• Please note that these guides are only informative. It can be dangerous to plug partially disassembled devices. Always unplug the device when working on it. If you’re not sure how to proceed, contact a local repair café or a professional.

Electronic problem

Blender The appliance turns on or off by itself, operates intermittently or the lights come on randomly
Electronic components are increasingly present in all "modern" household appliances. While they increase the functionality of the appliance, they also considerably increase the risk of problems.

STEP 1 Refine your diagnosiss

The symptoms of an appliance whose electronics are starting to malfunction can almost always be detected by "strange behaviour":

  • the appliance switches itself off;
  • it turns itself on;
  • it works intermittently;
  • the various lights come on at random;
  • the work cycle does not reach the end of the programme;
  • it no longer responds to commands;
  • the duration of the programmes is no longer thIn some kitchen mixers (food processors), there are functions for cutting ice, making smoothies, whipping cream, making mayonnaise, etc. Each function has a specific speed program, including maximum duration of operating and necessary breaks, which should be respected.
    Electronic components are therefore increasingly present in all "modern" household appliances. While they increase the functionality of the appliance, they also considerably increase the risk of problems.
  • ...

In this case, you know that you have an electronic problem.

Please note that fixing an electronic problem is often complex as there are hundreds of different components. If you have no idea what to do, we recommend that you go to a Repair Café or professional repairer. If, on the other hand, you feel able to venture out on your own, you will find below the 3 most commonly repaired electronic components in this type of device :

  • Capacitors - Go to step 2 for more information
  • Resistors - Go to step 3 for more information
  • Triacs - Go to step 4 for more info

STEP 2 Resolve a failure related to a capacitor

Capacitors are the components that undergo the most changes in their behaviour when they deteriorate. A damaged capacitor can cause the whole device to malfunction. 
To check a capacitor, you need a Multi-function Tester (see picture : TC1 Tester, 15-20 euro) or a multimeter with such an option. With it you can measure the capacitance of a capacitor. The unit of measurement is the Farad. In practice, however, the capacitors used have capacitances a thousand or million times lower than 1 Farad.

If you have connected your appliance to the wall, it is good practice to discharge the capacitor (which by its nature is an energy store and therefore may still be charged even if the appliance is disconnected). Beware, there are capacitors that are connected to 230V current. If they are still charged they will give you an electric shock!

Once you have identified the capacitor to be tested, use a 20 Ohm resistor to discharge it. If you do not have the resistor, you can use a 230V AC incandescent bulb, which you connect to the ends of the capacitor.

Once the capacitor is discharged, use the multimeter, set to Capacitance, to check if the measured value is e

STEP 3 Resolve a failure related to a resistor

Resistors sometimes change their capacitance due to the high temperature they have been subjected to, and cause the system to malfunction. 
To check whether a resistor is in good condition, use a multimeter in the Ohm (resistor) position. First read its value through the coloured bands on its body (see table: Resistor Identification). Once you have decrypted its theoretical value, use the tester to check that it is still good.

If the value you read on the tester is very different (resistors can have a tolerance of up to 10%), you must de-solder at least one of the two pins to isolate it from the circuit. If even in this condition the value does not match, the resistor is defective.

STEP 4 Resolve a failure related to a triac

Triacs have only two options: they work or they don't work. They do not exhibit strange behaviour. 
To give an idea of how a Triac works, let us make a comparison with a water tap. The more we turn the knob, the more water comes out of the tap. Triacs are used to 'dose' the amount of current that should reach the motor.

A potentiometer (a variable-value resistor) is always needed to operate a triac. As the current sent to the gate changes, the current sent to the motor will change. In this way, the speed of rotation can be varied. If the triac is faulty, no current will flow and the motor will not run.

A very empirical way to check whether the triac is faulty is to create a short circuit between A1 and A2 (the 2 pins on the left when you face the code of the triac). Simply solder a short copper wire between pins A1 and A2 to create a direct current flow.

If the triac is faulty, with this short-circuit, the motor will turn at its maximum speed. If, on the other hand, the motor does not turn, the fault lies elsewhere.

Background information

General repair tips :


  • Always unplug the device when working on it
  • If you’re not sure how to proceed, contact a local repair café of a professional.

Source of this information

This tutorial was written by Repair Together - the network of Repair Cafés in Wallonia and Brussels (Belgium)

Are you a maker who likes to repair things?

With this project, we try to create relevant guidelines on a product category and frequent faults level. The exercise is led by different repair networks, but our content can only grow and improve thanks to your help.

Guy repair item