Monday, February 15, 2021

Multimeter test EX2 test a diode with Digital multimeter DT-830B cheap multimeter

 Test    a   diode   with   Digital   multimeter    DT-830B 

The   digital   multimeter model  DT-830B  has  a diode check range ,  It  is  a  cheap  multimeter so some testing display may different from  an  advance and higher price multimeter.   Its  diode check range will supply  2.8V and 1mA test current so you can use it to check  LED  and  Zener diode  too , as it supply very small test current to save battery life time so  LED does not light , however , it still indicate good or bad condition  by  display  voltage  drop.


Diode test


Step  to   test  a   diode  with   cheap  multimeter.

1. Insert the red test lead to  VΩmA  terminal  and  the black test lead to COM terminal.

2. Turn the range switch to  Diode check and it  will  display    number 1    as above photo.

3.  Forward bias to diode by connecting  lead test with diode as below. Note the testing is done when diode is not on circuit and  there is  no voltage present on diode.  Always remove power source from diode before testing.

Test  Diode
 Forward bias to diode ,  good diode will display some forward   voltage drop and the unit is mV  so this testing value  is  536mV   ( 0.536V) 


4.  Reverse bias to diode connect test lead with diode as photo below.  The good diode will display number   " 1 ". ,  it   mean  ∞  Ohm  (  not connected  or  not  shorted  )


Test  Diode
   Reverse bias to diode , good diode will display number  "1"  mean  ∞  Ohm  (  not connected  or  not shorted  )


5. Bad diode  (shorted ) always  display  000  for  forward  biasing and reverse  biasing.

Multimeter  multimetro
   Shorted  diode  always  display  000 , switch the test lead  it still get the same display 000


6. Bad diode  ( open ) always  display  number "1"   for  forward  biasing and reverse  biasing. This Time is mean  ∞  Ohm  as  diode open so there is not forward voltage drop display and no current flow when   forwarding biasing.

multimetro   мультиметр
    Open  diode  always  display  "1" , switch the test lead it still get the same display "1"