How to repair the circuit board of a multimeter
Method 1: Observation method for circuit board repair
This method is quite intuitive. By carefully inspecting it, we can clearly see the burn marks. When this problem occurs, we must pay attention to the rules when performing maintenance and inspection to ensure that more serious damage does not occur when power is turned on. When we use this method, we need to pay attention to the following issues:
The first step is to determine whether the circuit board is artificially damaged by observation. The second step is to carefully observe the components related to the circuit board. Observe every capacitor and resistor to see if there is any blackening. Since resistance cannot be viewed, it can only be measured with instruments. Relevant damaged parts must be replaced promptly. The third step is to observe the integrated circuits on the circuit board, such as CPU, AD and other related chips. If bulges, burns and other related conditions are observed, they should be modified in time.
The cause of the above problems may occur in the current aspect. Excessive current may cause burnout, so check the relevant circuit diagram to see where the problem is.
Method 2: Static measurement method for circuit board repair
In circuit board repair, it is often difficult to find some problems by observation, unless they are obviously burned or deformed. However, most problems still require voltmeter measurements to draw conclusions. Circuit board components and related parts must be tested one by one. Maintenance steps should be carried out according to the following process.
Step one: Detect the short circuit between the power supply and the ground and check the cause. Step 2: Check whether the diode is normal. Step 3: Check whether the capacitor has a short circuit or even an open circuit. Step 4: Check the integrated circuits related to the circuit board, as well as related device indicators such as resistors.
There is no doubt that we can solve most of the problems in circuit board repair using observation methods and static measurement methods. However, when measuring, we must ensure that the power supply is normal and no secondary damage can occur.
Method 3: Online measurement method for circuit board repair
The online measurement method is often used by manufacturers. To facilitate maintenance, it is necessary to build a universal debugging and maintenance platform. When measuring in this way, you need to pay attention to the following steps.
Step 1: Power on the circuit board and check whether the components are overheated. If so, check them out and replace the relevant components. Step 2: Check the corresponding gate circuit of the circuit board, observe whether there are any problems with the logic, and determine whether the chip is good or bad. Step 3: Test whether the output of the digital circuit crystal oscillator is normal.
The online measurement method is mainly used to compare two good and bad circuit boards. Through comparison, problems can be found and solved. Thus completing the repair of the circuit board.
