Identification of common components
First, the resistance resistance is represented by "R" in the circuit, such as: R15 represents a resistor numbered 15. The main effect of the resistor in the circuit is divergence, current limiting, voltage division, bias, filter (in combination with capacitor) and impedance matching. 1. Parameter identification: The unit of resistance is ohmic (Ω), the magnification unit is: Qiano (KΩ), megoh (MΩ), etc. The conversion method is: 1 megoh = 1000 kiloo = 10,000 Euro resistance parameter labeling method has three types, namely straight standard, color labeling, and digital standard. A, the number of markings is mainly used for small volumes such as patch, such as: 472 denotes 47 × 102 Ω (ie, 4.7K); 104 is shown in 100KB, the color chassis labeling method is used, now, for example, the four-color ring resistance Ring resistance (precision resistance) 2, the color standard position and magnification relationship of the resistor is shown in the following table: color effective digitization rate allowed deviation (%) Silver / 10-2 ± 10 gold / 10-1 ± 5 black 0 100 / Brown 1 101 ± 1 red 2 102 ± 2 orange 3 103 / yellow 4 104 / green 5 105 ± 0.5 blue 6 106 ± 0.2 purple 7 107 ± 0.1 gray 8 108 / White 9 109 5 to -20 colorless / / ± 20
Second, the capacitor 1, the capacitor is generally expressed in the circuit (such as the C25 represents a capacitance number 25). The capacitor is a component composed of two metal films, and the intermediate is separated by an insulating material. The characteristics of the capacitance are mainly engaged in circulation. The size of the capacitance capacity is to indicate the size of the energy storage, and the obstacle effect of the capacitance on the AC signal is referred to as a capacitive, which is related to the frequency and capacitance of the AC signal. Rongx XC = 1 / 2πf C (f represents the frequency of the AC signal, c represents the type of electrolytic capacitance, porcelain capacitor, patch capacitance, monolithic capacitor, tantalum capacitance, and polyester capacitance, etc. . 2. Identification method: The recognition method of the capacitor is substantially the same as the identification method of the resistor, and three types of strain, color labeling, and digital standard method. The basic unit of capacitance is represented by Fara (F), and other units are: ml (MF), microfaway (UF), NaR (NF), and Pellets (PF). Among them: 1 Fara = 103 ml = 106 microscopic = 109 Nathemlet = 1012 Telling capacity capacitance The capacitance value is directly indicated on the capacitance, such as 10 UF / 16V capacity small capacitance value value to the capacitance Representation or numbers indicate letters: 1M = 1000 uf 1p2 = 1.2PF 1N = 1000pf digital representation: Generally, the three digits represent the size of the capacity, the first two indicate a valid number, the third digit is the magnification. Such as: 102 denotes 10 × 102pf = 1000pf 224 represents 22 × 104pf = 0.22 UF3, capacitive capacity error table number F g J k L M allow error ± 1% ± 2% ± 5% ± 10% ± 15% ± 20% Such as: a porcelain capacitor is 104J indicates that the capacity is 0. 1 Uf, the error is ± 5%. 4. Fault characteristics In actual repair, the fault of capacitors is mainly manifested as: (1) open circuit failure of corrosion of pin. (2) Fault failure of dewrapping and soldering. (3) The length of the capacity is small or open faults. (4) Leakage, severe leakage and breakdown failure.
Third, the crystal diode crystal diode is often used in the circuit to represent "D" plus numbers, such as: D5 represents a diode number 5. 1. Role: The main characteristics of the diode are unidirectional conductivity, that is, under the action of the forward voltage, the on-resistance is small; and the conductive resistance is large or infinite under the reverse voltage. It is because the diode has the above characteristics, and it is often used in rectification, isolation, regulatory, polar protection, coding control, frequency modulation, and static noise and other circuits. The crystal diode used in the telephone can be divided into: rectifier diode (e.g., 1 N4004), isolation diode (e.g., 1 N4148), Schottky diode (such as BAT85), a light emitting diode, a voltage regulator diode, and the like. 2, the identification method: the identification of the diode is very simple, the N-pole (negative electrode) of the small power diode, which uses a color loop in the outer surface of the diode, and some diodes are also dedicated to represent p-poles (positive electrodes) or N poles. (Negative electrode), there is also a symbol mark "P", "n" to determine the polarity of the diode. The positive and negative poles of the light emitting diode can be shorter from the lead, and the long feet are positive and the short foot is negative. 3, test precautions: When the diode is used to measure the diode, the positive electrode of the red table pen diode, the negative electrode of the black table pen diode, the measured resistance is the positive direction of the diode, which is related to the pointer type The form of a meter is just the opposite. 4, commonly used 1 N4000 series diode withstand voltage comparison: Model 1N4001 1N4002 1N4003 1N4004 1N4005 1N4006 1N4007 withstand voltage (V) 50 100 200 400 600 800 1000 Current (a) is 1 four, regulator diode regulator diode in the circuit Commonly represented by "ZD" plus, such as: ZD5 represents a regulator tube number 5. 1. The principle of regulating the regulator diode: The characteristics of the regulator diode are broken, and the voltage at both ends remains substantially unchanged. Thus, when the regulator access circuit is used, if the voltage fluctuates fluctuates fluctuates or other reasons, the voltage at both ends of the load will remain substantially unchanged. 2. Features: The failure of regulator diodes is mainly based on open circuit, short circuit and regulated value unstable. Among these three faults, the previous fault exhibits an increase in the power supply voltage; the latter two types of faults are expressed as the power supply voltage to zero volts or the output is unstable. The model and voltage regulator value of the commonly used regulatory diode is as follows: Model 1N4728 1N4729 1N4730 1N4732 1N4733 1N4732 1N4733 1N4734 1N4733 1N4734 1N4735 1N4744 1N4750 1N4751 1N4761 regulated value 3.3V 3.6V 3.2V 4.7V 5.1V 5.6V 6.2V 15V 27V 30V 75V
5. Inspiration inductors often use "L" plus numbers in the circuit, such as: L6 represents an inductance number 6. The inductor coil is made of an insulating wire on the insulated skeleton around a certain number of turns. DC can pass through the coil, the DC resistance is the resistance of the wire itself, the pressure drop is small; when the AC signal passes through the coil, the two ends of the coil will generate self-inductive momentum, the direction of the self-sensing force is opposite to the direction of the external voltage, hindering communication. According to the pass, the characteristics of the inductor are the flow resistance, the higher the frequency, the greater the coil impedance. Inductance can consist of an oscillation circuit with the capacitance in the circuit. Inductance is generally straight standard and color standard, and the color label is similar to the resistance. Such as: Brown, Black, Gold, and Gold indicates that 1uh (error 5%) inductors. The basic unit of inductance is: Heng (H) converted unit has: 1H = 103MH = 106uh.
Sixth, the variable diode variable diode is a special diode specifically designed to vary from the change of the "PN junction" in the ordinary diode, and the change in the change of the opposite voltage is specifically designed. The volatile diode is mainly used in the high-frequency modulation circuit of a mobile phone or landline in a cordless telephone, and the low frequency signal is modulated to the high frequency signal and emits it. In the working state, the variable diode modulation voltage is generally added to the negative electrode, and the internal junction capacitance capacity of the variable damping diode varies with the modulation voltage. The bell diode fault, mainly manifested as leakage or performance deterioration: (1) When a leakage is generated, the high-frequency modulation circuit will deteriorate the no work or modulation performance. (2) When the variable resistance is deteriorated, the operation of the high-frequency modulation circuit is unstable, so that the modulated high frequency signal is sent to the other party by the other party after receiving distortion. At one of the above cases, it should be replaced with the same type of container diode. 7. The crystal triode crystal triode is often used in the circuit to represent the "Q" plus digital representation, such as: Q17 represents a triode numbered 17. 1. Features: The crystal triode (referred to as a transistor) is a special device that includes 2 PN junctions and has an enlarged capacity. It is divided into two types of NPN and PNP types. These two types of trioders can be compensated from each other from working characteristics. The tubes in the so-called OTL circuit are used by PNP type and NPN type pairing. PNP triodes commonly used in telephones include: A92, 9015 and other models; NPN type triodes are: A42, 9014, 9018, 9013, 9012 and other models. 2. The crystal triode is mainly used to enlarge the amplification in the amplification circuit, and there are three ways in common circuits. In order to facilitate comparison, the characteristics of three connection circuits in transistors are listed in the table for reference.
Name Common Emitter Circuit Current Electrode Circuit (Aser Output) Circular Circuit Input impedance (several hundred ohms ~ thousands of Europe) large (tens of thousands of European above) small (several o'clock to dozens Ou) output impedance Zhong (thousands of o'cloud ~ dozens thousand Europe) small (several European dozens of Europe) large (tens of thousands of ohms ~ hundred thousand euros) voltage amplification large multiple (less than 1 close to 1) large current amplifier large (Dozens) Large (less than 1) small (less than 1) Power magnification (about 30 ~ 40 decibels) small (about 10 decibels) (about 15 ~ 20 decibels) frequency characteristics high frequency difference is good Continued to apply multi-stage amplifier intermediate level, low frequency amplification input stage, output stage or impedance matching high-frequency or wideband circuit and constant current source circuit 3, online work measurement is installed on the circuit board in actual maintenance. Every time you remove it, it is really a trouble, and it is easy to damage the circuit board. According to the actual maintenance, I summarize a method in which the failure is measured on the circuit, for the reference: Category Fault happens to test main point EB extreme open circuit VED> 1V veb = v EB ultra short circuit VEB = 0V VCD = 0V VBD elevated Re-opening VED = 0V RB2 open circuit VBD = VED = V RB2 short circuit VED is about 0.7V RB1 a lot, open VEC <0.5V VCD Elevation EC Extreme Opening Veb = 0.7V VEC = 0V VCD Elevation BC Extreme Open Veb = 0.7V VED = 0V BC Best Short Circuit VBC = 0V VCD is very low RC open circuit VBC = 0V VCD Elevation VBD constant RB2 resistance increases Many vers of VEDs about V VCD approximately 0V VED voltage unstable triode and surrounding components have a solder category failure occurrence site test Point RB1 Open VBE = 0 VCD = V VED = 0 RB1 Short Circuit Vbe approximately 1V VED = V-VBE RB2 Short Circuit VBD = 0V VBE = 0V VCD = V RE Open VBD Elevation VCE = 0V VBE = 0V RE Short Circuit VBD = 0.7 v Vbe = 0.7V RC open circuit VCE = 0V VBE = 0.7V VED about 0V CE ultra short circuit VCE = 0V Vbe =
