Cx is a non-polar capacitor, and the IC integrated circuit module Ux is an IC (Integrated circuit components) Kx is a component library of different manufacturers. Tx is a test point (Factory test)Spk1 is the Speaker (Buzzer, Horn) Qx is triode Jx is Jack (Such as Audio Jack) Y1 different vendors have different definitions of component libraries. In addition, there are CEx-Electrolytic capacitor, CNx-Discharge (Several capacitors together), RNx-Exclusion, CONx-Connector, Dx-Diode (Diode), Hx-Hole, JPx-Jumper, Lx-Inductance/magnetic beads, LEDx-Light emitting diode, Xx-Crystal oscillator. Each manufacturer has its own component library, and the components when drawing the circuit diagram are all taken from the library (Dachang) , For some uncommon, such as CON, JP, the definition of each manufacturer will also be different R (Resistance)FS (Insurance tube)RTH (Thermistor)CY (Y capacitor: high voltage ceramic capacitor, safety gauge)CX (X capacitor: High Voltage Film Capacitor, safety regulation)D (Diode)C (Capacitance)Q (Transistor)ZD (Zener diode)T (Transformer)U (IC chip)J (Jumper)VR (Adjustable resistance) W regulator K switch Class Y crystal oscillator 5 B * m7 f/R4 F circuit board often see R107, C118, Q102, D202 and other numbers, in general, the first letter identifies the device category, for example, R represents resistor, C represents capacitor, D represents diode, Q represents transistor, etc; The second is the number, which indicates the circuit function number. For example, '1' indicates the main board circuit, '2' indicates the power supply circuit, etc. , which is determined by the circuit designer himself; The third and fourth digits indicate the serial numbers of similar devices on the circuit board. R117: resistor on the motherboard, serial number 17T101: transformer on the motherboard. SW102: switch LED101: led lamp :(Indication)Lamp Q104 (E, B, C) : Transistor, E: emitter, B: base, C: collector EG: 'If R117 is a resistor, it should be on if both ends are measured by a multimeter ', it is unscientific to directly measure the resistance on the circuit board. The measurement result will be smaller or even smaller than the actual value. It is better to weld a lead wire before measuring.