An apparatus and circuit fault analysis training device for instrument use and a suitcase loaded with the device

Abstract

The utility model discloses an instrument and meter use and circuit fault analysis practical training device, including PCBA circuit board, be equipped with instrument and meter use training area and circuit fault analysis training area respectively on the PCBA circuit board. The utility model discloses still a kind of load instrument and meter use and circuit fault analysis practical training device's suitcase. The utility model is applicable to the user of electronic product research and development, debugging, teaching, training and so on, can be widely used in electronic technical field.

Description

Technical Field

[0001] This utility model relates to electronic technology, and in particular to a training device for the use of instruments and meters and circuit fault analysis, and a carrying case for loading the device. Background Technology

[0002] With the rapid development of electronic technology, the complexity of circuit systems is constantly increasing, placing higher demands on the professional skills and troubleshooting capabilities of practitioners in circuit system debugging and fault diagnosis. Therefore, it is particularly important to develop a training device for instrument use and circuit fault analysis that can simulate real-world scenarios and provide targeted training.

[0003] Current training for using instruments and meters primarily relies on the detailed descriptions of their functions and usage methods in the instrument's accompanying manual. However, it lacks accompanying external testing equipment, resulting in a lack of specific application scenarios. Many of the instrument's functions cannot be intuitively demonstrated (for example, the constant voltage output of a DC regulated power supply requires an external variable load (i.e., an external device) to demonstrate its characteristic of a constant output voltage and output current that varies with the load). This makes learning and training less intuitive, and understanding the instrument's functions more difficult, resulting in poor targeting and timeliness. Currently, there is no dedicated equipment to assist users in training the use of these instruments. Utility Model Content

[0004] The purpose of this utility model is to overcome the shortcomings of the above-mentioned background technology and provide an instrument and meter use and circuit fault analysis training device and a carrying case for loading the device, so that it can be used by users in the fields of electronic product research and development, debugging, teaching and training.

[0005] This utility model provides a training device for instrument usage and circuit fault analysis, including a PCBA circuit board, on which instrument usage training area and circuit fault analysis training area are respectively provided. This utility model also provides a carrying case.

[0006] The instrument and meter usage and circuit fault analysis training device and the carrying case containing the device of this utility model have the following beneficial effects: This invention features a portable, carrying case-style structure for easy equipment management and storage. The base plate (PCBA) is designed with scenario circuits covering most functions of commonly used testing instruments. Users drive these scenario circuits to achieve the expected functions, learning how to use the instruments during testing without needing their manuals. The base plate uses a combination of illustrations and scenario circuits to explain circuit fault diagnosis steps and methods, realistically presenting common fault phenomena, marking fault points, providing normal reference circuits, and comparing circuit faults for targeted observation. This invention also provides a circuit fault analysis training board consumable. This board features various types of fault points, allowing users to master circuit fault analysis and troubleshooting steps through practical operation and quickly grasp the learning content. Attached Figure Description

[0007] Figure 1 This is a schematic diagram of the overall structure of the instrument and meter use and circuit fault analysis training device of this utility model; Figure 2 This is a circuit diagram of the DC5V voltage output circuit in the DC regulated power supply area of ​​the instrument and meter use and circuit fault analysis training device of this utility model; Figure 3 This is a circuit diagram of the series output circuit of the DC regulated power supply area in the instrument and meter use and circuit fault analysis training device of this utility model; Figure 4 This is a circuit diagram of the adjustable voltage output circuit of the DC regulated power supply area in the instrument and meter use and circuit fault analysis training device of this utility model; Figure 5 This is a circuit diagram of the variable voltage output circuit in the DC regulated power supply area of ​​the instrument and meter use and circuit fault analysis training device of this utility model; Figure 6 This is a circuit diagram of the first specified parameter waveform output circuit in the function signal generator area of ​​the instrument and meter use and circuit fault analysis training device of this utility model; Figure 7 This is a circuit diagram of the second specified parameter waveform output circuit in the function signal generator area of ​​the instrument and meter use and circuit fault analysis training device of this utility model; Figure 8 This is a circuit diagram of the frequency meter and counter circuit in the function signal generator area of ​​the instrument and meter use and circuit fault analysis training device of this utility model; Figure 9 This is a circuit diagram of the buzzer test circuit in the multimeter section of the instrument and meter use and circuit fault analysis training device of this utility model. Figure 10This is a circuit diagram of the first DC voltage range circuit in the multimeter section of the instrument and meter use and circuit fault analysis training device of this utility model. Figure 11 This is a circuit diagram of the second DC voltage range circuit in the multimeter section of the instrument and meter use and circuit fault analysis training device of this utility model. Figure 12 This is a circuit diagram of the resistance range circuit in the multimeter section of the instrument and meter use and circuit fault analysis training device of this utility model. Figure 13 This is a circuit diagram of the capacitance range circuit in the multimeter section of the instrument and meter use and circuit fault analysis training device of this utility model. Figure 14 This is a circuit diagram of the diode circuit in the multimeter section of the instrument and meter use and circuit fault analysis training device of this utility model. Figure 15 This is a circuit diagram of the first transistor circuit in the multimeter section of the instrument and meter use and circuit fault analysis training device of this utility model; Figure 16 This is a circuit diagram of the multimeter section and the second transistor section circuit in the instrument and meter use and circuit fault analysis training device of this utility model. Figure 17 This is the circuit diagram of the oscilloscope area in the instrument and meter use and circuit fault analysis training device of this utility model; Figure 18 This is a circuit diagram of the addition circuit in the comprehensive training area of ​​the instrument and meter use and circuit fault analysis training device of this utility model; Figure 19 This is a circuit diagram of the signal phase-shifting circuit in the comprehensive training area of ​​the instrument and meter use and circuit fault analysis training device of this utility model; Figure 20 This is a circuit diagram of the LED driving circuit in the comprehensive training area of ​​the instrument and meter use and circuit fault analysis training device of this utility model. Figure 21 This is a schematic diagram of the regional structure of the circuit fault analysis training area in the instrument and meter use and circuit fault analysis training device of this utility model. Figure 22 This is a schematic diagram of the visual inspection area of ​​the circuit fault analysis training area in the instrument and meter use and circuit fault analysis training device of this utility model. Figure 23 This is a schematic diagram of the short-circuit detection area in the circuit fault analysis training area of ​​the instrument and meter use and circuit fault analysis training device of this utility model; Figure 24This is a schematic diagram of the power-on detection area in the circuit fault analysis training area of ​​the instrument and meter use and circuit fault analysis training device of this utility model; Figure 25 This is a schematic diagram of the area structure of the circuit fault diagnosis method display area in the instrument and meter use and circuit fault analysis training device of this utility model; Figure 26 This is a schematic diagram of the intuitive inspection area in the circuit fault diagnosis method display area of ​​the instrument and meter use and circuit fault analysis training device of this utility model; Figure 27 This is a schematic diagram of the impedance testing area in the circuit fault diagnosis method demonstration area of ​​the instrument and meter use and circuit fault analysis training device of this utility model; Figure 28 This is a schematic diagram of the parameter measurement area in the circuit fault diagnosis method display area of ​​the instrument and meter use and circuit fault analysis training device of this utility model; Figure 29 This is a schematic diagram of the signal tracing area in the circuit fault diagnosis method demonstration area of ​​the instrument and meter use and circuit fault analysis training device of this utility model; Figure 30 This is a schematic diagram of the short-circuit bypass area in the circuit fault diagnosis method demonstration area of ​​the instrument and meter use and circuit fault analysis training device of this utility model; Figure 31 This is a structural diagram of the replacement area of ​​the circuit fault diagnosis method display area in the instrument and meter use and circuit fault analysis training device of this utility model; Figure 32 This is a schematic diagram of the circuit segmentation area in the circuit fault diagnosis method display area of ​​the instrument and meter use and circuit fault analysis training device of this utility model; Figure 33 This is a schematic diagram of the structure of the suitcase of this utility model. Detailed Implementation

[0008] The purpose of this invention is to provide a training device for instrument use and circuit fault analysis. In a first aspect of this invention, the base plate of the instrument use and circuit fault analysis training device is a PCBA circuit board, which is respectively set as an instrument use training area and a circuit fault analysis training area. The overall area is divided as follows: Figure 1 As shown.

[0009] Furthermore, the instrumentation area of ​​the base plate of this invention is subdivided into a DC regulated power supply area, a function signal generator area, a multimeter area, an oscilloscope area, a comprehensive training area, and a comprehensive assessment area. Each subdivided area is equipped with a real circuit scenario. By inputting various types of excitation signals or measuring various types of electrical signals output by the circuit with the corresponding instruments (input and output test scenarios that can fully demonstrate the various functional characteristics of the instruments are designed), the functional test of the circuit can be completed, and the instrumentation usage methods can be learned during the test.

[0010] The DC regulated power supply area, designed for use with a DC regulated power supply, includes four circuit scenarios to train users to utilize the constant voltage output, series voltage output, and variable voltage output functions of the DC regulated power supply, driving the corresponding circuits to operate normally. The working area and corresponding circuit schematics are shown below: ①See Figure 2 A DC regulated power supply outputs a DC 5V voltage. The positive terminal of the power supply is connected to TP1, and the negative terminal is connected to TP2. A 2kΩ fixed resistor R19 and an adjustable resistor R21, along with an LED D42, are connected in series between the positive and negative terminals. When R21 is adjusted to simulate a change in the power supply load, the brightness of D42 will change. However, when measured with a multimeter, the voltage between the power supply outputs TP3 and TP4 remains constant. This is used to train users on how to use a DC regulated power supply to output a constant voltage. ②See also Figure 3 Using the series output function of a DC regulated power supply, two DC 5V voltage sources are connected in series to TP9, TP11, and TP14. A 1kΩ current-limiting resistor (R2, R3) and an LED (D3, D4) are connected in series between the positive and negative terminals of the two voltage sources, respectively. When the series voltage is input, the LEDs D3 and D4 are driven to light up. This is used to train users on how to use the series output method of a DC regulated power supply. ③See Figure 4 The adjustable DC voltage output of the DC regulated power supply is 9V, 12V, or 15V. The positive terminal of the power supply is connected to TP5, and the negative terminal is connected to TP8. After passing through the three-terminal regulator U1, the constant voltage output is 5V, which drives the LED D1 to light up through the series 1kΩ current-limiting resistor R1. This is used to train users on how to use the adjustable DC voltage output of the DC regulated power supply. ④See Figure 5 This device uses a DC regulated power supply with a variable voltage output of 9V, 12V, and 15V. The positive terminal of the power supply is connected to TP10, and the negative terminal is connected to TP12. After passing through a three-terminal regulator U2, a constant voltage output of -5V is generated. The LED D2 is then driven to light up through a 1kΩ current-limiting resistor R4 in series. This device is used to train users on how to use a DC regulated power supply with an adjustable DC voltage output.

[0011] The function signal generator area, used in conjunction with a function signal generator, includes three circuit scenarios designed to train users to use the function signal generator to output waveforms with specified parameters and perform counting input functions, thereby driving the corresponding circuits to operate normally. The working area and corresponding circuit schematics are shown below: ① See also Figure 6 The base of PNP transistor VT6 is connected to TP17 via a current-limiting resistor, and its emitter is connected to a +5V power supply. The collector is connected in series with buzzer BP1 and current-limiting resistor R6. A function generator outputs a square wave with a frequency of 1Hz, amplitude of 5V, bias of 2.5V, and duty cycle of 50%, which is then connected to TP17 and TP16. Transistor VT6 operates in a switching state, driving buzzer BP1 to sound at 1Hz intervals. This is used to train users on how to output waveforms with specified parameters using a function generator. ②See also Figure 7 After LEDs D5~D24 are connected in parallel, their negative terminals are connected to the reference ground of TP19, and their positive terminals are connected in series with a 100Ω current-limiting resistor R7. The other end of R7 is connected to the input terminal of TP18. A function signal generator is used to output a triangular wave with a frequency of 0.5Hz, an amplitude of 10V, and a bias of 1V. This wave is then connected to TP18 and TP19 to drive a pentagram pattern composed of LEDs to produce a breathing light effect. This method is used to train users on how to use a function signal generator to output waveforms with specified parameters. ③See Figure 8 The timer chip U3 (NE555) is connected to external resistors R8 and R10, and then to a selectable capacitor C7 or C8 to form a multivibrator. The frequency of the output Vo is calculated by the formula f = 1.43 * (R8 + 2 * R10) k / C (C can be connected to C7 or C8 via pin J1 to make the Vo output frequency 1Hz or 10Hz). A current-limiting resistor R9 and an LED D25 are connected in series at the Vo output terminal. After power-on, D25 will flash with the output frequency of Vo. The counter input terminals of the function signal generator are connected to TP20 and TP21 respectively, the frequency / count button is selected, and the parameters are set. The clock signal output by this circuit can be measured, which is used to train users to use the frequency meter and counter functions of the function signal generator.

[0012] The multimeter section, designed for use with a multimeter, includes six circuit scenarios to train users to utilize the multimeter's buzzer, DC voltage, resistance, capacitance, and diode functions to measure the electrical parameters of each test point in the corresponding circuit. The working area and corresponding circuit schematics are shown below: ①See Figure 9A resistor (R13 / R15 / R23) is connected in parallel to the black box circuit. Then, its two ends are connected to the test terminals (TP27 and TP35, TP36 and TP37, TP46 and TP47). Using the buzzer function of the multimeter, the red and black probes are connected to TP27 and TP35, TP36 and TP37, and TP46 and TP47 in sequence to measure the impedance between the two test points and observe whether the multimeter buzzer sounds. This is used to train users to use the buzzer function of the multimeter. ② See Figure 10 A resistor R25 and an LED D27 are connected in series between test terminals TP30 and TP32. These are then connected to terminals TP29 and TP31 respectively. A DC regulated power supply is used, with the positive and negative terminals connected to TP29 and TP31 respectively, and different DC voltages are input. The LED D27 lights up. At this point, the DC voltage range of a multimeter is used. The appropriate range is selected, and the red and black probes of the multimeter are connected to TP30 and TP32 respectively to measure the DC voltage between the two test points. This is used to train users to use the DC voltage range function of a multimeter. See Figure 11 U4 is a power supply voltage conversion chip with an input of 5V and an output of 3.3V. The input terminal is connected to test terminals TP28 and TP26, and the output terminal is connected to test terminals TP33 and TP34. At this time, the DC voltage range of the multimeter is used. Select the appropriate range, connect the red and black probes of the multimeter to TP28 and TP26, and TP33 and TP34 respectively, and measure the DC voltage between the two test points. This is used to train users to use the DC voltage range function of the multimeter. ③See Figure 12 Using the resistance range of a multimeter, select an appropriate range and measure the resistance values ​​of resistors R20, R22, R24, R26, R27, and R56 in sequence (test points are located on both sides of the resistors). This is used to train users to use the resistance range function of a multimeter. ④See Figure 13 Using the capacitance range of a multimeter, select an appropriate range and measure the capacitance values ​​of capacitors C11, C13, C15, C12, C14, and C16 in sequence (test points are located on both sides of the capacitors). This is used to train users to use the capacitance range function of a multimeter. ⑤ See Figure 14 Use the diode setting on a multimeter to determine the polarity of diodes D29, D30, D31, and D32 (there are test points on both sides of the diodes). This is used to train users to use the diode setting on a multimeter. ⑥See Figures 15 to 16 Use the transistor setting on a multimeter to determine the pin polarity of transistors VT3, VT4, and VT5 (each of the three transistor pins has a test point), which is used to train users to use the diode setting on a multimeter. The oscilloscope area, used in conjunction with an oscilloscope, includes a circuit scenario designed to train users to measure parameters such as amplitude, frequency, maximum value, minimum value, and power supply ripple of different types of waveforms.

[0013] This area features a function signal generator circuit designed with a dual 12V DC power supply. It utilizes an ICL8038 waveform generator chip in conjunction with external resistors and capacitors, theoretically capable of outputting square, sine, and triangle waves around 10kHz. Using oscilloscope probes, TP40, TP42, and TP41 are connected sequentially. The oscilloscope's vertical, horizontal, and trigger knobs are adjusted to ensure stable waveform display on the oscilloscope screen. The oscilloscope's test function is used to sequentially measure the electrical parameters of the output waveform at the three test points, including frequency, peak-to-peak value, maximum value, and minimum value. This trains users to stably measure the electrical parameters of unknown signals using an oscilloscope.

[0014] Using oscilloscope probes, connect TP134 and TP44, and TP133 and TP44 respectively. Adjust the oscilloscope's vertical, horizontal, coupling mode, and level trigger knobs to appropriate positions. Measure the ripple magnitude of the two power supplies to train the user to measure DC power supply ripple noise using an oscilloscope. The circuit schematic for this part is shown below. Figure 17 As shown.

[0015] The comprehensive training area requires the simultaneous use of multiple instruments. Three circuit scenarios are designed to train users to use multiple instruments to jointly complete the functional testing of the target circuit. ①See Figure 18 This circuit (summing circuit) functions as a signal synthesizer. A 100KΩ resistor is connected in series with each of the signal input terminals TP145 (Vi5) and TP141 (Vi6), and then connected to the inverting input of operational amplifier U15 (NE5534). The non-inverting input of operational amplifier U15 is connected to GND. A 91KΩ feedback resistor is connected to the output of operational amplifier U15 and then to the inverting input. Its output is connected to the test point TP139 (Vo10). The circuit is powered by the series output function of a DC regulated power supply (dual-channel DC). With 12V input to TP95, TP96, and TP99, a function generator is used to output two sine waves (one 6V, 1KHz, initial phase 0°, connected to TP145 and TP45; the other 2V, 3KHz, initial phase 0°, connected to TP141 and TP45). The signal waveform, frequency, amplitude, and other information at the circuit output terminal TP139 are observed using an oscilloscope. The output is an approximate square wave with a frequency of 1KHz and an amplitude of 5V, used to train users on how to use a DC regulated power supply, function generator, and oscilloscope in combination. ②See also Figure 19This circuit functions as a signal phase shifter. A 100Ω resistor (R31) and a 100nF capacitor (C17) are connected in series between the signal input terminals TP93 (Vi7+) and TP97 (Vi7-). The signal output terminals TP94 (Vo11+) and TP98 (Vo11-) are connected to the two ends of capacitor C17 respectively. A sine wave (frequency 16KHz, amplitude 5V, initial phase 0° connected to TP93 and TP97) is output using a function generator. The signal waveform, frequency, amplitude, and other information between the circuit output terminals TP94 and TP98 are observed using an oscilloscope and compared with the corresponding parameters of the input signal. There should be a significant phase change, with a phase shift of 45°. This circuit is used to train users on how to use a function generator and an oscilloscope together. ③See Figure 20 This circuit is a light-emitting diode (LED) driver circuit. It uses a function generator to output a sine wave signal with an amplitude of 3V, a frequency of 1Hz, an initial phase of 0°, and a bias of 1.5V. This signal is then connected to test points TP137 (Vi8) and TP138 (GND). Simultaneously, the input terminals of an oscilloscope are connected to these test points to observe the on / off status of D43. The signal frequency is gradually increased, and the on / off status of D43 is observed until D43 is visibly lit stably. The relevant parameters of the oscilloscope are then adjusted to observe the frequency, period, peak-to-peak value, maximum value, minimum value, and RMS value of the input signal. This circuit is used to train users on how to use a function generator and oscilloscope together.

[0016] The comprehensive assessment area is designed with circuits covering the functions of the aforementioned instruments and meters, used for practical skills assessment in instrument operation. It covers tests including constant voltage output from a DC regulated power supply, DC voltage range testing with a multimeter, AC voltage range testing, ohmmeter testing, using a function generator to drive a speaker to play sound with a specified type of signal, and measuring various electrical parameters of a specified type of waveform with an oscilloscope. All these assessment tests can have their initial states changed via adjustable potentiometers, ensuring that each test subject faces a different testing environment, preventing rote memorization or plagiarism from passing the instrument operation skills assessment.

[0017] Furthermore, the circuit fault analysis training area of ​​the base plate of this invention is subdivided into a circuit fault detection step display area and a circuit fault troubleshooting method display area, used to train users to learn general detection steps for circuit systems and typical troubleshooting methods for circuit system faults. Each area includes a faulty circuit and a normal reference circuit with identical parameters, allowing for comparative observation to understand the fault phenomena. The faulty circuit can be specifically eliminated using a shorting cap. The circuit fault analysis training area is as follows: Figure 21 As shown: ① The circuit fault detection steps display area divides the commonly used circuit system detection steps into three main steps: visual inspection, short circuit detection, and power-on detection.

[0018] First, visual inspection includes checking for faults such as cold solder joints, missing solder joints, incorrect soldering, short circuits, reversed polarity, and reversed insertion. The fault phenomena are first illustrated with a schematic diagram, then a detailed circuit is designed to present these faults, with arrows clearly indicating the fault points. A normal reference circuit is also designed after the fault is eliminated (the parameters of the normal reference circuit are exactly the same as the faulty circuit; since identical component numbers cannot appear on the same PCB, the component numbers of the faulty circuit and the normal reference circuit are distinguished by adding the letter 'A' after the component number, such as R66 and R66A in the diagram below). Targeted comparative observations are then conducted. Figure 22 As shown: A. A cold solder joint refers to a situation where the component pins and the corresponding pads on the PCBA are not securely fixed by solder. This occurs when solder is placed on the surface of the component pins or when there is insufficient solder, leading to unstable electrical connections at the solder joint and intermittent circuit functionality. As shown in the diagram, the left pin of R66 and the lower left pin of Q3 in the cold solder joint circuit are both in a cold solder joint state. This can be compared with the solder joints of R66A and Q3A in a normal reference circuit to gain a deeper understanding of the phenomenon of cold solder joints.

[0019] B. A solder short circuit occurs when the pins of a device, which should be electrically isolated, are accidentally connected together by solder during soldering, resulting in a short circuit. As shown in the solder short circuit diagram, pins 3 and 4 of U9 are connected by solder, exhibiting a solder short circuit state. This can be compared with the solder state of pins 3 and 4 of U9A in the normal reference circuit to gain a deeper understanding of the solder short circuit phenomenon.

[0020] C. Incorrect soldering refers to the situation where the corresponding component number on the circuit board requires the soldering of a component of the specified specification and model from the bill of materials, but in actual production, a component of a different specification and model is soldered due to negligence. In the incorrectly soldered circuit shown in the diagram, R81 should have been soldered as a 0805 package surface mount resistor, but it was actually soldered as a 0805 package surface mount capacitor; R82 should have been soldered as a 10KΩ resistor, but it was actually soldered as a 100Ω resistor. Both instances show incorrect electronic components soldered at their corresponding component numbers. This can be compared with the correct soldering of R81A and R82A in the reference circuit to gain a deeper understanding of the incorrect soldering phenomenon.

[0021] D. Missing / absent components refer to situations where a component with a corresponding part number on the circuit board is required to be soldered according to the specifications and model specified in the bill of materials, but the component is not actually soldered or only a portion of its pins are soldered. In the circuit shown in the figure, the left pin of C29 is not soldered, and no component is soldered to pad R97. This can be compared with the soldered electronic components at C29A and R97A in the normal reference circuit to gain a deeper understanding of the missing / absent component phenomenon.

[0022] E. Reverse soldering refers to the situation where a component is soldered in the opposite direction to a required orientation. As shown in the diagram, in the reverse soldering circuit, the polarity of LED D50 is reversed, and LED D57 is soldered with its back facing upwards. This can be compared with the soldered electronic components D50A and D57A in the normal reference circuit to gain a deeper understanding of the reverse soldering phenomenon.

[0023] F. Reverse insertion refers to a situation where a component is inserted into a socket with a specific insertion direction, but is inserted after being rotated 180°. In the reverse insertion circuit shown in the diagram, the notch direction marked U14 needs to match the silkscreen notch direction on the PCB; in reality, it is inserted after being rotated 180° into the socket. This can be compared with the component inserted at U14A in the normal reference circuit to gain a deeper understanding of the reverse insertion phenomenon.

[0024] Secondly, short-circuit detection primarily targets the input and output of the power supply in a circuit system to prevent short circuits from causing damage to components or equipment upon power-on. A three-terminal voltage regulator circuit is designed here, and short-circuit detection is performed on its input and output. A multimeter in buzzer mode is used to test whether the 5V input terminal is short-circuited relative to the reference ground plane GND, and to test whether the 3V3 output terminal is short-circuited relative to the reference ground plane GND. In "a. Faulty Circuit," a short circuit can be detected at the 3V3 output terminal, while in "b. Normal Reference Circuit," the 3V3 output terminal is not short-circuited. This trains users in short-circuit detection methods, such as... Figure 23 As shown.

[0025] Finally, the power-on test, performed after the aforementioned two main steps, involves supplying power to the circuit system and observing whether its functions and performance meet expectations. This test uses a voltage comparator circuit. Adjusting the adjustable resistor RP3 controls the output level by changing the brightness of the LED D70. After visual inspection and short-circuit testing, switch S6 is turned "ON" to power on. Regardless of adjusting the adjustable resistor RP3, LED D70 fails to light up, while D70A in the "b. Normal Reference Circuit" lights up. This identifies the fault, allowing for targeted troubleshooting, and ultimately reveals that D70 is damaged. Figure 24 As shown.

[0026] The circuit fault diagnosis method demonstration area compiles seven common circuit fault diagnosis methods, including visual inspection, impedance testing, parameter measurement, signal tracing, short-circuit bypass, replacement, and circuit segmentation. Each method is accompanied by circuit application scenarios (covering analog circuits, digital logic circuits, power supply circuits, and microprocessor circuits). Figure 25 As shown. Corresponding troubleshooting methods can be directly used, along with specialized instruments, to quickly identify and eliminate faulty circuit points. In this process, you will learn common circuit fault troubleshooting methods: 1. Visual inspection method refers to a troubleshooting method that uses human senses of sight, hearing, smell, and touch to detect and identify faults. It is the most basic method for fault diagnosis. Visual inspection mainly involves visually checking for soldering faults in components within the circuit system and observing for visible phenomena such as sparks or smoke after power is applied. Auditory inspection involves listening for abnormal sounds within the circuit system. Olfactory inspection involves smelling for any burnt or acrid odors within the circuit system. Tactile inspection involves touching components and integrated circuits in the circuit system to check for overheating; if any of these abnormalities are detected, the power must be immediately disconnected.

[0027] The carrier circuit used in the intuitive detection method is a light intensity detection circuit, whose function is to illuminate the function indicator D47 when there is no light after power-on.

[0028] like Figure 26 In the faulty circuit indicated in the diagram, after power switch S1 is turned "ON" and the photoresistor R68 is blocked to create a dark environment, diode D47 should light up. However, D47 does not light up, while D47 lights up under the same test conditions in the normal reference circuit. Using a visual inspection method, comparing the faulty circuit with the normal reference circuit one by one, it was finally discovered that transistors Q5 and Q5A were of different models. Q5 should have been soldered as an SS8050, but it was actually soldered as an SS8550, causing the circuit to malfunction. This can train users to learn how to use the visual inspection method to troubleshoot circuit faults.

[0029] 2. Impedance measurement method refers to using a multimeter in resistance mode to measure the resistance of suspicious locations or components in a circuit system, the resistance of each pin of an integrated circuit to ground on the circuit board, or the impedance of the power supply circuit VCC to GND, and comparing it with normal values ​​under power-off conditions. This method can directly measure whether the resistance value has changed, whether electronic components such as capacitors are short-circuited, whether there are open circuits or short circuits in the circuit, whether there are poor contacts in the circuit, and whether there are broken or short-circuited copper traces on the circuit board.

[0030] The carrier circuit used in the impedance measurement method is a NAND gate test circuit. When the input terminal J2 pin is configured to the "H" side through the jumper cap and the input terminal J3 pin is configured to the "H" side through the jumper cap, the output is low (L) when all inputs are high (H) and the D51 LED is off. In other cases, the output is high (H) and the D51 LED is lit.

[0031] like Figure 27In the faulty circuit indicated in the diagram, after power switch S3 is turned "ON" and both pins J2 and J3 are configured to the "H" side using jumpers, LED D51 remains constantly lit. However, in the normal reference circuit, when pins J2A and J3A are configured to the "H" side using jumpers, LED D51A remains off. A 74LS00 four-group two-input NAND gate chip is used here. Its first group of inputs, 1A and 1B, is used by the faulty circuit, and its third group of inputs, 3A and 3B, is used by the normal reference circuit. Both groups of input pins have test points led out. Using the impedance measurement method and the resistance setting of a multimeter, the faulty circuit and the normal reference circuit were compared one by one. It was found that the impedance to ground of pin 1A (the input pin of the faulty circuit) was infinite, while the impedance to ground of pin 3A (the input pin of the normal reference circuit) was about 2.6MΩ. The two impedances to ground were inconsistent (it should be noted that although pins 1A and 3A are different pins of the 74LS00, their functions are exactly the same, and their impedance values ​​should be basically the same). The problem was narrowed down to pin 1A of the 74LS00. It was found that the chip socket spring at pin 1A was missing, causing the pin to be floating, which led to the abnormal circuit function. This can train users to learn how to use the impedance measurement method to troubleshoot circuit faults.

[0032] 3. Parameter measurement method refers to the method of measuring some electrical parameters in a working circuit system using instruments and equipment. Commonly measured parameters include voltage, current, frequency, and noise. Specialized instruments are usually required for auxiliary analysis. For example, if a part of the circuit is not working properly, a multimeter in DC voltage mode is usually used to test whether the operating voltage of that part of the circuit is normal. For AC signals, an oscilloscope is used to check whether the waveforms of the input and output signals of the circuit are normal.

[0033] The carrier circuit used in the parameter measurement method is a 555 multivibrator circuit. The circuit output signal Vo is a periodic square wave with a frequency of 1Hz. Vo is connected to pin J4 (default jumper cap) to drive LED D54 to blink. J4 controls the working state of D54, and blinking indication is required when the jumper cap is connected.

[0034] like Figure 28 In the circuit marked in the middle, after the power switch S2 is turned to "ON" and the power is turned on, the pins at J4 and J4A are shorted with jumper caps. The LED D54 does not blink, while D54A blinks normally.

[0035] Since both D54 and D54A are connected to the output signal Vo, with only one header pin J4 in between, the faulty circuit can be located around J4 and D54. Using an oscilloscope, a 1Hz square wave can be measured at the positive terminal of D54, ultimately determining that D54 is faulty. This can train users to learn in-depth how to use parametric measurement methods to troubleshoot circuit faults.

[0036] 4. Signal tracing method is a detection method that finds signal traces based on the signal flow direction of the signal generation and processing circuit. It refers to the process of qualitatively and quantitatively detecting signals step by step with the help of testing instruments (oscilloscope, frequency meter, multimeter, etc.) during fault diagnosis.

[0037] The carrier circuit used in the signal tracing method is to phase-shift and amplify the signal generated by the RC oscillator circuit. Therefore, the circuit has three stages (signal generation, phase shifting, and amplification), and the final output signal Vo is a 1kHz sine wave.

[0038] like Figure 29 In the circuit indicated in the diagram, after the power switch S4 is turned to "ON" and the pin at J5A is connected to the "N" side (connecting to the improperly soldered C34) using a jumper cap, there is no signal observed at the Vo output terminal using an oscilloscope; when the pin at J5A is connected to the "Y" side (connecting to the properly soldered C34A) using a jumper cap, a 1kHz sine wave signal can be observed at the Vo output terminal using an oscilloscope.

[0039] In this circuit, an RC oscillator generates a 1kHz sine wave signal, which is connected to the "RCO" test point. After phase shifting via C34, it is connected to the "RCF" test point. An operational amplifier amplifies the signal, and the output is connected to the "Vo" test point. Based on the signal flow, the waveforms at the "RCO," "RCF," and "Vo" test points are observed sequentially using an oscilloscope. A signal is observed at "RCO," but not at the next test point, "RCF." There is only one capacitor, C34, between the "RCO" and "RCF" test points. Locating the fault around C34, it was found that C34 has a cold solder joint. This method can train users to deeply understand how to use signal tracing to troubleshoot circuit faults.

[0040] 5. The short-circuit bypass method refers to bypassing other suspected components or circuit units with a wire to ensure the circuit under investigation is not affected. Observe whether the signal is normal after this, thus identifying the cause of the fault.

[0041] The short-circuit bypass method uses an inverting amplifier circuit as its carrier circuit. Its purpose is to invert and amplify the signal generated by the RC oscillator circuit in "4. Signal Tracing Method". Therefore, this circuit has two stages. Since the final output signal is a sine wave, an oscilloscope is needed to test whether the signal output from the final stage matches the expected signal.

[0042] like Figure 30In the circuit indicated in the diagram, after the power switch S5 is turned to "ON" and the pin header at J6A is connected to the "N" side using a jumper cap (connecting the improperly designed resistor R104), there is no signal observed at the Vo output terminal using an oscilloscope. When the pin header at J6A is connected to the "Y" side using a jumper cap (shorting the non-inverting input of the LM358 to GND), a 1kHz sine wave signal can be observed at the Vo output terminal using an oscilloscope.

[0043] In this circuit, the 1kHz sine wave signal Vi generated by the RC oscillator circuit in Section 4, "Signal Tracing Method," is inverted and amplified by an LM358 operational amplifier. Vi is then connected to the inverting input pin 2 of the LM358 U12 via a series capacitor C33 and resistor R101. A sine wave signal can be measured at this point using an oscilloscope, but there is no output after amplification. Replacing the LM358 chip does not resolve the issue. The impedance at the non-inverting input is measured to be infinite, while the resistor R104 connected to the non-inverting input should be around 10KΩ. Replacing resistor R104 does not resolve the issue. Using a jumper cap to connect J6A to the "Y" side forces a short circuit to GND at the non-inverting input of the LM358. A sine wave signal amplified by 2 times can be observed at the Vo terminal, indicating a design flaw in the non-inverting input circuit of U12. This method can train users to learn how to use the short-circuit bypass method to troubleshoot circuit faults.

[0044] 6. Replacement method: For electronic circuit systems with unclear faults, when it is not possible to intuitively determine the suspected fault point, existing components of the same model (or with the same function and structure) or the same circuit module can be used for replacement. After replacement, observe whether the circuit function changes to locate the fault.

[0045] The replacement method uses an STC89C51 microcontroller to drive a digital tube display circuit, which normally displays 0-9 in a cycle.

[0046] like Figure 31 In the circuit marked in the middle, after the power switch S7 is turned to "ON" and the power is turned on, the digital tube LED1 (pluggable device) in "a. Faulty Circuit" displays some numbers incompletely. After disconnecting the power, LED1 is removed and replaced with a brand new LED1A device. After powering on again, the numbers are displayed normally. This method can train users to learn in depth how to use the substitution method to troubleshoot circuit faults.

[0047] 7. Circuit segmentation method: This method involves separating the electrical connections of the suspected circuit and inspecting each part individually. By confirming some faults and ruling out others, the search area is gradually narrowed down until the fault is found. This method is particularly suitable for short circuits. During operation, the corresponding components on the circuit are disconnected step by step to minimize the faulty circuit area until the source of the short circuit is found.

[0048] The circuit segmentation method uses a power supply step-down circuit as its carrier circuit, with the goal of converting the input 5V to a 3.3V output and using LEDs to indicate whether the 3.3V voltage output is normal.

[0049] like Figure 32 In the circuit indicated in the diagram, power is supplied when the power switch K2 is pressed. By default, the 3.3V power indicator D67 is not lit.

[0050] When a power supply circuit malfunctions, first use a multimeter in buzzer mode to check if the input and output terminals are short-circuited to ground. Inspection revealed that the 5V input terminal is not short-circuited to GND, but after outputting through U18, the 3V3 output terminal is short-circuited to GND. The 3V3 output terminal is connected to the subsequent circuit via a jumper cap on pin header J8A. Disconnecting the jumper cap on J8A breaks the electrical connection between the power supply and the preceding / following stages. Using a multimeter again, the 3V3 test point on the left side is not short-circuited to GND, but the 3V3 test point on the right side is still short-circuited to GND, indicating the short circuit is in the right-side circuit of J8A. The subsequent circuit of J8A uses pin header J9A to connect to filter capacitor C58 and J10A to connect to filter capacitor C59, and then drives LED D67 through a current-limiting resistor R120. Disconnect J9A to disconnect filter capacitor C58 from the 3V3 power supply. A multimeter test still shows a short circuit. Disconnect J10A to disconnect filter capacitor C59 from the 3V3 power supply; the short circuit is resolved, indicating that capacitor C59 is short-circuited. This method can train users to deeply understand how to use the circuit segmentation method to troubleshoot circuit faults.

[0051] To solidify and reinforce the training results in circuit fault analysis, three types of circuit fault analysis training boards have been designed as supporting components. These are all single-use consumable circuit boards, each equipped with various types of circuit fault points. The circuit principle knowledge points cover professional textbooks on digital circuits, analog circuits, and microcontroller application circuits. Users can utilize the circuit fault analysis steps and methods learned above to troubleshoot and eliminate various faults on the consumable training boards, achieving the intended functions of the training boards and improving their ability to analyze and solve circuit faults.

[0052] In a second aspect of the invention, the overall structure of the instrument and circuit fault analysis training device includes a portable carrying case (case body + case lid), a base plate (PCBA circuit board), and an AC / DC voltage converter. The power adapter is fixed inside the carrying case, adaptable to 110~220V AC power input, and outputs ±5V, ±12V, and 3.3V DC voltages. It is connected to the base plate via a cable to power the entire device. The base plate is fixed to the surface of the case body, and the case lid is fixed to the rear of the case body via hinges. Figure 33 As shown.

[0053] The device base plate of this invention is designed with a scenario circuit that can cover most of the functions of commonly used testing instruments. The instruments drive the scenario circuit to achieve the expected functions. The scenario circuit supports the independent use of a single instrument and also supports the combined use of multiple instruments. During the testing process, users can learn how to use the instruments.

[0054] The device base plate of this invention introduces the three major steps and seven troubleshooting methods for circuit fault diagnosis in a way that combines pictures and text with scene circuits (teaching a man to fish). It presents common fault phenomena in a realistic manner and marks the fault points. It also provides normal reference circuits and circuit fault analysis and comparison, which is highly targeted.

[0055] The device of this invention is equipped with a circuit fault analysis training board consumable. The consumable board is set with various types of fault points to help users practice circuit fault diagnosis training in a timely manner and consolidate their circuit fault diagnosis skills.

[0056] The training device developed in this invention is suitable for users in the fields of electronic product research and development, debugging, teaching, and training. It should be noted that learning how to use instruments and mastering circuit fault analysis methods will help users quickly troubleshoot circuit faults in the target circuit system. Therefore, the device of this invention is mainly divided into two major areas: instrument usage training and circuit fault analysis training.

[0057] The instrument and meter training area is divided into DC regulated power supply, function signal generator, multimeter, oscilloscope, comprehensive training area, and comprehensive assessment area. Each sub-area is equipped with a real circuit scenario. Users can input various types of excitation signals or measure various types of electrical signals output by the circuit using the corresponding instruments (input and output test scenarios that fully demonstrate the functional characteristics of the instruments are designed) to complete the circuit function test and learn how to use the instruments during the test.

[0058] The circuit fault analysis training area is further divided into a circuit fault troubleshooting step demonstration area and a circuit fault troubleshooting method introduction area. Each area first introduces the troubleshooting steps and up to seven troubleshooting methods. It also includes a faulty circuit with identical parameters and a typical, functional circuit for comparative observation. The faulty circuit can be quickly resolved using a shorting cap. Through comparative observation, users can visually observe both the fault symptoms and the circuit behavior after troubleshooting, improving the relevance and timeliness of the fault troubleshooting training and rapidly enhancing users' ability to resolve real-world circuit faults.

[0059] The invention is a portable carrying case structure. Its internal circuit board is divided into two main areas: instrument usage training and circuit fault analysis training. Each area has relatively independent functions. The contents of a single area of ​​the circuit board can also be designed as a single independent circuit board box / module, which can be independently powered and placed in the perforated board of the desktop structure for selection and use as needed.

Claims

1. A training device for instrument use and circuit fault analysis, comprising a PCBA circuit board, characterized in that: The PCBA circuit board is equipped with an instrument and meter usage training area and a circuit fault analysis training area.

2. The instrument and meter usage and circuit fault analysis training device according to claim 1, characterized in that: The instrumentation training area is equipped with a DC regulated power supply, a function signal generator, a multimeter, an oscilloscope, a comprehensive training area, and a comprehensive assessment area.

3. The instrument and meter usage and circuit fault analysis training device according to claim 2, characterized in that: The DC regulated power supply includes a DC 5V voltage output circuit, a series output circuit, an adjustable voltage output circuit, and a variable voltage output circuit. The DC 5V voltage output circuit has access terminals TP1 and TP2 that are respectively connected to the positive and negative terminals of the power supply. A fixed resistor R19, an adjustable resistor R21, and a light-emitting diode D42 are connected in series between the positive and negative terminals of the power supply. The fixed resistor R19 and the light-emitting diode D42 are respectively connected to the power output terminals TP3 and TP4. The series output circuit has access terminals TP9, TP11 and TP14 respectively connected to two series voltage sources. Access terminal TP9 is connected in series with current limiting resistor R2 and light-emitting diode D3 in sequence, and access terminal TP14 is connected in series with current limiting resistor R3 and light-emitting diode D4 in sequence. The adjustable voltage output circuit has an input terminal TP5 connected to the positive terminal of the power supply and an input terminal TP8 connected to the negative terminal of the power supply. The input terminal TP5 is connected to the bypass capacitor C1 and the input terminal of the three-terminal regulator U1, respectively. The ground terminal of the three-terminal regulator U1 is connected to the negative terminal of the power supply through the input terminal TP8. The output terminal of the three-terminal regulator U1 is connected to the output terminal TP6, and is connected to the ground through a current limiting resistor R1 and a light-emitting diode D1 in series. The output terminal of the three-terminal regulator U1 is also grounded through a filter capacitor C3. The variable voltage output circuit has an input terminal TP10 connected to the positive terminal of the power supply and an input terminal TP12 connected to the negative terminal of the power supply. The input terminal TP12 is connected to the bypass capacitor C4 and the input terminal of the three-terminal regulator U2, respectively. The ground terminal of the three-terminal regulator U2 is connected to the positive terminal of the power supply through the input terminal TP10. The output terminal of the three-terminal regulator U2 is connected to the output terminal TP13, and is connected to the ground in series with the current limiting resistor R4 and the light-emitting diode D2. The output terminal of the three-terminal regulator U2 is also grounded through the filter capacitor C6.

4. The instrument and meter usage and circuit fault analysis training device according to claim 3, characterized in that: The function signal generator includes a first specified parameter waveform output circuit, a second specified parameter waveform output circuit, and a frequency meter and counter circuit. The first specified parameter waveform output circuit has a PNP transistor VT6 and input terminals TP16 and TP17. The base of the PNP transistor VT6 is connected to the input terminal TP17 through a bias resistor R5. The emitter of the PNP transistor VT6 is connected to the power supply. The collector of the PNP transistor VT6 is connected to the buzzer BP1 and the current limiting resistor R6 in series and then grounded. The second specified parameter waveform output circuit has an input terminal TP18 connected to the function signal generator and an output terminal TP19 connected to the negative terminal of the function signal generator. The positive terminals of LEDs D5~D24 are connected in parallel and then connected to the input terminal TP18 after being connected in series with a current-limiting resistor R7. The negative terminals of LEDs D5~D24 are connected in parallel and then connected to the output terminal TP19 and grounded. The frequency counter circuit has a time base chip U3. The discharge terminal of the time base chip U3 is connected to the power supply through a bias resistor R8 and to the pin header J1 through a bias resistor R10. The pin header J1 is grounded through energy storage capacitors C7 and C8 respectively. The threshold terminal of the time base chip U3 is connected to the pin header J1. The output terminal of the time base chip U3 is connected to the current limiting resistor R9 and the light-emitting diode D25 in series and then grounded.

5. The instrument and meter usage and circuit fault analysis training device according to claim 4, characterized in that: The multimeter includes a buzzer circuit, a DC voltage circuit, a resistance circuit, a capacitance circuit, a diode circuit, and a transistor circuit. The buzzer test circuit has three black box circuits, which are connected to resistors R13, R15 and R23 respectively, and are connected to test terminals TP27 and TP35, test terminals TP36 and TP37 and test terminals TP46 and TP47 respectively. The DC voltage range circuit includes a first DC voltage range circuit and a second DC voltage range circuit. The resistor range circuit has resistors R20, R22, R24, R26, R27, and R56, which are respectively connected to test terminals TP48 and TP49, test terminals TP52 and TP53, test terminals TP50 and TP51, test terminals TP56 and TP57, test terminals TP54 and TP55, and test terminals TP60 and TP61. The capacitor circuit has capacitors C11 to C16, which are respectively connected to test terminals TP65 and TP66, test terminals TP67 and TP68, test terminals TP71 and TP72, test terminals TP73 and TP74, test terminals TP82 and TP83, and test terminals TP84 and TP85. The diode circuit includes diodes D28 to D32. The anode of diode D28 is connected to test terminal TP63 and connected in series with current-limiting resistor R29 to pin header J6. The cathode of diode D28 is connected to test terminal TP64 and grounded. Diodes D29 to D32 are respectively connected to test terminals TP89 and TP90, test terminals TP77 and TP78, test terminals TP75 and TP76, and test terminals TP91 and TP92. The transistor gate circuit includes a first transistor gate circuit and a second transistor gate circuit.

6. The instrument and meter usage and circuit fault analysis training device according to claim 5, characterized in that: The first DC voltage level circuit in the DC voltage level circuit has a current-limiting resistor R25 and a light-emitting diode D27 connected in series. The current-limiting resistor R25 is connected to the positive terminal of the power supply, and the negative terminal of the light-emitting diode D27 is grounded. The current-limiting resistor R25 is connected to the input terminal TP29 and the output terminal TP30 respectively. The input terminal TP29 and the output terminal TP30 are connected to the positive terminal of the power supply respectively. The light-emitting diode D27 is connected to the input terminal TP31 and the output terminal TP32 respectively. The input terminal TP31 and the output terminal TP32 are connected to the negative terminal of the power supply respectively. The second DC voltage range circuit in the DC voltage range circuit has a power supply voltage conversion chip U4. The input terminal of the power supply voltage conversion chip U4 is connected to the power supply and the access terminal TP28 respectively. The positive terminal of the output terminal of the power supply voltage conversion chip U4 is connected to the power supply and the output terminal TP33 respectively. The negative terminal of the output terminal of the power supply voltage conversion chip U4 is connected to the adjustment pin terminal of the power supply voltage conversion chip U4 and connected to the access terminal TP26. The negative terminal of the output terminal of the power supply voltage conversion chip U4 is grounded. The first transistor circuit in the transistor circuit includes transistors VT3 to VT5. The base of transistor VT3 is connected to test terminal TP86, the emitter is connected to test terminal TP88, and the collector is connected to test terminal TP87. The base of transistor VT4 is connected to test terminal TP81, the emitter is connected to test terminal TP79, and the collector is connected to test terminal TP80. The base of transistor VT5 is connected to test terminal TP58, the emitter is connected to test terminal TP132, and the collector is connected to test terminal TP59. The second transistor circuit in the transistor gate circuit has a transistor VT2. The base of the transistor VT2 is connected to the header J8 in series through the test terminal TP69 and the bias resistor R30. The emitter of the transistor VT2 is connected to the test terminal TP70 and grounded. The collector of the transistor VT2 is connected to the positive terminal of the power supply in series through the test terminal TP62, the light-emitting diode D36 and the pull-up resistor R28.

7. The instrument and meter usage and circuit fault analysis training device according to claim 6, characterized in that: The oscilloscope includes an ICL8038 waveform generator chip. The sine wave output terminal of the ICL8038 outputs a sine wave and is connected to test terminal TP40. The triangular wave output terminal of the ICL8038 outputs a triangular wave and is connected to test terminal TP41. The two adjustment terminals of the ICL8038 waveform generator chip are connected in parallel to the corresponding configuration resistors R16 and R17, respectively, and then connected to the positive power supply terminal. The positive power supply terminal of the ICL8038 waveform generator chip connected to the positive power supply terminal is grounded through a filter capacitor C2. The internal frequency adjustment bias voltage input terminal of the ICL8038 waveform generator chip is connected to the external scanning frequency voltage input terminal. The square wave output terminal of the ICL8038 waveform generator chip outputs a square wave and is connected to the test terminal TP42. The square wave output terminal is connected to the positive terminal of the power supply through a pull-up resistor R18. The timing terminal of the ICL8038 waveform generator chip is grounded through an oscillation capacitor C9. The negative power supply terminal of the ICL8038 waveform generator chip, which is connected to the negative terminal of the power supply, is grounded through a filter capacitor C10. The sine wave adjustment terminal of the ICL8038 waveform generator chip is grounded through a pull-down resistor R14.

8. The instrument and meter usage and circuit fault analysis training device according to claim 7, characterized in that: The integrated training area includes an adder circuit, a signal phase-shifting circuit, and a light-emitting diode driving circuit. The adder circuit includes an operational amplifier U15. The inverting input of operational amplifier U15 is connected to parallel input resistors R58 and R60. Input resistor R58 is connected in series with test terminal TP141, and input resistor R60 is connected in series with test terminal TP145. The non-inverting input of operational amplifier U15 is grounded. The power supply of operational amplifier U15 is connected to a DC regulated power supply. The output of operational amplifier U15 is connected in series with test terminal TP139 and feedback resistor R59 before being connected to the inverting input of operational amplifier U15. The positive terminal of the operational amplifier U15 is connected to a +12V DC voltage and then to test terminal TP95. The negative terminal of the operational amplifier U15 is connected to a -12V DC voltage and then to test terminal TP99. The ground terminal of the operational amplifier U15 is connected to test terminal TP96. Test terminal TP95 is connected to ground via a current-limiting resistor R32 and an LED D33 in series. Test terminal TP99 is connected to ground via a current-limiting resistor R33 and an LED D34 in series. The negative terminal of LED D33 is grounded, and the positive terminal of LED D34 is grounded. The signal phase shifting circuit has signal input terminals TP93 and TP97 and signal output terminals TP94 and TP98. A phase shifting circuit resistor R31 and a phase shifting circuit capacitor C17 are connected in series between the signal input terminals TP93 and TP97 to form a phase shifting circuit. The two ends of the phase shifting circuit capacitor C17 are respectively connected to the signal output terminals TP94 and TP98. The LED driving circuit has test terminals TP137 and TP138. A current-limiting resistor R57 and an LED D43 are connected in series between the test terminals TP137 and TP138. The negative terminal of the LED D43 is grounded.

9. The instrument and meter usage and circuit fault analysis training device according to claim 8, characterized in that: The circuit fault analysis training area is divided into a circuit fault detection step display area and a circuit fault troubleshooting method display area. The circuit fault detection step display area includes a visual inspection area, a short circuit detection area, and a power-on detection area. The visual inspection area includes components with poor soldering, missing soldering, incorrect soldering, short circuit, reverse polarity soldering, and reverse insertion. The circuit fault diagnosis method display area includes a visual inspection area, an impedance testing area, a parameter measurement area, a signal tracing area, a short-circuit bypass area, a replacement area, and a circuit segmentation area.

10. A suitcase, comprising a lid and a body, characterized in that: One side of the enclosure is provided with an instrument and meter usage and circuit fault analysis training device as described in any one of claims 1 to 9, and the other side of the enclosure is provided with a power adapter electrically connected to the instrument and meter usage and circuit fault analysis training device.

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