ConMed ExcaliburPLUS PC - Page 56

Exc
4.2.3 Power Conversion Assembly A4
The Power Conversion PWB A4 contains the A4
PWB and the six Power Transistors. See Figure
4.3. Refer to Section 4.7.8 for precautions to be
taken when replacing these devices.
Most A4 PWB components may be replaced
without removing the A4 Assembly from the
unit. Removal of A4C8, C9, C11, and C20 can
be accomplished by removing the A4 PWB. It
should be removed as a unit including the
heatsinks. Removal is accomplished by removing
the heatsink mounting fasteners and five harness
connections. See Figure 4.3. When replacing this
assembly, tighten all heatsink mounting fasteners
before tightening the PWB fasteners.
CAUTION: This assembly is fragile when not
mounted in the unit. Do not bend or flex the
A4 assembly.
4.2.4 Output Assembly A5
Removal of A5 the Output PWB is accomplished
by removing ten cable connections, three screws
and unsnapping the four plastic support posts.
Refer to Figure 4.3.
4.2.5 Power Transformer and Resonating
Capacitor
Refer to Schematics 4.1 and 4.7. The ferroreso-
nant power transformer A9T1 and its resonating
capacitor A6C] are conservatively rated and are
unlikely to require replacement due to failure. The
most common reason for replacing these compo-
nents is to change mains frequency. Consult the
factory for information on changing the mains
frequency. The Excalibur Plus PC™ should be
operated ONLY at the mains frequency marked
on the unit’s Nameplate.
Transformer A9T1 is supplied with captive, self-
locking nuts in each of its four feet. The feet are
secured to the bottom of the Base Assembly with
Allen-head screws and lock washers through
vibration isolating grommets.
Primary and secondary electrical connections to
A9TI are via leads terminated on A6, TB1 and
Cs
TB2. A lead number is printed on each of these
wires which corresponds with its terminal number
on TB] and TB2.
The transformer frame is grounded via a green-
yellow wire with a ring lug secured to a ground-
ing stud on the bottom of the Base Assembly.
The two red resonating winding leads, #5 and
#6, connect to A6CI via slip-on connectors
accessible after pulling up the insulating boot.
Capacitor A6CI is secured to the Rear Panel
Assembly by a strap.
4.2.5.1 Primary Strapping
The unit may be adapted to various mains volt-
ages by changing connections on A6TB1 and
replacing A9CB1. Figure 4.1 and 4.7 illustrate
the variations available for each model. If possi-
ble, reuse the factory supplied wires. Note that
the transformer and its accompanying capacitor
must be changed between 50 and 60 Hz only
versions. Otherwise use #18 AWG stranded wire
with 300 V, 80° C insulation or better. Ensure
that all strands are inserted into the terminals
before tightening the terminal screws. Chassis
leakage tests per Section 4.5.6 should be conduct-
ed after restrapping to verify the safety of the
unit.
4.2.5.2 Replacing A9T1 and A6C1
A9TI and A6CI can only be ordered and
replaced as a unit. AGC] may be removed by dis-
connecting red leads A9T1-5 and -6 and loosen-
ing one of the strap mounting nuts enough to
permit the capacitor to slide out. Before remov-
ing the A9T1 mounting screws, disconnect all of
the transformer leads from A6TB1 and TB2, the
frame grounding lead from the grounding stud.
Replace the other grounding lugs which also are
connected to this stud and loosely reinstall the
nut.
Disconnect and remove A6C1. On 50-60 Hz
units, disconnect A4P4 and the OVP sense con-
nections at A6BR1, A6BR2 and the lugs connect-
ing to A6W1. Reconnect A6W1 lugs to the
proper terminals on A6BR1 and A6BR2 to aid
correct reassembly.