How to test the fuses and elements in your Delonghi Coffee Machine

I often get customers calling me telling me they require a replacement thermoblock or flash boiler. I ask them, Did you test the fuses and element, often they have not. To avoid ordering and paying for the incorrect part, I will quickly go over the procedure for testing the fuses and elements in your machine. You will need a multimeter and you will need to know how to use it. You will need to know how to get an ohms reading and complete a continuity test. So get this covered and then come back.

Right so you have a multimeter and you know how to use it. Your are now armed and dangerous. Please at this point unplug the coffee machine from the wall. Don’t just switch it off, unplug it and make sure its the right plug you have removed, not the toaster. Technicians have died by unplugging the wrong appliance. I survived thats why I’m warning you.

Testing thermal fuses

Ok first we will check the thermal fuses. See photo one on the flash boiler.

testing a thermal fuse

Testing a thermal fuse on the Delonghi flash boiler



I have my meter on continuity tester (makes the beep when a circuit is closed, but you know that). In the photo I am checking the fuse makes a circuit. Note I have removed the wiring. In the second photo you will see the fuses on the main thermoblock, called a Generator by Delonghi. To check these you have a problem. The fuses have a clear insulation material over them. You have 2 options and both are easy. Firstly you could slide the insulation material up the wire and test both sides of the fuse with the wires disconnected. No I did not post a photo, its too easy. Or you could test from each end of the wire for a circuit. You just want to make sure the fuse is conducting.

thermal fuses

thermal fuses on the Delonghi Generator

Now if you find one fuse is open circuit, your element may possibly be ok and its a faulty fuse. If you find both thermal fuses open circuit, wow we have had a thermal event that has taken both fuses out together. You have a problem beyond this tutorial.

Now to testing the elements

In the first photo I am testing the flash boiler (horse shoe one). I got 54 ohms, which is what I expected. Why you ask well if you look on the boiler it says 1000W @ 230V, not in this precise words. I know from the equation Resistance=Volts squared over Power,  so 230V squared divided by 1000W = 52.9 ohms. That’s close enough. If my element had failed often there is very high ohms or no circuit at all. But a wise old technician once told me “elements do strange things”. So we can not completely exonerate the element if it passes this test, but we have a higher degree of certainty that the issue lies else where.

Delonghi element testing

Testing the element on a Delonghi Flash Boiler

The next photo shows me testing the main generator element. I got 80 ohms. The element is marked 230V, 600W, so I calculate 88 ohms. Again close enough.

Element wattage
















However please note the above result I obtained by testing the elements separately, there are 2 elements wired in parallel in the Delonghi machine. So if you just test the top element with the wires connected to the top element as the picture below shows, you should get 40 ohms not 80 ohms as resistance in parallel halves the total resistance. If you get 80 odd ohms then either a fuse is out to one element or the element is out. So this test is easy as you do not have to dig for the second element or thermal fuses in order to tell instantly if all is well with the thermoblock.

So in summary, before ordering a new thermoblock or generator, eliminate the thermal fuses and test the elements. If two thermal fuses have gone or the thermoblock appears to have got excessively
hot (burning on connectors etc), then your machine may have a triac issue that requires further testing. As the thermal fuses have just done their job. If the element show no circuit or very high ohms or leaks to earth (another test I did not talk about) then it has failed and needs replacing.

find the element wattage 



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