PCB circuit boards are prone to failure during use, which involves maintenance. So, what problems do you need to pay attention to in PCB circuit board maintenance?

First. understand the vulnerable parts on the circuit board

1. the place where the design is unreasonable is most prone to failure

The first is the heat dissipation problem, many pcb board damage is caused by poor heat dissipation design; Followed by copper foil wire, poor quality circuit board power line copper foil is very thin,

easy to burn due to overcurrent.

2. frequently used places prone to failure

For example, the drive motor of the circuit board, the rotating shaft, the switching tube of the switching power supply, the operation panel, etc.

3. heavy load, high power, high working voltage parts are the most prone to failure

Including circuit board power supply, drive circuit, power control device, operation amplifier, etc., is the most easily damaged.

4. the protection circuit is the most easily damaged

Valuable chips or components on the circuit board are protected, once the equipment is abnormal, the first damage is these protection circuits.

5. The interface and line of the inliner seat and connector are easy to contact poorly or break the line

Poor contact between the board and the slot, poor contact between the wire plug and the terminal, and virtual welding of components are all of these types.

Second. commonly used components damage characteristics and detection

1. resistance value of small resistance and large capacity of electricity is easy to break

Resistors with small resistance values are often used to limit the current on the power supply line, and if the current is too large, it will burn off. In addition, many ground capacitors are used to filter

the power supply line, and if the voltage or current is unstable, it will break down the capacitor and cause leakage.

2. capacitor damage fault characteristics and maintenance

The failure caused by capacitor damage is the highest in electronic equipment, which is manifested as: smaller capacity, complete loss of capacity, leakage, short circuit, etc.

3. the operational amplifier is good or bad discrimination method

No matter what type of amplifier, there is a feedback resistance Rf, we can check this feedback resistance from the circuit during maintenance, use a multimeter to check the resistance between the

output and the reverse input.

Three. maintenance to “chest frame”

For example, the switching power supply, always inseparable from the oscillation circuit, switching tube, switching transformer, to check whether the circuit is vibrating, the capacitor is not

damaged, each transistor, diode is not damaged, etc.