Chapter 3
Theory of Operation
Electrical System (Electric Stretcher)
Control Board
The control board contains the necessary analog and digital circuitry to control
powered bed movement as outlined in this manual.
Power Supply
Connector P5 is the AC power input.
3
WARNING:
Fuses F1 and F3 protect the stretcher’s electrical system. For 120 V AC
power, a 7 A UL 198G time-lag fuse should be used. For 230 V AC, a
3 A IEC 127.3 time-lag fuse should be used. Refer to the assembly
drawing or schematic for the correct fuse. Failure to use the correct fuse
could cause personal injury.
Resistors R37, R39, and R40 are used to configure the primary coils of the
transformer (T1) for series or parallel connection. R37 and R40 supply parallel
connection for a 120 V AC input. Only R39 supplies series connection for a
230 V AC input.
The transformer full load rated output (as configured for this supply) is 15 V
rms at 670 mA rms.
The PTC overcurrent protection device, R38, protects the secondary circuit
and raw supply from overloads. This component is necessary for regulatory
approval.
Diodes CR21 - CR24 and capacitor C21 rectify and filter the transformer’s
secondary output.
Q1 reg12 +/- 0.5 V DC. Maximum output current for this application is
approximately 250 mA. Q1 can maintain regulation with an input voltage
down to 14.6 V DC.
Hill-Rom® Transport, Procedural, and Specialty Stretchers
Page 3 - 1
Service Manual (144386 REV 2)
Summary of Contents for P8000
Page 2: ......
Page 441: ...Schematic Wiring Diagram Control Board P N 49603 ...
Page 442: ...Schematic Wiring Diagram Electric Stretcher P N 60389 ...
Page 443: ......