ConMed 7550 User manual

Service Manual

LIMITED WARRANTY
For a period of two years following the date of delivery,
CONMED Corporation warrants the CONMED Sys-
tem 7550 Electrosurgical Generator against any defects
in material or workmanship and will repair or replace (at
CONMED’s option) the same without charge, provided
that routine maintenance as specified in this manual has
been performed using replacement parts approved by
CONMED. This warranty is void if the product is used in
a manner or for purposes other than intended.
© 2006 CONMED Corporation
525 French Road
Utica, New York 13502 U.S.A.
U.S. Patent Numbers 4,437,464 - 4,569,345 - 4,617,927
- 4,727,874 - 4,848,335 - 4,961,739 - 5,152,762 -
5,626,575 and other patents pending.
For Technical Service or Return Authorization Phone:
303-699-7600 / 1-800-552-0138 Extension 5274
Fax [phone]
For Customer Service or to order parts phone:
1-800-448-6506 / 315-797-8375 / Fax [phone]
or contact your CONMED Representative.
European Authorized Representative
MDSS GmbH
Burckhardtstr 1
D - 30163 Hannover
Germany
The revision level of this manual is specified by the
highest revision letter found on either the inside front cover
or enclosed errata pages (if any).
Manual Number 60-7552-ENG Rev. D 10/06
Unit Serial Number_________________________________

Table of Contents
& List of Illustrations
Section Title Page
1.0 General Information ...........Refer to Operator’s Manual (P/N 60-7551)
2.0 System Components .................................... Refer to Operator’s Manual
3.0 Operation .................................................... Refer to Operator’s Manual
4.0 Operator Service ......................................... Refer to Operator’s Manual
5.0 Technical Information ................................. Refer to Operator’s Manual
6.0 Circuit Descriptions .......................................................................... 6-1
6.1 Introduction ........................................................................................................ 6-1
6.2 Display Panel Assembly [A5] ............................................................................... 6-1
6.2.1 General Information ..........................................................................................................6-1
6.2.2 Mailbox [U19] ..................................................................................................................6-1
6.2.3 Power Adjustments [U16 & U33] ..................................................................................6-1
6.2.4 Activation Requests [U16 & U33] ....................................................................................6-2
6.2.5 Mode Select Encoders [U31 & U32] ................................................................................6-2
6.2.6 Display Drivers - Seven Segment [U14, U20, U39, U40, U41, & U17] .........................6-3
6.2.7 Indicator Driver [U34] .....................................................................................................6-3
6.2.8 Firmware [U28 & U1] ......................................................................................................6-3
6.2.9 RAM [U2 -6116] ..............................................................................................................6-3
6.2.10 A/D Inputs [Control Microcontroller] ..............................................................................6-3
6.2.11 A/D Inputs [Monitor Microcontroller] .............................................................................6-4
6.2.12 EEPROM & Driver [U37, U27] ......................................................................................6-4
6.2.13 D/A Converter [U12] .......................................................................................................6-4
6.2.14 Keyboard Scanner [U5] ....................................................................................................6-5
6.2.15 5V Monitoring [U29] .......................................................................................................6-5
6.2.16 Output PIA [U21] ............................................................................................................6-5
6.2.17 T_MON [U35] .................................................................................................................6-5
6.3 Power Control Assembly [A4] ............................................................................. 6-5
6.3.1 Power Control - Full Bridge Amplifier ..............................................................................6-6
6.3.2 RF Logic [U7 on the Power Control Assembly] ...............................................................6-7
6.3.3 Power Control - I/O Signals ..............................................................................................6-8
6.3.4 ABC™ Arc Sense ...............................................................................................................6-8
6.4 High Voltage Power Supply [A7] ........................................................................ 6-9
6.4.1 Power Supply Topology ....................................................................................................6-9
6.4.2 Phase Control Output ......................................................................................................6-9
6.4.3 HVPS Isolation Components ..........................................................................................6-10
6.4.4 HVPS Low Voltage Components ...................................................................................6-11
6.5 HV/Flow Control Assembly [A1] ..................................................................... 6-11
6.5.1 Line Synchronization Circuit ...........................................................................................6-11
6.5.2 HV Regulation Control Loop .........................................................................................6-12
6.6 Argon Flow Control [A1] ................................................................................. 6-13
6.6.1 Pneumatic Circuit ............................................................................................................6-13
6.6.2 Mass Flow Rate Regulation ............................................................................................6-14
6.6.3 Smart Sense .....................................................................................................................6-15
6.7 Full Bridge Amplifier [A8] ................................................................................ 6-15

Section Title Page
6.8 Single-Ended Amplifier [A9] ............................................................................. 6-16
6.9 RF Output Assembly/Components [A10] ......................................................... 6-17
6.10 Low Voltage Power Supply [A6] ....................................................................... 6-18
6.11 HS/A.R.M. Assembly [A11] ............................................................................. 6-18
6.11.1 Handsense Circuit ...........................................................................................................6-18
6.11.2 Aspen Return Monitor (A.R.M.) ....................................................................................6-19
6.11.3 RF Leakage Monitor .......................................................................................................6-20
6.11.4 Transformer Select Relays ................................................................................................6-20
6.11.5 Arc Sense Transformer ....................................................................................................6-20
7.0 Maintenance/Checkout ...................................................................... 7-1
7.1 Introduction ........................................................................................................ 7-1
7.2 Cleaning .............................................................................................................. 7-1
7.3 Generator & Mobile Storage Assembly ................................................................ 7-1
7.4 Access to Circuits & Factory Settings .................................................................. 7-2
7.5 Default Settings (Factory Settings) ...................................................................... 7-2
7.6 AC Mains Frequency & Voltage .......................................................................... 7-2
7.7 Initial Setup & Test ............................................................................................. 7-3
7.7.1 Accessory Connections ......................................................................................................7-3
7.7.2 Display Panel Testing ........................................................................................................7-3
7.7.3 Activation Testing .............................................................................................................7-5
7.7.4 RF Output Power Checks .................................................................................................7-5
7.7.5 Argon Flow Testing ..........................................................................................................7-6
7.7.6 Remote Power Control Testing .........................................................................................7-6
7.7.7 Return Monitor (A.R.M. - Aspen Return Monitor) ..........................................................7-7
7.8 Pulsed Cut Mode ................................................................................................. 7-8
7.9 RF Leakage Test .................................................................................................. 7-8
7.10 Final Checks ........................................................................................................ 7-8
7.11 Mobile Storage Pedestal (Cart) ............................................................................ 7-8
8.0 Calibration ........................................................................................ 8-1
8.1 Introduction ........................................................................................................ 8-1
8.2 Equipment List ................................................................................................... 8-1
8.2.1 Standard Equipment List ..................................................................................................8-1
8.2.2 Optional Calibration Equipment List ................................................................................8-1
8.2.3 Test Leads & Adaptors ......................................................................................................8-1
8.3 Calibration Set-Up .............................................................................................. 8-1
8.4 A.R.M. Calibration (HS/A.R.M. Assembly - A11) ............................................ 8-1
8.4.1 10 Ohm A.R.M. Calibration .............................................................................................8-1
8.4.2 150 Ohm A.R.M. Calibration ...........................................................................................8-2
8.5 High Voltage Calibration (HV/Flow Control Assembly - A1) ............................. 8-2
8.5.1 HV RAMP Calibration .....................................................................................................8-2
8.5.2 High Voltage Adjust .........................................................................................................8-2
8.5.3 HV_MON Adjust .............................................................................................................8-2
8.6 Argon Flow Calibration (HV/Flow Control Assembly - A1) ............................... 8-2
8.6.1 dP Calibration (Differential Pressure) ................................................................................8-2
8.6.2 PABS Calibration (Absolute Pressure) ...............................................................................8-2
8.6.3 Flow Rate Calibration (Optional) .....................................................................................8-2
8.6.4 FMON Calibration ...........................................................................................................8-3
8.7 Power Calibration ................................................................................................ 8-3
8.7.1 Filter Calibration - Full Bridge Modes (Optional) .............................................................8-3
8.7.2 Cut Power Calibration (Power Control Assembly - A4) ....................................................8-3

Section Title Page
8.7.3 Pinpoint Coag Calibration (Power Control Assembly - A4) ..............................................8-3
8.7.4 Spray Coag Calibration (Power Control Assembly - A4) ...................................................8-3
8.7.5 Bipolar Calibration (Power Control Assembly - A4) .........................................................8-4
8.7.6 ABC Calibration (Power Control Assembly - A4) .............................................................8-4
8.7.7 ABC Over Voltage Calibration (Power Control Assembly - A4) [Optional] .....................8-4
8.8 EEPROM Calibration ......................................................................................... 8-4
8.8.1 Spray Coag PW_MEA Loading ........................................................................................8-4
8.8.2 ABC PW_MEA Loading ...................................................................................................8-4
8.8.3 A.R.M. Max Voltage Loading ...........................................................................................8-4
8.9 IEC RF Leakage Measurement [Optional] .......................................................... 8-5
Appx. A Mnemonic List ................................................................................. A-1
Appx. B Troubleshooting Guide .....................................................................B-1
Introduction ........................................................................................................ B-1
Control Microcontroller Failure Codes and Troubleshooting Tips ........................ B-2
Monitoring Microcontroller Failure Codes and Troubleshooting Tips .................. B-3
Additional Troubleshooting Tips (Non-Error Code Related) ............................... B-5
Error Storage and Retrieval ................................................................................. B-7
Error Display Configuration .............................................................................................B-7
Example Error ...................................................................................................................B-8
Appx. C Schematics & BOMs ........................................................................ C-1
Bill of Material: Chassis & Cart ...........................................................................C-1
Bill of Material: HV/Flow Control PCB Assembly ..............................................C-2
Bill of Material: Power Control PCB Assembly ...................................................C-4
Bill of Material: Display PCB Assembly ..............................................................C-5
Bill of Material: LV Power Supply PCB Assembly .............................................C-10
Bill of Material: HV Output PCB Assembly ......................................................C-11
Bill of Material: FB Amplifier PCB Assembly ....................................................C-12
Bill of Material: SE Amplifier PCB Assembly ....................................................C-13
Bill of Material: RF Output PCB Assembly .......................................................C-14
Bill of Material: ARM/Handsense PCB Assembly .............................................C-15

Figure/Title Page
Figure 6.1 RF Drive Signals ....................................................................................................... 6-8
Figure 6.2 Line Sync/RAM ...................................................................................................... 6-11
Figure 6.3 Flow Diagram ......................................................................................................... 6-14
Figure 6.4 Resistance vs. Bargraph ........................................................................................... 6-19
Figure 7.1 Test Adapters ............................................................................................................ 7-9
Figure 7.2 Test Analyzer Connections ...................................................................................... 7-10
Figure 3.1 RAMP Flat Spot ....................................................................................................... 8-2
Figure 3.2 IEC Method RF Leakage Test Setup ......................................................................... 8-5
Figure B-1 Signal Status for a Handcontrol 1, Cut Activation Request ..................................... B-9
Figure B-2 Signal Status for ABC® Activation ........................................................................ B-10
Figure C-1a Assembly Location Diagram ..................................................................................C-1
Figure C-1b Pneumatic Assembly ..............................................................................................C-1
Figure C-2 Interconnect Diagram .............................................................................................C-1
Figure C-3 A1 HV/Flow Control PCB .....................................................................................C-2
Figure C-4a A1 HV/Flow Control PCB Schematic, Sheet 1 (of 2) ...........................................C-2
Figure C-4a A1 HV/Flow Control PCB Schematic, Sheet 2 (of 2) ...........................................C-3
Figure C-5 A4 Power Control PCB ...........................................................................................C-4
Figure C-6 A4 Power Control PCB Schematic ..........................................................................C-4
Figure C-7 A5 Display PCB ......................................................................................................C-5
Figure C-8a A5 Display PCB Schematic, Sheet 1 (of 4) ............................................................C-6
Figure C-8b A5 Display PCB Schematic, Sheet 2 (of 4) ...........................................................C-7
Figure C-8c A5 Display PCB Schematic, Sheet 3 (of 4) ............................................................C-8
Figure C-8d A5 Display PCB Schematic, Sheet 4 (of 4) ...........................................................C-9
Figure C-9 A6 LV Power Supply PCB ....................................................................................C-10
Figure C-10 A6 LV Power Supply PCB Schematic .................................................................C-10
Figure C-11 A7 HV Output PCB ...........................................................................................C-11
Figure C-12 A7 HV Output PCB Schematic ..........................................................................C-11
Figure C-13 A8 FB Amplifier PCB .........................................................................................C-12
Figure C-14 A8 FB Amplifier PCB Schematic ........................................................................C-12
Figure C-15 A9 SE Amplifier PCB .........................................................................................C-13
Figure C-16 A9 SE Amplifier PCB Schematic .........................................................................C-13
Figure C-17 A10 RF Output PCB ..........................................................................................C-14
Figure C-18 A10 RF Output PCB Schematic .........................................................................C-14
Figure C-19 A11 A.R.M./Handsense PCB ..............................................................................C-15
Figure C-20 A11 A.R.M./Handsense PCB Schematic .............................................................C-15

6-1
Circuit Descriptions
Section 6.0
6.1 Introduction
The information on the System 7500™ circuits
identifies specific signals and I/O ports that help
identify the appropriate signal levels. The text
uses the word SET for high and CLEAR for
low. To locate the assemblies within the System
7500™, refer to Figure C-1. Use the system inter-
connect (Figure C-2) to identify wiring harness
terminations and individual signals within a har-
ness.
6.2 Display Panel Assembly [A5]
6.2.1 General Information
The System 7500™ has two 80C550 microcon-
trollers with one dedicated to system control and
the other dedicated to system monitoring. The
control microcontroller (U15) sets the system
enables and control limits, while the monitor
microcontroller (U22) monitors system perfor-
mance and sets “inhibits” when an error is detect-
ed. Both of these devices have “on-board” A/D
converters, and each device independently moni-
tors separate analog signals. The address, data
and control buses of both microcontrollers are
isolated by a device called the “mailbox”, U19, a
dual port RAM that allows two-way data transfer
between the two microcontrollers.
On the schematic, the signal labels will have either
a “C” or “M” attached. The “C” is for the con-
troller logic (U15) or control microcontroller and
the “M” is for the monitor logic (U22) or moni-
tor microcontroller interface. The schematic for
the display panel (Figure C-8) is on four separate
sheets. Sheet 1 is the schematic for the displays
and drivers only; sheet 2 shows all the connec-
tors that are on this assembly along with some
discrete non-logic circuitry; sheet 3 is the control
microcontroller logic; and sheet 4 is the monitor
microcontroller logic.
This assembly has several programmable logic
devices to interface signals to the data bus for
both the control and monitor microcontrollers.
During the discussion when two reference desig-
nators are listed together it means the logic func-
tions are the same and can be interchanged.
6.2.2 Mailbox [U19]
A dual port logic device that allows data transfer
between the two microcontrollers. All system
setups and messages are communicated through
the mailbox between the two microcontrollers.
When data is loaded by either microcontroller, a
bit labeled DA (data available) is SET to inform
the other microcontroller that it has mail. Once
the data is read from the mailbox, another bit
labeled DC (data cleared) is CLEARED to inform
the sender that the mail has been retrieved. Each
microcontroller has independent access to the
mailbox and the mailbox is the only component
that connects the two data buses. Each instruc-
tion sent through the mailbox requires two bytes
of information with the first byte (command byte)
identifying the instruction and the second byte
(data byte) containing the data for the instruction.
6.2.3 Power Adjustments [U16 & U33]
(C for controller; M for monitor) Power adjust-
ments on the System 7500™ are made by rotat-
ing the power control encoders. The mnemon-
ics for the power encoders are: CT - CUT; CG
- COAG; BP - BIPOLAR; BM - ABC™. Each
encoder is a two bit counter (i.e.; CT0 & CT1)
where the two counts are used to identify the
direction of rotation. The logic devices (U16
& U33) store the previous count and compare
it to the new count in order to recognize if the
count is increasing or decreasing, which defines
if the encoder is rotated clockwise or counter-
clockwise. Each “click” of the encoder is a count
and the number of counts are stored within
U16 & U33 until the microcontroller reads the
port. The microcontroller reads each encoder
port independently and if an encoder has been
rotated, the count will be greater than zero. The
data the micro will see is a number (0 to 32) rep-
resenting the number of “clicks” the encoder has
been rotated and a separate bit that signifies the
direction of the count, either up or down. The
microcontroller then takes this count and adds or

6-2
subtracts it to the existing power value.
The control microcontroller reads and controls
power change requests, however the monitor
microcontroller also looks at the encoders to verify
the change is valid. If the two microcontrollers
disagree on the direction (up or down), number
of counts, or which encoder is rotating, the power
will not be changed; i.e. the change request is
ignored.
6.2.4 Activation Requests [U16 & U33]
Activation requests are “looked at” by both micro-
controllers, and if the two do not agree on an acti-
vation request, an error code (Err 303 or Err 307)
will be displayed.
Activation Requests: Handcontrol or
Footcontrol
H2CT Handcontrol 2, Cut, Active Low
H2CG Handcontrol 2, Coag, Active Low
H1CT Handcontrol 1, Cut, Active Low
H1CG Handcontrol 1, Coag, Active Low
HIP Handcontrol, Bipolar, Active Low
FCT Footcontrol, Cut, Active High
FCG Footcontrol, Coag, Active High
FBIP Footcontrol, Bipolar, Active High
FAB Footcontrol, ABC™, Active High
Note: HABC Handcontrol is activated at
handcontrol 2 and is a result of H2CT * H2CG *
HABC_DR, which is an output of U16.
6.2.5 Mode Select Encoders [U31 & U32]
Blend Level (BL) and Argon Flow (FL) rate is
adjusted by the same type of encoders as used for
power adjustments. The logic within U31 & U32
for these two encoders is the same as for power
adjustment and the discussion for power adjust-
ment applies here.
These logic devices have I/O ports also, and the
following text provides a brief description of each
port signal.
U31: Port B (PB0 - PB7) Inputs for Control
Microcontroller
LPSW: Low Pressure Switch
SET when the argon tank pressure is less than
240 psi. Low Tank warning is illuminated.
FDEV: Flow Deviance
SET if an occlusion occurs to the argon flow.
A_T: Active Mode or Target Mode
ABC™ mode and used for tone selection only.
A_T SET, tone is 500 Hz and ABC™ is active
- A_T CLEARED, tone is 250 Hz and
ABC™ is in the Target mode.
BRN_OUT: Brown Out
Holds high for at least 6 seconds when power
fails and is used to identify a temporary power
loss. The user settings are returned following
a temporary power loss.
Tone_A: Tone Signal
Mode Activation and Alarms. Square wave sig-
nal with frequency between 250 Hz to 1KHz
for audible tone.
KB_DA: Keyboard Data Available
SET when a front panel switch is pressed, cleared
when the device is read.
U31: Port C (PC0 - PC6) Outputs from
Control Microcontroller
ABC>80: ABC™ Power is Greater than 80W
SET when ABC™ power is set to greater than
80W. CLEARED when ABC™ power is 80W
or less.
RFEN: RF Enable
SET to enable the RF drive for all activations.
FB_EN: Full Bridge Enable
CLEARED when activation for Cut, Blend,
Pinpoint, & Bipolar occurs.
OV_TST: Over Voltage Test
Test pin that allows the control microcontroller
to test and verify the ABC™ over voltage
circuit is operational. During Power-On Self-
Test (POST), this signal is clocked for a dura-
tion of about 7mS.
Alarm: Tone for alarms
1KHz signal tone for alarm - volume cannot be
adjusted.
Tone_B: Tone, Mode
Signal for all Tones except alarm tones. Volume
can be adjusted.
U32: Port B (PB0 - PB7) Monitor Inputs
This port has the switch for setting the system
defaults. The switch is located on the back side of
the Display PCB for accessibility. Default settings
are with the switch in the “OFF” position (off
= high on the input pin of U32). To change a
default setting, move the appropriate switch to the

6-3
“ON” position. To verify the selection, turn the
power off for at least 10 seconds, and then restore
power.
1-TEST-RUN (Default: RUN MODE)
TEST mode allows the system to be operated
without error detection and shut down. This
mode can be changed anytime while the sys-
tem is in standby. Test mode can be selected
before the unit is powered on, however the
“store” button must be held down until an
“Err 1” is displayed. Test mode is to be used
only for system level testing.
2-SIN-DUAL PAD (Default: DUAL PAD)
SIN is for single foil return electrodes.
3-ZERO-LAST (Default: LAST SETTING)
When ZERO is selected, all power levels will
default to zero when the system is powered
on. Last setting only applies to power levels
of the default modes.
4-SPRAY-PPT (Default: PINPOINT COAG)
Spray Coagulation can be selected as a default
mode.
5-NON_SIM-SIM (Default: SIMULTANEOUS)
When the switch is set for non-simultaneous
activation, dual activation will not occur for
coag modes.
6-GAS TEST (for testing purposes only)
Allows the ABC™ mode to be tested without
argon gas connected. Can only be set after
the unit has been powered on and completed
initialization.
U32 - PORT C: Outputs from Monitor
This port has three (3) active outputs only and the
outputs are used solely to inhibit internal circuits
when a system fault is detected.
GAS_En: Gas Enable
SET to enable argon gas flow - CLEAR inhibits
argon gas flow. Drives the solenoid valve that
is part of the argon flow control manifold.
HV_INH: High Voltage Inhibit
SET inhibits the HV to the amplifiers.
RF_INH: RF Drive Inhibit
CLEAR inhibits the RF Drive to the amplifiers.
6.2.6 Display Drivers - Seven Segment [U14,
U20, U39, U40, U41, & U17]
Converts Hex to Seven-Segment. The hex value
on bits 0-3 drive the “ones” digit; the hex value
on bits 4-7 drive the “tens” digit; and the hex
value on the address (A0, A1) is used to drive
the “hundreds” digit. The displays are common
anode, therefore each segment is illuminated with
an active low on the drivers. The digits are mul-
tiplexed, allowing only one digit to be on at any
one time for each section.
6.2.7 Indicator Driver [U34]
All indicators on the display panel with the excep-
tion of the numeric displays are driven with this
logic device in a 4x7 matrix. The outputs labeled
S0-S3 are multiplexed at a 25% duty cycle and
these outputs are converted to 15V at U38 &
U42, which provide drive current for all LED
indicators. U9 and U10 sink the current for the
indicators. The monitor microcontroller loads
4- eight bit registers, with each bit dedicated to a
specific display panel indicator. The outputs S0-
S3 are “send” and the outputs labeled R0-R7 are
“receive”. All the send and receive outputs are
active high at a 25% duty cycle.
6.2.8 Firmware [U28 & U1]
The firmware or program for the control
microcontroller is stored in U1 and the program
for the monitor microcontroller is stored in U28.
6.2.9 RAM [U2 -6116]
U2 is the external RAM for the con-
trol microcontroller only and the monitor
microcontroller only uses internal RAM.
6.2.10 A/D Inputs [Control Microcontroller]
Only four of the 8 internal A/D inputs are uti-
lized, and three of these inputs are for the A.R.M.
(Aspen Return Monitor).
2VARM: A voltage that represents the resistance of
the patient plate.
ARM_10: Calibration limit for 10 ohms. (See
A.R.M. cal)
ARM_150: Calibration limit for 150 ohms (See
A.R.M. cal)
FMEA: Back pressure monitoring for argon gas
flow. The control microcontroller monitors this
signal as a means of detecting occlusions or special
accessories with small orifice sizes.
When the monitor microcontroller senses an error
at ARM_10 or ARM_150, it will display an error
code to identify which input has the fault. These
are fatal errors that require the system to be reset

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 PABS. When testing or troubleshooting, use
the calibration procedure for PABS to determine
the value of FMEA 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 (VCON)
•Output Power (PCON)
•Maximum voltage at each dial setting (ILIM)
for Cut, Blend, Pinpoint, & Bipolar Modes
•Argon Flow Rate (VGAS).
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.