Testing Diodes - Agilent Technologies U1251A User Manual

2 Making Measurements

Testing Diodes

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N O T E
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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 the diodes, turn the circuit power off, and remove
the diodes from the circuit. Then proceed as follows:
1 Set the rotary switch to
2 Connect the red and black test leads to the input
terminals and COM respectively.
3 Use the red probe lead on the positive terminal (anode)
and use the black probe lead on the negative terminal
(cathode).
The cathode is the side with band(s).
4 Read the display.
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.
5 Reverse the probes and measure the voltage across the
diodes again. The 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 U1251A/U1252A User's and Service Guide
.