One of the biggest problems encountered in the maintenance of electronic products is short circuit. The short circuit on the PCBA has caused considerable damage, ranging from burning out components to scrapping the PCBA. We just try to avoid short circuit generation, we must master every step of production, check not to miss every suspicious point.
1. If it is manual soldering, develop a good habit. First, visually inspect the PCB board before soldering, and use a multimeter to check whether the key circuits (especially power and ground) are short-circuited. Second, use a multimeter every time you solder a chip To measure whether the power supply and ground are shorted; if the solder is poured on the solder pins of the chip (especially surface mount components), it is not easy to find.
2. Open the PCB diagram on the computer, light up the short circuit of the network, and see which one is the closest and the easiest to connect to one piece. Special attention should be paid to IC internal short circuits.
3. A short circuit was found. Take a board and cut the line (especially suitable for single/double board), after cutting the line, power up each part of the function block, and partially exclude it.
4. Use a short-circuit location analyzer, such as: Singapore PROTEQCB2000 short-circuit tracker, Hong Kong Lingzhi Technology QT50 short-circuit tracker, British POLAR ToneOhm950 multi-layer board circuit short-circuit detector.
5. Care must be taken when soldering capacitors pasted on small-sized meters, especially the power filter capacitors (103 or 104), which are large in number and can easily cause short circuits between power and ground. Of course, sometimes you are unlucky and you run into a short circuit in the capacitor itself, so the best way is to solder the capacitor before soldering.
6. If there is a BGA chip, because the chip cannot see all the solder joints, and it is also a multi-layer board (more than 4 layers), it is best to design the power supply of each chip, with magnetic beads or 0 European resistor connections, so that the power supply and ground are short-circuited When disconnecting the magnetic bead detection, it is easy to find the chip. Because BGA soldering is very difficult, if there is no automatic soldering machine, a little attention should be paid to short-circuiting the two adjacent power and ground solder balls.
