Shield box maintenance has always been an indispensable part of wireless product companies. Because only through it can make the original test erroneous situation be solved. The maintenance of shielded boxes is the largest part of this type of company. Because it not only applies to many kinds of radio frequency, mechanical expertise, but also sometimes requires extensive field experience. The following describes how to routinely maintain the shielding box.
Tap the hand pressure method. The phenomenon of good and bad operation of the pneumatic shield box is often encountered. The majority of this phenomenon is caused by poor contact or imaginary welding. For this situation, tapping and hand pressure can be used. The so-called "knocking" is to lightly hit the board or component with a small rubber hoe or other knocker to see if it will cause an error or stop failure. The so-called "hand pressure" is when the fault occurs, after the power is turned off, the plugged parts and the plug and the base are pressed again by hand, and if the power supply is turned on, it will eliminate the fault. If it is found that knocking the case is normal and the pounding is not normal, it is best to re-insert all joints and try again.
Observation. Normally, damaged components will discolor, blistering or scorch spots; burned devices will produce some special odors; short-circuited chips will become hot; visible or unwelded areas can also be observed with the naked eye.
Exclusion. The so-called exclusion method is to determine the cause of the fault by inserting and removing some plug-in boards and devices. When the instrument returns to normal after removing a certain board or device, it indicates that the failure occurred.
Replacement method. Two instruments of the same type or enough spare parts are required. Replace a good spare with the same component on the faulty machine and see if the fault is eliminated.
Comparison method. Two shielded boxes of the same type are required, and one is in normal operation. Use this method also has the necessary equipment, such as multimeters and oscilloscopes. According to the nature of comparison, there are voltage comparison, waveform comparison, static impedance comparison, output comparison, and current comparison. The specific method is: let the faulty shield box and the normal shield box run under the same conditions, and then detect the signals of some points and then compare the measured two signals. If they are different, you can conclude that the fault is out here. This method requires maintenance personnel with considerable knowledge and skills.
2018-03-26