The circuit board is short and how to check that the element has burned
Circuit board (Manufacture of printed circuit boardsr) The problem does not apply to power. Open up HDI pcb Print Bootd circuit board file on your computer to find the VCC and GND network. Using the multimeter beep, verify that the VCC and GND on the circuit board are actually short-circuited if the short-circuit has a "drop".
Look at the magnifying glass or the open eye to find out where the VCC and GND are on the printed circuit board, and these places are easily short-circuited.
In particular, we need to see chips that are powered by VCC and GND. The pins of these chips can be very dense and the distance between VCC and GND is very close. It may even be that the VCC and GND pins are mutually tapered, causing a short circuit.
If you do not find a short circuit in step 2, check the separation capacitor for the chip power, generally there is a small capacitance and a large capacitor. The size of the small capacitance is very small and the two pins are very close, especially for the patch capacitor, which is even more of a case. In the middle of the center, the two pins can be glued by welding the slag, resulting in a VCC and GND short circuit.
If you do not find a short circuit in step 3, the circuit board is connected and the supply voltage will be limited. As the circuit board is short-circuited, the direct VCC supply is likely to further damage the circuit. Half voltage may have VCC power, temperature touch on suspicious chips (not the power chip refers to normal supply voltage) because the supply voltage is far away from the chip if the chiller heating, the base can confirm the short circuit.
If you do not find a short circuit in step 3, the cutting board can not be cut with a blade. The VCC line on the printed circuit board should be divided according to the following principles:
Damage to the line should be as small as possible, and the original shape is easily restored by welding after cutting.
If possible, the VCC module will be reduced. On the one hand, the VCC network of the same module is concentrated into one block.
Cutting as much of the top or bottom layer as the VCC mesh in the inner layer is difficult to cut;
It is divided into two parts, such as part + B A, which are used to check part A and part B.
If Part A is short, part B is not short-circuited. Only part of the circuit must be truncated by the VCC. Depending on the size from small to large, step by step as a short circuit, the site is moved forward until a short circuit is detected: a component.
After finding a short circuit, we analyze and remove the shorted parts with an electric iron. After finishing the finish, we repair and re-weld the cutting area.