8
HSF(A) 300W 040215
3.2
FRONT PANEL ACCESS.
The front panel provides a power ON/OFF switch controlling input power and a “VDC ON” indica-
tor which lights green when the unit is operating. If the unit is connected in a parallel configuration,
the indicator lights red if the unit shuts off automatically, or the POWER switch is set to OFF.
CAUTION: DO NOT repeatedly toggle the power ON/OFF switch as this may cause unit to
fault. The ON/OFF switch must be set to OFF before removing unit from rack
adapter.
If remote on-off is not enabled (see PAR. 3.5), the OUTPUT RESET button restores output power
in the event that overcurrent or overvoltage protection has tripped, or thermal overload or fan mal-
function has occurred.
If remote voltage control (see PAR. 3.4.2) is not enabled, the front panel Vadj trimmer (see PAR.
3.4.1) provides adjustment of the output voltage within the limits specified in Table 2; test points
are available at the front panel for monitoring the DC output.
Figure 5 shows the location of all operating controls, indicators and test points followed by an
explanation of each.
3.3
KEYING
Keying of the HSF (A, AM) 300W is established at the factory. The output voltage determines
which key pins are installed (see Figure 3, Detail A). When the proper holes in the rack adapter
are blocked by keying screws installed by the user, only a power supply of the correct voltage can
be inserted in the rack adapter slot. Refer to the RA 19-4C Manual for rack adapter keying instruc-
tions.
3.4
OUTPUT VOLTAGE CONTROL
Output Voltage can be controlled from either the front panel (PAR. 3.4.1) or externally using a
trimpot or voltage source (PAR. 3.4.2).
3.4.1 FRONT PANEL VOLTAGE CONTROL
Output voltage can be manually adjusted with the voltage adjustment control, Vadj (see Figure 5
for location). Configuration options are as follows:
Output from maximum to minimum specified in Table 2 (Figure 6A (factory default)).
SW1: pos 1 to ON, pos 2 to ON;
SW2: pos 1 to OFF, pos 2 to OFF, pos 7 to OFF
Output from maximum to 0V (requires multiple turns of Vadj for full range)
SW1: pos 1 to OFF, pos 2 to OFF
SW2: pos 1 to ON, pos 2 to ON, pos 7 to ON
To adjust voltage, first place the unit under an operating load. Then monitor the (+) and (–) test
points on the front panel with a precision voltmeter and turn the voltage control to the desired
operating value.
The minimum output voltage required to ensure proper operation of the alarm relay, meter (on AM
models) and LED indicator is listed in Table 5.
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