back on with two-part epoxy.

New Born said...

Thanks for the guide. Managed to open it with your tips.

Alex Fiz said...

Wow! Great post it helps me a lot, I'm impressed; Your idea is outstanding; the issue is something that not enough people are speaking intelligently about. I am pleased that I stumbled across this in my search for something relating to this.
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