Fluke Biomedical 956A-201-M2 - Manual (Page 69)

3-43
Power Supply
The U DR power supply is rated at +5 volts @ 3 amps, + 15 volts @ 2.0 amps, and -15 volts @ .5 amps.
The input is user selectable at 115 Vac (92 to 132 Vac) or 230 Vac (180 to 264 Vac). The power supply is
designed to meet safety requirements UL/CSA/VDE. EMI emissions comply with FCC/Class B
requirements.
The AC input to the power supply may range from 90 to 204 Vac @ 50.60 Hz. The 956A, however, must
be configured for use at 125 Vac, 50/60 Hz as a factory option.
The power supply provides all internal UDR voltages as well as detector supply voltages. All outputs are
protected with automatic recovery upon removal of overload or short circuit condition.
Relay Circuit Board
The relay circuit board contains five independently controlled electromechanical relays, High alarm, Warn
alarm, Auxiliary (Rate) alarm, Fail, and Check Source. Each relay provides two Form C sets of contacts.
For the check source and alarm relays, a single Form C set of contacts is available for customer use.
Interconnection is from J2 on the relay board to J2 on the main circuit board. The control signals (active
low) and + 15 volts common are provided. The relays typically perform the following functions:
• K1: Spare
• K2: Check Source
• K3: Fail
• K4: Warn
• K5: Alarm
• K6: Auxiliary (Optional)
The relay contacts are provided to the user via rear panel connector P1. See specifications for contact
ratings. Varistors (V1-V16) provide transient protection across the contacts.
Front Panel Circuit Board
The front panel circuit board consists of the 7-segment display, backlights, status indicators, switches, and
bargraph assembly. The front panel interfaces to the main circuit board via interconnecting row 100, 200,
and 300. The main power switch also mounts to the front panel circuit board. Refer to Figure 3-7 for a
view of the front panel.
Circuit Description (Front Panel Circuit Board)
The 7-segment displays are controlled by the display controller as described in "Display Control". The
bargraph is controlled by the circuitry described in "Bargraph (Write Only)". The status indicators are
described in "Status Indicators (Write Only)". Switches are described in "Switch Inputs".