Power Probe PPCT - Continuity Tester - Manual (Page 8)

Diode Check Diode Check
Forward Bias Reverse Bias
8
Anode
Cathode
Anode
Tone No Tone
No tone in
either direction
Open Diode Shorted Diode
Tone in both
directions
Forward Bias
1. Touch the green lead to the cathode side of the diode.
2. Touch the probe tip to the anode side of the diode.
3. Take note of the SCT’s response.
(Should hear tone)
Reverse Bias
1. Reverse the lead and the probe tip connections
2. Touch the green lead to the anode and the probe
tip to the cathode side of the diode.
3. Take note of the SCT’s response.
(Should not hear tone)
A good diode causes a tone to sound in one direction
only and nothing in the other direction.
When the probes are reversed, (or vice-versa) and you
hear a tone in both directions, or hear nothing in both
directions, the diode is either shorted or open.
See the illustration