Fluke 78 User Manual page 29

1 Insert the test leads as shown.
Turn the rotary switch to diode test.
2
Press the pushbutton for 2 seconds to toggle to the diode test function.
3
Touch the red test probe to a diode contact and touch the black to ground.
4
Typical voltage drop is 0.5-0.8 V and causes the meter to beep.
(Some diodes may drop 0.3 V.)
Reverse the probes. If the diode is:
5
Good -- the display shows OL.
Shorted -- the display shows near 0 in both directions.
Open -- the display shows OL in both directions.
Repeat steps 4 and 5 for the other diodes.
6
RECTIFIER BRIDGE
DIODE CONTACTS
4
4
GROUND
Figure 6. Testing Diodes in Alternator Rectifier Bridge
3
Press for
2 seconds
5
BLACK
Typical Testing Applications
78 AUTOMOTIVE METER
DC
V
1 2 3 4
V
OFF
V Hz
V Hz
RPM
2 1
C F
A
PRESS
MIN / MAX 1 SEC
Hz
1 2 SEC
RPM V
+
300V 30V
COM
10A COM COM
CAT C F
30V
FUSED
2
1
mt06f.eps
17