How to use a multimeter, to troubleshoot the circuit board?
The red meter pen is grounded, the red circle of the feet are locations, the negative terminal of the capacitor are locations. The black pen is placed on the IC foot to be measured, then the multimeter will display a dipole value, according to the dipole value to determine the IC good or bad. In the end, the value of how much is good, this is to evaluate the experience, either you have a piece of the motherboard, to do a comparison of the measurement on the line.
1. Look at the state of the components
Get a faulty board, the first observation of the board there is no obvious component damage, such as electrolytic capacitors burned and bulging, resistors burned and power devices burned.
2. Look at the circuit board welding
Such as printed circuit board has no deformation warpage; there is no solder joint off, obvious false welding; circuit board copper skin has no warping, burning paste black.
3. Observe the plug-in components
Such as integrated circuits, diodes, circuit board power transformers and other directions have not been inserted wrong.
4. Simple test of resistance capacitance inductance
Use a multimeter to conduct a simple test on the range of resistance, capacitance, inductance and other suspect components, test whether the resistance value of resistance becomes large, capacitance short circuit, open circuit and capacitance change, inductance short circuit and open circuit and other phenomena.
5. Power on test
After the above simple observation and test, can not exclude the fault, power on test. First test the board power supply is normal. Such as whether the board's AC power supply is abnormal, the voltage regulator output is abnormal, switching power supply output and waveform is abnormal, etc.
6. Brush program
For a microcontroller, DSP, CPLD and other programmable components, consider rebrushing the program to exclude the circuit failure caused by abnormal operation of the program.
How to repair the circuit board?
Method 1: Observation method
This method is quite intuitive, and by carefully examining it, we can clearly see the burn marks. When this problem occurs, we have to pay attention to the laws of it when we carry out maintenance tests to ensure that no more serious damage occurs when the power is on. When we use this approach, we need to pay attention to the following issues:
Determine whether the board is artificially damaged by observation.
Carefully observe the components related to this board, each capacitor and resistor, etc., to see if there is a blackened condition. Since the resistance is impossible to see, you can only use the instrument to measure. The relevant bad parts should be replaced in a timely manner.
The circuit board integrated circuit observation, such as the CPU, AD and other related chips, observed bulging, burnt and other related conditions should be modified in a timely manner.
The cause of the above problems may appear in the current, too much current caused by burning, so check the relevant circuit diagram to see where the problem is.
Method two: static measurement method
Circuit board repair, observation method is often difficult to find some problems, unless it is very obvious burn-in or deformation may be visible. But most of the problems still need to be measured by voltmeter before a conclusion can be drawn. Circuit board components and related parts should be tested one by one. Repair procedures should be based on the following process.
Test the power supply and ground for short circuit and check the cause.
Test the diode to see if it is normal.
Check whether the capacitor is a short circuit or even a broken circuit. Step 4: Check the circuit board related integrated circuits, and resistors and other related device indicators.
We use the observation method as well as the static measurement method can solve most of the problems in circuit board repair, it is undoubtedly, but in the measurement to ensure that the power supply is normal, there should be no secondary damage.
Method Three: Online measurement method
Online measurement method is often used by the manufacturer, in order to facilitate maintenance and special build a universal commissioning maintenance platform is a very necessary thing. This method of measurement needs to pay attention to follow the steps below.
Apply power to the board, check whether the components have high temperature phenomenon, if so, check out the relevant components for replacement.
Test the corresponding gate circuit of the board, observe whether there is a problem with the logic, determine the chip good or bad.
Test the output of the digital circuit crystal is not normal.
Online measurement method is mainly used for the comparison of two good and bad circuit boards, through the comparison, find the problem, solve the problem. So as to complete the repair of the circuit board.
The red meter pen is grounded, the red circle of the feet are locations, the negative terminal of the capacitor are locations. The black pen is placed on the IC foot to be measured, then the multimeter will display a dipole value, according to the dipole value to determine the IC good or bad. In the end, the value of how much is good, this is to evaluate the experience, either you have a piece of the motherboard, to do a comparison of the measurement on the line.
1. Look at the state of the components
Get a faulty board, the first observation of the board there is no obvious component damage, such as electrolytic capacitors burned and bulging, resistors burned and power devices burned.
2. Look at the circuit board welding
Such as printed circuit board has no deformation warpage; there is no solder joint off, obvious false welding; circuit board copper skin has no warping, burning paste black.
3. Observe the plug-in components
Such as integrated circuits, diodes, circuit board power transformers and other directions have not been inserted wrong.
4. Simple test of resistance capacitance inductance
Use a multimeter to conduct a simple test on the range of resistance, capacitance, inductance and other suspect components, test whether the resistance value of resistance becomes large, capacitance short circuit, open circuit and capacitance change, inductance short circuit and open circuit and other phenomena.
5. Power on test
After the above simple observation and test, can not exclude the fault, power on test. First test the board power supply is normal. Such as whether the board's AC power supply is abnormal, the voltage regulator output is abnormal, switching power supply output and waveform is abnormal, etc.
6. Brush program
For a microcontroller, DSP, CPLD and other programmable components, consider rebrushing the program to exclude the circuit failure caused by abnormal operation of the program.
How to repair the circuit board?
Method 1: Observation method
This method is quite intuitive, and by carefully examining it, we can clearly see the burn marks. When this problem occurs, we have to pay attention to the laws of it when we carry out maintenance tests to ensure that no more serious damage occurs when the power is on. When we use this approach, we need to pay attention to the following issues:
Determine whether the board is artificially damaged by observation.
Carefully observe the components related to this board, each capacitor and resistor, etc., to see if there is a blackened condition. Since the resistance is impossible to see, you can only use the instrument to measure. The relevant bad parts should be replaced in a timely manner.
The circuit board integrated circuit observation, such as the CPU, AD and other related chips, observed bulging, burnt and other related conditions should be modified in a timely manner.
The cause of the above problems may appear in the current, too much current caused by burning, so check the relevant circuit diagram to see where the problem is.
Method two: static measurement method
Circuit board repair, observation method is often difficult to find some problems, unless it is very obvious burn-in or deformation may be visible. But most of the problems still need to be measured by voltmeter before a conclusion can be drawn. Circuit board components and related parts should be tested one by one. Repair procedures should be based on the following process.
Test the power supply and ground for short circuit and check the cause.
Test the diode to see if it is normal.
Check whether the capacitor is a short circuit or even a broken circuit. Step 4: Check the circuit board related integrated circuits, and resistors and other related device indicators.
We use the observation method as well as the static measurement method can solve most of the problems in circuit board repair, it is undoubtedly, but in the measurement to ensure that the power supply is normal, there should be no secondary damage.
Method Three: Online measurement method
Online measurement method is often used by the manufacturer, in order to facilitate maintenance and special build a universal commissioning maintenance platform is a very necessary thing. This method of measurement needs to pay attention to follow the steps below.
Apply power to the board, check whether the components have high temperature phenomenon, if so, check out the relevant components for replacement.
Test the corresponding gate circuit of the board, observe whether there is a problem with the logic, determine the chip good or bad.
Test the output of the digital circuit crystal is not normal.
Online measurement method is mainly used for the comparison of two good and bad circuit boards, through the comparison, find the problem, solve the problem. So as to complete the repair of the circuit board.