How to find the short point between VCC and GND

When debugging a circuit, you may often encounter a short circuit between VCC and GND. There are too many VCC and GND points on the board, and you may feel that don't know where to find the short point. Here are a few methods for your reference.

1. Visual inspection

The easiest way is to observe with the naked eye or a magnifying glass. Especially chips with fine pitch pins and small package capacitors are prone to short circuits when the soldering is not good. Sometimes conductive objects such as tin beads or copper wires may have fallen on the circuit board, just between the VCC and GND pins, causing a short circuit. This kind of problem is easier to solve, just use a soldering iron to deal with it.

2. Knife cut

For the board without obvious short circuit, it is very likely that the short circuit is caused by the damage of the components on the board. At this time, you can use a blade to cut off the suspected short-circuit part, and then conduct a test to find the problem step by step.
If you don't want to damage the circuit board, you can remove the suspected short-circuit components one by one, and then gradually eliminate them, but this method is more troublesome. If you are lucky, you may find it quickly, if not, you may have to remove the last one then find the problem.

3. Hand touch

Knife cutting and component removal methods are both troublesome and are rarely used. Another method is to touch the suspected chip after power-on. If the heat is abnormally severe, it must be damaged. Of course, be careful not to get hand scalded when touching it. In addition, because it has been short-circuited, the power-on time should not be too long, otherwise PCB may burn directly.

4. Thermal imaging camera observation

You can use instruments instead of hand touches, such as infrared thermal imaging cameras, which can easily find unusually hot places.

5. Colophony smoking

Finally, I recommend a simple and practical method, it also uses the phenomenon that a short circuit will generate heat. Smoke a layer of colophony on the circuit board, and then power on, the short circuit will generate more heat. Observe where the colophony melts, it shows where the short circuit is.