7-8
7.8 Pulsed Cut Mode
Pulsed Cut is a mode that delivers RF energy in
pulsed durations for precise control of dissection.
The repetition rate of Pulsed Cut is approximately
640mS with RF “ON” time of approximately
75ms and RF “OFF” time of approximately
565mS for a duty cycle of 12%. The activation
tone consists of two different frequencies, with
the higher frequency being the tone that identi
-
fies when RF is delivered and the lower frequency
tone identifying when the RF is off. The power
delivered during the RF “ON” time of the Pulsed
Cut is the power that is displayed in the Cut win
-
dow, so the rms power is approximately 12% of
the displayed power.
To select the Pulsed Cut mode, press the “Down”
switch in the Program section on the Front Panel
until “P” (P for Pulsed) is displayed. When select
-
ing Pulsed Cut, all power levels on the display
panel will be set to zero, therefore all power levels
will have to be adjusted to desired settings. When
leaving the Pulsed Cut mode, all powers will also
be set to zero. Because of the low repetition rate,
it is difficult to measure the rms power using stan
-
dard electrosurgery analyzers, therefore to test this
mode, use an oscilloscope and verify the output or
RF drive on the Full Bridge (30-0134 assy.) are
pulsed at a rate of approximately the values listed
above.
To test the RF output with 1:1 or 10:1 scope
probes, simply lay the scope probe cable across
a lead connected to the dispersive electrode. Do
not connect the scope probe directly to the lead as
damage may occur to the probe. Set Cut power
to about 50W into a 500 ohm load and set the
scope for 100mS/Div. Activate Pulse Cut and
verify the output is pulsed.
7.9 RF Leakage Test
See Calibration Section for Test and Calibration of
RF Leakage.
7.10 Final Checks
1. Ensure the internal switch setting is set for
Run Mode and ABC Argon Monitoring
Mode. This can be verified by turning on the
Main Power. If an Err 20 is displayed, the
default switch settings are not properly set.
(Positions 1 and 6 should be down or off.)
2. Ensure the lid or cover is secured by the two
screws on either side.
3. Ensure the argon tank valve is off. The pres
-
sure within the argon lines will not bleed off
and it is not necessary to bleed the lines.
4. Ensure the Power Cord is secured by the
strain relief that is connected to the argon
tank strap support.
7.11 Mobile Storage Pedestal (Cart)
The System 7550 Mobile Storage Pedestal (Cart)
houses the High Pressure pneumatics, pressure
relief valve, tank pressure switch, tank pressure
gauge, and wiring harness for the footswitch con
-
nectors. A block diagram of the argon pneumat
-
ics within the cart is shown in figure 6.3 on page
6-15. There are no requirements for annual main
-
tenance on any components within the Cart.
The argon tank pressure input is rated for 3000
psi and is stepped down to 30 psi using a dual
stage pressure regulator assembly. The first stage
of the dual stage pressure regulation reduces the
tank pressure down to approximately 175 psi and
the second stage reduces the 175 psi down to 30
psi. The output of the second stage regulator
connects to a fitting that carries the argon into
the Generator Assembly and has a 50 psi pressure
relief valve. In the event a pressure regulator fails,
the pressure relief valve will open and vent the
argon in the atmosphere so that argon tubes are
not ruptured.
The low pressure switch and pressure gauge are
both on the input side to the dual stage pressure
regulator assembly. The pressure gauge measures
the pressure within a tank of argon that is con
-
nected. The “low tank” pressure switch is simply
a set of contacts that are held “open” when the
tank pressure is greater than 250 psi and close at
lower pressures. When the switch closes, a yellow
indicator on the display panel flashes to inform
the user that the argon supply is low.
WARNING: Input pressure lines can hold
up to 3000 psi (200 bars) of pressure. Do
not attempt service of pneumatic components
within the cart before disconnecting the tank
of argon. Replacement of any pneumatic com
-
ponents within the cart should have all fittings
sealed with pipe sealant to prevent slow leaks.
Soapy water should be applied to all fittings to
insure proper sealing against small leaks.
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