Electronics Maintenance and Repairs

 INTRODUCTION:

Electronics is a science of how to control electric energy in which the electrons have a fundamental role. Electronics deal with electrical ccts that involve active electrical component such as transistor, diodes ,integrated cct (IC) and associated passive electrical components and interconnection technologies. Commonly, an electronics device contains   circuitry consisting primarily or exclusively of active semiconductors supplemented with passive element, such cct is what is called electronics

  Maintenance: can be described as an action necessary for retaining or rectory a piece of equipment, machine or  system  to the  specify operable condition so as to achieve its maximum useful life.

Repair is an action means to put in means order or restore to a suds or at or even below their rated value and thus reduces their rate of failure component such as capacitor which characteristics of static field are known to have a failure rate which is approx proportional to the 10⁵power of the applied voltage at fixed temperature.

CURRENT SURGE: also known as in rush current or input surge current or switching surge is the max, instantaneous input current, or input surge current or switch surge , is the maximum instantaneous input current drawn by an electric device when first switch ON. These sudden fluctuations of current in excess of value contribute to component failure in exactly the same way as voltage surge do.  

Failure of electronics component:

 Attention will be given to failure experience by common electronic components, due to the operation stress, environmental stress and manufacturing defects.

-     Fixed   resistor: the commonest type of failure associate with resistor is due to either: Open circuit, this may happens as a result of excessive heat burning out resistor centre  and mechanical stress fracturing the resistor as in case of Carbon resistor, while a Wire wound resistor may became open circuited due to fracture of wire resulting from corrosion  of wire due to the electrolyzing action  set u by absorbed moisture. Mean while a film field May experience, applied voltage.

 

-         Intermitted contact resulting from wearing or excessive current flow over small segment of low resistance value.

-         Increase in résistance value, which is very common in carbon composition resistance and is due to the movement of carbon under the influence of heat, voltage or moisture absorption of moisture, result in swelling or forcing of carbon particle to separate.

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Capacitor:

                             

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-         Failure of capacitor may be characterized by short/circuit which occurs due to fracture of Di-electric result 4rm shock & vibration liking of seals.

-          Intermittent open-circuit may be course by mechanical thermal shock and fracture of internal fraction. Polarized Capacitor

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Fluctuation in capacitance value, which occurs due to the loss electricity via liking seals forces by pressure, thermal or mechanical shock.

-         Transformer/ induct-or are normally characterized by failure due to:-open-circuit in windy, short circuit of coil to the frame, over loading, perhaps through failure of another component.

-         Semi conductors device, failures in it are mainly due to. Open- circuit or short cut at a junction electrical interference failure due to the excessive temp and humility exceeding the max supply voltage.

-         Relay: failure in a relay may be as result of, corrosion of fine wire result in to open-circuit, metal fatigue in armature spring. Dirty contact coursed by action of chemical produce by sparking. Formation of dust on the relay contact which may be due to factors external to the system or equipment such as weathers and sea water. weather condition affect a system performance  can be categories as follows: