Fluke 789 - Manual (Page 42)

789
Users Manual
34
Replacing a Fuse
! Warning
To avoid personal injury or damage to the
meter, 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 meter 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 meter 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 11
as necessary:
1. Remove the test leads from the meter and turn the
meter OFF.
2. With a standard blade hand screwdriver, turn each
battery 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 access door. Secure the door by
turning the screws one-quarter turn clockwise.
If the Meter does not Work
• Examine the case for physical damage. If there is
damage, make no further attempt to use the meter,
and contact a Fluke Service Center.
• Check the battery, fuses, and test leads.
• Review this manual to make sure you are using the
correct jacks and rotary function switch position.