"μPC1366C + μPC1353C TV assembly debugging, TV set Adjusting
Keywords: μPC1366C, μPC1353C, TV debugging
Author: Su Xinglong
A general black and white television is assembled by purchasing a three-piece moving JG-988 type. The main feature is that the image channel is employed by integrated circuit μPC1366C. The sound channel is used in μPC1353C, and the field scanning circuit uses μPC1031H2, the power supply circuit and the row scanning circuit using discrete components. The integrated circuit μPC1366C contains image, detection, premium, noise suppression, AGC voltage detection, medium amplification, and high amplification of AGC amplification; μPC1353C integrated circuit has a sound intermediate frequency limit, visual frequency, electronic volume control , Audio preamplifies, power amplification and internal regulation, etc.; μPC1031H2 integrated circuits are mainly formed by field scanning oscillation, sawtooth wave forming, field promotion and field output. In this way, the peripheral components of the public channel, the sound channel, and the field scanning circuit are less, installed, and debugging. The power supply circuit and row scan circuit consists of discrete components, can train students installation and commissioning skills, so the model movement is suitable for the installation and commissioning of the school for black and white TV. The installation of the machine in the specific training, commissioning can be carried out as follows: 1. Detecting more components in the component television. Once in error, it is easy to cause poor circuit operation, or malfunctions. 1. Detection of resistance: Most of the resistors used are color-ring resistors. First, let students arrange all resistors, all with transparent tape in paper, write the resistance by the color standard, and finally use the multi-use table core. High power resistance is marked with special symbols. 2, the detection of the capacitor: arrange the same model of the capacitance in ~ start, fixed on the paper, write the capacitance and the rated voltage in the capacitance according to the symbols labeled on the capacitor. Some manufacturers are in porcelain capacitors and mica capacitors, labeled 103, 332, etc., 103 represent 10 × l0 (cubic) = 10000pf, 332 representation 33 × L02 = 3300PF.3N3 representation 3300PF, etc., these must be identified . 3, the detection of diodes: According to the positive direction of the diode, the resistance of the anti-closed nature is easy to detect the good and bad of the diode. Students can also guide the method of taking the two-stage normal battery to detect the polarity of the diode, when the diode is connected to the positive terminal of the battery, the lamp is emitted, the diode is turned on, and the diode is not turned on. Students use this method, more intuitive, can cause students' interest in learning. On the use of diodes, the power rectifier circuit current is large, and a surface contact diode should be used; the point contact diode 1N4148 is used for the AFC and field reverse circuit; the boost and row damping Diode is used. 4, the triode of the triode: (a) determines the base. The positive and reverse resistance values between the three electrodes in the three electrodes of the multi-purpose table R × 100 or R × 1K meter. When the electrode is applied with the first table, and the second table brush contacts the other two electrodes to measure very low resistance, the electrode connected to the first table is the base B. At this time, you should pay attention to the polarity of the multimeter form, if the red table pen is used, the base B. When the black table pen is connected in other two poles, the measured resistance is smaller, and it can be determined that the triode is a PNP tube; if the black table pen is connected to the base B, the red table pen contacts other two poles, measured If the resistance is small, the triode is measured as an NPN tube. (b), determine the collector C and the emitter E. (Take the PNP as an example) Position the multimeter in the R × 100 or R × 1K gear, the red table pen is connected to the base B, and the two resistance values measured should be a large when the black sheet is touched. Some, a little. In one measurement at a small resistance, the taking the foot of the black table pen is a collector; in one measurement larger than the value of the resistance, the taking foot taken in the black table pen is an emitter. When discriminating the polarity of the triode, it is also possible to use the battery to take the flashlight bulb to use the battery, and the other end of the battery's ~ end of the triode is connected to the other end of the battery, and if the lamp is emitted, it will be described. A pole is a polar B, (the base is not moving), and the additional ends are the collector C and the emitter E. If the battery is on the base, the triode is an NPN type, and the negative end is a base, then the triode is a PNP type. The method of discriminating the collector and the emitter is (as an example of NPN-type blue pole tube): the two poles are opposite the battery and the bulb in series, respectively, with a 100Ω resistor to the base and the battery positive electrode. One pole, if the lamp is emitted, the electrical resistance is a pole, and the other is an emitter. The detection circuit is shown below.
2, component installation divides the TV motherboard into power part; line scanning part; field scan part; synchronous separation part; visual part; sound part; public channel part. Then follow the steps to block the part components according to the steps. After the installation is part, this piece of circuit is required to be debugged, and the next portion is installed after meeting the requirements. Note the following when installing: 1, before assembly, the components should be treated with the components. 2, the resistance takes a tight surface assembly (no gap mode), the capacitor uses upright assembly mode, and the large capacity of the capacitor should be applied at its pin to prevent it from skew. 3, which is also an upright assembly method for small power triodes. High-power triodes should be assembled on the "L" type heat. 4, the assembly of the rectifier diode, if the 2CZ × type rectifier diode is used, and the vertical assembly method is used; if it is a 1N × × type rectifier diode, the generic gap assembly is used, which allows the diode to leave the bottom plate of about 0.5 ~ 1 cm. It is conducive to heat dissipation during diode work. 5, the welding operation of the row oscillation coil and the row excitation transformer is fast, and generally require welding of a solder joint in 2 to 3 seconds. 6, line reverse capacitance and damping diodes are not missing or open. 7, when assembling the integrated circuit, requires the soldering iron housing to be reliably grounded, the speed is fast, the solder joint is uniform, no durable welding, short circuit, no hair.
3, circuit detection, commissioning 1 Power circuitry debugging: The power output of black and white TV should be stabilized at 12V. If not 12V, you can correct the method of sampling resistors. If it is not adjustable, it must be that there is a fault in the power part. If the output voltage is high, it is necessary to check if the voltage regulator diode is open or the voltage is high, and the sampling comparison is open. If the output voltage is low, check whether the reference regulator diode is contrary or breakdown, sampling Compare the triode breakdown, etc. Only after the power is adjusted to make adjustments to other circuits. 2 row circuit detection and debugging: Because the line scan circuit works on high voltage, large current state, after assembly, it is impossible to eager to power, should first check that the assembly of the component is correct, the process meets the requirements, and then detects a down scan The circuit is on the radial resistance value. When the power supply opening is not sealed, the red watch pen is grounded, and the black table pen test is 10K. The black table pen is grounded, the red table pen test is about 8.5k; after the sealing, the red table brush, black table The supply power supply is around 850Ω; the black table brush is grounded, the red table pen measures power supply at the channel resistance of 800Ω. After the inspection work is completed, power-on detection can be performed, otherwise it may cause damage to components due to assembly. The detection steps after power is as follows: (a) current detection: The power supply process opening of the front stage circuit is temporarily unbeded, but the first use of the multimeter DC current stops in the opening to measure the current, normal, when the opening is currently It should be around 55 ~ 65mA (when the field circuit is not working). After the opening is normal, the opening can be closed by solder. (B) Row oscillating level detection: After the power supply opening is closed, the drainage is provided with the row oscillation level, and the drain excitation level provides a DC power supply. The detection of the row oscillator level is first to determine whether it is oscillating, and the common method of judging is to listen to whether the frequency is called to determine whether or not. Since my country's TV system specified in the frequency of 15625 Hz, it is just within the hearing frequency of the human vectors, so when the oscillator is oscillating, the slight row "吱" can be heard. The magnetic core of adjusting the row oscillation coil will change the frequency of the "" ". (C) Detection of the active stage: normal, the row of excitation-level base DC voltage is generally a negative maneulent or zero. The active tube collecting electrode voltage is about 10.5V. The normal waveform of the row excitation tube set electrode can be observed using an oscilloscope. (D) Detection and commissioning of the post-horizontal scanning circuit: Power supply openings of the multimeter string, in the case where the output tube collector current is about 300 ~ 400 mA in the case where the non-deflecting coil is not connected. If the current value is normal, it can be sealed with the solder; if the current is too large or too small, the output of the line output is also faulty and should be carefully checked. After the row output stage opens, the line output tube base current is detected. The detection method is as follows: Welding a foot on the linear output tube base, place the multimeter in the DC current gear, string into the loop, at which time the current value indicated on the table should be about 50 mA. There should be a "DB" voltage value of about 1.5V, and the average DC voltage of from -0.3V and the normal row pulse signal are applied to the base of the line output tube base. There should be a voltage of about 27V on the line output tube collector. If the current collector voltage of the output tube is only 12V, or the line output stage does not work properly. In (e), the detection of high voltage circuits: The task of 100V medium voltage circuit is mainly to accelerate the electrode, the via circuit, and the brightness control circuit. The main task of the 400V medium voltage circuit is to provide a focus voltage to the image tube. The high voltage circuit is to provide the desired anode high pressure to the image tube, and the normal value should be around 13 kV. 3, the detection of the field circuit: For the detection of the field oscillation portion, it is mainly to determine whether the field oscillation is oscillating and whether the sawtooth wave can be produced. Field excitation, the detection of the amplification output part is mainly to determine whether the field excitation circuit has a sawtooth input and output. The waveform of the field scanning circuit can be observed using an oscilloscope, and can be formed from the field oscillation level → sawtooth wave output in the order of the signal flow. 4, debugging and detection of the video circuit: (a) Detection before power is. In order to verify that the discharge circuit assembly is correct and avoiding the components damaged by power, it should be detected on the path resistance of the via circuit before power-on. (B) Detection debugging after power-on. When the path of the path of the video circuit is substantially normal, it can be detected. The collector voltage indicated by the exhausting after power is 30 to 40V, because the current amplifier has not been connected, and there is no bias voltage on the base of the tube base. The vessel collector voltage can be again tested by adding a simulated offset to the vision tube. 5, the detection of the high frequency header: The TV is a power supply voltage and a 3V AGC voltage of 11.5V from the DC voltage supply to the high frequency head. The multimeter is placed in DC current gear, divided into two power supply circuits, respectively, the high frequency head power supply current is about 15 mA, and the AGC current is about 50 to 100 μA. The two currents are basically normal, indicating that the DC path in the high frequency head is basically normal. 6, the detection of public channels: After assembly of the public in the public, the components should be inspected whether the components are installed correctly, and the multimeter is placed on 100mA gear, and the string eight public channel is supplied, and the measured current is about 70 mA. To compare the resonant frequency of the circuit, you can debug as follows. (A), change automatic gain control is manual gain control. The AGC circuit inside the μPC1366c has a strong automatic control of the medium and high placed circuit. Adjusting μPC1366C (1) and ㈣ foot external interior core makes the resonant frequency from 38 MHz, using the hand control gain, the voltage of the μPC1366C should not change as the increase in the amplitude of the detection output signal, that is, the medium release, high discharge circuit The gain is fixed, the medium-week magnetic core changes to image quality will be obvious. The 3 foot voltage value of μPC1366C is monitored with a multimeter DC voltage gear. After receiving the image signal, the medium-sized magnetic core is adjusted with an also induced man, and the μPC1366C3 foot voltage value is minimized. (B) Adjustment of the AGC circuit. Tune the static voltage value of high amplifiers from 2.8 to 3V. (C) Debugging the amplitude of frequency characteristics in the scanner. On the 4 feet of UPC1366C and a fixed capacitance of 22μF / 16V to increase the charge and discharge time constant, the output waveform is stabilized. At both ends of the medium week, one of a fixed resistance of about 100 w is connected to exhibit wideband. Connect the circuit as shown in the figure above. After booting, use the unusual start to adjust the medium-sized magnetic core, and observe whether the magnitude frequency characteristic curve meets the requirements shown below, and the output attenuation changes from 60 dB to 30dB, the curve shape should be substantially unchanged.
7. Detection of the audio circuit: (a) Multi-use recultural power supply circuit, the amount of volume should be 30mA at the time of the volume, and the current is about 200mA when the volume is maximum. (B) Adjustment of frequency of verification: The adjustment of the identification characteristics in general, mainly relying on monitoring sound quality. Adjust the magnetic core position of the inviting frequency coil with the unusual trip to make the sound quality of the audio. If the adjustment of the frequency coil does not make the sound quality to the ideal state, the core of the fine-tuning inductance can be adjusted to make the sound effect.
4. After the assembly of each of the entire machine is assembled, although step-by-step debugging, the overall quality of the whole machine must be performed. The whole machine is divided into (1) debugging of the power supply part; in the AC 220V power supply, the active type of 80,000 tables, the AC current value should be around 130mA; in the rectifier filter Warls, the DC current should be 1 N12A after power-on; adjust the sampling adjustable resistor, so that the power supply output voltage is 12 ± 0.2V, the ripple voltage is less than 2mV. (2) Synchronous range and brightness, contrast check receiving television programs, adjusting line synchronization with field synchronization knobs, making it normally synchronously and synchronized. Adjusting the brightness and contrast knob, the adjustment direction should be made consistent with the brightness, the contrast change, and place the snap button in place. (3) Adjustment of the deflection coil adjusts the deflection coil, so that the image is not skewed and is in the center position of the screen. The deflection coil is tightened with a tube cone, so that the four-corner of the screen does not appear in a dark corner. (4) Adjust the brightness potentiometer in the development of the developing tube cathode current, and the cathode current is always changed between 10 and 120 μma. (5) Row linear adjustment adjustment line linear coil, makes black and white squares, the widest and narrowing squareness difference should be less than 10%, such as adjustment line lineability still does not satisfy linear requirements, can be used to change S correction capacitor The capacity method is for adjustment. (6) Adjustment of the line, the test of the television stationTest card, there should be 2 to 1.5 grids in the left and right; when the board is received, there should be 16 to 17 chessboards in the horizontal direction. The wider threshold will turn the TV image test card into a flat elliptical, resulting in linear distortion, and minimizing the image content. The adjustment of the threshold can be carried out by changing the method of changing the reverse capacitance, the threshold, can reduce the reverse capacitance; the line is insufficient, then the reverse capacitor can be increased. (7) Adjustment of the synchronization range 1, and the line synchronization is adjusted. When adjusting the row oscillation coil, within the left and right 3 to 4 laps, the frequency of frequency can remain synchronized, while the image is just left and right. Turn the row frequency cable to the middle position, then turn a circle left or right, when the channel is converted, the line is not synchronized. 2, field synchronization adjustment. Adjust the field synchronous potentiometer to turn it to the bottom, the field is always synchronized; when the right is rotated to the end, the image begins to roll down. (8) The field linear adjustment regulating field linear adjustable resistor, so that the black and white chessboard is symmetrical, the size is uniform, and the amplitude difference between the square should be less than 5%. (9) The adjustment of the field level receives the TV test card. When the field potentiometer makes the field level, there should be from about 0.5 to 1 gauge, or when using black and white chess, there should be 13 in the vertical direction. ~ 14 checkerboards. "
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