PCB Resistor Damage Characteristics
Many beginners often encounter resistor damage problems when overhauling the printed circuit board. In fact, the characteristics of the resistance damage can be summarized as follows.
Resistance has the largest number among electrical equipment components, but its damage rate is not the no.1. Resistor damage is always found in the open circuit, larger resistance is less common, smaller resistance is very rare.
Common resistors are carbon film resistors, metal film resistors, wire wound resistors and insurance resistors, among them the first two kinds of resistors are the most widely used.
The failure rate of low resistance (below100Ω) and high resistance (above 100kΩ) are very high, while the intermediate resistance (such as hundreds Ω to tens of thousands Ω) are rare to break; the second is low resistance Value resistance damage is often scorched black, it is easy to find, while there is little trace of high resistance damage. Moreover, low-resistance resistors tend to be scorched and black when damaged, thus traces are easily found, while traces are very little when high-resistance resistors are damaged.
Wire wound resistors are generally used for high current limit with small resistance. Cylindrical wire around the resistance burn out sometimes black or surface burst, cracks, and some without signs. Cement resistance is a kind of wire wound resistor, it may rupture when burned, or there is no visible trace. When the insurance resistance burn, the surface may blow up a little, or there is no trace, but there is no black. According to the above characteristics, you can quickly find the damaged resistor.