Current-Input Fuses - Tektronix DMM4020 Technical Reference Manual

DMM4020
Technical Reference

Current-Input Fuses

The 200 mA and 10 A inputs are protected by user-replaceable fuses.
For protection against fire or arc flash, replace a blown fuse
with a fuse of an identical rating.
To test the current-input fuses:
To avoid electric shock, remove the power cord and any test
leads from the Meter before opening the current-input fuse
cover.
To replace the current-input fuses:
2-6
• The 200 mA input is protected by a fuse (F2) rated at 440 mA, 1000 V (fast
blow), 10,000 A minimum breaking capacity.
• The 10 A input is protected by a fuse (F1) rated at 11 A, 1000 V (fast blow),
10,000 A minimum breaking capacity.
1. Turn on the Meter and plug a test lead into the INPUT V HI terminal.
2. Press .
3. Press to set the range to 200 Ω. Only the 200 Ω, 2 kΩ, and 20 kΩ ranges can
be used to test the mA input fuse.
4. Insert the other end of the test lead into the mA terminal. If the fuse is good, the
Meter displays a reading of < 10 Ω but not 0 Ω. If the fuse is blown, the Meter
displays  to indicate an overload.
5. Remove the test lead from the mA terminal and insert it into the 10 A terminal.
If the fuse is good, the Meter displays a reading of <2.000 Ω but not 1.000 Ω. If
the fuse is blown, the Meter displays  to indicate an overload.
1. Remove power from the Meter by unplugging its power cord.
2. Turn the Meter upside down.
3. Remove the retaining screw on the fuse access door located on the bottom of the
Meter. See Figure 2-2.
4. Remove the protective cover from the fuse holders by slightly depressing the
back edge of the cover to unlatch it from the printed circuit board. Pull up on the
back edge of the cover and remove it from the fuse compartment.
5. Remove the defective fuse and replace it with a fuse of an appropriate rating. See
Table 2-1.
6. Replace the protective cover by pushing it over the fuses while aligning the
catches with the holes in the printed circuit board. Press the cover down until the
catches engage the printed circuit board.
7. Replace the fuse access door and install the retaining screw.
 Warning
 Warning