What is a tachogenerator in a washing machine?

Sometimes, after giving the washing machine to the service for diagnostics, the owners of the equipment hear from the technician that it would be a good idea to replace the tachogenerator. Without understanding what part is being discussed, people agree to pay an extra thousand or one and a half thousand for the repair. But is the tachogenerator really broken, or is the technician forcing an unnecessary service on you? Let's figure out what function the Hall sensor performs and how to check if the part is working properly.

Purpose of the tachometer sensor

The "heart" of any washing machine is the electric motor. It is the one that makes the device work, converting electrical energy into mechanical energy. The tachogenerator in the washing machine is an element that controls the engine speed. The Hall sensor is located on the engine rotor.

The tachogenerator monitors the voltage of the electric current generated by the motor. Thanks to the tachogenerator, all the units of the automatic machine operate as specified by the program. If an element fails, the drum will rotate chaotically, slower or faster than specified by the settings.

It is easier to find and check the tachogenerator in washing machines with collector motors. It is very easy to understand what motor your machine is equipped with. Remove the back wall of the case and see if there is a pulley with a drive belt behind it. If so, you have a collector in front of you.

If there is no belt drive mechanism, then the washing machine is equipped with an inverter motor, and the Hall sensor is built into the housing. The tachogenerator measures the speed of the electric motor and transmits this information to the main control unit. The data is processed, and the module gives a signal to either speed up the rotation or, conversely, slow down.

How does a broken tachometer show itself?

When the tachogenerator stops performing its functions, the normal operation of the entire automatic machine is disrupted. The "brain" of the washing machine does not receive information about the motor rotation speed, so it cannot control the drum speed during washing, rinsing and spinning. What are the main "symptoms" of a faulty Hall sensor? What problems can such a breakdown lead to?

 

• The engine of the automatic machine constantly operates at high speed. Due to this, there is a strong vibration of the body, noise, hum and knocking are heard inside the washing machine.
• The engine experiences increased load, which is transmitted to both the drum pulley and the shock absorbers. Therefore, the parts wear out faster.
• When the engine speed is not controlled, the drum and the entire drive mechanism become unbalanced. For this reason, the pulley belt quickly wears out and breaks.
• Due to the chaotic rotation of the drum, the bearing assembly fails faster.
• In machines with an inverter engine, when the Hall sensor breaks down, a constantly increasing squeak is heard. The rotation of the drum is blocked in this situation.
• If the tachogenerator breaks down, the washing machine starts to work in jerks, and it also does not start spinning.

If the washing machine vibrated and hummed a lot, and then the cycle stopped and the error code lit up on the display, look at the equipment manual. The designation of the breakdown on different models of equipment is different, so only the user manual will help to decipher the error.

How to test the tachometer correctly?

If you suspect that the machine has stopped working due to a broken Hall sensor, check the part yourself. The tachogenerator is diagnosed using a multimeter. The device will help measure the voltage of the element and draw a conclusion about its serviceability.

First, turn on the multimeter and switch it to the dialing mode. Apply the tester probes to the tachogenerator contacts, and with your free hand, rotate the engine rotor, no matter in which direction. If the measuring device "beeps" while rotating, and the arrow on the display oscillates, then the Hall sensor is working properly.

Next, switch the measuring device to voltmeter mode. Set the reading limit to 4-5 volts and place the tester probes against the tachogenerator contacts. Rotate the rotor again and observe the values ​​on the multimeter screen. If the tachogenerator is working properly, the voltage generation will be 0.2-2 volts.

If the multimeter test did not reveal a sensor fault, make sure it is securely fastened to the electric motor. The mounting bolt may have come loose or the power contacts may have come loose. In this situation, you will need to tighten the screw or tighten the wires. You can also use a multimeter to measure the resistance output by the tachogenerator. Normally, the reading should be about 60 Ohms. If the Hall sensor shows no activity at all when tested with a tester, the element will have to be replaced.

We replace the faulty part

Having found that the tacho sensor is faulty, you will have to buy and install a new part. You need to buy components suitable for a specific model of washing machine. Before starting work, be sure to de-energize the equipment. Next, dismantle the back wall of the case and find the electric motor, and on it - the tachogenerator.

Then you need to unhook the Hall sensor contacts and pull it out of the mounting location. During the dismantling of the element, you will need a small thin screwdriver. When the connectors are disconnected, remove the top cover of the tachogenerator. It may either not be fixed or held by several screws.

When dismantling the part, it is better to take photos so as not to make a mistake during reassembly and connect the contacts correctly. Using the photos as a guide, install a new tachogenerator. Then put the back wall of the machine body back in place and run a test wash.