Diode Test; Dc And Ac Current Test; Temperature Test - Fluke 78 Service Manual

78
Service Manual

3-21. Diode Test

1. Set the Fluke 78 rotary switch to G and press the pushbutton for 2 seconds to put
2. Connect the DC Voltage Calibrator output to the zand COM input terminals
3. Referring to Table 3-9, set the DC Voltage Calibrator for the output indicated in the
Step
1
2

3-22. DC and AC Current Test

1. Set the Fluke 78 rotary switch to A .
2. Set the output of the Current Calibrator to standby and connect it to the 10 A and
3. Set the Current Calibrator to the output shown in Table 3-10, and verify that the
Step
1
2
3

3-23. Temperature Test

The meter and any test leads plugged into the input during the temperature
test must be at the same room temperature, 23 °C +/-5°C. Handling, and
nearby warm equipment, can alter temperature readings.
1. Set the Fluke 78 rotary switch to °C°F. Apply a short between the z and
2. Remove the short from the input. The display will flash the same temperature
3. Construct an ambient temperature lag bath as shown in Figure 3-3. Immerse the
3-12
the meter in the diode test function.
of the meter.
steps. Verify that the Fluke 78 display reading is within the limits shown in the table.
Range
2.45 V
2.45 V
Common input terminals of the meter.
Fluke 78 display reading is within the limits shown in the table.
Table 3-10. DC and AC Current Test
Range
4 A DC
10 A DC
To enter AC Amps, press and hold the button for 2 seconds.
10 A AC
COM inputs.
The display will show a steady reading of the meter's internal temperature.
reading about once every 1.3 seconds.
thermometer into the bath.
Table 3-9. Diode Test
Input
open
+2.00 V
Input
A Frequency
+3.5 A
+10 A
Note
10 A
Note
Display Reading
OL
1.920 to 2.080 V DC
Display Reading
-- 3.460 to 3.540 DC
-- 9.88 to 10.12 DC
1 kHz 9.73 to 10.27 AC