Maintenance | Mahlkonig E65s & E80s GbW Load Cell Troubleshooting

Maintenance | Mahlkonig E65s & E80s GbW Load Cell Troubleshooting

Sep 7th 2023 Written by John Erler

Hi, this is John with Prima Coffee and in this video, we're going to talk about troubleshooting the load cell on the E65 and E80 grind by weight, espresso grinders. So recently I did a Q&A about general coffee maintenance. One question I got to ask was, is it worth the risk of getting the Mahlkonig GbW Grinder series? And I think there's a lot of lore about the reliability of the load cell on these grinders. It's actually pretty robust. It's fast and efficient, and when well-maintained, it should last for quite a while. So definitely recommend getting the GbW if that fits within your workflow in your budget. Okay. So let's go ahead and take a quick look at the load cell assembly on this grinder.


Mahlkonig Espresso Grinders

Mahlkonig E80S GbW

Fast, Precise, Reliable

Pull off the grounds catch, and then pull off the cover plate, and here we can see the load cell. If you don't know how a load cell works, basically we put pressure on this device and resistance changes, and that's calculated into a voltage change. That calculation goes into this computer in the grinder and that measures the weight that the load cell is weighing. So on this, we have the portafilter fork assembly. As we put the portafilter on, it presses down on the load cell and that shows us our weight. One thing to keep in mind is keeping the load cell area clean free of moisture and coffee grounds. Coffee grounds will get down in there. So I recommend just doing a nightly cleaning to make sure that that's clean. Another thing is handling. Don't want to grab this grinder by the portafilter fork. You don't want to hit the portafilter fork with the Portafilter because that can overload the load cell here and could possibly deform or damage it and then it won't properly weigh any longer. Another thing that can happen is you can throw the fork assembly out of alignment or deform that. And that again may just continue to put pressure on the load cell when you don't want it to. It can cause ghost grinding or can cause inaccurate weight output. So generally I like to just if I'm having problems, I like to look at the assembly and make sure everything looks in order. Specifically where the fork is here you want to see that you have kind of a uniform space from top to bottom, and it's not obviously pushing down on the load cell when it should not be. Okay so the way this grinder works is when you put the portafilter under the portafilter fork, it tethers the weight out of the existing weight on the fork before it starts grinding, so it can accurately measure what comes out of the grinder. There are three resolution modes on this grinder, a high, a medium, and a low. On the highest setting, you're getting your most accurate measurement. However, in a busy cafe, that high resolution setting because of vibrations, because of movement, may make it difficult to use the grinder. It will just take longer to tare out. I don't have a lot going on here, but I do have it set on high resolution and I'll just show you how long it takes. Okay. Obviously, again, not a lot going on here. If it was vibrating, I would end up waiting a bit longer. I'll demonstrate that for you. Okay. And then it settles and then it grinds. Not ideal for a busy workflow.

So if you are experiencing that problem before you look into any issues with the load cell operation, I recommend checking to see that your resolution is set appropriately for the space of the grinder sitting. And so to do that, we're going to go into the settings menu. Okay. To get there, I enter a password. Okay, successful log in. Okay, Now I'm going to go back to the settings menu and I'm going to go down to Internal Presets. Okay? Here we see the BW resolution. As I mentioned before, we're currently set on high, so I'm going to go ahead and select that and I'm going to set it on low. Okay. And then I'm going to exit. And now we should be able to grind with some amount of vibration without the delay that we would have had on the high resolution. All right. Much quicker. In some cases, you can put down rubber matting underneath the grinder to dull the vibrations coming up through the counter. But generally, especially in a cafe environment, I like to be on medium to low for the most efficient use of the grinder. After we've looked at the load cell assembly to make sure there's nothing going on there, we know our resolution is where we need it to be. The next thing we'll do is we'll actually look at how the load cell is actually measuring out. So I've already sabotaged this grinder, so I know it's out of calibration, but I'll just go ahead and show 18 grams. Put the portafilter in, it’s gonna grind. It thinks it's at 18 grams. I'm going to go and weigh it on the scale. We're getting about seven and a half. So obviously it's off. Though, before I go in and just recalibrate, I'm going to see what the Grinder thinks things weigh and in order to do that, I'm going to use our calibration weight. The one kilogram, 1000 gram weight you can get pretty much anywhere, but does not come with the grinder. So you have to buy this separately. In order to do this easily, I'm going to go to Portafilter detection just on the main screen and I'm going to go ahead and insert the weight and it says unknown. So I'm going to go ahead and add portafilter.

Okay. So as you can see here, it thinks that this one kilogram weight is nearly 2.5 kilograms, which is obviously not correct. That's pretty extreme. For general knowledge, you don't want to see a difference of more than about 3%. You wouldn't want to see anything less than 997 grams or 1003 grams. You see anything higher than that? That may be an indication that there's an actual problem with the load cell or the calibration is off. We're currently showing 1000 kilograms at 2503 grams. So we're going to go ahead and calibrate. Okay, so we've already entered the menu so I don't have to put in password again, go out of there and I'm going to go down to service and then I'm going to go down to calibrate. Okay. It's going to prompt you to remove the portafilter. Obviously, that's out of the way. So we're going to go and press the jogdial. Okay, I'm going to go ahead and take our one kilogram weight again and I'm going to put it on the forks and then I'm going to press the jogdial. Okay, so calibration is complete. I don't need to redo it. I'm going to remove the weight and I'm going to say complete. Okay. So after we've calibrated, I'm actually going to go ahead just in case it shouldn't be a factor because it should not receive this weight as anything but close to where it should actually weigh, but I'm going to go back into the settings and go to Portafilter management, and I'm going to select our overweight portafilter that we did on the previous check. And I'm going to delete it and I'm going to go back out to the main screen and I'm going to go back to detection and I'm going to place our weight again, unknown. Good. So we're going to add it. Okay, great. As you can see, we are almost right on the mark at 1,000.3 grams. So we know that we have successfully calibrated the grinder to go ahead and test for the coffee. Just keep in mind that the grinder tends to triangulate. So after you do a calibration, it may take 5 to 6 grind cycles before you're really honed in. And it should be fairly close. But it may take up to that many to get as accurate as this grinder can get. All right. Let's go ahead and grind some coffee. Okay. 17.8, 17.9, getting pretty close again. You would go ahead and do about five or six cycles to really hone it in and then you should be good to go. All right. I'm John with Prima Coffee, and that is our video on how to troubleshoot issues with the load cell on the E65 and E80 GbW Mahlkonig espresso grinders. Thanks for watching.

Sep 7th 2023 John Erler

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