1. Check the status of the components
Get a faulty circuit board and first observe whether there are any obvious component damages on the board, such as burnt and swollen electrolytic capacitors, burnt resistors, and burnt power devices.
2. Check the soldering of the circuit board
Whether the printed circuit board is deformed or warped; Is there any solder joint detachment or obvious virtual soldering; Is there any warping or blackening of the copper coating on the circuit board.
3. Observing the plugin of the component
Whether the direction of integrated circuits, diodes, circuit board power transformers, etc. is correctly plugged in.
4. Simple testing of resistance, capacitance, and inductance
Use a multimeter to perform simple tests on suspicious components such as resistors, capacitors, and inductors within the range, testing for increased resistance, capacitor short circuits, open circuits, changes in capacitance values, inductor short circuits, and open circuits.
5. Power on test
After the above simple observation and testing, the fault cannot be eliminated, and a power on test can be carried out. Firstly, test whether the power supply of the circuit board is normal. Whether the AC power supply of the circuit board is abnormal, whether the output of the voltage regulator is abnormal, whether the output and waveform of the switching power supply are abnormal, etc
6. Brush program
For programmable components such as microcontrollers, DSPs, CPLDs, etc., it is possible to consider flashing the program again to eliminate circuit faults caused by abnormal program operation.
7. Repair according to functional modules
If the circuit board cannot be repaired according to the above steps, it is necessary to determine the possible problematic circuit module based on the circuit fault and carry out further repairs according to the design drawings.