The general law of Electronic PCB Card Damaged Components Reworking (this can greatly improve the repair speed), the probability of electronic PCB card component damage in turn is: electrolytic capacitors, power modules, high-power transistors, zener diodes, resistors less than 100Ω, resistances greater than 100kΩ , relay, small ceramic capacitors.
Circuit characteristics for repairing damaged capacitors in circuit boards Faults caused by damaged capacitors are among the highest in electronic equipment circuit board restoration, especially electrolytic capacitors are the most common. Capacitor damage manifests itself as:
1. capacity becomes smaller;
2. complete loss of capacity;
3. leakage;
4. short circuit.
Capacitors play different roles in the circuit, and the faults they cause also have their own characteristics. In industrial automation controller PCB board recovery, digital circuits account for the vast majority. Capacitors are mostly used for power supply filtering and less for signal coupling and oscillation circuits.
If the electrolytic capacitor used in the switching power supply is damaged, the switching power supply may not be vibrated and there is no voltage output; or the output voltage is not well filtered, and the circuit is chaotic due to the unstable voltage.
It appears that the machine is working up or down or cannot be turned on. If the capacitor is between the positive and negative poles of the power supply of the digital circuit, the fault performance is the same as above.
This is especially obvious on computer motherboards. Many computers have been used for a few years and sometimes they cannot be turned on, and sometimes they can be turned on. When you open the case, you can often see electrolytic capacitors bulging. If you remove the capacitors, measure the capacity. It is found to be much lower than the actual value.
