The following are key principles for PCB maintenance, intended as guidelines for industry professionals. The goal is to maintain an organized and systematic approach to repair work.
**Principle 1: Prioritize Quantity**
Begin by visually inspecting the repaired circuit board. If needed, use a magnifying glass for a more detailed examination.
Focus on the following areas:
1. Check for any disconnections or short circuits, with particular attention to any potential fractures in the printed circuit board.
2. Inspect the relevant PCB components (resistors, capacitors, inductors, diodes) for signs of disconnection.
3. Determine if previous repairs have been made. Which components were modified, and are there any issues such as cold solder joints, leaks, or post-insertion errors?
Once these conditions have been ruled out, use a multimeter to measure the resistance between the power supply and the ground of the circuit board. If the resistance is too low (only a few ohms) or unusually high (over ten ohms), this indicates that a component on the board may be damaged or partially punctured. In this case, further action must be taken to locate the faulty component.
The recommended approach is to power up the board during this process (note: this is a critical step). Ensure that the board’s operating voltage is correctly matched and that the input voltage is higher than the required working voltage. This step is essential for accurate diagnosis and repair.
**Voltage Value**: Otherwise, it could damage the repair circuit board! Previous errors have not been addressed, and new issues have been introduced! The temperature of each component on the circuit board should be measured with a spot thermometer. Faster temperature rises and higher temperatures are key indicators of potential problems.
If the resistance value is normal, use a multimeter to measure other parts, such as the blocked container, the three-terminal MOSFET, and the switch on the peeling part of the circuit. The goal is to ensure that the tested component is functioning properly. Don’t overcomplicate problems that basic test tools (e.g., utility tables) can easily diagnose.
**Principle 2: External First, Then Internal.**
If possible, it is ideal to use a working circuit board similar to the one being repaired as a reference. Then, use the tester’s double-edge VI curve scanning function to compare the two boards. Start testing from the input port of the circuit board and then proceed through the comparison of the test points, such as the table and capacitors. This compensates for the limitations of standard meters, which can make it difficult to detect capacitor leakage.
**Principle 3: Start with Difficulties, End with the Easier Ones.**
To improve the effectiveness of the test, conduct preliminary repairs and technical adjustments to the single board before performing the online function test. This minimizes the impact of various interferences during the testing process. Specific steps include:
1. **Pre-test Preparation**:
Short-circuit the crystal oscillator (note: for a four-pin oscillator, identify the signal output pin and short those two pins). Be sure that the power pins of the crystal oscillator are not shorted! For large electrolytic capacitors, disconnect the circuit by desoldering the corresponding leg. This helps prevent interference caused by the charging and discharging of large capacitors.
2. **Device Exclusion Test**:
During online or comparative testing, the PCB manufacturer should log all devices that pass (or appear normal) by directly verifying the test results. If the test fails (or worse), re-test the component. If it still fails, confirm the result and proceed with testing until all devices on the board have been tested. Then, remove and discard any components that fail the test (or show worse results).
Some test instruments for components that fail online tests offer a more practical alternative: these instruments can apply power and ground to the device via a test clip, allowing the device to be removed from the onboard power system during testing.
If you have any PCB manufacturing needs, please do not hesitate to contact me.Contact me
**Principle 1: Prioritize Quantity**
Begin by visually inspecting the repaired circuit board. If needed, use a magnifying glass for a more detailed examination.
Focus on the following areas:
1. Check for any disconnections or short circuits, with particular attention to any potential fractures in the printed circuit board.
2. Inspect the relevant PCB components (resistors, capacitors, inductors, diodes) for signs of disconnection.
3. Determine if previous repairs have been made. Which components were modified, and are there any issues such as cold solder joints, leaks, or post-insertion errors?
Once these conditions have been ruled out, use a multimeter to measure the resistance between the power supply and the ground of the circuit board. If the resistance is too low (only a few ohms) or unusually high (over ten ohms), this indicates that a component on the board may be damaged or partially punctured. In this case, further action must be taken to locate the faulty component.
The recommended approach is to power up the board during this process (note: this is a critical step). Ensure that the board’s operating voltage is correctly matched and that the input voltage is higher than the required working voltage. This step is essential for accurate diagnosis and repair.
**Voltage Value**: Otherwise, it could damage the repair circuit board! Previous errors have not been addressed, and new issues have been introduced! The temperature of each component on the circuit board should be measured with a spot thermometer. Faster temperature rises and higher temperatures are key indicators of potential problems.
If the resistance value is normal, use a multimeter to measure other parts, such as the blocked container, the three-terminal MOSFET, and the switch on the peeling part of the circuit. The goal is to ensure that the tested component is functioning properly. Don’t overcomplicate problems that basic test tools (e.g., utility tables) can easily diagnose.
**Principle 2: External First, Then Internal.**
If possible, it is ideal to use a working circuit board similar to the one being repaired as a reference. Then, use the tester’s double-edge VI curve scanning function to compare the two boards. Start testing from the input port of the circuit board and then proceed through the comparison of the test points, such as the table and capacitors. This compensates for the limitations of standard meters, which can make it difficult to detect capacitor leakage.
**Principle 3: Start with Difficulties, End with the Easier Ones.**
To improve the effectiveness of the test, conduct preliminary repairs and technical adjustments to the single board before performing the online function test. This minimizes the impact of various interferences during the testing process. Specific steps include:
1. **Pre-test Preparation**:
Short-circuit the crystal oscillator (note: for a four-pin oscillator, identify the signal output pin and short those two pins). Be sure that the power pins of the crystal oscillator are not shorted! For large electrolytic capacitors, disconnect the circuit by desoldering the corresponding leg. This helps prevent interference caused by the charging and discharging of large capacitors.
2. **Device Exclusion Test**:
During online or comparative testing, the PCB manufacturer should log all devices that pass (or appear normal) by directly verifying the test results. If the test fails (or worse), re-test the component. If it still fails, confirm the result and proceed with testing until all devices on the board have been tested. Then, remove and discard any components that fail the test (or show worse results).
Some test instruments for components that fail online tests offer a more practical alternative: these instruments can apply power and ground to the device via a test clip, allowing the device to be removed from the onboard power system during testing.
If you have any PCB manufacturing needs, please do not hesitate to contact me.Contact me
