In 2019, the transition of Russian television to digital format ended. This circumstance caused a lot of trouble for owners of old TVs. They had to buy new televisions or special set-top boxes that would allow the new television to work on old devices.
Digital terrestrial broadcasting set-top box of the international standard DVB-T2, a full-fledged device that performs complete signal processing and transmission to a TV or monitor.
Most digital set-top boxes in Russia come from China and have a very limited working resource. Even if the manufacturer is a serious company, the quality of the components used in the devices leaves much to be desired.
This fact is not very pleasant for users on the one hand; on the other hand, work has appeared for electronics repair specialists.
A broadcast TV set-top box is a complex electronic device and a malfunction can occur with any of many elements.
The most common cause of malfunction of the DVB-T2 set-top box
For electrical power supply of set-top boxes, standard external and internal switching power supplies are used.
If the external power supply malfunctions, it is enough to replace it with a new one; an experienced electronics engineer should deal with the internal power supply.
The practice of repairing digital TV set-top boxes is not yet widespread, since the devices appeared relatively recently. But still, some faults are marked by specialists as typical, that is, repeated on many devices of the same type.
One of these malfunctions is the failure of the filtering electrolytic capacitor of the secondary circuit.
This capacitor is installed on the secondary voltage bus and connects the plus to ground. This is necessary to eliminate pulsations.
When the capacitor fails, a short circuit occurs. The power supply goes into protection. The capacitor is inflated, but may remain intact.
Analysis of the “behavior” of the set-top box helps to identify this malfunction. In some cases, when the set-top box is connected to the network, it emits a high-frequency “whistle” of varying degrees of volume. In other cases, the device is “silent”, but the main factor is the lack of light on the indicator.
There are several reasons for the breakdown
- The first reason is the use of a set-top box with an active antenna. This type of antenna uses a signal amplifier, and it is powered from an external power supply via a standard coaxial cable. For this case, the set-top box provides an active antenna power mode. Using an external power supply instead of the built-in mode leads to overload and failure of the capacitor in question.
- In the second case, the part fails due to poor quality.
To eliminate the malfunction, in most cases it is enough to replace the failed capacitor.
