For beginers basic electronic

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How to Check  Basic Electronic Components Using a  Multi-Meter

Basic electronic components such as resistors,  capacitors, diodes and transistors are widely used in any electronic  devices and gadgets. Knowing how to conduct a test on this components  using a multimeter would give you an idea on how to trouble shoot and  repair any defective cellphones or electronic equipments at home. Below  are some basic D.I.Y. regarding proper testing of this components using a  multimeter.


How to Check Resistors?

Read the  indicated  code value indicated in Schematic Diagram then select the  Ohm-scale within but not way below the indicated value. A resistor is  good if its resistance is close to the indicated value.Tolerance should  be considered with the ohmmeter reading. While, no resistance reading at  all on the ohmmeter scale settings means that the resistor is open. A  zero resistance reading on all ohmmeter scale settings means that the  resistor is shorted.


  How to Check Capacitors?


In most cases, a capacitor fails due to the deterioration of the  dielectric material between its plate.Defective capacitors can have an  internal shorted terminals, excessive leakage and degradation of  capacitance meter. For an electrolytic capacitor (capacitors with  polarity), short the terminal capacitor to discharge it prior to  testing.

To test a capacitor, set the multimeter to Rx10 or Rx1K scale. Connect  the tester negative probe to the capacitor positive terminal and the  positive probe to the negative terminal.

A good indication for electrolytic capacitor shows the meter needle  deflecting towards zero and moves back again to infinite resistance  position.
For ceramic, Mylar and other capacitor with a capacitance with less than  1.0 uF, the meter will not deflect at all.

A defective indication for an electrolytic capacitor shows that the  meter will rest on zero and remain stationary at a point which is an  indication that the capacitor is shorted.

   How to Check Diodes?


Set the multimeter knob to any of the resistance position (x1, x10, x1K  or 10K ohm ).Connect the positive probe to the anode and the negative  probe to the cathode.Then connect the positive probe to the cathode and  the
negative probe to the anode of the diode. A good indication in the first  procedure will show the meter deflected very little or may not deflect  at all.

And in the second procedure, the meter will deflect towards zero.The  actual resistance reading is the forward resistance of the diode.

A defective indication shows that the meter won't deflect at all even  when the probes are reversed. Or the meter deflects at the same time or  almost the same resistance reading for both steps.

   How to Check Transistors:


Bipolar transistors are usually checked out of a circuit by means of an  ohmmeter. When it is desired to check for the resistance across the  transistor emitter and collector, NPN or PNP, ohmmeter probes may be  connected either way. A good transistor will show above a reading above  1000 ohm.

How to determine if it is NPN or PNP transistor?

To determine the correct terminal of the transistors, set the range  selector to x 1 or 10 ohm.Connect the positive probe to the emitter and  the negative probe to the base of the transistor. Note the reading  interchange the connection of the probes to the leads of the transistor.

Base your conclusion on the table:

POSITIVE PROBE TO: -----NEGATIVE PROBE  TO: -----RESISTANCE READING-- CONCLUSION:  
  Emitter-------    --   Base---------- Less than 150 ohm  ------Transistor is NPN
 Base --------------Emitter --------Infinity ----------------Transistor  is NPN


POSITIVE PROBE TO:   NEGATIVE PROBE TO:   RESISTANCE READING:    CONCLUSION:  
-Emitter------------Base ---------Infinity   ----------------   Transistor is PNP
Base --------------- Emitter --- - Less than 150 ohm -------  Transistor  is PNP

Some defective indications of transistors: Resistance between any pair  of the terminals is less than 10 ohms, means that the transistor is  shorted. Resistance between base and emitter or base collector for both  the forward and reverse application of ohmmeter probes is infinity  (meter needle don't deflect), means that the transistor is open.  Transistors overheats (except power transistors) during normal operating  condition means that the transistor is shorted.


    How Check an LED ( Light Emitting Diode)

Set  the Muti-meter to x1 connect the positive probe to cathode and the  negative probe to anode. The good and working LED will then light up or  glow, a busted LED will not.



   How to Check a Coil?

Set the  multimeter to X1 a good and working coil have a reading  approximately  point to zero ohms, without any reading means the coil is open or  busted.


  How to Check a Fuse?

A blown SMD  Fuse is not visible to our naked eye, just set the multi-meter to x1 and  put both test probe to both end side of the fuse. A full reading here  to zero or continuity check is full. without any reading means the fuse  is already busted.


  How to Check IC chips (Integrated  Circuits)?

IC Chips is hard to determine faulty by using only a  multi-meter, some advance equipment like the one that the manufacturer  used during their productions. However; you can determine a faulty chips  by some few experiences when it comes to troubleshooting, One  techniques is that by comparing two same components from one another.  like for example; if one chips is suspected to be faulty, then by  replacing it with a good and working same chips, you can now determine  it if the said chips got a problem. It is a trial and error method at  first; but as long as your experience and knowledge skills increases,  you can determine it more quickly and accurately.