Weak current College】 【electronic components of fault characteristics】.

<br> Electrical device internal electronic components while a large number, but whose fault is that there are rules to follow. 1. characteristics of damage resistance <br> Resistance is the electrical equipment in the largest number of components, but not damage the components .with the highest rate. Resistance to damage to the most common open circuit, the resistance of the larger more rare, very rare resistance value gets smaller. Common carbon film resistor metal film resistors, wire wound resistors and several insurance resistance. The first two resistance .most widely used, its characteristics of damage to a low resistance (100 Ω) and high resistance (100 k Ω or more) of the failure rate is high, intermediate resistance (such as several hundred thousand euro to dozens of Europe), very little .damage; the second is a low-resistance damage are often burned black, it is easy to find, and high resistance to damage when very few traces. Wire-wound resistors generally used for high-current-limiting, resistance. Cylinder wire wound resistors .when some will burn out the blackening or surface blasting Peel, crack, no traces. Cement resistors are wire-wound resistors, or else you may rupture, otherwise no visible traces. When you have burned the insurance resistance of surface will blow up a piece .of skin, there is no trace of it, but never burned black. According to the above features, check the resistance can be focused, quickly identify damage resistance. 2. characteristics of damage to the electrolytic capacitor <br> Electrolytic Capacitor in the amount .of electrical equipment, the failure rate is very high. Electrolytic Capacitor damage have the following features: first, the total loss of capacity or the capacity of smaller; the second is a minor or serious leakage; the third is the loss of capacity or capacity .is smaller and leakage. Find damaged Electrolytic Capacitor methods are: (1) see: there is leakage capacitance damage, capacitance circuit board surface below even capacitor has a layer of appearance is the grease stains, this capacitor should never be used again; after a .damage of the capacitor will muster, this capacitor cannot continue to use; <br> (2) touch: after some serious power of electrolytic capacitor leakage current are fever, fingers touch, or even hot, this capacitor must be replaced; <br> .(3) internal electrolyte capacitors, long curing makes the electrolyte dry, resulting in reduced electrical capacity, so important to check the heatsink and the capacitor in the vicinity of high power components, from the closer, the greater the possibility of damage. 3. .Second, transistor and other characteristics of semiconductor device damage <br> Second, the transistor's damage is usually a pn junction breakdown or open circuit, short circuit in the breakdown. In addition there are two bad performance: first, thermal stability, characterized by normal .post, working time, soft breakdown occurs; the other is a pn junction characteristics variation, Multimeter, measuring R × 1k PN junctions are OK, but when the computer does not work, if you use R × 10 or R × 1 low range stalls ., discovered the PN forward resistance than normal. Measurement, triode can use the pointer to the measurement of the road, the multimeter is accurate by multimeter reset R × 10 or R × 1 files (generally used R × 10 stalls, not apparent when reuse .R × 1 stall) at RoadTest, triode of pn junction, reactive resistance, if you are not too big to resistance (normal), reverse resistance is large enough (as opposed to values), indicating that the pn junction, on the contrary it .is doubtful that the required welding after logging in. This is because General circuit diode, triode peripheral resistance, mostly in the hundreds, thousands of euro cent multimeter low resistance measurement in road, rail, you can basically ignored peripheral resistance on the influence of the .pn junction resistive. 4. the characteristics of the integrated circuit is damaged <br> The internal structure of complex integrated circuits, feature a lot, any part of the damage does not work. Integrated circuit damage to either completely damaged, thermal stability. Completely .damaged, it can be removed, and normal contrast with model IC measuring its each pin on land, reactive resistance, can always find one or several pin resistance anomalies. On the thermal stability of difference, when the unit is working, use absolute alcohol cooling .is suspected of integrated circuit, if the failure occurs time delay or no longer fails, then the judgment. Usually you can only change the new IC to exclude..