ConMed ExcaliburPLUS PC - Theory of Operation; Power Supply and Conversion Theory

Theory of Operation
Section 3.0
This section contains the theory of operation for
the Excalibur Plus PC™ circuitry. The functional
block diagram and schematics are located in
Section 4.0. These figures are folded such that
they may be pulled out for viewing while reading
the appropriate section.
3.1 Functional Block Diagram Description
The Functional Block Diagram appears in
Schematic 4.0. This diagram illustrates the func-
tional partitioning of the unit, without regard to
physical location. Each block defines a major
function (as noted inside the block) along with
the reference designator(s) of the components(s)
that serve primary roles in implementing the
function. Each reference designator includes an
assembly number (Al, A2, etc.) for cross-refer-
encing to the Schematics in Section 4.
The relationships among each block are described
by the signals that interconnect them. Narrow
lines represent individual signals and are marked
with the same signal mnemonics used in the
schematics.
Broad lines denote busses, or groups of signals
which together serve a common function. To
avoid clutter, busses are not necessarily marked
with signal mnemonics. Where a bus contains
signals all bearing a common mnemonic form,
the characters common to all of the mnemonics
are shown, with XXs denoting characters which
differ among the signal names. For example, the
bus marked /FXX contains the signals named
/ECT, /FCG and /FBP. These refer to the foot
switch activation signals for Cut, Coag, and.
Bipolar respectively.
Arrowheads describe the direction of signal flow.
Most signals are generated at a single source and
have one or more destinations. An exception is
the Data Bus on the A3 Controller PWB. This
bus is bi-directional in that signals may travel
either direction from any one of a number of
sources. However, only one source may be active
at a given time. That source is determined by the
Microprocessor which drives the proper signal
states out on the Address and Control busses.
3.2 Power Supplies and Distribution
The Power Supply for the Excalibur Plus PC™
converts ac mains power into the various dc volt-
ages required to operate the internal circuitry.
This conversion takes place in three stages.
1. Mains power is ac-regulated and isolated by a
ferroresonant power transformer.
2. Power from the transformer secondaries is then
rectified and capacitively filtered to produce three
separate sources of de power (nominally +110
Vdc, +16 Vdc and +8 Vdc). The +110 Vdc
source is used exclusively to power the RF Power
Amplifier on the A4 Power Conversion PWB
without further regulation.
3. The +16 and +8 Vdc sources are distributed
throughout the unit where they are modified fur-
ther by regulation or switching to supply the vari-
ous loads in the unit.
MAINS DISTRIBUTION. Refer to the
Interconnect Schematic, Figure 4.1. The mains
power cord is terminated at a grounding lug and
a nylon screw terminal block, A6TB1, for ease of
field replacement. Harness AW] delivers power
to the two-pole circuit breaker, A9CB1, mounted
on the output panel. A9CB1 serves both as a
lighted power switch and to protect the unit from
overloads. On overload, this device automatically
switches its handle to the OFF position.
Harness A9W1 returns switched mains power to
A6TBI for connection to the primary windings
of power transformer A6T1. Strapping options
on A6TBI allow setting the unit for a given
mains voltage range (120 V or 240 V) by con-
necting the primary windings in parallel or series,