Electrician Q&A. Real questions and professional answers. Part 2

  • Dec 21, 2020
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I continue the series of articles in the "question-and-answer" format for electrical and household electrical equipment. You can find the first part of the answers to the questions at the link at the bottom of this collection.

Question N1. Asked by Stepan. The question itself is literally:

Recently, my dishwasher began to draw up water uncontrollably, up to overflow. Tell me, what could this be connected with and is there a possibility of self-repair? The machine is still under warranty, but you don't want to turn it off and take it to the service.

My answer was given like this:

There are several reasons why overflow occurs, that is, a constant collection of water in the absence of a drain. The problem can be caused by:
- Violation of the Aquastop protection.
- Faulty water level sensor.
- Breakage of the intake valve.
- Incorrect hose connections.
You can find out how to directly eliminate the listed malfunctions by visiting thematic sites (search in a search engine).
Before proceeding with self-repair, it should be borne in mind that such actions lead to a complete loss of the product warranty.
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Question N2. Dmitry asked. The question itself is literally:

Hello. For more than 3 months now, my washing machine has begun to emit a strong hum as it draws water. In addition to discomfort, there are no other shortcomings in the work. Tell me, what can cause this and does it make sense to call the wizard, or let it continue to work like this?

I gave the following answer:

Let's consider several possible reasons:
1. The hum is produced by solenoid valves. This is due to their resource depletion, which occurred due to long-term operation of the solenoids or due to low pressure in the water supply system. The hum produced by the valves does not affect their operation in any way. That is, if the noise does not cause discomfort, then the solenoid valves can be left, otherwise, install new ones.
2. A blockage in the strainer of the filling valve, which makes the latter noisy due to a decrease in pressure. The problem is treated by replacing or cleaning the filter.

Question N3. Fedor asked. The question itself is literally:

Good day! While renovating a recently purchased apartment, I discovered a problem with ventilation. Instead of drawing in air, it creates a reverse flow, that is, blows. Tell me what caused this and suggest the most effective solution.

My answer was as follows:

Backdraft formation in ventilation systems is a rather unpleasant phenomenon, which can be caused by the following reasons:
1) Incorrectly installed exhaust pipe on the ventilation duct.
2) "Clogging" of the ventilation duct with steam or cold air.
3) The presence of foreign objects in the ventilation ducts, for example, broken bricks or other debris.
4) Formation of established air flows (drafts). This is typical for large rooms.
5) Creation of air flows by various household appliances, such as fans, air conditioners, etc.
Installation of forced ventilation allows you to effectively cope with this problem.

Question N4. Kolya asked. The question itself is literally:

Good day. On the Chinese garland, two of the four channels stopped working. The lights rang, everything is normal. As I understand it, the fault is in the control board itself. Is there a way to fix it yourself or do you need to buy a new garland?

Kolya received the following answer:

Everything that the Chinese have done, in theory, can be repaired. Most likely, your daisy chain control board is similar to the one shown in the figure.

Since two lines out of four are working, it is highly likely that two control thyristors (VS1-VS4) have failed. All you need to do is check the thyristors and replace the burnt ones.

P.S. Part 1 of answers to electrical questions.