How to replace a triac in a washing machine?

Replacing a triac in a washing machine is quite simple; anyone who knows how to use a soldering iron can cope with this task. The main difficulty is to determine which semiconductor on the board is damaged and select an element completely similar to the faulty one. These two problems are not so easy for the average person to solve. Let's figure out how to properly diagnose and find suitable components.

Let's make sure the element is faulty

First of all, you will need to gain access to the control board of the washing machine. To diagnose semiconductor elements you will need a special device - a multimeter. To partially disassemble the machine, one screwdriver is enough. The algorithm of actions will be as follows:

• turn off the power to the automatic machine;
• turn off the tap responsible for the water supply;
• remove the top cover of the case by unscrewing 2 bolts;
• pull out the powder receptacle;
• unscrew the bolts holding the control panel;
• take a photo of the connection diagram of the “device” to the board so as not to make a mistake during subsequent assembly;
• reset the contacts and remove the dashboard.

To obtain more accurate results, it is recommended to unsolder the triac before diagnosing it.

However, the method of soldering semiconductors is more complicated; you will have to perform additional manipulations with radio components on the control board. Therefore, beginners prefer to check triacs directly on the spot, without disconnecting them from the module.

To check the semiconductor for penetration, you need to lean the multimeter probes against the power contacts of the triac (these are the left and middle “legs”).The tester screen may display either 0 (indicating that the element is faulty) or one (which means the part is fully functional). On some devices, the letters OL are displayed instead of 1; they also indicate sufficient resistance.

At the second diagnostic stage, you need to move one of the multimeter probes to the control terminal. In this case, the voltage drop should be from 100 to 200, minor differences are acceptable.

Next, it is checked whether the junction of the semiconductor opens. To do this, hold the multimeter probes on the power terminals and quickly touch the control contact. The readings on the tester screen should change immediately. This adjustment will indicate the serviceability of the triac.

When the semiconductor being tested produces correct results at all diagnostic stages, it means that the problem is not in this circuit element. We'll have to test other triacs. If a breakdown is confirmed, be sure to replace the part.

How to choose a replacement part?

When deciding to replace a semiconductor, it is important to responsibly select components. When buying a new triac, you should pay attention to the isolation of the element, its peak rating and opening current. But how can you find out the characteristics of a part removed from the control board of a washing machine?

Look at the markings of the faulty triac - by deciphering the inscription, you can find out all the necessary information about the semiconductor element.

Therefore, the first thing to do after desoldering and diagnosing the triac is to copy its markings onto paper. For example, if the original semiconductor bears the inscription BTB 15-700BAK, then it carries the following information:

• BT – semiconductor element series;
• B - indicates that the triac case is not insulated (at the same time, the index “A” will indicate the isolation of the semiconductor);
• 15 – peak current of the triac (in this example, respectively, 15 Amperes);
• 700 – peak voltage (in our case it is 700 Volts);
• VAK is a combination indicating the opening current of the triac, in this example it is 50 mA. The designation CB will indicate an opening current of 10 mA.

The last letters of the marking are of great importance. If there was a triac on the control board with an opening current of 50 mA, and the purchased element is characterized by only ten mA, then the machine will not operate at full power, but only at 10-20% of the possible potential.

You cannot buy replacement triacs with a lower peak current and voltage - these parameters must correspond to the original ones or exceed them.

It is also worth paying attention to the index indicating whether the triac is insulated or not. For example, it is quite possible to replace the semiconductor with characteristic “B” considered in the example with an analogue with the index “A”.

If your control board had an insulated triac, for example, BTA 15-700BAK, then you should buy a replacement semiconductor with the index “A”. If you install a new element without insulation, the control module may well short out. Therefore, it is better not to take risks.

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