Hill-Rom Advanta P1600, Service Manual

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Theory of Operation
Chapter 3: Theory of Operation
Page 3 - 18 Advanta™ Bed Service Manual (man168ra)
Power Supply P.C. Board—P/N 63349
The overall power supply system of an Advanta™ Bed consists of four major
subassemblies:
• The power supply P.C. board assembly, part number 63349, is the heart of
the system, containing all the active components that regulate, rectify, and
manage the power sources (see figure 3-25 on page 3-21).
• Cabling links all the major modules of the bed frame and conducts the
signal from module to module.
• An oversized transformer, part number 64149, with 3X safety factors
provide an isolated down conversion in voltage.
• Included with the power supply P.C. board assembly is the feature-based
circuitry of the night light and the ground fault circuit.
A power supply P.C. board assembly consists of five distinct regulator circuits
that power individual unique modules of the bed:
• Individual protection for each regulator is provided to prevent one or more
modules from bringing down the whole bed system.
• The individual regulators have over-temperature protection.
• The individual regulators have protection from voltage and current
overloads.
• All linear regulators are adjusted in voltage and current output to match the
individual requirements of each module.
• The switcher used for the logic control module is sized to accommodate the
needs of the logic components.
Each has different characteristics unique to that particular module.
The foremost concern of the power supply module is safety. All circuits
involved in over-current, over-temperature, and dielectric strength is redundant
or 100% tested and burned in. This is done to prevent any safety-related
incident with the power supply module. All cabling is double insulated. The
transformer has built-in safety factors and has two levels of fuse protection,
both in the primary and in the secondary. All components used in the power
supply module have a safety factor of at least 2X or have been tested to life
without issue at the worst possible environmental condition.
AC line current from the transformer is rectified, filtered, and then presented
unregulated to the linear and switching regulators. Each of the regulators acts
as a pre-regulator for each functional module. There are two low current