78
Service Manual
3-12
3-21. Diode Test
1. Set the Fluke 78 rotary switch to G and press the pushbutton for 2 seconds to put
the meter in the diode test function.
2. Connect the DC Voltage Calibrator output to the zand COM input terminals
of the meter.
3. Referring to Table 3-9, set the DC Voltage Calibrator for the output indicated in the
steps. Verify that the Fluke 78 display reading is within the limits shown in the table.
Table 3-9. Diode Test
Step Range Input Display Reading
1 2.45 V open OL
2 2.45 V +2.00 V 1.920 to 2.080 V DC
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
Common input terminals of the meter.
3. Set the Current Calibrator to the output shown in Table 3-10, and verify that the
Fluke 78 display reading is within the limits shown in the table.
Table 3-10. DC and AC Current Test
Step
Input
Display Reading
Range A Frequency
1 4 A DC +3.5 A -- 3.460 to 3.540 DC
2 10 A DC +10 A -- 9.88 to 10.12 DC
Note
To enter AC Amps, press and hold the button for 2 seconds.
3 10 A AC 10 A 1 kHz 9.73 to 10.27 AC
3-23. Temperature Test
Note
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
COM inputs.
The display will show a steady reading of the meter’s internal temperature.
2. Remove the short from the input. The display will flash the same temperature
reading about once every 1.3 seconds.
3. Construct an ambient temperature lag bath as shown in Figure 3-3. Immerse the
thermometer into the bath.
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