6-4
when they occur. An error for 2VARM is a return
electrode fault and occurs when the resistance
measured on the return electrode is not within
specified limits for either a single or dual foil
return electrode. An error code is not displayed,
however the “red” indicator for a return electrode
fault is illuminated.
In many cases, intermittent or continuous alarms
associated with these signals can be rectified
by going through the calibration procedure for
A.R.M.
FMEA has an idle voltage of one-half of the value
of P
ABS. When testing or troubleshooting, use
the calibration procedure for P
ABS to determine
the value of F
MEA when no argon flow is occur-
ring. This voltage increases with flow. A voltage
that exceeds 3.3V in all flow modes will set a flow
alarm by illuminating the “red” Flow Fault indica
-
tor.
6.2.11 A/D Inputs [Monitor Microcontroller]
Seven of the eight available inputs are used for
monitoring system signals. A failure with any one
of the inputs will be displayed as an error code.
HV_MON: High Voltage Power Supply Monitoring
This A/D input is 200mV±40mV when the
system is in the idle mode. The resolution is
20mV/V or 20mV for every volt on the +DC
& -DC terminals of the High Voltage power
supply. Calibrated for 1V with 50V on the
High Voltage Power Supply.
IMEA: Current Measure
A ratio of the output current that is applied to
the patient when Cut, Blend, Pinpoint or
Bipolar modes are used. Used in conjunction
with the HV_MON to determine the output
power.
F_MON: Flow Monitor
The current through the flow control valve rep
-
resents the flow rate. A flow rate that exceeds
requested flow by more than 2 SLPM will
set an alarm and inhibit both RF Output and
argon flow. This signal is calibrated for 2V
with a flow setting of 4 SLPM.
PW_MEA: Pulse Width Measure
Spray and ABC™ modes only. A DC average of
the RF Drive pulse width to the single ended
amplifier. In ABC™, the voltage increases as
the power increases if a load is connected to
the ABC™ output. In Spray, the voltage is
constant for all dial settings.
FB_MON: Full Bridge Monitoring
Cut, Blend, Pinpoint and Bipolar modes only.
A DC average of the full bridge RF Drive.
With Cut activated, FB_MON is approxi
-
mately 2.85V and for each blend, the voltage
is about 225mV less than the previous blend
or cut mode.
10V Reference:
The 10V reference is monitored and must be
4.46V±.2V.
15V Supply:
The system 15V for control circuits is moni
-
tored. This voltage is used for op amps,
relays and flow control valves. This voltage
must be 3.72V±.5V.
6.2.12 EEPROM & Driver [U37, U27]
The EEPROM (U37) is used to store user set
-
tings and these settings are recalled when the unit
is first powered on or if a 5 second brown out
occurs. On power-up, power settings will be the
last settings for the default modes. Included in
the EEPROM are the calibration limits for ABC™
and SPRAY PW_MEA settings. A failure detected
with the EEPROM during system initialization
will default all power settings to “0”. A failure
detected with the PW_MEA stored data will
inhibit the system from being used until the prob
-
lem is corrected.
U27 is a parallel-to-serial interface device.
The EEPROM is loaded serially, however the
PCF8584 allows the control microcontroller to
load the serial data from the parallel data bus.
6.2.13 D/A Converter [U12]
The D/A converter is used to control the follow
-
ing:
•High Voltage (V
CON)
•Output Power (P
CON)
•Maximum voltage at each dial setting (I
LIM)
for Cut, Blend, Pinpoint, & Bipolar Modes
•Argon Flow Rate (V
GAS).
Each of these signals should be zero volts in the
idle mode and increase as the power or flow
increases. The voltages listed below are the maxi
-
mum limits at full power settings.
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