We check and change the UBL of the washing machine

All automatic washing machines are equipped with hatch blocking devices - these devices are abbreviated only as UBL. What is UBL for and what function does it perform? This device is necessary to ensure safety during washing - it blocks the hatch door. If the UBL is broken, then washing will become impossible. How to check the UBL of a washing machine with a tester and make sure that it works?

Before starting an article on repairing UBL, you need to talk about the fact that there are two types of these locks:

• Thermal locks operating on the basis of a bimetallic plate;
• Electric locks built on electromagnets.

Almost all modern washing machines are equipped with the first option. The hatch blocking device with a thermal lock has higher reliability and endurance. In addition, it is simpler in design and less likely to break. Therefore, in this review, we will pay attention to thermal locks.

The principle of operation of the UBL washing machine

The device for blocking the hatch of a washing machine based on a thermal lock is very, very simple - inside there is a bimetallic plate and a thermoelement that heats up when voltage is applied to it.Under the action of heat, the bimetallic plate instantly heats up, bends and, with the help of a special lock, blocks the loading hatch door.

At the same time, the contact closes, signaling to the control module that the door has really closed - then the selected washing program starts. By the way, the indicated contact is part of the self-diagnosis system. If for some reason the hatch lock does not work (the hatch is not closed correctly, the thermocouple is broken), then the control module will display the corresponding error on the machine display.

Reasons for Unlock Delay

Have you noticed that after the end of the program, the washing machine does not open the hatch immediately, but after a few minutes? Why is there such a delay? The thing is that after the program is stopped, the supply voltage is removed from the thermal lock. Due to this, a gradual cooling of the bimetallic plate occurs. As soon as its temperature reaches a certain value, it will take its original shape and move the latch of the loading door - you can take out the laundry and send it to dry. Sometimes it happens that you just need turn off the washing machine during washing - how to deal with such a problem, we told in a separate review.

Another advantage of the thermal lock

Thus, UBL washing machine has an extremely simple and durable design. And even if the power goes out, after a few minutes the lock will automatically unlock. If an electromagnetic lock is installed in the washing machine, then the lock will be released only after the power supply is restored - this is another drawback of this type of locks.

How to check the UBL of a washing machine

In order to check the UBL of the washing machine, you need to find a suitable power supply and connect it to the appropriate pins. As soon as voltage is applied to the thermoelement, the bimetallic plate will fix the lock - a click will be heard. If everything is in order with the lock, you need to check other nodes.

For example, you should check the voltage supply from the control module. To do this, we apply the tester's probes to the contacts of the lock and run any program, controlling the presence of voltage. If there is no voltage, we check the control module and the UBL electrical circuits.

Replacing the locking device of the hatch in the washing machine

Do-it-yourself UBL repair of a washing machine comes down to a complete replacement of the lock. But what can cause it to break? The most common cause of failure is the loss of the properties of the bimetallic plate. Over time, it is destroyed due to constant heating and cooling. As a result, it breaks down and the lock itself can jam in the open or closed position. Let's figure out how to replace the UBL on a washing machine.

The description of the repair process should begin with a situation where we have the opportunity to open the hatch. We arm ourselves with a screwdriver (or pliers, depending on the design of the clamp) and remove the clamp of the sealing rubber cuff. After that, carefully remove it and unscrew the two screws with a screwdriver, the caps of which are visible on the sides of the lock hole. Next, we put our hand into the space between the tank and the front wall and remove the lock out.

The lock itself can be changed very easily - remove the connectors with wires, and then connect a new lock to them. Next, install it in a regular place, fix it with screws. After that, we return the cuff to its place, making every effort so that it is put on correctly. We fix the cuff with the removed clamp and proceed to the test wash.

What to do if the lock is stuck in the closed position? Without access to the screws, we simply cannot remove it.. Therefore, we arm ourselves with tools and remove the top cover of the washing machine. We reject its body back and stretch our hand between the body and the drum - here we need to feel for the lock latch and move it to the open position. After that, open the hatch and proceed to the above repair procedure.

Is it possible to start a washing machine without UBL

As already mentioned, in the design of the thermal lock there is a special contact related to the diagnostic system of the washing machine. As soon as it is in the closed position, the washing machine will understand that the loading door is securely locked, and you can start the washing program.

If the lock is still broken, then it will send one of two errors to the electronic module:

• The hatch does not close;
• The castle is permanently closed.

In any case, we will see the corresponding error on the display of the machine. It is impossible to start the machine without UBL, as this is contrary to safety - an unlocked hatch can be opened, which will lead to flooding of the room (and at the same time the neighbors below). Therefore, all washing programs start only after a signal is received to close the hatch.

But we can generate this signal ourselves by closing the corresponding contacts.This is only permissible when testing the washing machine. In real operating conditions, this cannot be done (besides, this process is very difficult). It is best to replace the UBL and forget about the breakdown - thermal locks are characterized by a fairly reasonable cost and are not in short supply.