Open the PCB design drawing on the computer, light up the short-circuited network, and see which is the closest and easiest to connect to. Pay special attention to short circuits inside the IC.
If it is manual welding, it is necessary to develop a good habit:
1. Before welding, check the PCB board visually, and use a multimeter to check whether the key circuits (especially the power supply and ground) are short-circuited;
2. Use a multimeter to test whether the power supply and ground are short-circuited every time a chip is soldered;
3. Do not shake the soldering iron when soldering. If you throw the solder on the solder pins of the chip (especially surface mount components), it will not be easy to find out.
A short circuit was found. Take a board to secant (especially suitable for single/double-layer boards), and after secanting, electrify each part of the functional blocks separately, and gradually eliminate them.
Using Short Circuit Locating Analytical Instruments
If there is a BGA chip, since all solder joints are covered by the chip and cannot be seen, and it is a multi-layer board (more than 4 layers), it is best to separate the power supply of each chip during design and connect it with magnetic beads or 0 ohm resistors , In this way, when there is a short circuit between the power supply and the ground, disconnect the magnetic bead detection, and it is easy to locate a certain chip. Due to the difficulty of BGA soldering, if it is not automatically soldered by the machine, a little carelessness will short-circuit the adjacent power and ground solder balls.
Be careful when soldering small-sized surface-mount capacitors, especially the power filter capacitors (103 or 104), which are large in number and can easily cause a short circuit between the power supply and ground. Of course, sometimes if you are unlucky, you will encounter a short circuit in the capacitor itself, so the best way is to check the capacitor before welding.