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 to 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.
Further, we will tackle this issues and give you some
tips and tricks
