Before reviewing more about protection, the System Should Be reviewed first ON / OFF or standby system of the TV. Standby methods include:
1. Menghidupmatikan power supply, power supply is characteristic of the output voltage has 'substantially' different Pls ON and STANDBY. If sorted out the power control pin of the IC directly controls the power supply program. Most of TV is currently using this type of system standby.
2. Menghidupmatikan H-VCC voltage. For example, chassis engine china, the which is dihidupmatikan VCC supply voltage H-ic oscillator. Another example is the TV-ic TDA8361 TV era, TA8690AN. Output voltage power supply of this type Remain.
3. Menghidupmatikan bias voltage to the horizontal driver transistor. This species cans be found on the chassis of TVs That TDA83xx use sharp, while the H-VCC Constantly getting voltage. Output voltage power supply of this type Remain.
4. Through the data bus, I2C (SDA / SCL), this type rarely encountered. Almost all new types of ic, support for this method.
5. The combination, in Addition to H-VCC menghidupmatikan Also menghidupmatikan Power Supply.
DOOR OR PIN-PIN PROTECTION
1. Pin IC program, Because the IC program is a 'brain' of the TV set, then the IC program is equipped with a pin protectionism. Generally high-state manifold, the which is normally at level / logic high (voltage Almost / the same as VCC). If the detected Decrease in the voltage on this pin, the IC will of course soon menshutdown TV devices.
2. IC Pin Jungle / chroma / oscillator. Generally, the new IC type (eg AN5606, TDA836xx, etc.) Equipped with protection ENT pin, the pin is usually type Low State, the which is logic low (0 volts or A Few volts Pls only the normal). If the detected voltage exceeds the threshold voltage protection, the IC Immediately turn off the horizontal oscillator.
3. Power supply control, can be found on TV jadul models, if found to be normal, the protection circuit will from Immediately shut down / to standby powersupply.
PROTECTION SYSTEM BY WORKSHOP
The existence of the protection system on the TV, not a means to remove / deactivate the protection of arable TVnya Considered already finished. Many workshops are just off protectionism and direct-hire, regardless of the function of Such protectionism.
TYPES OF PROTECTION
1. Voltage Protection Over Current Large (overvoltage 1)
This type of protection is enabled to protect the device from harm / voltage AC_IN Increasing voltage or lightning. Characteristics of protection against lightning is to find a cable tuner That Is connected from GND to the 'point is not connected' near AC_IN input connector. The basic principle uses a maximum capacity of the capacitor voltage. If observed, the cable is connected to the PCB track is 'accidentally' made for the trajectory of electrons / voltage electrical lines leading to the input. If there is a voltage That exceeds its capacity, the voltage / electron will from some of 'Discarded' so just go to the grid.
Another major protection is AC_IN voltage current protection, using similar components zener voltage AC (DIAC), this component cans be read on its voltage. Placement in parallel to the AC_IN and after a fuse. If there is a voltage of the which exceeds the limit of this component, the component will from be a short-circuit by itself, Because a short-circuit, eventually break fuse. The form is similar to the physical components of high voltage capacitors, and is generally blue.
2. Small Flows Over Voltage Protection (overvoltage 2)
This protection function to detect excessive voltage at the point of censoring. The main components are Generally Used using zener diodes. Basically, the zener diode will from Produce a voltage difference Pls energized in a reverse / upside down. For more details, see the Following scheme:
In the above scheme, the output voltage (VOUT) is produced from the calculation of VIN - VZ. VZ is the voltage of the zener. The formula is only a simplification, does not include elements of R LOAD.
From the formula it cans be concluded That if there is output voltage (VO) means the input voltage has exceeded the specified voltage (VZ). In conclusion, there is tension if protectionism.
3. No Voltage Protection (NoVoltage)
Unlike the Over-Voltage protection, this protection is whether or not to censor the voltage at a point. Try to Observe the Following scheme:
VIN is a stable voltage, Generally for voltage ic program VCC (5V or 3v3). Voltage VIN through R_PULL_UP to be voltage VOUT. The main requirements of these sensors is the voltage VOUT must not exceed the V_DIPROTEK. While the load on the voltage R_LOAD is censored.
How it works is Quite simple, if the voltage is not censored, then the voltage out (VOUT) will from dikonsletkan by the diode (see the arrow direction diodes) so That the VOUT earnest go down in value (due R_LOAD). Degrees / Large Decrease in voltage VOUT is censored. Conversely, if there is voltage at the point of outtakes, an automatic voltage VOUT will from Remain Because the voltage will from not be censored 'jump' diode (except the protection diode leakage / Damaged). In conclusion, there is no voltage if protectionism.
4. Over Temperature Protection (OverThermal)
In the modern TV series, this protection has been included in the active component, Such as STR-Wxxxx. How it works only censor if the working temperature exceeds the point of protection.
5. X-ray Emission Protection (X-RayProtection)
One of the radiation / emission of 'undesirable' from the electron tube is the X-ray emission Naturally, the will of electron tubes emit X-rays at perform certain values are allowed. If the tubes get a working voltage in excess of normal voltage, then the quantity of X-rays produced is Also Enlarged so dangerous for the wearer. In modern CRT, has been equipped with a screen protector That AIM to reduce these emissions. Not only the HV voltage of the which affects the level of emissions, whether or not the light of the image Also affects the quantity of emissions.
In Addition to installing a screen protector, voltage supply HV to CRT was censored Also, Because to censor the HV voltage (the which is at about 20 an 14in TV kilovolt) is Very Difficult then to censor these voltages using ABL feet from TFB. The principle is great ABL voltage will of always follow from the absence of light the screen. If a bright CRT, CRT will from automatically attract a lot of electrons, so the voltage ABL Also earnest go down.
Conversely, if the CRT displays dark images, ABL will of voltage rise. The censored is the minimum point of the ABL voltage. Can not be Less than the level / minimum voltage specified.
In Addition to ABL-voltage protection X-Ray Also uses a censor secondary overvoltage protection voltage TFB, for example Heater voltage. Sensors are installed at the point of the cathode current cans Also function as a protection X-Ray, for example in RGB out pin5 IC (TDA6107) is a sensor IK (cathode current). The principle works is to remove the stress That is similar to ABL but large reverse voltage, the more light, the higher the voltage.
6. Protection Synchronization
Without the video signal, the tv by Itself earnest Produce a signal Sandcastle (images ant / sand) are shown. Free running frequencies (horizontal and vertical) is set at perform certain values (depending on model and type of his IC.) If there is a video signal, sync separator (sync separator) will from mengadjust frequencies are based on synchronization signals carried by the video. If it fails in penyinkronan, earnest automatically be protectionist.
Vertical sync pulses require vertical-out, while the horizontal synchronization requires the AFC signal from the TFB. So synchronization purpose to lock freerunning oscillator frequencies are based on the incoming video signal. Synchronization protection is generally already included in the jungle IC / oscillator.
-Continued-
{ 0 comments... read them below or add one }
Post a Comment