Ametek 7280 Instruction Manual page 14

Chapter 2, INSTALLATION & INITIAL CHECKS
2-2
Input Assembly on the rear panel of the unit. Instruments are normally shipped from
the factory with the line voltage selector set to 110-130 V AC, unless they are
destined for an area known to use a line voltage in the 220-260 V range, in which
case, they are shipped configured for operation from the higher range.
The line voltage setting can be seen through a small rectangular window in the line
input assembly on the rear panel of the instrument (figure 2-1). If the number
showing is incorrect for the prevailing line voltage (refer to table 2-1), then the barrel
selector will need to be repositioned as follows.
Observing the instrument from the rear, note the plastic door immediately adjacent to
the line cord connector (figure 2-1) on the left-hand side of the instrument. When the
line cord is removed from the rear-panel connector, the plastic door can be opened
outwards by placing a small, flat-bladed screwdriver in the slot on the right-hand side
and levering gently. This gives access to the fuse and to the voltage barrel selector,
which is located at the right-hand edge of the fuse compartment. Remove the barrel
selector with the aid of a small screwdriver or similar tool. With the barrel selector
removed, four numbers become visible on it: 100, 120, 220, and 240, only one of
which is visible when the door is closed. Table 2-1 indicates the actual line voltage
range represented by each number. Position the barrel selector such that the required
number (see table 2-1) will be visible when the barrel selector is inserted and the door
closed.
VISIBLE #
Next check the fuse rating. For operation from a nominal line voltage of 100 V or
120 V, use a 20 mm slow-blow fuse rated at 2.0 A, 250 V. For operation from a
nominal line voltage of 220 V or 240 V, use a 20 mm slow-blow fuse rated at 1.0 A,
250 V.
To change the fuse, first remove the fuse holder by pulling the plastic tab marked
with an arrow. Remove the fuse and replace with a slow-blow fuse of the correct
voltage and current rating. Install the fuse holder by sliding it into place, making sure
the arrow on the plastic tab is pointing downwards. When the proper fuse has been
installed, close the plastic door firmly. The correct selected voltage setting should
now be showing through the rectangular window. Ensure that only fuses with the
Figure 2-1, Line Input Assembly
VOLTAGE RANGE
100 90
120 110
220 200
240 220
Table 2-1, Range vs. Barrel Position
- 110 V
- 130 V
- 240 V
- 260 V