How to find out diode is good or bad
Remember what is diode
Remove
the diode from pcb (printed circuited board) than Identify Anode, Cathode
Now
set the multimeter knob to diode test mode.
First Forward
test
Remember -Diode
is allow electric current in only one direction is called forward direction.
multimeter
POSITIVE(+) lead put to anode side than
multemeter
Negative (-) lead put to cathode side
see below the image
Now check
multimeter display show some reading.
A good forward-based diode displays a
voltage drop ranging from 0.5 to 0.8 volts for the most commonly used silicon
diodes. Some germanium diodes have a voltage drop ranging from 0.2 to 0.3 V.
Second Reverse test,
Remember- diode is Blocking electric
current in the opposite direction is called reverse direction
Now multimeter lead put to reversely
(see below image)
multimeter POSITIVE(+) lead put to
Cathode(-) side than
multemeter Negative (-) lead put to
Anode(+) side
Now check multimeter
display not show any reading, show only in display OL (mean by over load) the multimeter displays OL when a good diode is reverse-biased
Note the point, Diode is allow electric
current in only one direction
Blocking electric current in the
opposite direction
Good diode Forward test show some
reading, and reverse test not show any reading,
how to identify Good diode:
Forward bias test silicon diode show
reading =0.5v to 0.8v
Germanium diode show reading =0.2v to
0.3v
how to identify Open diode
Show OL (over lode) both side testing
forward and reverse
how to identify Shorted diode
Show both side testing 0v to 0.4v with
beep sound
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