Fluke 789 Calibration Manual - Page 18

Checking and Replacing the Fuses, Calibration Verification - repair

Get Fluke 789 PDF manuals and user guides View all Fluke 789 manuals
Add to My Manuals
Save this manual to your list of manuals

Page 18 highlights

789 Calibration Manual Checking and Replacing the Fuses  Warning To avoid personal injury or damage to the ProcessMeter, use only the specified replacement fuse, 440 mA 1000 V fast-blow, Fluke PN 943121. Both current input jacks are fused with separate 440 mA fuses. To determine if a fuse is blown: W 1. Turn the rotary function switch to . 2. Plug the black test lead into COM, and the red test lead into the Ac input. 3. Using an ohmmeter, check the resistance between the ProcessMeter test leads. If the resistance is about 1 Ω, the fuse is good. An open reading means that fuse F1 is blown. 4. Move red test lead to . 5. Using an ohmmeter, check the resistance between the ProcessMeter test leads. If the resistance is about 14 Ω, the fuse is good. An open means that fuse F2 is blown. If a fuse is blown, replace it as follows. Refer to Figure 1 as necessary: 1. Remove the test leads from the ProcessMeter and turn the ProcessMeter OFF. 2. With a standard blade hand screwdriver, turn each battery compartment door screw counterclockwise so that the slot is parallel with the screw picture molded into the case. 3. Remove either fuse by gently prying one end loose, then sliding the fuse out of its bracket. 4. Replace the blown fuse(s). 5. Replace the battery compartment door. Secure the door by turning the screws onequarter turn clockwise. Calibration Verification  Warning Some of the calibration verification tests involve the use of high voltages and should be performed by qualified personnel only. To avoid electrical shock, always place the calibrator in the Standby (STBY) mode between tests and before handling the test connections or test cables. Calibration verification tests confirm the complete functionality of the ProcessMeter and check the accuracy of each ProcessMeter function against its specifications. If the ProcessMeter fails any calibration verification test, it needs calibration adjustment or repair. The ProcessMeter's performance and accuracy are specified for one year after calibration at operating temperatures of +18 °C to +28 °C (64 °F to 82 °F), in relative humidity to 90 %. The specifications assume the ProcessMeter has been warmed up for 5 minutes before use. To perform the calibration verification tests, it is not necessary to open the case; no adjustments are necessary. Merely make the required connections, source the designated 10

  • 1
  • 2
  • 3
  • 4
  • 5
  • 6
  • 7
  • 8
  • 9
  • 10
  • 11
  • 12
  • 13
  • 14
  • 15
  • 16
  • 17
  • 18
  • 19
  • 20
  • 21
  • 22
  • 23
  • 24
  • 25
  • 26
  • 27
  • 28
  • 29
  • 30
  • 31
  • 32
  • 33
  • 34
  • 35
  • 36
  • 37
  • 38
  • 39
  • 40
789
Calibration Manual
10
Checking and Replacing the Fuses

Warning
To avoid personal injury or damage to the ProcessMeter, use only the
specified replacement fuse, 440 mA 1000 V fast-blow, Fluke PN
943121.
Both current input jacks are fused with separate 440 mA fuses. To determine if a fuse is
blown:
1.
Turn the rotary function switch to
W
.
2.
Plug the black test lead into COM, and the red test lead into the
A
c
input.
3.
Using an ohmmeter, check the resistance between the ProcessMeter test leads. If the
resistance is about 1
Ω
, the fuse is good. An open reading means that fuse F1 is
blown.
4.
Move red test lead to
.
5.
Using an ohmmeter, check the resistance between the ProcessMeter test leads. If the
resistance is about 14
Ω
, the fuse is good. An open means that fuse F2 is blown.
If a fuse is blown, replace it as follows. Refer to Figure 1 as necessary:
1.
Remove the test leads from the ProcessMeter and turn the ProcessMeter OFF.
2.
With a standard blade hand screwdriver, turn each battery compartment door screw
counterclockwise so that the slot is parallel with the screw picture molded into the
case.
3.
Remove either fuse by gently prying one end loose, then sliding the fuse out of its
bracket.
4.
Replace the blown fuse(s).
5.
Replace the battery compartment door. Secure the door by turning the screws one-
quarter turn clockwise.
Calibration Verification

Warning
Some of the calibration verification tests involve the use of high
voltages and should be performed by qualified personnel only.
To avoid electrical shock, always place the calibrator in the Standby
(
STBY
) mode between tests and before handling the test connections
or test cables.
Calibration verification tests confirm the complete functionality of the ProcessMeter and
check the accuracy of each ProcessMeter function against its specifications. If the
ProcessMeter fails any calibration verification test, it needs calibration adjustment or
repair.
The ProcessMeter’s performance and accuracy are specified for one year after calibration
at operating temperatures of +18
°
C to +28
°
C (64
°
F to 82
°
F), in relative humidity to
90 %. The specifications assume the ProcessMeter has been warmed up for 5 minutes
before use.
To perform the calibration verification tests, it is not necessary to open the case; no
adjustments are necessary. Merely make the required connections, source the designated