Testing Diodes - Agilent Technologies U1252B User's Manual And Service Manual

2 Making Measurements

Testing Diodes

C A U T I O N
N O T E
38
Disconnect the circuit power and discharge all the high-voltage capacitors
before testing the diodes to prevent any possible damage to the meter.
To test a diode, turn the power off to the circuit and remove
the diode from the circuit. Set up the multimeter as shown
in Figure 2- 10, then use the red probe lead on the positive
terminal (anode) and use the black probe lead on the
negative terminal (cathode) and read the display.
• The cathode is the side with band(s).
• The meter can display the diode's forward bias of up to approximately
2.1 V. A typical diode's forward bias is between the range of 0.3 V to
0.8 V.
Next, reverse the probes and measure the voltage across the
diodes again as shown in
diode's test result is based on the following:
• The diode is considered good if the meter displays "OL"
in reverse bias mode.
• The diode is considered shorted if the meter displays
approximately 0 V in both forward and reverse bias
modes, and the meter beeps continuously.
• The diode is considered open if the meter displays "OL"
in both forward and reverse bias modes.
Agilent U1251B/U1252B User's and Service Guide
Figure 2- 11 on page 40. The