
3
3. INSTALLATION
3.1. GENERAL
The Model 556 is normally used in conjunction with
other modular electronics and may be installed in a
standard NIM bin such as an ORTEC Model 4001A.
Since the bin may be rack mounted, any high
temperature equipment that may be installed in the
same rack as the bin must be sufficiently cooled by
circulating air to prevent exceeding the +50EC
(120EF) maximum operating temperature of the 556.
The ORTEC M127/N NIM Fan is available for
forced-air cooling of a rack of equipment.
3.2. CONNECTION TO POWER
The Model 556 requires a grounded ac-power
source of nominal 115 V ac or 230 V ac. A rear
panel international-standard IEC connector allows
the connection of many different types of line cords
between the ac outlet and the 556. A rear-panel
slide switch allows the choice of 115 V ac or
230 V ac input voltages. The 556 is shipped with a
choice of two fuse holder caps to accommodate
either 3AG or 5×20 mm size fuses. On 115 V ac
operation a 1.5 A (FAST) (250V) size 3AG fuse
should be used; on 230 V ac operation, a 0.75A(F)
(250V) size 5×20 mm fuse should be used.
This power supply may be operated entirely
removed from the 4001A bin if desired, since it is
totally self-contained and requires no dc-operating
power levels from the NIM bin. However,
precautions should be taken to ensure that
personnel is aware of the shock hazard at the rear
connectors, and that air space should be provided at
the top and bottom of the instrument.
3.3. CONNECTING INTO A SYSTEM
1. Check to see that the power switch is in the Off
position.
2. Check rear panel 115/230 V ac switch and set to
appropriate position.
3. Install a 1.5 A, 250 V fuse for 115 V ac setting or
a 0.75 A, 250 V fuse for 230 V ac setting in the
rear-panel-mounted fuse holder.
4. Check the polarity switch on the rear panel and
set it for either positive or negative output
polarity as required for the application.
5. Connect a high-voltage cable from either output
connector on the 556 to the instrument to be
powered. Use the other output connector if a
second instrument is to be operated at the same
output voltage.
6. Set the front-panel selector switches and
potentiometer for the desired voltage level. This
is normally specified for the instruments to
which the voltage is to be applied. The adjusted
output voltage will be the sum of the settings of
all three controls.
7. Turn on the power with the switch on the front
panel. The indicator lamp next to the switch will
light to show that input power is being applied.
The indicating meter at the top of the front panel
will also indicate the polarity and amplitude of
either the 556 output voltage or load current,
depending on the setting of the meter switch.
3.4. CONNECTING AN EXTERNAL
REFERENCE INPUT
The Model 556 output voltage level can be
controlled by an external reference level that is
furnished through the rear-panel BNC connector
when the Control locking switch is set at Ext. The
range of input voltage is 0 to 6.9 V to provide an
output from 0 to 3000 V. The front- panel voltage
level controls are ineffective for external reference
operation.
For positive output the polarity selector switch on the
rear panel is set at Pos, and the external reference
should be positive. For negative output the polarity
switch is set at Neg and the external reference
should be negative. The external reference voltage
should be stable and filtered since the output is
linearly proportional to this reference. The external
reference should be capable of driving the 45 kΩ
input impedance.