Abbreviated as TV by Abbreviationfinder, television works under the principle of technology called I2C.
This technology was developed by PHILIPS since 1982, and later updated. Initially conceived for televisions, it is currently in use in a wide variety of electronic devices. It is the latest technology available, and since 1998 practically all TVs in the world are manufactured under this principle.
As televisions have been modernized, they have become more reliable and easier to adjust. The introduction of the Remote Control or Remote Control makes its use more pleasant, but requires additional circuits for its operation. Until not long ago, adjusting a color TV required a lot of effort and time, and now this has been simplified thanks to I2C technology.
This technique now allows the adjustment of the TV by means of a computer (which is done in the production factory) guaranteeing its uniformity, or also by means of the same Remote Control, without having to open it. In other words, an I2C TV has almost no internal settings. This is not to say that there are not a few settings left, they are minimal. On this TV, there are 3 internal settings, the Source Voltage, the Focus Voltage, and the Screen Voltage. Everything else is done via Remote Control.
The TV has a microprocessor, also called a CPU (Central Processing Unit) that will control the operation of the other circuits. This CPU comes with a small integrated memory called EEPROM (sometimes written E2PROM). In English, EEPROM stands for Electrical Erasable Programmable Random Only Memory. In Spanish, it means, Programmable Random Read Memory that can be electrically erased. This means in practical terms, that in it we can write a piece of information (say, the number of the favorite channel that we want to see, or the level of contrast that we want to have, etc.) and have it stored in memory, to use it every time we do it. lack. This data can be changed whenever desired, as happens when we decide to change the brightness, contrast, color, and all of this is automatically stored in the PERSONAL position of the Image Control.
The EEPROM will store the data of ALL the parameters of the TV that can be changed, both those that a user changes continuously, and those that the technician defines that the TV must have, and that are not normally accessible to the user, such as vertical size, sub-brightness, etc.
This means that there is going to be a very close relationship between the Microprocessor and the EEPROM. So close is this relationship that it is important to understand that many defects can occur in distant circuits (for example, absence of vertical deflection) or not turn on the TV, and be the cause of a memory problem, when the technician has traditionally looked for the problem in the circuit that is not working. The Microprocessor also directly controls the Integrated Video Processor (known as Video Jungle) that is IC LA76814, from SANYO, and the Channel Selector. These two devices are I2C devices, which means that they are designed to be controlled using this protocol. The communication between them is carried out through two lines, which are known as I2C Bus.
I2C-controlled ICs are generally highly integrated ICs, and contain within them the necessary circuits that eliminate the need to use traditional potentiometers. We will not see in an I2C TV therefore, the voltage lines that change the brightness, contrast, sub-brightness, etc, etc. There are also no potentiometers to change vertical size, linearity, etc. There are, therefore, no false contacts associated with them, due to dirt, dust and the effect of time. All of this simplifies TV, but requires a different approach than traditional.
The I2C Bus
This BUS consists of two lines, an SDA line, through which the data travels, and an SCL line, which contains the clock pulses, necessary to synchronize the devices to be controlled. Both lines are bi-directional. This means that there is a communication in both directions between the different devices.
A complete description of the operation of this Bus is not within the scope of this Service Manual. However, it is advisable to make a brief review of its basic characteristics.
Functions that perform these lines we can find
- Lower and raise the volume
- Read from memory the information of a channel recorded in it
- Inform the PLL of the Channel Selector what is the bit code corresponding to a required channel
- Tell the RGB demodulator the standard of the received or required channel.
All this transfer and reception of data could not be carried out without the existence of the aforementioned protocol. By simply making a channel change, an important data exchange is carried out, which if not ordered, could not be carried out. But in addition to the protocol, within the data line, the clock line is extremely important.
The entire control system is governed by an oscillator located in the microprocessor, which has as a reference a ceramic resonator or a crystal generally of 4 MHz. Within the microprocessor, successive divisions are carried out from this frequency that will result in final the micro communication time values. Optimal system synchronization makes it possible to apply the microprocessor on TV. After receiving instructions and processing them, the micro has internally digital-analog converters that transform the results into continuous variable voltage, in order to control the user variables. (Volume, sub-brightness, contrast, etc.) These outputs are properly connected continuously polarized to the corresponding circuits to be controlled.
Currently, microprocessors have achieved a level of integration and power in data handling so great that, in addition to the above, they are used to control certain adjustments and calibrations that until recently were made with potentiometers. This technique is known as “service mode.”