Repair a Nespresso MX 100 Coffee Machine

With this instructable, we will look into fixing a refurbished Nespresso coffee machine that won't power up.

When plugged in with the power button switched on, nothing happens : no light, no sound and worst of all... no coffee!

How to fix this coffee machine, that still worth more than a hundred bucks, knowing it's now been out of warranty for a long time?

Step 1: The RTFM Principle

A former colleague onboard the first boat I worked on kept telling me "RTFM", which means "Read This Fu**ing Manual". Indeed.

I found a user manual after a quick search online, on the website manualslib.com, which I highly recommend. Unfortunately, as many of other user manuals, it won't help much. Though, it did allow me to confirm this coffee machine was not working as it should.

We'll have to go for a further investigation, and open the beast.

Step 2: Dive In

Let me tell you something. I worked as a maintenance officer onboard the world largest luxury motoryachts for about 8 years, and it at least teached me one thing: 90% of breakdowns can be fixed really easily (ok, the last 10% usualy tend to be proper nightmare). And the first thing to do is to observe attentively our machine.

As everything seems to look fine from the outside, we'll have to dig in and open the beast to try and find what's wrong. Remember to always unplug your appliance before doing any work on it (and allow for a few minutes until the condensators discharge themselves).

The first surprise that always drive me crazy is finding out Nespresso super-engineers seem to love oval-shaped screw heads. No philips, tork nor triangle screw heads. Oval ones. You know, that kind of screw heads that most of regular screwdrivers kits can't deal with. Thanks guys, very nice move.

Luckily, I'm not the only one to find this unpleasant, and the great guys from iFixIt made multi-purpose kits to get through all the nasty tricks that anti-repair engineer squads could come with. Thus, I would strongly recommend you to get one of these to get ready for further repairs. I got the iFixIt Manta Driver kit from ebay, and it has loads of bits. Highly recommended.

Now being properly equipped, I can open the coffee machine: there's a total of 8 screws (6 on the bottom, 2 below the capsule box). Once those 8 screws are removed, you'll have to get rid of the side covers (the red parts you see on the picture). To remove them, slightly pull them up until they get free. Make sure you don't force them so you won't risk to break anything. Once this done, remove the base, and make sur you unclip the little white module (not sure what this is? a filter? a tiny pump?).

Step 3: Keep Calm and Observe

Now is the time to understand how all this is supposed to work. Luckily a coffee machine is fairly simple: a pump, a boiler, and a couple of buttons. However, nothing lights on, although it's properly plugged.

There must be a problem with the power supply, but no power supply card can be noticed, only a kind of control card. Let think and go step by step. We will investigate and follow the power supply from the power cord.

It seems that, before powering the control card and the buttons, the cables sneak behind the boiler (the big metal round shape you can see on the first picture). You know, the tricky part that gets really hot, is filled with water, and has a high risk of shorts or overheating issues... ok, you see where I'm going? We'd better have a look behind.

You only have to remove 3 screws maintaining the boiler and you can access behind it. We find both the live wire (brown) and the neutral wire (blue) are in contact with the boiler using a thermistor. Bingo!

Step 4: Erh... Thermiwhat?

A thermistor is a thermal breaker. It's a safety device that, when it reaches a specified temperature, switches the circuit off. As regular breakers, they're used to protect from overheating and avoid damages or fire. Problem is, once triggered, they can't be reset. They need to be replaced.

So we'll test each breaker. It's fairly easy: they should be closed (current can go through). If one is open, it means it has triggered and will need to be replaced. Using a tork screwdriver, you can easily remove the protective sheath and test the breaker. Connect your multimeter to both sides of the breaker, and mesure the resistance: you should read a value. If it shows an infinite value, it's broken.

In our case, it's pretty obvious : when I test the resistance, it shows an infinte value, an open circuit. The thermistore has triggered and the current can't go through anymore: it needs to be replaced.

We found our problem... now let's fix it!

On the outside of the damaged thermistore we can read "MICROTEMP SXHAWE E5A01 167°c".

A quick search on internet brings us to an adequate replacement: for a few euros, you can find a thermal breaker that will do just fine. Okay, the alternative solution would be to have a bunch of thermistore spares in store, but this time we'll have to wait a few days until we receive our order... Once we have it, we check the reference first, and then we can replace it.

Be carefull when you solder it: the thermistore will trigger at 167°c, and your soldering iron can heat up to 300°c... you'll have to be quick! Next time, I'll buy the one with the crimps...

Once the thermistore is soldered, put back the sheath an fix it as it was on the back of the boiler. Put all the parts back in place... but make sure that all the hoses are properly connected before you close everything!