Valleylab Force FX-8C User manual

Service Manual

Force FX ™ -8C Electrosurgical Generator

with Instant Response ™ Technology

Preface

This manual and the equipment it describes are for use only by qualiﬁed medical professionals trained in the particular technique and surgical procedure to be performed. It is intended as a guide for servicing the Valleylab Force FX™-8C Electrosurgical Generator only. Additional information about using the generator is available in the Force FX™-8C

Electrosurgical Generator User’s Guide .

Caution

Federal (USA) law restricts this device to sale by or on the order of a physician.

Equipment covered in this manual:

Valleylab Force FX™-8C Electrosurgical Generator with Instant Response™ Technology— 100–120 V ~ Nominal, 220–240 V ~ Nominal (auto selected)

The Force FX™-8C Electrosurgical Generator Service Manual consists of two parts—the text (part 1 of 2) and a Schematics Supplement (part 2 of 2) which contains the schematics.

Valleylab Part Number:

Effective Date:

Trademark Acknowledgments:

September 2000

945 103 068

Force GSU™ Argon System, PolyHesive™ Adhesive Conductor, REM™ Contact Quality Monitoring System, Force EZ™ Electrosurgical Generator, Force Argon™ II-20 System, Instant Response™ Technology, The EDGE™ Coated Electrode, ACCUVAC™ Smoke Evacuation Attachment, and CUSA™ or CUSA EXcel™ Ultrasonic Surgical Aspirator are trademarks of Valleylab.

Teﬂon is a registered trademark of E.I du Pont de Nemours and Company.

Patent Information:

Protected by U.S. Pat. Nos. 4,416,276; 4,416,277; 4,658,820; 5,599,344; and 5,628,745.

Manufactured by:

Valleylab, a division of Tyco Healthcare Group LP Boulder, Colorado 80301-3299 USA

Tyco Healthcare UK Ltd. Gosport, PO130AS, UK

For information call:

1-303-530-2300

Force FX-8C Service Manual

Conventions Used in this Guide

Warning

Indicates a potentially hazardous situation which, if not avoided, could result in death or serious injury.

Caution

Indicates a hazardous situation which, if not avoided, may result in minor or moderate injury.

Important

Indicates an operating tip or maintenance suggestion.

Notice

Indicates a hazard which may result in product damage.

Force FX-8C Service Manual

iii

Table of Contents

Preface

Conventions Used in this Guide

List of Figures

iii

Section 1. Introduction

General Description

List of Components

Service Personnel Safety

General Fire/Explosion Hazards Electric Shock Hazards Servicing Calibration Cleaning

1-2

1-3

1-4

1-5

1-6

Section 2. Controls, Indicators, and Receptacles

Front Panel

Bipolar Controls

Bipolar Instrument Receptacle

Monopolar Cut Controls

Monopolar Coag Controls

Monopolar Instrument Receptacles

REM Alarm Indicator

Rear Panel

Footswitch Receptacles

Monopolar Footswitch Receptacles Bipolar Footswitch Receptacle

Power Entry Module

Activation Tone Volume Control

Option Panel

2-2

2-3

2-4

2-5

2-6

2-7

2-8

2-9

2-10

2-11

Section 3. Technical Specifications

Performance Characteristics

General

3-1

Dimensions and Weight Operating Parameters Transport and Storage Duty Cycle

3-3

Internal Memory Audio Volume

3-3

3-1

3-2

3-3

Force FX-8C Service Manual

REM Contact Quality Monitor Serial Port RF Activation Port Expansion Port

3-5

Low Frequency (50–60 Hz) Leakage Current High Frequency (RF) Leakage Current Input Power

3-7

Standards and IEC Classifications

Class I Equipment (IEC 601-1)

3-4

3-6

3-8

Type CF Equipment (IEC 601-1)/Defibrillator Proof Drip Proof (IEC 601-2-2) Electromagnetic Interference

3-9

Electromagnetic Compatibility (IEC 601-1-2 and IEC 601-2-2) Voltage Transients (Emergency Generator Mains Transfer)

Output Characteristics

3-10

Maximum Output for Bipolar and Monopolar Modes Maximum Output for Ultrasonic Electrosurgery Available Power Settings in Watts Output Waveforms

3-12

Output Power vs. Resistance Graphs

Bipolar Graphs Monopolar Cut Graphs Monopolar Coag Graphs

3-14

3-17

3-20

3-11

3-14

3-10

3-8

3-9

3-10

Section 4. Principles of Operation

Block Diagram

Functional Overview

Instant Response Technology Ultrasonic Electrosurgery Simultaneous Coag REM Contact Quality Monitoring System

Control Board

Microcontrollers Main Microcontroller Feedback Microcontroller Shared RAM I/0 Expansion Keyboard Interface and Activation Inputs Power Supply Supervisor Circuit A/D and D/A Conversion Waveform Generation (T_ON ASIC) T_ON Average Check Audio Alarm

4-2

4-3

4-5

4-6

4-7

4-8

4-9

4-4

4-7

4-8

Force FX-8C Service Manual

Serial Interface Dosage Error Algorithm Instant Response Algorithm

Front Panel

4-12

Membrane Keyboard Power Switch REM Connector/Switch CEM Mechanism Switch

Display Board

RF Indicator Lamps REM Indicators

4-9

4-10

4-11

4-12

4-13

LED and Seven-Segment Display Drivers CEM Switch Circuit

4-14

Mode Selection and Power Control Switches

Footswitch Board

Footswitch Decode Circuit Audio Circuit

Power Supply/RF Board

4-15

4-16

4-17

Power Supply/RF Board Interfaces High Voltage Power Supply 4-18 Low Voltage Power Supply 4-21 RF Output Stage 4-21 Spark Control Circuit 4-24 RF Leakage Reduction Circuit 4-25 REM Circuit 4-25 IsoBloc Circuit 4-25 Temperature Sense Circuits 4-26

4-13

4-14

4-18

Section 5. Setup, Tests, and Adjustments

Setting Up the Generator 5-2

Connections for Bipolar or Macrobipolar Surgery 5-4 Setting the Bipolar Output 5-5 Connections for Monopolar Surgery 5-6 Selecting Cut and Coag Modes 5-8 Simultaneous Coag 5-8 Using Two Generators Simultaneously 5-9 Connecting the CUSA Handpiece with CEM Nosecone 5-10 Setting the Output Power 5-11 Simultaneous Coag with a CUSA System 5-11 Changing the Mode 5-11 Changing the Power Setting 5-11 Activating the Surgical Instrument 5-12

Force FX-8C Service Manual

Periodic Safety Check 5-13

Recommended Test Equipment 5-13 Inspecting the Generator and Accessories 5-14 Inspecting the Internal Components 5-15 Testing the Generator 5-16 Verifying REM Function 5-17 Confirming Outputs 5-17 Check the Output for the Cut Modes 5-19 Check the Output for the Coag Modes 5-20 Checking Low Frequency Leakage Current and Ground Resistance 5-21 Checking High Frequency Leakage Current 5-23

Calibrating the Generator 5-24

Preparing for Calibration 5-25 Entering Calibration Mode 5-25 Exiting Calibration Mode 5-26 Verify the Generator Data 5-26 Adjust the Calendar 5-27 Adjust the Clock 5-28 Check and Adjust the REM Oscillator Frequency and Impedance 5-29 Check and Adjust the Current Sense Gain 5-30 Check and Adjust the Voltage Sense Gain 5-32 Check and Adjust the Reactance Gain 5-34 Check and Adjust the ECON Factor 5-36

Using the RS-232 Serial Port 5-40

Establish the Communications Link 5-40 Enter the Commands 5-41 Disconnect the Computer from the Generator 5-44

Section 6. Troubleshooting

Inspecting the Generator 6-1

Inspecting the Receptacles 6-2 Inspecting the Internal Components 6-3

Correcting Malfunctions 6-4

Responding to System Alarms 6-10

Correcting IC U3 Malfunctions 6-19

Correcting IC U6 Malfunctions 6-21

Correcting T_ON ASIC Malfunctions 6-23

Correcting Battery-Backed RAM Malfunctions 6-25

Section 7. Replacement Procedures

Interconnect Diagram 7-2

Battery Replacement 7-3

Force FX-8C Service Manual vii

Control Board Replacement 7-4

Display Board Replacement 7-5

Remove the Display Board 7-5 Install the Display Board 7-6

Display Board Seven-Segment LED Replacement 7-7

Fan Replacement 7-8

Footswitch Board Replacement 7-8

Front Panel Replacement 7-9

Remove the Front Panel Assembly 7-9 Remove and Reinstall the Front Panel Components 7-9 Install the Front Panel Assembly 7-10

Front Panel REM Module Replacement 7-11

Front Panel Power Switch Replacement 7-12

Fuse Replacement 7-13

Replacing Fuses in the Fuse Drawer 7-13 Replacing the Fuse on the Power Supply/RF Board 7-14

Left Front Heat Sink and Component Replacement 7-15

Remove the Left Front Heat Sink 7-15 Replace Left Front Heat Sink Components 7-16 Install the Left Front Heat Sink 7-16

Left Rear Heat Sink and Component Replacement 7-17

Remove the Left Rear Heat Sink 7-17 Replace Left Rear Heat Sink Components 7-18 Install the Left Rear Heat Sink 7-19

Right Heat Sink and Component Replacement 7-20

Remove the Right Heat Sink 7-20 Replace Right Heat Sink Components 7-21 Install the Right Heat Sink 7-22

Low Voltage Power Supply Replacement 7-23

Remove the Low Voltage Power Supply 7-23 Install the Low Voltage Power Supply 7-24

Power Entry Module Replacement 7-25

Remove the Power Entry Module 7-25 Install the Power Entry Module 7-26

Power Supply/RF Board Replacement 7-27

Remove the Power Supply/RF Board Assembly 7-27 Remove Components from the Old Board 7-28 Install Components on the New Board 7-29 Install the Power Supply/RF Board Assembly 7-30

viii Force FX-8C Service Manual

Section 8. Repair Policy and Procedures

Responsibility of the Manufacturer 8-1

Returning the Generator for Service 8-2

Obtain a Return Authorization Number 8-2 Clean the Generator 8-2 Ship the Generator 8-3

Returning Circuit Boards 8-3

Service Centers 8-4

Section 9. Service Parts

Ordering Replacement Parts 9-1

Generator Assembly 9-2

Parts List 9-4

Front Panel Assembly 9-6

Parts List 9-8

Control Board Components 9-9

Display Board Components 9-10

Footswitch Board Components 9-11

Power Supply/RF Board Assembly 9-14

Parts List 9-16

Power Supply/RF Board Components 9-18

Appendix A. Warranty

Schematics Supplement. Board Drawings and Schematics

Force FX-8C Service Manual ix

List of Figures

Figure 2-1. Layout of controls and indicators on the front panel 2-2

Figure 2-2. Buttons and indicators for bipolar controls 2-3

Figure 2-3. Buttons and indicators for cut controls (monopolar) 2-5

Figure 2-4. Buttons and indicators for coag controls (monopolar) 2-6

Figure 2-5. Controls and receptacles on the rear panel 2-8

Figure 2-6. Components in the power entry module 2-10

Figure 2-7. The three ports behind the option panel 2-11

Figure 3-1. Output power versus impedance for Precise bipolar mode 3-14

Figure 3-2. Precise bipolar mode—output power vs. peak voltage 3-14

Figure 3-3. Output power versus impedance for Standard bipolar mode 3-15

Figure 3-4. Standard bipolar mode—output power vs. peak voltage 3-15

Figure 3-5. Output power versus impedance for Macrobipolar mode 3-16

Figure 3-6. Macrobipolar mode—output power vs. peak voltage 3-16

Figure 3-7. Output power versus impedance for Low cut mode 3-17

Figure 3-8. Low cut mode—output power vs. peak voltage 3-17

Figure 3-9. Output power versus impedance for Pure cut mode 3-18

Figure 3-10. Pure cut mode—output power vs. peak voltage 3-18

Figure 3-11. Output power versus impedance for Blend cut mode 3-19

Figure 3-12. Blend cut mode—output power vs. peak voltage 3-19

Figure 3-13. Output power versus impedance for Desiccate 1 coag mode 3-20

Figure 3-14. Desiccate 1 coag mode—output power vs. peak voltage 3-20

Figure 3-15. Desiccate 2 coag mode—load resistance vs. output power 3-21

Figure 3-16. Desiccate 2 coag mode—output power vs. peak voltage 3-21

Figure 3-17. Desiccate 3 coag mode—load resistance vs. output power 3-22

Figure 3-18. Desiccate 3 coag mode—output power vs. peak voltage 3-22

Figure 3-19. Output power versus impedance for Fulgurate coag mode 3-23

Figure 3-20. Fulgurate coag mode—output power vs. peak voltage 3-23

Figure 3-21. Output power versus impedance for LCF Fulgurate mode 3-24

Figure 3-22. LCF Fulgurate mode—output power vs. peak voltage 3-24

Figure 3-23. Output power versus impedance for Spray coag mode 3-25

Figure 3-24. Spray coag mode—output power vs. peak voltage 3-25

x Force FX-8C Service Manual

Figure 5-1. Bipolar or macrobipolar connections—footswitch activation and a

handswitching or footswitching instrument 5-4

Figure 5-2. Bipolar or macrobipolar connection—handswitching

instrument 5-5

Figure 5-3. Monopolar connection—footswitch activation and a footswitching or

handswitching instrument using Monopolar 1 Footswitch receptacle and Monopolar 1/CEM Instrument receptacle 5-6

Figure 5-4. Monopolar connection—footswitch activation and a footswitching or

handswitching instrument using Monopolar 2 Footswitch receptacle and Monopolar 2 Instrument receptacle 5-7

Figure 5-5. Monopolar connection—handswitch activation and a monopolar

handswitching instrument using either Monopolar Instrument receptacle

Figure 5-6. Connections for simultaneous coag—two handswitching

instruments 5-9

Figure 5-7. Connection for simultaneous coag—two footswitching

instruments 5-9

Figure 5-8. Connections for combined monopolar/ultrasonic surgery 5-10

Figure 5-9. Leakage current test circuit per IEC 60601-1 5-21

5-7

Figure 7-1. Removing and disconnecting the power switch 7-12

Figure 7-2. Replacing fuses in the fuse drawer 7-13

Figure 7-3. Replacing left front heat sink components 7-16

Figure 7-4. Components of the left rear heat sink 7-18

Figure 7-5. Components of the right heat sink 7-21

Figure 7-6. Low voltage power supply 7-24

Figure 7-7. Cable connections on the power entry module 7-26

Figure 9-1. Generator assembly 9-2

Figure 9-2. Generator assembly – continued 9-3

Figure 9-3. Front panel assembly 9-6

Figure 9-4. Front panel assembly – continued 9-7

Figure 9-5. Power Supply/RF board assembly 9-14

Figure 9-6. Power Supply/RF board assembly – continued 9-15

Schematics Supplement

Schematic 1. Control board layout S-1

Schematic 2. Control board schematic, page 1 of 3 S-2 Schematic 3. Control board schematic, page 2 of 3 S-3

Schematic 4. Control board schematic, page 3 of 3 S-4 Schematic 5. Display board layout S-5

Force FX-8C Service Manual xi

Schematic 6. Display board schematic, page 1 of 3 S-6 Schematic 7. Display board schematic, page 2 of 3 S-7

Schematic 8. Display board schematic, page 3 of 3 S-8 Schematic 9. Footswitch board layout S-9

Schematic 10. Footswitch board schematic, page 1 of 2 S-10 Schematic 11. Footswitch board schematic, page 2 of 2 S-11

Schematic 12. Power supply/RF board layout S-12

Schematic 13. Power supply/RF board schematic, page 1 of 7 S-13

Schematic 14. Power supply/RF board schematic, page 2 of 7 S-14

Schematic 15. Power supply/RF board schematic, page 3 of 7 S-15

Schematic 16. Power supply/RF board schematic, page 4 of 7 S-16

Schematic 17. Power supply/RF board schematic, page 5 of 7 S-17

Schematic 18. Power supply/RF board schematic, page 6 of 7 S-18

Schematic 19. Power supply/RF board schematic, page 7 of 7 S-19

xii Force FX-8C Service Manual

1Introduction

SECTION

This manual provides instructions for servicing the Valleylab Force FX-8C Electrosurgical Generator with Instant Response Technology. This section

introduces the features and components of the generator and reviews the precautions associated with generator repair.

Force FX-8C Service Manual 1-1

General Description

The Valleylab Force FX-8C is an isolated output electrosurgical generator that provides the appropriate power for cutting, desiccating, and fulgurating tissue during bipolar and monopolar surgery.

It includes the following features:

• Instant Response Technology

• Three bipolar modes: precise (low), standard (medium), and macro (macrobipolar)

• Three monopolar cut modes: low, pure, and blend

• Three monopolar coag modes: desiccate (low), fulgurate (medium), and spray (high)

• Support for simultaneous coagulation

• The Valleylab REM Contact Quality Monitoring System

• Support for ultrasonic electrosurgery using the Valleylab CUSA System 200 or CUSA EXcel system and a CUSA handpiece with a CUSA electrosurgical module (CEM) nosecone

• Handswitch or footswitch activation

• Recall of most recently used mode and power settings

• Adjustable activation tone volume

• An RF activation port, RS-232 serial port, and expansion port

• Force GSU system and Force Argon system compatibility.

1-2 Force FX-8C Service Manual

List of Components

The Force FX-8C generator is a self-contained unit, consisting of a main enclosure (cover and base) and power cord. The main components of the generator are the following:

• Front panel components—power switch; controls for setting the modes and output power; a button for recalling the power settings and modes that were used last; receptacles for connecting electrosurgical accessories; and indicators that alert you to the current settings and patient return electrode status.

• Rear panel components—volume control; three footswitch receptacles; power entry module; equipotential grounding lug; and three ports (serial port, RF activation port, and expansion port).

• Internal components—control (microcontroller) board; display board; footswitch board; power supply/radio frequency (RF) board; low voltage power supply; fan; and heat sinks.

A handle is located on the underside of the chassis. For details about the interaction of the main components and circuit board

descriptions, refer to Section 4, Principles of Operation.

Introduction

Service Personnel Safety

Before servicing the generator, it is important that you read, understand, and follow the instructions supplied with it and with any other equipment used to install, test, adjust, or repair the generator.

General

Use the generator only if the self-test has been completed as described. Otherwise, inaccurate power outputs may result.

The instrument receptacles on this generator are designed to accept only one instrument at a time. Do not attempt to connect more than one instrument at a time into a given receptacle. Doing so will cause simultaneous activation of the instruments.

Do not stack equipment on top of the generator or place the generator on top of electrical equipment (except a Force GSU unit, a Force Argon unit, a CUSA System 200, or a CUSA EXcel unit). These conﬁgurations are unstable and/or do not allow for adequate cooling.

Provide as much distance as possible between the electrosurgical generator and other electronic equipment (such as monitors). An activated electrosurgical generator may cause interference with them.

Warning

Caution

Force FX-8C Service Manual 1-3

Service Personnel Safety

Caution

Do not turn the activation tone down to an inaudible level. The activation tone alerts the surgical team when an accessory is active.

Notice

If required by local codes, connect the generator to the hospital equalization connector with an equipotential cable.

Connect the power cord to a wall receptacle having the correct voltage. Otherwise, product damage may result.

Active Accessories

Warning

Electric Shock Hazard Do not connect wet accessories to the generator.

Electric Shock Hazard Ensure that all accessories and adapters are correctly

connected and that no metal is exposed.

Caution

Accessories must be connected to the proper receptacle type. In particular, bipolar accessories must be connected to the Bipolar Instrument receptacle only. Improper connection may result in inadvertent generator activation or a REM Contact Quality Monitor alarm.

Set power levels to the lowest setting before testing an accessory.

Notice

During bipolar electrosurgery do not activate the generator until the forceps have made contact with the patient. Product damage may occur.

Patient Return Electrodes

Warning

Using a patient return electrode without the REM safety feature will not activate the Valleylab REM Contact Quality Monitoring System.

Fire/Explosion Hazards

Warning

Danger: Explosion Hazard Do not install the generator in the presence of ﬂammable anesthetics, gases, liquids, or objects.

Fire Hazard Do not place active accessories near or in contact with ﬂammable materials (such as gauze or surgical drapes). Electrosurgical accessories that are activated or hot from use can cause a ﬁre. Use a holster to hold electrosurgical accessories safely away from personnel and ﬂammable materials.

Fire Hazard Do not use extension cords.

1-4 Force FX-8C Service Manual

Service Personnel Safety

Warning

Fire Hazard For continued protection against ﬁre hazard, replace fuses only with fuses of the same type and rating as the original fuse.

Electric Shock Hazards

Warning

Connect the generator power cord to a properly grounded receptacle. Do not use power plug adapters.

Do not connect a wet power cord to the generator or to the wall receptacle.

To allow stored energy to dissipate after power is disconnected, wait at least ﬁve minutes before replacing parts.

Always turn off and unplug the generator before cleaning.

Do not touch any exposed wiring or conductive surfaces while the generator is disassembled and energized. Never wear a grounding strap when working on an energized generator.

Introduction

When taking measurements or troubleshooting the generator, take appropriate precautions, such as using isolated tools and equipment, using the “one hand rule,” etc.

Potentially lethal AC and DC voltages are present in the AC line circuitry, high voltage DC circuitry, and associated mounting and heat sink hardware described in this manual. They are not isolated from the AC line. Take appropriate precautions when testing and troubleshooting this area of the generator.

High frequency, high voltage signals that can cause severe burns are present in the RF output stage and in the associated mounting and heat sink hardware described in this manual. Take appropriate precautions when testing and troubleshooting this area of the generator.

Servicing

Caution

Read all warnings, cautions, and instructions provided with this generator before servicing.

The generator contains electrostatic-sensitive components. When repairing the generator, work at a static-control workstation. Wear a grounding strap when handling electrostatic-sensitive components, except when working on an energized generator. Handle circuit boards by their nonconductive edges. Use an antistatic container for transport of electrostatic-sensitive components and circuit boards.

Notice

After installing a new low voltage power supply, verify that the voltages are correct.

Force FX-8C Service Manual 1-5

Service Personnel Safety

Calibration

Caution

To avoid inadvertent coupling and/or shunting of RF currents around the resistor elements, keep the resistors at least 10.2 cm (4 in.) away from any metal surface including tabletops and other resistors. This is especially true if several resistors are connected in series or parallel to obtain a speciﬁed value. Do not allow the resistor bodies to touch each other.

Notice

After completing any calibration step, proceed to the next step to save the values from the completed calibration step.

Do not activate the generator with any load resistor higher than 10 ohms while calibrating the current sense gain. Otherwise, product damage will result.

Do not activate the generator with any load resistor lower than 1000 ohms while calibrating the voltage sense gain for bipolar output. Otherwise, product damage will result.

Do not activate the generator with any load resistor lower than 3000 ohms while calibrating the voltage sense gain for the Low and Pure cut modes. Do not activate the generator with any load resistor lower than 2000 ohms while calibrating the voltage sense gain for the Blend mode. Otherwise, product damage will result.

Do not adjust the current sense gain (I factor), the voltage sense gain (V factor), or the reactance (Z factor) gain while the generator is activated.

After calibration, the generator will be ready to use only after you initiate the internal self-test by turning the generator off, then on.

Calibrate the generator after you install a new battery. Calibration values are lost when the battery is replaced.

Calibrate the generator after you install a new control board. Otherwise, the default calibration values are used.

Calibrate the generator after you install a new heat sink or replace components on the heat sink. Component differences may affect output waveforms.

Calibrate the generator after you install a new power supply/RF board. Component differences may affect output waveforms.

Cleaning

Notice

Do not clean the generator with abrasive cleaning or disinfectant compounds, solvents, or other materials that could scratch the panels or damage the generator.

1-6 Force FX-8C Service Manual

SECTION

2Controls, Indicators, and Receptacles

This section describes the front and rear panels, including all controls, indicators, receptacles, the fuse drawer, and ports.

Force FX-8C Service Manual 2-1

Front Panel

Recall button

Pressing this button sets the generator to the most recently used mode and power settings.

Bipolar controls Cut controls Coag controls

CEM indicator

Bipolar instrument receptacle

Monopolar 1/CEM instrument receptacle

Monopolar 2 instrument receptacle

Power switch

This switch supplies power to the generator.

Patient return electrode receptacle

For monopolar electrosurgery, connect a patient return electrode to this receptacle.

To turn on the generator, press (|). To turn off the generator, press (

O).

REM alarm indicator

Front Panel

Figure 2-1.

Layout of controls and indicators on the front panel

2-2 Force FX-8C Service Manual

Bipolar Controls

Figure 2-2.

Buttons and indicators for bipolar controls

Bipolar display

Shows the power setting, in watts, for the selected mode.

Mode indicators

Illuminate green when you press the corresponding mode button.

Bipolar indicator

When you activate bipolar, this indicator illuminates blue and an activation tone sounds.

Power buttons

Press

∆ to increase the power. ∇ to decrease the power.

Press

Controls, Indicators,

and Receptacles

Precise mode button

Select for ﬁne bipolar tissue desiccation.

Macro mode button

Select for macrobipolar output.

Standard mode button

Select for standard bipolar tissue desiccation. This is the default bipolar mode.

Force FX-8C Service Manual 2-3

Bipolar Instrument Receptacle

Caution

You can connect either a footswitching or handswitching bipolar instrument to the Bipolar instrument receptacle.

Connect a footswitching instrument with a two-pin connector.

Connect a handswitching instrument with a three-pin connector.

2-4 Force FX-8C Service Manual

Monopolar Cut Controls

Figure 2-3.

Buttons and indicators for cut controls (monopolar)

Cut display

Shows the power setting, in watts, for the selected mode.

Monopolar Cut Controls

Cut indicator

When you activate cut, this indicator illuminates yellow and an activation tone sounds.

Mode indicators

Illuminate green when you press the corresponding mode button.

Low mode button

Select for a cut with little or no sparking.

Power buttons

Press

∆ to increase the power.

Press

∇ to decrease the power.

Blend mode button

Select for slower cutting and additional hemostasis.

Pure mode button

Select for an even cut with little or no hemostasis. This is the default monopolar cut mode.

Controls, Indicators,

and Receptacles

Force FX-8C Service Manual 2-5

Monopolar Coag Controls

Figure 2-4.

Buttons and indicators for coag controls (monopolar)

Coag display

Shows the power setting, in watts, for the selected mode.

Mode indicators

Illuminate green when you press the corresponding mode button.

Coag indicator

When you activate coag, this indicator illuminates blue and an activation tone sounds.

Power buttons

Press Press

∆ to increase the power. ∇ to decrease the power.

Desiccate mode button

Select to desiccate the area of tissue that is in direct contact with the active electrode.

Spray mode button

Select to evenly coagulate a wide area of tissue with a spray of sparks; penetration is shallower and tissue area is larger than in fulgurate mode.

Fulgurate mode button

Select to fulgurate an area of tissue with a spray of sparks.

This unit is equipped with an additional fulgurate mode which incorporates a lower crest factor (LCF) than the factory default fulgurate mode. For details about this additional fulgurate mode, LCF Fulgurate, refer to Section 4, Before

Surgery, in the Force FX-8C Electrosurgical Generator User’s Guide.

Fulgurate is the default monopolar coag mode. However, the default coag mode can be changed to either Desiccate or Spray through the serial port on the rear panel.

2-6 Force FX-8C Service Manual

Monopolar Instrument Receptacles

Warning

You can connect a footswitching or handswitching monopolar instrument to the monopolar receptacles. Some footswitching instruments may require a single-pin adapter (E0502 Series) or E0017, available from Valleylab.

Connect one monopolar instrument to the Monopolar 1/CEM Instrument receptacle:

Monopolar Instrument Receptacles

REM Alarm Indicator

• A single-pin footswitching instrument or a three-pin handswitching instrument

• A four-pin CUSA handpiece with CEM nosecone. (The CEM indicator in the upper right of the front panel illuminates green. Refer to Section 4, Connecting the CUSA Handpiece with CEM Nosecone, in the Force FX-8C Electrosurgical Generator User’s Guide.

Connect one monopolar instrument to the Monopolar 2 Instrument receptacle:

• A single-pin footswitching instrument or a three-pin handswitching instrument

This indicator illuminates red until you properly apply a REM patient return electrode to the patient and connect it to the generator. Then the indicator illuminates green. (When you connect an electrode without the REM safety feature, the indicator does not illuminate.)

If the REM system senses an alarm condition, the indicator ﬂashes red until you correct the alarm condition—then the indicator illuminates green. (If you are using a return electrode without the REM safety feature, the red indicator light is extinguished when you correct the alarm condition.)

Controls, Indicators,

and Receptacles

Force FX-8C Service Manual 2-7

Rear Panel

Volume control

Power entry module

Monopolar Footswitch receptacles

Option panel Bipolar Footswitch

receptacle

Equipotential grounding lug

Use to connect the generator to earth ground.

Rear Panel

Figure 2-5.

Controls and receptacles on the rear panel

2-8 Force FX-8C Service Manual

Footswitch Receptacles

The rear panel contains three footswitch receptacles: two for monopolar and one for bipolar.

Monopolar Footswitch Receptacles

You must connect a monopolar footswitch if you connect a monopolar footswitching instrument to the generator.

Footswitch Receptacles

Connect a two-pedal monopolar footswitch to the Monopolar 1 Footswitch receptacle.

The connected footswitch activates monopolar output for the instrument that is connected to the Monopolar 1/CEM Instrument receptacle on the front panel.

Connect a two-pedal monopolar footswitch to the Monopolar 2 Footswitch receptacle.

The connected footswitch activates monopolar output for the instrument that is connected to the Monopolar 2 Instrument receptacle on the front panel

Controls, Indicators,

and Receptacles

Bipolar Footswitch Receptacle

You must connect a bipolar footswitch if you connect a bipolar footswitching instrument to the generator.

Connect a single-pedal bipolar footswitch to the Bipolar Footswitch receptacle.

The connected footswitch activates bipolar output for the instrument that is connected to the Bipolar Instrument receptacle on the front panel.

Force FX-8C Service Manual 2-9

Power Entry Module

The power entry module consists of a power cord receptacle and a fuse drawer.

Figure 2-6.

Components in the power entry module

Activation Tone Volume Control

Fuse drawer

The fuse drawer contains two fuses. Refer to the Force FX-8C Electrosurgical Generator Service Manual for instructions on changing the fuses.

Power cord receptacle

Turn to adjust the volume of the tones that sound when the generator is activated (activation tone). To ensure that the surgical team is alerted to inadvertent activation, these tones cannot be silenced.

To increase the volume of activation tones, turn the knob clockwise. To decrease the volume, turn the knob counterclockwise.

2-10 Force FX-8C Service Manual

Option Panel

A removable plate on the rear panel covers a serial port, an expansion port, and an RF (radio frequency) activation port. Remove this plate to obtain information through the RS-232 port or to install a peripheral device such as a Bipolar Current Monitor, but retain the original cover plate. After obtaining information or removing a peripheral device, reinstall the original cover plate.

Caution

To avoid product damage, do not operate the Force FX-8C without an appropriate cover plate in place.

To review the technical speciﬁcations for each port, refer to Section 3, Technical Speciﬁcations.

Figure 2-7.

The three ports behind the option panel

Serial port

Allows connection of a computer to the generator. You can obtain information about the generator using RS-232 communications protocol or change the default coag mode from Fulgurate to Desiccate or Spray. Refer to Section 5, Using the RS-232 Serial Port, for instructions.

Controls, Indicators,

and Receptacles

Expansion port

Allows a connected device to receive information about the RF voltage and current being generated as well as signal the generator to halt RF output.

RF Activation port

Allows a connected device to receive information during RF activation of the generator, which will then generate a response in the device.

Force FX-8C Service Manual 2-11

Notes

2-12 Force FX-8C Service Manual

3Technical Speciﬁcations

All speciﬁcations are nominal and subject to change without notice. A speciﬁcation referred to as “typical” is within ± 20% of a stated value at

SECTION

room temperature (25° C/77° F) and a nominal input power voltage.

Performance Characteristics

General

Output conﬁguration Isolated output

Cooling Natural convection; side and rear panel vents; fan

Display Eight digital seven-segment displays: 1.9 cm (0.75 in.)

Mounting Valleylab cart (E8006, E8008 or UC8009), CUSA EXcel

each

System, CUSA System 200 (using CUSA System 200 optional mounting brackets), a Force GSU unit, a Force Argon unit, or any stable ﬂat surface

Force FX-8C Service Manual 3-1

Performance Characteristics

Dimensions and Weight

Width: 35.6 cm (14 in.)

Depth 45.7 cm (18 in.)

Height 11.1 cm (4 3/8 in.)

Weight < 8.2 kg (< 18 lbs.)

Operating Parameters

Ambient temperature range

Relative humidity 30% to 75%, noncondensing

Atmospheric pressure 700 to 1060 millibars

Warm-up time If transported or stored at temperatures outside the

10° to 40° C (50° to 104° F)

operating temperature range, allow one hour for the generator to reach room temperature before use.

Transport and Storage

Ambient temperature range

Relative humidity 10% to 100%, condensing

Atmospheric pressure 500 to 1060 millibars

-40° to 70° C (-40° to 158° F)

Duration of storage If stored longer than one year, the battery must be replaced

and a full checkout, including calibration, must be completed before use. For instructions, refer to Section 5, Calibrating the Generator, in this manual.

3-2 Force FX-8C Service Manual

Performance Characteristics

Duty Cycle

Under maximum power settings and rated load conditions (Pure cut, 300 watt setting, 300 ohm load) the generator is suitable for activation times of 10 seconds on, 30 seconds off for one hour.

If the internal temperature of the generator is too high, an alarm tone sounds and a number (451) ﬂashes in the Cut display alternately with the power settings. You can activate the generator and change the power settings while this condition exists.

Internal Memory

Nonvolatile, batterybacked RAM

Storage capacity • One conﬁguration, including three power settings and

Battery type: 3 V lithium button cell Battery life: 5 years

three mode settings

• The last 20 error codes detected by the generator

• The number of times and length of activation for each

mode

• The average power setting used for each mode

• The total time the generator is on

• Other service-related information.

Audio Volume

The audio levels stated below are for activation tones (bipolar, cut, and coag) and alarm tones (REM and system alarms) at a distance of one meter. Alarm tones meet the requirements for IEC 601-2-2.

Activation Tone

Technical Speciﬁcations

Volume (adjustable) 45 to ≥ 65 dB

Frequency Bipolar: 940 Hz

Cut: 660 Hz Coag: 940 Hz

Duration Continuous while the generator is activated

Force FX-8C Service Manual 3-3

Performance Characteristics

Alarm Tone

Volume (not adjustable) ≥ 65 dB

Frequency 660 Hz

Duration 250 to 500 ms

REM Contact Quality Monitor

REM current is measured according to IEC 601-1, Ed. 1988, Figure 15.

Measurement frequency 80 kHz ± 10 kHz

Measurement current < 10 µA

Acceptable Resistance Range

REM resistance measurements are ± 10% during RF activation and ± 5% when RF output is not activated.

REM patient return electrode: 5 to 135 ohms or up to a 40% increase in the initial measured contact resistance (whichever is less).

Patient return electrode without the REM safety feature (single section electrode): 0 to 20 ohms.

If the measured resistance is outside the acceptable range(s) noted above, a REM fault condition occurs.

REM Alarm Activation

REM patient return electrode: When the measured resistance exceeds the standard range of safe resistance (below 5 ohms or above 135 ohms) or when the initial measured contact resistance increases by 40% (whichever is less), the REM Alarm indicator ﬂashes red, a tone sounds twice, and RF output is disabled. The indicator remains illuminated red until you correct the condition causing the alarm. Then, the indicator illuminates green and RF output is enabled.

Patient return electrode without the REM safety feature: When the measured resistance between the patient return electrode pins exceeds 20 ohms, the REM Alarm indicator ﬂashes red, a tone sounds twice, and RF output is disabled. The indicator remains illuminated red until you correct the condition causing the alarm. Then, the red indicator is extinguished and RF output is enabled.

3-4 Force FX-8C Service Manual

Performance Characteristics

Serial Port

RS-232 compatible; 9600 baud, 8 data bits, 1 stop bit, no parity

9-pin connector supports the following signals

Pin 2 – isolated transmit (serial data output transmit line)

Pin 3 – isolated receive (serial data input receive line)

Pin 5 – isolated ground (reference for transmit and receive).

RF Activation Port

The RF activation port is a subminiature telephone jack attached to the contacts of a small relay. The contacts are closed when the output is energized and open at all other times. This port provides a means to tell other equipment that RF current is being generated. This may be useful when making EEG or ECG measurements.

Expansion Port

15-pin connector; supports the following signals

• Pin 2 – isolated transmit

(serial data output transmit line)

• Pin 3 – isolated receive (serial data input receive line)

Expansion power (from the low voltage power supply)

• Pin 5 – isolated ground

(reference for transmit and receive)

• Pin 9 – RF disable: input signal which, when activated by an external device, disables active RF output

• Pin 10 – RF current: output signal proportional to active RF current

• Pin 11 – RF voltage: output signal proportional to active RF voltage.

+ 5 V (pin 6), – 12 V (pin 14), + 12 V (pin 15), and ground (pins 12 & 13)

Technical Speciﬁcations

Force FX-8C Service Manual 3-5

Performance Characteristics

Low Frequency (50–60 Hz) Leakage Current

Enclosure source current, ground open

Source current, patient leads, all outputs

Sink current at high line, all inputs

< 300 µA

Normal polarity, intact ground: < 10 µA Normal polarity, ground open: < 50 µA Reverse polarity, ground open: < 50 µA

< 50 µA

High Frequency (RF) Leakage Current

Bipolar RF leakage current < 59.2 mA

Monopolar RF leakage current (additional tolerance)

CEM output modes < 150 mA

< 150 mA

rms

at ≤ 50 W

rms

3-6 Force FX-8C Service Manual

Input Power

110–120 Volt 220–240 Volt

Performance Characteristics

Maximum VA at nominal line voltage:

Idle: 52 VA Bipolar: 450 VA Cut: 924 VA Coag: 530 VA

Input mains voltage, full regulation range: 104–132 Vac

Input mains voltage, operating range: 85–132 Vac

Mains current (maximum):

Idle: 0.4 A Bipolar: 2.0 A Cut: 7.0 A Coag: 4.0 A

Mains line frequency range (nominal): 50 to 60 Hz

Fuses (2): F8 A Fuses (2): T4 A

Maximum VA at nominal line voltage:

Idle: 52 VA Bipolar: 450 VA Cut: 924 VA Coag: 530 VA

Input mains voltage, full regulation range: 208–264 Vac

Input mains voltage, operating range: 170–264 Vac

Mains current (maximum):

Idle: 0.2 A Bipolar: 1.0 A Cut: 3.5 A Coag: 2.0 A

Mains line frequency range (nominal): 50 to 60 Hz

Power cord: 3-prong hospital grade connector

Power cord: 3-prong locally approved connector

Technical Speciﬁcations

Force FX-8C Service Manual 3-7

Standards and IEC Classifications

Standards and IEC Classiﬁcations

ATTENTION

Consult accompanying documents.

The generator output is ﬂoating (isolated) with respect to

ground.

DANGER

Explosion risk if used with ﬂammable anesthetics.

To reduce the risk of electric shock, do not remove the cover. Refer servicing to qualiﬁed service personnel.

Class I Equipment (IEC 601-1)

Accessible conductive parts cannot become live in the event of a basic insulation failure because of the way in which they are connected to the protective earth conductor.

Type CF Equipment (IEC 601-1)/Deﬁbrillator Proof

The Force FX-8C generator provides a high degree of protection against electric shock, particularly regarding allowable leakage currents. It is type CF isolated (ﬂoating) output and may be used for procedures involving the heart.

The Force FX-8C generator patient return electrode terminal is protected from deﬁbrillator discharge according to ANSI/AAMI HF18 and IEC 601-2-2.

3-8 Force FX-8C Service Manual

Standards and IEC Classifications

Drip Proof (IEC 601-2-2)

The generator enclosure is constructed so that liquid spillage in normal use does not wet electrical insulation or other components which, when wet, are likely to affect adversely the safety of the generator.

Electromagnetic Interference

When placed on or beneath an activated Valleylab electrosurgical generator, the Force FX-8C generator operates without interference. The generator minimizes electromagnetic interference to video equipment used in the operating room.

Electromagnetic Compatibility (IEC 601-1-2 and IEC 601-2-2)

The Force FX-8C generator complies with the appropriate IEC 601-1-2 and IEC 601-2-2 speciﬁcations regarding electromagnetic compatibility.

Voltage Transients (Emergency Generator Mains Transfer)

The Force FX-8C generator operates in a safe manner when the transfer is made between line AC and an emergency generator voltage source.

Technical Speciﬁcations

Force FX-8C Service Manual 3-9

Output Characteristics

Maximum Output for Bipolar and Monopolar Modes

Power readouts agree with actual power into rated load to within 15% or 5 watts, whichever is greater.

Mode

Bipolar

Precise Standard Macro

Monopolar Cut

Low Pure Blend

Monopolar Coag

Desiccate 1 Desiccate 2 Desiccate 3 Fulgurate LCF Fulgurate Spray

Open Circuit Peak

Voltage (max)

230 V 170 V 430 V

770 V 1400 V 1710 V

2500 V

575 V

685 V 5000 V 3660 V 5550 V

Open Circuit P–P

Voltage (max)

450 V 320 V 750 V

1350 V 2300 V 3300 V

3500 V 1000 V 1200 V 8500 V 6900 V 9000 V

Rated Load

(max)

100 Ω 100 Ω 100 Ω

300 Ω 300 Ω 300 Ω

500 Ω 300 Ω 300 Ω 500 Ω 500 Ω 500 Ω

Power

(max)

70 W 70 W 70 W

300 W 300 W 200 W

120 W 120 W 120 W 120 W 120 W 120 W

Crest Factor*

1.5

2.5

5.0

1.5

7.0

5.5

8.0

* An indication of a waveform’s ability to coagulate bleeders without a cutting effect

Maximum Output for Ultrasonic Electrosurgery

Open Circuit P–P

Mode

Monopolar Cut

Low 1000 V 300 Ω 100 W 1.5

Monopolar Coag

Desiccate 1 3500 V 500 Ω 70 W 5.0

* An indication of a waveform’s ability to coagulate bleeders without a cutting effect

Voltage (max)

3-10 Force FX-8C Service Manual

Rated Load

(max)

Power

(max)

Crest

Factor*

Output Characteristics

Available Power Settings in Watts

Bipolar and Macrobipolar

12345678910

11 12 13 14 15 16 17 18 19 20

21 22 23 24 25 26 27 28 29 30

31 32 33 34 35 36 37 38 39 40

45 50 55 60 65 70

Monopolar Cut: Low and Pure

12345678910

11 12 13 14 15 16 17 18 19 20

21 22 23 24 25 26 27 28 29 30

31 32 33 34 35 36 37 38 39 40

45 50 55 60 65 70 75 80 85 90

95 100 110 120 130 140 150 160 170 180

190 200 210 220 230 240 250 260 270 280

290 300

Monopolar Cut: Blend

12345678910

11 12 13 14 15 16 17 18 19 20

21 22 23 24 25 26 27 28 29 30

31 32 33 34 35 36 37 38 39 40

45 50 55 60 65 70 75 80 85 90

95 100 110 120 130 140 150 160 170 180

190 200

Technical Speciﬁcations

Force FX-8C Service Manual 3-11

Output Characteristics

Monopolar Coag

12345678910

11 12 13 14 15 16 17 18 19 20

21 22 23 24 25 26 27 28 29 30

31 32 33 34 35 36 37 38 39 40

45 50 55 60 65 70 75 80 85 90

95 100 110 120

CEM Cut

12345678910

11 12 13 14 15 16 17 18 19 20

21 22 23 24 25 26 27 28 29 30

31 32 33 34 35 36 37 38 39 40

45 50 55 60 65 70 75 80 85 90

95 100

CEM Coag

12345678910

11 12 13 14 15 16 17 18 19 20

21 22 23 24 25 26 27 28 29 30

31 32 33 34 35 36 37 38 39 40

45 50 55 60 65 70

Output Waveforms

Instant Response Technology, an automatic adjustment, controls all bipolar modes and all cut modes. It does not control the coag modes because of their fulguration capabilities. As tissue resistance increases from zero, the generator outputs constant current followed by constant power followed by constant voltage. The maximum output voltage is controlled to reduce capacitive coupling and video interference and to minimize sparking.

3-12 Force FX-8C Service Manual

Output Characteristics

Bipolar

Precise 470 kHz sinusoid

Standard 470 kHz sinusoid

Macro 470 kHz sinusoid

Monopolar Cut

Low 390 kHz sinusoid. Similar to the Pure cut mode except the

maximum voltage is limited to a lower value.

Pure 390 kHz sinusoid

Blend 390 kHz bursts of sinusoid, recurring at 27 kHz intervals.

50% duty cycle.

Monopolar Coag

Desiccate 1 240 kHz sinusoid repeated at 39 kHz. 8% duty cycle

Desiccate 2 393 kHz sinusoid

Desiccate 3 393 kHz sinusoid

Fulgurate 470 kHz damped sinusoidal bursts with a repetition

frequency of 30 kHz into 500 ohms

LCF Fulgurate 470kHz damped sinusoidal bursts with a repetition

frequency of 57 kHz into 500 ohms

Spray 470 kHz damped sinusoidal bursts with a randomized

repetition centered at 28 kHz. Frequencies include 21 kHz < f < 35 kHz. Output is further modulated by a random 250 Hz envelope with a variable duty cycle.

Technical Speciﬁcations

Force FX-8C Service Manual 3-13

Output Power vs. Resistance Graphs

The graphs that follow depict the changes for each mode at speciﬁc power settings.

Bipolar Graphs

The insulating surface described in IEC 601-2-2 was used to obtain the bipolar output measurements.

Figure 3-1.

Output power versus impedance for Precise bipolar mode

Figure 3-2.

Precise bipolar mode— output power vs. peak voltage

Output Power (watts)

Load Resistance (ohms)

Open Circuit Peak Voltage (volts)

Output Power (watts)

3-14 Force FX-8C Service Manual

Output Power vs. Resistance Graphs

Figure 3-3.

Output power versus impedance for Standard bipolar mode

Output Power (watts)

0 200 400 600 800 1000

70 W 35 W

Load Resistance (ohms)

Figure 3-4.

Standard bipolar mode— output power vs. peak voltage

Technical Speciﬁcations

Open Circuit Peak Voltage (volts)

Output Power (watts)

Force FX-8C Service Manual 3-15

Output Power vs. Resistance Graphs

Output Power (watts)

Open Circuit Peak Voltage (volts)

Figure 3-5.

Output power versus impedance for Macrobipolar mode

Figure 3-6.

Macrobipolar mode— output power vs. peak voltage

Output Power (watts)

0 200 400 600 800 1000

Load Resistance (ohms)

70 W

35 W

3-16 Force FX-8C Service Manual

Output Power vs. Resistance Graphs

Monopolar Cut Graphs

These measurements were taken using short (< 0.5 meter) leads.

Figure 3-7.

Output power versus impedance for Low cut mode

Figure 3-8.

Low cut mode— output power vs. peak voltage

325 300 275 250 225 200 175 150 125 100

Output Power (watts)

75 50 25

0 200 400 600 800 1000 1200 1400 1600 1800 2000

300 W 150 W

Load Resistance (ohms)

Open Circuit Peak Voltage (volts)

Technical Speciﬁcations

Output Power (watts)

Force FX-8C Service Manual 3-17

Output Power vs. Resistance Graphs

Output Power (watts)

Open Circuit Peak Voltage (volts)

Figure 3-9.

Output power versus impedance for Pure cut mode

Figure 3-10.

Pure cut mode— output power vs. peak voltage

325 300 275 250 225 200 175 150 125 100

Output Power (watts)

75 50 25

0 200 400 600 800 1000 1200 1400 1600 1800 2000

300

150

Load Resistance (ohms)

3-18 Force FX-8C Service Manual

Output Power vs. Resistance Graphs

Figure 3-11.

Output power versus impedance for Blend cut mode

Figure 3-12.

Blend cut mode— output power vs. peak voltage

250

225

200

175

150

125

100

Output Power (watts)

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Load Resistance (ohms)

200 W

100 W

Open Circuit Peak Voltage (volts)

Technical Speciﬁcations

Output Power (watts)

Force FX-8C Service Manual 3-19

Output Power vs. Resistance Graphs

Output Power (watts)

Open Circuit Peak Voltage (volts)

Monopolar Coag Graphs

These measurements were taken using short (< 0.5 meter) leads.

Figure 3-13.

Output power versus impedance for Desiccate 1 coag mode

Figure 3-14.

Desiccate 1 coag mode— output power vs. peak voltage

140

120

100

Output Power (watts)

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Load Resistance (ohms)

120 W

60 W

3-20 Force FX-8C Service Manual

Figure 3-15.

Desiccate 2 coag mode— load resistance vs. output power

Figure 3-16.

Desiccate 2 coag mode— output power vs. peak voltage

Output Power vs. Resistance Graphs

Output Power (watts)

Load Resistance (ohms)

Open Circuit Peak Voltage (volts)

Technical Speciﬁcations

Output Power (watts)

Force FX-8C Service Manual 3-21

Output Power vs. Resistance Graphs

Figure 3-17.

Desiccate 3 coag mode— load resistance vs. output power

Figure 3-18.

Desiccate 3 coag mode— output power vs. peak voltage

Output Power (watts)

Load Resistance (ohms)

Open Circuit Peak Voltage (volts)

Output Power (watts)

3-22 Force FX-8C Service Manual

Figure 3-19.

Output power versus impedance for Fulgurate coag mode

Output Power vs. Resistance Graphs

140

120

Figure 3-20.

Fulgurate coag mode— output power vs. peak voltage

100

Output Power (watts)

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Load Resistance (ohms)

120 W

60 W

Open Circuit Peak Voltage (volts)

Technical Speciﬁcations

Output Power (watts)

Force FX-8C Service Manual 3-23

Output Power vs. Resistance Graphs

Figure 3-21.

Output power versus impedance for LCF Fulgurate mode

Figure 3-22.

LCF Fulgurate mode— output power vs. peak voltage

140

120

100

Output Power (watts)

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Load Resistance (ohms)

120 W

60 W

ircuit Peak Voltage (volts)

pen

Output Power (watts)

3-24 Force FX-8C Service Manual

Output Power vs. Resistance Graphs

Figure 3-23.

Output power versus impedance for Spray coag mode

Figure 3-24.

Spray coag mode— output power vs. peak voltage

140

120

100

Output Power (watts)

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Load Resistance (ohms)

120 W

60 W

Open Circuit Peak Voltage (volts)

Technical Speciﬁcations

Output Power (watts)

Force FX-8C Service Manual 3-25

Notes

3-26 Force FX-8C Service Manual

4Principles of Operation

This section provides detailed information about how the Force FX-8C Electrosurgical Generator functions and how the internal components

SECTION

interact.

The circuitry resides on four printed circuit boards: the Control board, the Display board, the Footswitch board, and the Power Supply/RF board.

This section includes the following information:

• A block diagram that illustrates how the generator functions

• A general description of how the generator works

• Detailed descriptions of the circuitry for each printed circuit board.

Force FX-8C Service Manual 4-1

Block Diagram

4-2 Force FX-8C Service Manual

Functional Overview

The Force FX-8C generator is speciﬁcally designed to cut and coagulate (desiccate and fulgurate) tissue during bipolar or monopolar electrosurgery.

During electrosurgery, radio frequency (RF) current ﬂows from the generator to an active electrode, which delivers the current to the patient. The resistance to the current, provided by the patient’s tissue and/or the air between the active electrode and the tissue, produces the heat that is necessary for the surgical effect. The RF current ﬂows from the active electrode, through the patient’s body tissue to the return electrode, which recovers the current and returns it to the generator.

Instant Response Technology

The Force FX-8C generator automatically senses resistance and adjusts the output voltage to maintain a consistent tissue effect across different tissue density. This adjustment is based on the selected mode (bipolar or cut modes only), the power setting, and the level of tissue resistance. For details, refer to Instant Response Algorithm later in this section.

Ultrasonic Electrosurgery

The Force FX-8C generator works in conjunction with the Valleylab CUSA System 200 and CUSA EXcel for procedures where ultrasonic electrosurgery is desirable. When you connect a CUSA handpiece with CEM nosecone to the generator for ultrasonic electrosurgery, the generator limits the monopolar output power automatically.

• The maximum power setting for monopolar cut is 100 watts.

• The maximum power setting for monopolar coag is 70 watts. When you activate the handpiece for cut or coag output, the Low cut

mode or the Desiccate 1 coag mode is in effect automatically. The remaining cut modes and coag modes are not available.

For more information, refer to CEM Mechanism Switch and CEM Switch Circuit later in this section.

Simultaneous Coag

When you simultaneously activate two monopolar instruments for coag output, each receives a percentage of the coag power setting set for the selected mode. The amount of power each instrument receives depends on the tissue resistance sensed by the generator at each surgical site. Generally, the site with lower resistance receives proportionately more power. The combined total output power does not exceed the coag power setting.

Principles of Operation

You can also use a CUSA handpiece with a CEM nosecone for simultaneous coag when you connect a monopolar instrument to the Monopolar 2 Instrument receptacle. Only Desiccate 1 coag is available; the maximum power setting is 70 watts.

Force FX-8C Service Manual 4-3

Functional Overview

REM Contact Quality Monitoring System

The Force FX-8C generator uses the Valleylab REM Contact Quality Monitoring System to monitor the quality of electrical contact between the patient return electrode and the patient. The REM system is designed to eliminate the risk of burns at the return electrode site during monopolar electrosurgery.

When you connect a REM patient return electrode to the Patient Return Electrode receptacle, you activate the REM system. When you activate monopolar output, the generator connects the patient return electrode path. If you activate bipolar output while a return electrode is connected to the patient, the return electrode circuit is deactivated automatically to eliminate the possibility of current dispersal.

The REM system continuously measures resistance at the return electrode site and compares it to a standard range of safe resistance (between 5 and 135 ohms), thus eliminating intermittent false alarms that could result from small changes in resistance. The REM system also adapts to individual patients by measuring the initial contact resistance (baseline resistance) between the patient and the patient return electrode. If the tissue impedance at the return electrode decreases during electrosurgery, the REM system resets the baseline resistance.

REM Alarm Activation

The REM Alarm indicator ﬂashes red, a tone sounds, and the generator stops producing output power when either of the following occurs:

• The measured resistance is below 5 ohms or above 135 ohms, the limits of the standard range of safe resistance.

• An increase in contact resistance is greater than 40% from the initial measurement (baseline resistance).

The REM Alarm indicator remains illuminated red until you correct the condition causing the alarm. Then, the indicator illuminates green and RF output is enabled.

Electrodes Without the REM Safety Feature

When you use a patient return electrode that does not have the REM safety feature, the REM system does not monitor the patient contact area. The REM system can monitor only the pin-to-pin resistance at the connector and can detect broken wires or connectors in the return electrode cord.

The REM Alarm indicator does not illuminate green when you connect a patient return electrode. Instead, the indicator light is extinguished. If the generator detects a break in continuity between the electrode and the generator, the indicator illuminates red.

4-4 Force FX-8C Service Manual

Control Board

When resistance between the Patient Return Electrode receptacle pins exceeds 20 ohms, the REM Alarm indicator ﬂashes red, a tone sounds twice, and RF output is disabled. The indicator remains illuminated red until you correct the condition causing the alarm. Then, the red indicator light is extinguished and RF output is enabled.

For additional information, refer to REM Circuit later in this section.

Refer to Section 9 for components and the Schematics Supplement for Board Drawings and Schematics.

The Control board contains the circuitry that controls the generator, including the indicators and switches on the Display board and the RF output stage on the Power Supply/RF board. Firmware on the Control board performs many diagnostic and initialization routines. Errors are reported as alarm numbers on the front panel.

The Control board interfaces with the Power Supply/RF board through a 96-pin card edge connector. It interfaces with the Display board through a 64-pin ribbon cable.

Microcontrollers

Two microcontrollers on the Control board control the Force FX-8C generator. These microprocessors communicate with each other through a shared RAM. The main microcontroller (U5) performs all system functions, except the time-critical real time feedback control of generator RF output. The feedback microcontroller (U11), which is a separate, dedicated microcontroller, handles the time-critical real time feedback control of generator RF output. All system analog signals are available to these microcontrollers.

A third microcontroller (U9) functions as an application-speciﬁc integrated circuit, or ASIC. It generates the RF drive waveforms (T_ON\) for the RF output stage.

Main Microcontroller

The main microcontroller (U5) is an 80C562 that incorporates an 8-input multiplexed 8-bit A/D converter. The main microcontroller is responsible for overall system control. It monitors all dosage error functions and safety circuits. It implements the user interface, including activation control. It is primarily responsible for these functions:

• Segment display drivers and LED update

• Power control buttons, mode buttons, and the activation interface

Principles of Operation

• Serial port interface

• Alarm handling

• REM

Force FX-8C Service Manual 4-5

Control Board

• Audio control

• Memory control and storage (system alarms with time stamps; calibration values)

• Real-time clock control and interface

• Internal self-tests

• Communicating with the feedback microcontroller.

Main Microcontroller Memory

A PSD413 programmable peripheral (U3) provides program memory (128K x 8 external EPROM) and data memory (2K x 8 external batterybacked static RAM) for the main microcontroller. Additional data memory is available from these sources:

• 256K x 8 microcontroller internal RAM

• 4K x 8 external static RAM (U4) shared with the feedback microcontroller.

Battery-Backed RAM

A socket on the Control board contains a 3.0 V lithium button cell battery (BT1) that provides backup power for the 2K x 8 external RAM on the PSD413 device (U3) used by the main microcontroller. The battery-backed RAM stores calibration constants, last setup parameters, and temporary data.

Feedback Microcontroller

The feedback microcontroller (U11), like the main microcontroller, is an 80C562. It receives commands from the main microcontroller and, when the generator is activated, establishes the appropriate relay closures and activates RF output. It continually adjusts the output signal of the generator by controlling the high voltage DC power supply and the RF clock circuitry. It is primarily responsible for these functions:

• Scaling relay control and output relay control

• T_ON ASIC waveform control

• Leakage control (coag)

• Constant voltage, current, and power feedback control

• ECON initialization

• Real-time information update (actual voltage, current, power, impedance, effect mode)

• Memory tests

• Communicating with the main microcontroller.

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Control Board

Feedback Microcontroller Memory

A PSD412 (U6) provides program memory (64K x 8 external EPROM) and data memory (2K x 8 external static RAM) for the feedback microcontroller. Additional data memory is available from these sources:

• 256K x 8 microcontroller internal RAM

• 4K x 8 external static RAM (U4) shared with the main microcontroller.

Shared RAM

The 4K x 8 external shared static RAM is provided by an IDT 713425A device (U4) with semaphore ﬂags. The shared RAM allows the main microcontroller (U5) and the feedback microcontroller (U11) to share common variables. It functions as a communications interface between the main and feedback microcontrollers. It also provides additional general purpose RAM to these microcontrollers.

I/0 Expansion

Three devices provide I/O expansion capabilities:

• One PSD412 programmable peripheral (U6)

• One PSD413 programmable peripheral (U3)

• One 82C55 expansion port (U2). Each programmable peripheral device incorporates forty individually

programmable I/O pins divided into ﬁve 8-bit ports. Twenty-four of the general I/O pins can alternatively be used as I/O for two PLDs, featuring a total of 59 inputs, 126 product terms, and 24 macrocells. Each device also contains EPROM (64K x 8 for the PSD412; 128K x 8 for the PSD413), 2K x 8 of static RAM, and a power management unit for battery backup. The I/O expansion capabilities of both devices are conﬁgured as outputs for relay control, lamp control, keyboard scanning, and chip selects.

The expansion port 82C55 (U2) is a generic I/O expander that incorporates twenty-four I/O pins divided into three 8-bit ports. It is conﬁgured as all inputs. It reads the keyboard, activation signals, accessory switches, and system status ﬂags.

Keyboard Interface and Activation Inputs

The keyboard interface is a simple row and column matrix between three bank select output lines (BANK0–BANK2) on port A of the PSD413 (U3) used by the main microcontroller and eight keyboard (KBD_D0–KBD_D7) input lines on port A of the expansion port 82C55 (U2).

Principles of Operation

Port B of the expansion port 82C55 reads activation inputs from the IsoBloc decoding circuits on the Power Supply/RF board.

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Control Board

Power Supply Supervisor Circuit

The power supply supervisor circuit (U14), a MAX691, generates a Reset signal and a Reset\ signal for the main microcontroller (U5) if the power supply voltage to the Control board drops below 4.65 V. It also generates a voltage sensitive chip select for the PSD412 (U6) and the PSD413 (U3). The low voltage threshold (4.65 V) places U3 and U6 in sleep mode and disables the 2K x 8 external static RAM.

A/D and D/A Conversion

Each 80C562 microcontroller (U5 and U11) contains an 8-channel multiplexed 8-bit A/D converter. Resolution of voltage and current sense inputs is enhanced by incorporating gain scaling relays in the sense circuits on the Power Supply/RF board and prescaling based on the expected input voltage or current values.

An MP7226 quad D/A converter (U15) provides 4-channel 8-bit D/A capabilities for the feedback microcontroller to output 0 to 5 Vdc analog voltages.

Waveform Generation (T_ON ASIC)

A dedicated 89C54 microcontroller (U9) generates the RF drive waveforms (T_ON\) for the RF output ampliﬁer on the Power Supply/ RF board. The microcontroller functions as an application-speciﬁc integrated circuit, or ASIC, performing an endless series of repetitive tasks while enabled.

The feedback microcontroller (U11) holds the T_ON ASIC (U9) in a reset state until the feedback microcontroller detects a valid activation request. After validating the request, the feedback microcontroller releases the T_ON ASIC from reset and communicates a 4-bit code that represents the generator mode to be activated. The acceptable activation codes are listed below:

0: Precise bipolar 1: Standard and Macro bipolar 2: Low Cut, Pure Cut, Desiccate 1, and Desiccate 2 3: Blend cut 7: Desiccate coag 8: LCF Fulgurate coag 9: Spray coag 11: Spark-controlled Blend 12: Fulgurate Coag Codes 4, 5, 6, 10 and A–F are unused.

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Control Board

Each code generates a unique waveform pattern to be delivered to the RF output stage of the generator. The T_ON ASIC reads and evaluates the code and, if the code value is acceptable, repetitively generates the appropriate waveform until the activation request ends. After the request ends, the feedback microcontroller places the T_ON ASIC back into reset.

If the code received by the T_ON ASIC is not valid, the internal program sets an error ﬂag, deactivates all output signals, and remains in an error state until the system is reset.

T_ON Average Check

The T_ON waveform generator output waveform is integrated in hardware and returned to the main microcontroller as an analog value called T_ON average. The T_ON average is different for each distinct output mode of the T_ON waveform generator. The main microcontroller continually checks the T_ON average for compliance with the calibrated value to ensure that the T_ON waveform generator is operating properly.

The T_ON average signal rests at 5 V when the generator is not activated and drops to the calibrated value when activation occurs. The main microcontroller checks to make sure the T_ON average signal is within ± 15 counts of the calibrated value.

During wak control in the coag modes, the T_ON average rises an indeterminate amount. Due to this unknown, the T_ON average is allowed to rise to 253 counts, which guarantees the T_ON waveform generator is still operating. The T_ON average is still not allowed to drop below the lower limit of 15 counts mentioned above.

Audio Alarm

The audio alarm circuit is located on the Footswitch board. The audio alarm is controlled by software and hardware.

• Software control is provided by the UP_TONE\ (microcontroller tone) and LO_TONE signals generated by the main microcontroller in response to activation inputs, alarms, and at power-up. These signals connect from the Control board to the Power Supply/RF board through the 96-pin connector and then from the Power Supply/RF board to the Footswitch board through the 16-pin footswitch ribbon connector.

• Hardware control is provided by the RF_TONE\ signal generated in the RF output stage by RF sensing circuitry on the Power Supply/RF board.

Serial Interface

Principles of Operation

The RS-232 serial port is a software-polled interface to the main microcontroller (U5). It is used for diagnostics and calibration. Transmission and receipt of command strings do not stop real time processing, except as single characters are read from or written to the

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Control Board

serial port. The serial port is conﬁgured to 9600 baud, 8 data bits, 1 stop bit, with no parity. This timing is derived from the main microcontroller oscillator frequency of 11.0592 MHz.

The control board serial port signals connect to the Power Supply/ RF board through the 96-pin connector. The signals are then connected to the 9-pin serial port connector on the Power Supply/RF board.

Dosage Error Algorithm

Dosage Error Algorithm for Closed-Loop Modes

The dosage error algorithm for the closed-loop modes (bipolar and cut) is based on a comparison between the actual power as calculated by the main microcontroller (U5) using the backup sensors and the maximum allowed power. While the feedback microcontroller is operating the generator output, the main microcontroller calculates and checks the values to make sure the feedback microcontroller is operating the generator properly.

In a closed loop mode, there is a 500 ms delay before the dosage error algorithm monitors the RMS output of the generator. After the delay, the algorithm ﬁrst checks to see that the voltage, current, and power calculated by the backup sensors are less than 125% of the value calculated by the primary sensors. On passing this test, the feedback mode of the generator is taken into account.

• In current control mode, the current calculated by the backup sensors is not allowed to deviate from the current calculated by the primary sensors by more than 50% of the value calculated by the primary sensors.

• In voltage control mode, the voltage calculated by the backup sensors is not allowed to deviate from the voltage calculated by the primary sensors by more than 50% of the value calculated by the primary sensors.

During closed loop activation, the main microcontroller continually checks for broken backup sensors. The current and voltage sensor analog values are compared to the previous readings to ensure that the sensor values are not constant or falling while ECON is rising.

When the generator drops into spark control, the software makes allowances for the shift in frequency. The voltage sensor returns a value that is approximately 20–25% high, and the rms value calculated for the voltage sensor is reduced by 25%. The current sensor returns a value that is approximately 10–15% low, and the rms value calculated for the current sensor is increased by 12.5%.

The dosage error algorithm for the open loop modes (coag) is based on the ECON calculated for the mode. The main microcontroller calculates an ECON that represents 125% of the front panel power setting and veriﬁes that SYS_ECON and HV_SEN do not exceed this value while the generator is activated.

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Control Board

These tests detect stuck or aberrant sensors and improperly delivered power in all modes. The dosage error ﬁrmware executes in less than one second.

Instant Response Algorithm

This mode is a closed loop control algorithm implemented in microcontroller ﬁrmware. It is applied to the bipolar modes and the cut modes. It is not applied to the coag modes.

As tissue impedance increases from short circuit to open circuit, the algorithm implements ﬁrst constant current, then constant power, and ﬁnally, constant voltage. The maximum output voltage is controlled to reduce capacitive coupling, reduce video interference, and eliminate sparking. At low impedances, constant current protects output circuitry. At high impedances, constant voltage control limits arcing and electromagnetic interference.

Constant current: output voltage is held at constant output current according to

I = (P/R) ˆ(1/2) where I is the output current, P is the power set by the user, and R is the

constant current to constant power impedance switchpoint. Constant power: the power set by the user is maintained. Constant voltage: the output voltage is maintained according to V = (P*R) ˆ(1/2) where V is the output voltage, P is the power set by the user, and R is the

constant power to constant voltage impedance switchpoint.

High Impedance Operation

The ﬁrmware algorithm clamps the output voltage to speciﬁc levels for high impedance conditions. The clamp level is a function of the mode that is activated. This helps prevent arcing and electromagnetic interference.

Analog to Digital Saturation

Analog to digital saturation works in conjunction with RF leakage current limiting. If the analog to digital converter is saturated, the effect mode feedback loop reduces the output voltage to allow for an unsaturated operating condition. The feedback loop switches the control function to maintaining the analog to digital converter in the linear operating range.

Principles of Operation

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Front Panel

The front panel consists of an injection molded plastic bezel with a membrane keyboard, power switch, CEM mechanism switch, and REM connector with switch. These front panel components interface with the Display board and the Power Supply/RF board.

Membrane Keyboard

The membrane keyboard is attached to the bezel with a high strength adhesive. It is not removable. The membrane contains 16 metal dome push-button switches. Six of these switches control the up and down sequencing of the power seven-segment LEDs (light-emitting diodes). One switch controls the previous settings Recall function and nine switches control each of the nine output modes of the generator.

The membrane also contains nine LEDs, one for each mode. A 25-pin ﬂat ribbon cable connects the membrane keyboard switches and LEDs to the Display board.

Power Switch

A double pole single throw switch snaps into the front of the bezel. This switch supplies the AC mains current to the generator.

REM Connector/Switch

An internal REM connector and sense switch connects to the inside of the bezel with two screws. Two cables leave this assembly. One cable is the actual REM connector; the other cable is the output of the internal switch that senses the presence or absence of the center pin on the REM plug.

CEM Mechanism Switch

A small plastic lever arm mechanism is attached to the inner wall of the front panel bezel on the Monopolar 1/CEM output jack. When you connect a CUSA handpiece with a CEM nosecone to the Monopolar 1/ CEM Instrument receptacle, the arm actuates a small switch that connects to the Display board with a 4-pin connector.

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Display Board

Refer to Section 9 for components and the Schematics Supplement for Board Drawings and Schematics.

The Display board is located in the front panel assembly. It contains RF indicator lamps, seven-segment LED power setting displays, REM alarm LEDs, and a CEM indicator LED. The display board switch circuitry includes the LED and lamp driver circuitry, power selection switches, mode selection switches, the REM switch circuit, and the CEM switch circuit.

RF Indicator Lamps

The RF indicator lamps illuminate during RF activation to visually indicate the presence of RF power. Each of the three indicator bars (Bipolar, Cut, and Coag) on the front panel is illuminated by four incandescent bulbs (LP1–LP12).

• LP1–LP4 illuminate the blue Bipolar bar, indicating bipolar activation.

• LP5–LP8 illuminate the yellow Cut bar, indicating cut activation.

• LP9–LP12 illuminate the blue Coag bar, indicating coag activation. The RF indicator lamps are controlled by the BIP_LMP, CUT_LMP, and

COAG_LMP signals. These signals originate from port A of the main microcontroller programmable peripheral (U3) on the Control board.

Buffers in U1 turn the RF indicator lamps on and off. Resistors R1–R12 set the amount of current ﬂowing through the lamps when they are turned on. The value of these resistors varies for each indicator bar, depending on the color of the bar, to make the different colors of the bars illuminate with equal intensities.

REM Indicators

The REM indicator consists of two bicolor LED arrays incorporating one red and four green LEDs per array. The LEDs are controlled by the REM_RED and REM_GREEN signals originating from port A of the main microcontroller programmable peripheral (U3) on the Control board. The signals are buffered on the Display board by driver U1. Both the red and green LEDs are current limited by 100 ohm resistors (R13, R14, R15, and R16).

LED and Seven-Segment Display Drivers

Principles of Operation

This circuit contains three display drivers for the LEDs and the sevensegment displays. The LEDs indicate modes of operation, and the REM condition. The seven-segment displays indicate bipolar, cut, and coag power settings.

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Display Board

Each display driver (U6, U10, and U14) can drive up to eight banks of eight LEDs by multiplexing the time that each bank is turned on. The banks can be wired together to increase the time that a group of LEDs is on, effectively increasing the brightness of that group.

U10 drives the discrete LEDs and the CEM LED. These include green indicators for the bipolar modes (Precise, Standard, and Macro), the cut modes (Low, Pure, and Blend), and the coag modes (Desiccate, Fulgurate, and Spray). The anode of the mode selection LEDs are tied to driver U10. By using pairs of the driver digit lines, the duty ratio for these LEDs is effectively 1/4.

U6 drives the seven-segment displays that indicate power settings. U4 and U5 indicate the bipolar power setting, U7–U9 indicate the cut power setting, and U11–U13 indicate the coag power setting. The anodes of these displays are each tied to only one digit line of the driver. The effective duty cycle is 1/8 for each seven-segment display.

Some ﬁltering components are associated with U6, U10, and U14. Bypass capacitors C3, C4, C7, C8, C9, and C10 are connected between + 5V and DGND. C3, C4, and C10 have a relatively small capacitance value of

0.1 µF to ﬁlter higher frequency noise. C7, C8, and C9 have a relatively

large capacitance value of 47 µF to supply the large spikes of current for the LEDs generated by the multiplexing action of the drivers, which typically occurs at 250 Hz.

Resistor array R18 reduces the input impedance of the display driver inputs as seen by the main microcontroller on the Control board. This rounds off the edges of these digital signals, reducing high frequency emissions. The lowered impedance also reduces the susceptibility of the circuit to noise from other circuits.

CEM Switch Circuit

When you plug a CUSA handpiece with a CEM nosecone into the Monopolar 1/CEM Instrument receptacle, the small nonconductive pin in the plug pushes a spring-loaded plastic lever arm mounted inside the front panel. This lever arm activates a small switch that plugs into the Display board. The switch signal tells the microcontroller to limit the power.

Mode Selection and Power Control Switches

The mode selection and power control switches are arranged in a matrix. The main microcontroller selects a bank of switches to read by asserting a bank select signal (BANK0, BANK1, or BANK2) through port A of programmable peripheral U3 on the Control board. These signals are buffered by Q1, Q2, and Q3 respectively and become the switch drive signals COM0, COM1, and COM2.

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Footswitch Board

• When COM0 is selected, the power control switches may be read.

• When COM1 is selected, the recall switch and the bipolar mode select switches may be read.

• When COM2 is selected, the cut and coag mode select switches may be read.

To read the switches, the main microcontroller asserts the desired BANK select line and reads the state of the keyboard switch return lines KBD_D0 through KBD_D7. These lines are read through port A of the I/O expansion port (U2) on the Control board.

Refer to Section 9 for components and the Schematics Supplement for Board Drawings and Schematics.

The Footswitch board is mounted inside the rear panel. It contains circuitry accepting and decoding footswitch keying inputs and an audio circuit for announcing generator keying and various alarm tones. The Footswitch board interfaces with the Power Supply/RF board.

Footswitch Decode Circuit

Two monopolar footswitch connectors and a bipolar footswitch connector are mounted on the Footswitch board and extend through the rear panel. The monopolar footswitch connectors (J3 and J2) accept monopolar footswitches and provide footswitching capability for the Monopolar 1/ CEM and Monopolar 2 Instrument receptacles located on the front panel. The bipolar footswitch connector (J4) accepts a bipolar footswitch and provides footswitching capability for the Bipolar Instrument receptacle on the front panel. Capacitors C39–C46 provide ﬁltering that blocks high frequency noise from exiting the generator on the footswitch cables.

As required by the IEC, the footswitch circuit is isolated from patient connected and ground referenced circuits and is able to withstand a potential of 500 Vrms (50/60 Hz). To obtain this isolation, the footswitch connected circuitry is powered from an isolated power supply (U2). The isolated power supply, an HPR-107, operates from the ground referenced +12 V power supply and supplies an isolated 12 volts.

Resistors R18 and R19 form a voltage divider that yields a signal (Vref2) of approximately 6 volts. This reference voltage is applied to the noninverting inputs of comparators U3A, U3B, U4A, U4B, and U5A. The common terminal of each footswitch is connected to the +12 V isolated power source. Footswitch activation causes this voltage to be applied to a resistor divider. The values of the resistors comprising the input divider are selected to provide a switching threshold of approximately 750 ohms. The divided voltage is then applied to the inverting input of one of the ﬁve comparators. When the voltage at the inverting input exceeds the voltage at the noninverting input, the open collector output of the comparator turns on, causing current to ﬂow in the LED of the corresponding optoisolator. This current generates an IR beam that causes

Principles of Operation

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Footswitch Board

the associated photo-transistor to conduct. The collectors of the transistors are connected to input pins of an I/O port on the microcontroller where they activate the desired mode of operation.

Audio Circuit

The audio system consists of an audio oscillator, tone control signals, a volume control potentiometer, an audio ampliﬁer, and a speaker. A reference voltage (Vref) is used throughout the audio circuit and is generated by dividing the +12 V power supply down to about 2 V by R9 and R8.

The audio circuit annunciates the presence of RF output and provides an auditory indication of alarm conditions. A potentiometer adjusts the volume of RF output activation tones. The speaker volume cannot be turned off entirely. The volume of the tone issued during alarm conditions is not adjustable.

The audio oscillator is enabled when UP_TONE\ or RF_TONE\ is pulled low. Diodes D1 and D2 provide a wired OR function for the two signals. Since UP_TONE\ and RF_TONE\ are +5 V (logic level) signals, resistors R4 and R6 divide the +12 V audio power supply down to about 4.85 V to prevent D1 and D2 from sourcing current into the output pin of U3 on the Control board. When either UP_TONE\ or RF_TONE\ is enabled low, the voltage at the noninverting input of U1B is pulled below the Vref threshold present at U4B’s inverting input, the open collector output of U4B is turned on, grounding R31 and allowing U6A to oscillate.

U6A is a relaxation oscillator whose frequencies are determined by the RC time constants of R30, C35, and C18. This design allows the oscillator to produce two distinct frequencies that can be selected by the state of the LO_TONE signal.

• When LO_TONE is not asserted, R30 and C35 determine the frequency of operation of the oscillator (approximately 900 Hz).

• When LO_TONE is asserted (+5 V), the voltage at the noninverting input of U4A exceeds the 2 V Vref signal at the inverting input, turning on its output transistor. This effectively connects C18 in parallel with C35 to produce a higher RC time constant for the oscillator, which results in a lower audio frequency of approximately 700 Hz.

The ALARM signal selects the user-controlled audio volume or the ﬁxed alarm level volume. U1C and U1D are conﬁgured in an exclusive OR arrangement in which the state of the output transistors of U1C or U1D is complementary. In other words, the output transistor of one of these two devices is always on, but both cannot be on simultaneously. Under normal operating conditions, the ALARM signal is low, allowing the U1C output to ﬂoat while the U1D output transistor is turned on. The output of U1D creates a voltage divider through R11, R12 (the volume control potentiometer), and R32 to attenuate the audio signal to levels acceptable for input to the audio ampliﬁer. R32 determines the maximum audio volume and R11 determines the minimum audio volume. R10 determines the audio alert volume level. R34 provides an alternate audio signal path in the event of an open volume control potentiometer.

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Power Supply/RF Board

When the ALARM signal is high, the U1C output transistor is turned on while the output of U1D ﬂoats. When the U1C output transistor is on, R10 is pulled to ground and creates a ﬁxed voltage divider with R32 to produce the alarm volume level at the input to audio ampliﬁer U7. Meanwhile, the output of U1D is allowed to ﬂoat, thus removing the variable resistor divider from the circuit. In this case, the volume control potentiometer becomes a small resistance in series with the high impedance input from the audio ampliﬁer, negating the effect of the volume setting.

Audio ampliﬁer U7 and speaker SP1 comprise the ﬁnal stage in the audio system. The audio signal is AC coupled to the ampliﬁer by C25 to eliminate the need for well-controlled input biasing. The voltage gain of U7 is set to about 20 by ﬂoating its gain select pins. Because the U1 output signal is internally biased to Vcc/2, it is necessary to AC couple the speaker through C2 to prevent the ampliﬁer from DC biasing the speaker.

Refer to Section 9 for components and the Schematics Supplement for Board Drawing and Schematics.

The Power Supply/RF board is the main board of the generator. It contains the high voltage power supply and the RF output stage. Circuitry on this board performs several other functions:

• Output voltage monitoring

• Output current monitoring

• Leakage current sensing (RF leakage sensing and reduction circuits)

• Spark control circuit

• REM impedance monitoring (REM circuit)

• Handswitch closure detection (IsoBloc circuit)

• RS-232 connector

• Expansion connector

• EKG contact closure connector

• Output high voltage relays

• Temperature monitoring and fan control.

Principles of Operation

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Power Supply/RF Board

Power Supply/RF Board Interfaces

The Power Supply/RF board interfaces to other boards and components as noted below:

• AC input line ﬁlter

• Control board

• Footswitch board

• Heat sink components (RF damping resistor, RF MOSFET, and high voltage power supply MOSFETs)

• Single-wire attachment points for connecting the sense transformers

• Low voltage power supply (AC input and DC output)

• Low noise fan.

A series of fuse clips connect the RF outputs and other front panel interfaces (i.e., REM and handswitching signals). The fuse clips mate to lugs located in the output portion of the front panel.

High Voltage Power Supply

Warning

The high voltage power supply section contains the power entry circuitry, auto mains switching circuitry, AC/DC conversion circuitry, and a DC/DC switching regulator.

Power Entry Circuit

The power entry circuit consists of an integral three wire power cord receptacle, fuse drawer, EMI ﬁlter, and a separate power switch. The power switch is mounted on the front panel. The receptacle/ﬁlter is mounted on the rear panel of the generator. AC line fuses are changeable from the rear of the generator.

Auto Mains Switching Circuitry

The auto mains switching circuit detects the AC line voltage level and controls the triac (D1). This triac controls the topology of the AC/DC converter. For 120 Vac operation, the triac is on, which connects the AC neutral to the center of the AC/DC converter capacitor bank (C3, C10, C11, and C22). In this conﬁguration, the circuit acts as a doubler using the right hand half of the bridge rectiﬁer (CR80). For 240 Vac operation the triac is off and CR80 is used as a full wave rectiﬁer.

The control IC (U1) functions as follows: The series circuit (CR1, R1, R2, and C9) provides power for U1. Pin 1 (Vss) is a shunt regulator that provides a –9 V (nominal) output. The divider (R3 and R4) measures the

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Power Supply/RF Board

input line voltage. Since the voltage at pin 8 varies with the line, it can sense the line voltage zero crossing as well as the peak voltage. Pins 2 and 3 are inputs to an oscillator used for triac triggering timing. R7 and C1 set the oscillator frequency. Pin 7 is tied to Vss, which places the circuit in the fail-safe mode. Thus, once the circuit enters full bridge mode, it remains in that mode until input power is recycled. A power dropout cannot cause the circuit to accidentally act as a doubler when the higher input voltage range is used.

AC/DC Converter

The AC/DC converter uses CR80 as either a doubler or full wave rectiﬁer, depending on the input voltage. In either case, an unregulated nominal 300 Vdc is provided to the DC/DC switching regulator. Thermistors R32 and R33 provide inrush current limiting, and fuse F4 provides protection against faults in the DC/DC switcher.

Capacitors C3, C10, C11, and C22 are an energy storage reservoir for the DC/DC switcher. C29 is a high frequency bypass ﬁlter. Bleeder resistors R5 and R6 discharge the capacitors when the AC line is disconnected or the power switch is turned off.

DC/DC Switching Regulator

The DC/DC switching regulator is a buck derived, pulse width modulated (PWM) transformer. It is an isolated, ﬁxed frequency, full bridge converter. The PWM IC (U5) is used in the voltage mode. The output of the regulator is adjustable from approximately zero (0) to 180 Vdc.

The full bridge consists of four power MOSFETs (Q1, Q3, Q4, and Q5) that operate at AC line potential. Transistors Q3 and Q5 are on while Q1 and Q4 are off, and the reverse. In this manner, power signals to the power transformer are bidirectional, or push-pull. This allows full utilization of the transformer core magnetization capability. Regulation is achieved by modulating the time that each MOSFET pair is on. Capacitor C32 in series with the power transformer T3 primary prevents DC ﬂux imbalance. A snubber circuit (C27 and R31) absorbs leakage energy spikes. Another snubber circuit (C49 and R51) reduces spikes due to reverse recovery of the output bridge rectiﬁer.

The gate driver circuitry for each MOSFET is transformer-coupled through T1 to provide AC line isolation. It consists of a dual MOSFET driver (U3) and various damping resistors. Resistors R12, R18, R21, and R26 minimize turn-off oscillations. Resistors R22 and R23 damp ringing due to parasitic inductances in T1. Blocking capacitors C24 and C25 prevent DC ﬂux imbalance in T1.

Note: T1 consists of two transformers electrically and magnetically isolated from each other but assembled into the same package. T1A and T1B form one transformer; T1C and T1D form the other.

Principles of Operation

The output of the power transformer is full wave rectiﬁed by a high voltage diode bridge (CR10, CR13, CR19, and CR23). L1, C33, and C35 ﬁlter the rectiﬁed power signal. The regulated DC output from this supply is the input to the RF stage of the generator.

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Power Supply/RF Board

The SYS_ECON signal from the microcontroller controls the output voltage level. This 0 to 5 Vdc signal sets the reference for the PWM control loop. An external op-amp (U7B) is used for gain and integration, since common mode voltage limitations in U5’s internal op-amp preclude its use over the full range of 0 to 5 V. The internal op-amp is connected as a follower. SYS_ECON is compared to the feedback voltage from the output divider (R34, R35, and R49), and an error signal (ECON) is sent to the PWM microcontroller. In addition to the error signal, U7B and the associated R-C networks provide lead-lag loop compensation to increase the bandwidth of the regulator beyond that of the output L-C ﬁlter.

Note: U7A is used for random gain switching in the Spray mode and is conﬁgured for unity gain in all other modes.

The output of U5 is a pair of 180° out-of-phase signals that are pulse width modulated by comparing ECON with the internal oscillator ramp waveform. At the start of an oscillator cycle, an output is turned on. It turns off when the ramp voltage crosses the ECON level. The two output signals from U5 (pins 11 and 14) feed the MOSFET drivers (U3A and U3B).

R36 and C42 set the U5 oscillator frequency to approximately 170 kHz. C45 controls the ramp-up of the pulse width at power on for slow start control. Transformer T2 limits the power transformer primary current, protecting against faults in the DC/DC switcher power stage and faults in circuitry downstream of the switcher. The output of T2 is rectiﬁed (CR3–CR6), ﬁltered (R30 and C30), and fed to the current limit pin (pin 9 of U5). During an overcurrent condition the U5 current limit function resets the slow start circuit, resulting in the output cycling from on to off until the current falls. Pin 9 of U5 is also used for remote shut down of the DC/DC switcher through U6A and CR8. The shut down signal comes from the main microcontroller on the Control board.

The resistor divider on the high voltage DC output formed by R52 and R53 is used for dosage error sensing.

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Power Supply/RF Board

Low Voltage Power Supply

The low voltage power supply is rated for 40 watts. It delivers a regulated +5 Vdc and ±12 Vdc output. This power supply automatically adjusts for both input voltage ranges. It also has internal current limiting. The pinouts between the low voltage power supply and the Power Supply/ RF board are listed below:

PIN Voltage Test Point

1 +5 Vdc TP8

2 –12 Vdc TP5

3 +12 Vdc TP6

4 GROUND TP9

The low voltage power supply speciﬁcations are as follows:

Output Voltage Output Current Output Power*

+5 Vdc 4000 mA 20.0 W

–12 Vdc 400 mA 4.8 W

+12 Vdc 2000 mA 24.0 W

* Total output power cannot exceed 40 W.

RF Output Stage

Warning

The RF stage consists of a single MOSFET power switch with associated gate drive circuitry, an RF power transformer, tuning capacitors, an RF output L-C-C ﬁlter, output directing relays, and topology selecting relays. Also included in this section are the RF voltage and current sense circuits and a switched damping network for certain operational modes.

Principles of Operation

The MOSFET gets its gating signal from the T_ON ASIC on the control board. The T_ON ASIC also provides the gating signal for the switched damping network.

Force FX-8C Service Manual 4-21

Power Supply/RF Board

When the topology selecting relays (K2 and K14) are unenergized, the RF stage is in the Fulgurate and Spray coag modes; when both are energized, the RF stage is in the cut and bipolar modes. For the Desiccate coag mode, K2 is unenergized and K14 is energized.

Primary Sense Circuits

The primary voltage and current sense circuits provide feedback information to the feedback microcontroller in the bipolar and cut modes.

For voltage sensing, the two 10 k ohm resistors (R148 and R149) in series with the primary of T13 work with the 100 ohm resistor across the secondary to divide the output voltage down. Depending on the front panel power setting, one of the four relays (K3 to K6) is switched in to give optimum scaling. The four AD827 high speed op-amps, along with the associated resistors, capacitors, and diodes, form a precision full wave rectiﬁer circuit. U11B is a high input impedance follower to prevent the rectiﬁer circuit from loading down the resistive divider. U11A is a follower that adds phase delay, which improves balance in the rectiﬁed waveform between positive and negative half cycles of the input signal. The actual rectiﬁcation is done with U8A and U8B. The rectiﬁed waveform is converted to DC by the R-C ﬁlter after the last op-amp, with full scale being 5 Vdc.

The current sense circuit, which uses current transformers T6 and T8, works the same as the voltage sense circuit. T6 senses bipolar current and T8 senses monopolar current. Relay K7 selects the appropriate current. Note that the current scaling relays (K8 to K11) switch at different power settings than the voltage scaling relays.

Redundant Sense Circuits

Redundant voltage and current sense circuits provide dosage error monitoring.

T16 monitors the current through the output capacitors (C150, C152, and C158). This current is proportional to the output voltage of the generator. A full bridge rectiﬁer is formed by CR25–CR28. The rectiﬁer output is ﬁltered by R118 and C96. Op-amp U18 buffers the DC signal. R119 and C97 provide additional ﬁltering.

T17 and the associated circuitry operate the same as the redundant voltage sense circuit. The output is a signal proportional to the output current of the generator.

Cut Modes

In the cut modes, K2 is set so that diode CR2 is in parallel with the MOSFET body drain diode, C34 and C41 are across the MOSFET, and the transformer primary consists of windings 1-2 and 3-4 in series. K14 is closed so the series capacitor bank (C150–C152, C158, and C159) is across the output.

In the Low and Pure cut modes, the T_ON\ signal is a continuous pulse train with a pulse width of 846 ns and a frequency of 390 kHz. In this case, essentially two resonant circuits operate in tandem. The output L-C ﬁlter

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Power Supply/RF Board

is tuned just slightly higher than the RF switching frequency, achieving a high degree of ﬁltering. The output is very sinusoidal over the full range of load impedances. Capacitors C34 and C41 are tuned with the RF transformer primary so that the ﬂyback voltage appearing across the MOSFET at turn off is a half sine pulse and returns to zero volts before the next cycle begins. The T_ON\ pulse width is chosen to support this tuning. This zero voltage switching improves the efﬁciency of the RF stage and is effective over a wide range of load impedances.

The circuit topology of the Blend cut mode is the same as the Pure cut mode. In Blend mode, however, the T_ON\ signal is an interrupted pulse train with a 50% duty cycle and a pulse train repetition rate of 27 kHz. For a given power setting, Blend gives a higher peak current, providing better hemostasis than Pure or Low. To minimize ringing at the beginning of the off period of the Blend waveform envelope, the damping resistor is switched on just before switching ends and stays on for part of the off period.

Bipolar Modes

The circuit topology for the bipolar modes is essentially the same as the cut modes, except the output voltage is tapped off C152 and the switching frequency is 470 kHz. These differences allow for the higher currents and lower voltages required in bipolar surgery while still maintaining the advantages of zero voltage switching in the MOSFET. The T_ON\ signal is a continuous pulse train with a 423 ns pulse width.

Coag Modes

In the Fulgurate and Spray coag modes, K2 is set so that diode CR2 blocks reverse current in the power MOSFET, C40 as well as C34 and C41 are across the MOSFET, and the transformer primary consists of winding 1-2 only. K14 is open, keeping the series capacitor bank (C150–C152, C158, and C159) out of the circuit.

In the LCF Fulgurate coag mode, the T_ON\ signal is a continuous pulse train with a pulse width of 1.69 µs and a frequency of 57 kHz. When the MOSFET turns on, some energy is delivered to the output and some is stored in the T4 core. When the MOSFET is turned off, the energy stored in the core rings out with a frequency of 591 kHz. The frequency is set by C34, C40, C41, and the inductance of winding 1-2 of T4. CR2 blocks reverse current in the body drain diode of the MOSFET so that the power waveform can ring negative. This allows high peak voltages to be achieved at the output. In most cases, all the energy stored in the transformer core during one switching cycle is delivered to the load before the next cycle begins. The Fulgurate mode works the same as the LCF Fulgurate mode, except the T_ON\ signal is a continuous pulse train with a pulse width is 1.69 µs and a repetition frequency of 30 kHz.

The Spray mode works essentially the same as the Fulgurate mode, except the T_ON\ pulse frequency is randomized over the range of 21.6 kHz to

35.23 kHz. In addition, ampliﬁer U7A randomly varies the output amplitude by 10%. The ECON–GAIN signal from the Control board changes the gain of U7A between 1 and 1.1.

Principles of Operation

Force FX-8C Service Manual 4-23

Power Supply/RF Board

To minimize ringing on the output voltage waveform at light loads, transistor Q7 switches in the 50 watt, 150 ohm heat sink mounted resistor in series with the transformer primary for part of the RF switching cycle.

In the Desiccate coag mode, K2 is closed and K14 is open. The T_ON\ signal is a continuous pulse train with a pulse width of 2 µs and a frequency of 39 kHz. The output resonates with a frequency of 308 kHz.

Output Relays

In all monopolar modes, K13 is closed and routes patient return current through the Patient Return Electrode receptacle. K15 routes active current through the Monopolar 1/CEM Instrument receptacle. K16 routes the active current through the Monopolar 2 Instrument receptacle.

In bipolar mode, the Patient Return Electrode receptacle relay is open. Relays K12 and K17 route bipolar current to the Bipolar Instrument receptacle.

All output relays are open when the generator is not being activated.

Spark Control Circuit

The spark control uses the voltage sense circuit to monitor the output voltage. It interrupts the delivery of power if the output voltage exceeds a preset threshold. This greatly reduces sparking when an activated accessory is removed from tissue. The sparking occurs because the RF stage tuning results in a higher natural gain at light loads than at heavy loads. Thus, during sudden transitions from heavy to light loads, the output voltage rises faster than the microcontroller can respond. This analog circuit works outside the microcontroller loop at a much greater speed.

The rectiﬁed but unﬁltered waveform from the output voltage sense circuit is fed into a peak detector (U23A, CR29, and C104). A high impedance buffer (U23B) maintains the integrity of the peak detected signal. The output of this buffer is divided and fed to a comparator. The other input to the comparator is an analog threshold level (VMAX_CLP) that is set by the main microcontroller on the Control board and depends on the mode and power setting.

When the peak detected sample of the output voltage exceeds the threshold, one-shot U14A is ﬁred and generates a 3 ms pulse (SPARK_CON) that is sent to the T_ON ASIC on the Control board. This pulse is ignored if it occurs during the ﬁrst 0.2 seconds of activation. Otherwise, SPARK_CON causes the T_ON\ signal to stop. The feedback microcontroller on the Control board senses this and realizes that a spark has been suppressed. The feedback microcontroller waits 100 ms in Pure cut, then re-initiates T_ON\ with a frequency of 470 kHz. The frequency returns to 394 kHz after 1 second of continuous activation or when the generator is reactivated.

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Power Supply/RF Board

RF Leakage Reduction Circuit

Fulgurate and Spray Coag Modes

For the Fulgurate and Spray coag modes, the high voltage RF output pulse repetition period varies with changes in spark and patient tissue impedance to limit the RF leakage current to a desired level. The VSENSE signal is obtained from the divider (R58, R25) located on the primary side of T4. VSENSE is input to a negative peak detector (U24A) that generates the analog signal (VPEAK–). Then U25A ampliﬁes and inverts the signal.

The averaged signal (now called VPK+) is input to the feedback microcontroller on the Control board and added to the ECON value at the selected power setting. The sum of these signals, with the proper gain factors, varies linearly with load impedance at the patient site. This sum is input into a pulse width modulator that sends its output (WAK\) to a NAND gate. Thus, the T_ON\ signal is inhibited for up to four consecutive cycles. Without the leakage control, the pulse repetition period is 17 µs. With the leakage control fully activated, the total pulse train repeats every 84 µs with a maximum dead time of 60% or 51 µs.

REM Circuit

Components U17 along with R95, R96, R97, and C79 form a precision oscillator. R96 is adjusted for the frequency that will produce maximum voltage amplitude (80 ± 10 kHz) at the REM connector (J17). R98 is a temperature compensating thermocouple that cancels temperature drift from the components forming the oscillator.

The REM transformer (T10) provides isolated reﬂected impedance sensing for tissue impedance across the REM patient return electrode terminals (connected to J17, pins 1 and 2). In addition to tuning the REM circuit, capacitors C155, C156, C169, and C170 provide a return path for high frequency RF signals through C157 to the RF output transformer. The REM transformer (T10) and capacitors C155, C156, C169, and C170 form a resonant circuit with a nominal operating frequency of 80 kHz.

Pin 1 of T10 clocks the active synchronous rectiﬁer formed by CMOS switch U28A. This device is closed during the positive period of the REM_AC signal and open during the negative period. When the switch is closed, C122 is charged to the peak positive value of REM_AC. Then, U31B ampliﬁes, ﬁlters and buffers the charge on C122 to produce the R_SEN signal. The microcontrollers monitor the R_SEN signal (which is a DC voltage proportional to impedance) to determine the patient return electrode status.

Principles of Operation

IsoBloc Circuit

The IsoBloc circuit provides a means of detecting a switch closure in an output accessory while maintaining electrical isolation between the generator output and ground referenced circuitry. The IsoBloc circuit consists of an isolated DC power supply, a comparator to detect switch closure, and an optoisolator link from the output connected circuitry to

Force FX-8C Service Manual 4-25

Power Supply/RF Board

the ground referenced low voltage circuitry. Each handswitching output of the generator is associated with its own IsoBloc power source and isolated signal paths.

Oscillator

The oscillator circuit consists of a 4060 CMOS oscillator/divider (U30) using a 5 MHz ceramic resonator (XT1) as the frequency determining element. The output of the oscillator is connected internally to the input of a counter/divider chain. The output of the divider yields a 78.125 kHz square wave that is applied to the input of three 4081 buffers (U29).

Power Supply

The three 4081 buffers (U29) drive three VN0808L FETs connected to transformers which are operated in a quasi-resonant ﬂyback mode with their associated 6800 pF capacitors. The voltages at the secondaries of the three transformers are half-wave rectiﬁed and referenced to three separate isolated grounds to provide -8 V for operating the isolated activation circuitry.

Optoisolators

The isolated power supply voltages produced by the IsoBloc power supplies are connected to the active output terminals of the generator. Handswitch activation is accomplished by sensing active to CUT or active to COAG switch closure in a handheld accessory. Switch closure is detected by comparing the voltage across the switch to a divider reference with comparators U32, U33, and U34. Current limiting resistors, in series with the LEDs in the optoisolators, cause the LEDs to light. The phototransistor in the optoisolator detects this light. The phototransistor, which is connected to an input on the 82C55 expansion port in the main microcontroller circuit, turns on, pulling the associated input low. This is interpreted by the software as an activation request, and the generator is activated accordingly.

Temperature Sense Circuits

The Force FX-8C generator features two temperature sense circuits. The ﬁrst temperature sense circuit measures the air temperature adjacent

to the RF output FET heat sink. When the temperature at this location reaches approximately 40° C, a cooling fan switches on to minimize heat buildup. The fan switches off when the temperature drops below approximately 35° C.

The second temperature sense circuit measures the air temperature near the Control board, which is located in the forward third of the generator enclosure. When this temperature reaches approximately 50° C, the main microcontroller ﬂashes number 451 alternately with the power settings to indicate that the generator is too hot. Generator operation reverts to normal when the temperature decreases to below 40° C.

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Power Supply/RF Board

Thermal Sensing (Fan Control)

A reference voltage is applied to the noninverting input of comparator U2A. Resistors R15 and R16 determine the reference voltage. When the temperature of NTC thermistor R19 is 40° C, the reference voltage is set to be equal to the voltage at the inverting input of U2A. Resistor R10 provides positive feedback causing approximately 5° C of hysteresis.

At temperatures below 40° C, the output of U2A is low. When the thermistor exceeds the threshold, the voltage comparator changes state causing the output at U2A to go high, turning on FET Q2. This applies 12 V to the cooling fan. When the temperature drops to 35° C, the circuit reverts to its low temperature state, and the cooling fan switches off.

Thermal Sensing (High Temperature Limit)

A reference voltage is applied to the non-inverting input of comparator U26A. Resistors R111 and R110 determine the reference voltage. When the temperature of NTC thermistor R109 is 50° C, the reference voltage is set to be equal to the voltage at the inverting input of U26A. Resistor R94 provides positive feedback causing approximately 10° C of hysteresis.

When the thermistor exceeds the threshold, the voltage comparator changes state, causing the output at U26A to go high. The main microcontroller reads this signal (TEMP_HI) and ﬂashes number 451 alternately with the power settings. When the temperature drops to 40° C, the circuit reverts to its low temperature state, and the generator allows activation for an unlimited duration.

Force FX-8C Service Manual 4-27

Principles of Operation

Notes

4-28 Force FX-8C Service Manual

SECTION

5Setup, Tests, and Adjustments

After unpacking or after servicing the Force FX-8C generator, set it up and verify that it functions correctly.

If the generator does not satisfactorily complete the self-test, calibrate it to ensure its accuracy.

Force FX-8C Service Manual 5-1

Setting Up the Generator

Electric Shock Hazard Connect the generator power cord to a properly grounded receptacle. Do not use power plug adapters.

Fire Hazard Do not use extension cords.

Provide as much distance as possible between the electrosurgical generator and other electronic equipment (such as monitors). An activated electrosurgical generator may cause interference with them.

If required by local codes, connect the generator to the hospital equalization connector with an equipotential cable.

Warning

Caution

Notice

Connect the power cord to a wall outlet having the correct voltage. Otherwise product damage may result.

1. Verify the generator is off by pressing the power switch off (O).

2. Place the generator on a stable ﬂat surface, such as a table, platform, or

Valleylab cart. Carts with conductive wheels are recommended. For details, refer to the procedures for your institution or to local codes.

Provide at least four to six inches of space from the sides and top of the generator for cooling. Normally, the top, sides, and rear panel are warm when the generator is used continuously for extended periods of time.

Ensure that the generator rests securely on the cart or platform. The underside of the generator contains four rubber feet and additional holes that allow you to reposition the feet to ensure stability. Use a Phillips screwdriver to remove the rubber feet from the generator. Then, reinstall the feet in the preferred location.

3. According to the procedures used by your institution, connect an

equipotential grounding cable to the grounding lug on the rear panel of the generator. Then, connect the cable to earth ground.

4. Plug the generator power cord into the rear panel receptacle.

5. Plug the generator power cord into a grounded receptacle.

6. Turn on the generator by pressing the power switch on (|). Verify the

following:

• All visual indicators and displays on the front panel illuminate.

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Setting Up the Generator

Important

If the coag mode has been optionally changed to default to Desiccate or Spray, that corresponding indicator illuminates after the self-test is performed successfully.

• Activation tones sound to verify that the speaker is working properly.

If the self-test is successful, a tone sounds. Verify the following:

• Indicators above the default mode buttons (Standard bipolar, Pure cut, and Fulgurate coag) illuminate green.

• Each display shows a power setting of one watt.

• The REM Alarm indicator illuminates red.

If the self-test is not successful, an alarm tone sounds. A number may momentarily appear in the Cut display and, in most cases, the generator is disabled. Note the number and refer to Responding to System Alarms in Section 6.

Setup, Tests, and Adjustments

Force FX-8C Service Manual 5-3

Setting Up the Generator

Figure 5-1.

Bipolar or macrobipolar connections—footswitch activation and a handswitching or footswitching instrument

Connections for Bipolar or Macrobipolar Surgery

If you plan to use a footswitching bipolar instrument, you must connect a bipolar footswitch. You may also use a footswitch to activate a handswitching instrument.

Warning

Electric Shock Hazard

• Do not connect wet accessories to the generator.

• Ensure that all accessories and adapters are correctly connected and that no

metal is exposed.

Caution

Accessories must be connected to the proper receptacle type. In particular, bipolar accessories must be connected to the Bipolar receptacle only. Improper connection may result in inadvertent generator activation or a REM Contact Quality Monitor alarm.

Footswitching or handswitching instrument

Bipolar footswitch

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Setting Up the Generator

Figure 5-2.

Bipolar or macrobipolar connection— handswitching instrument

Setup, Tests, and Adjustments

Handswitching instrument

Setting the Bipolar Output

Caution

Set power levels to the lowest setting before testing an accessory.

1. (Optional) To display the previous settings, press the Recall button.

2. To set the Bipolar mode, press the Precise, Standard, or Macro button.

The corresponding indicator illuminates green.

3. To increase the power for the selected mode, press the white up arrow

( ∆ ) button. To decrease the power, press the white down arrow ( ∇ ) button. The maximum power setting is 70 watts.

Force FX-8C Service Manual 5-5

Setting Up the Generator

Figure 5-3.

Monopolar connection—footswitch activation and a footswitching or handswitching instrument using Monopolar 1 Footswitch receptacle and Monopolar 1/CEM Instrument receptacle

Connections for Monopolar Surgery

If you plan to use a footswitching monopolar instrument, you must connect a monopolar footswitch. You may also use a footswitch to activate a handswitching instrument or a CUSA handpiece with CEM nosecone.

Warning

Electric Shock Hazard

• Do not connect wet accessories to the generator.

• Ensure that all accessories and adapters are correctly connected and that no

metal is exposed.

Footswitching or handswitching instrument

Monopolar footswitch

Patient return electrode

5-6 Force FX-8C Service Manual

Setting Up the Generator

Figure 5-4.

Monopolar connection—footswitch activation and a footswitching or handswitching instrument using Monopolar 2 Footswitch receptacle and Monopolar 2 Instrument receptacle

Figure 5-5.

Monopolar connection—handswitch activation and a monopolar handswitching instrument using either Monopolar Instrument receptacle

Setup, Tests, and Adjustments

Footswitching or handswitching instrument

Monopolar footswitch

Patient return electrode

Handswitching instrument

Patient return electrode

Force FX-8C Service Manual 5-7

Setting Up the Generator

Selecting Cut and Coag Modes

Caution

Set power levels to the lowest setting before testing an accessory.

1. (Optional) To display the previous settings, press the Recall button.

2. To select a cut mode, press the Low, Pure, or Blend button. The

corresponding indicator illuminates green.

3. To increase the power for the cut mode you selected, press the yellow up

arrow ( ∆ ) button. To decrease the power, press the yellow down arrow ( ∇ ) button. The maximum power setting for Low and Pure is 300 watts. The maximum power setting for Blend is 200 watts.

4. To select a coag mode, press the Low (Desiccate), Med (Fulgurate), or

High (Spray) button. The corresponding indicator illuminates green. To select the LCF Fulgurate mode, press the Med button and hold for

two seconds. A tone sounds and an "L" appears on the left side of the Coag display. To return to the standard Fulgurate mode, press the Med button and hold for two seconds. A tone sounds and the "L" disappears from the left side of the Coag display.

5. To increase the power for the selected coag mode, press the blue up arrow

( ∆ ) button. To decrease the power, press the blue down arrow ( ∇ ) button. The maximum power setting for each coag mode is 120 watts.

In the LCF Fulgurate mode, an "L" appears on the left side of the Coag display. When the LCF Fulgurate power setting is above 95 watts, the power setting display alternates between the power setting (for example, 110 watts) and "L--".

Simultaneous Coag

Connect two monopolar instruments for simultaneous coag. Each receives a percentage of the overall power setting. The amount of power provided to each instrument depends on the tissue resistance sensed by the generator at each surgical site. Generally, the site with lower resistance receives proportionately more power. The combined total output power does not exceed the overall power setting for the coag mode selected.

5-8 Force FX-8C Service Manual

Setting Up the Generator

Figure 5-6.

Connections for simultaneous coag— two handswitching instruments

Figure 5-7.

Connection for simultaneous coag— two footswitching instruments

Setup, Tests, and Adjustments

Monopolar instrument or CUSA handpiece with CEM nosecone

Patient return electrode

Monopolar instrument

Monopolar instrument or CUSA handpiece with CEM nosecone

Patient return electrode

Monopolar instrument

Monopolar footswitches

Using Two Generators Simultaneously

Caution

Two generators (and two patient return electrodes) may be used simultaneously on the same patient, provided the generators are the same type (both are isolated or both are ground referenced). However, the two

Force FX-8C Service Manual 5-9

Setting Up the Generator

Figure 5-8.

Connections for combined monopolar/ultrasonic surgery

generators are not synchronized. One return electrode frequently acquires a high positive voltage while the other acquires an opposite negative voltage. When this occurs, the potential voltage difference between them may cause the current to ﬂow from one patient return electrode to the other. The current causes no harm if it produces no sparks or high current densities on the patient.

Place each patient return electrode as close as possible to the site of the surgery to be performed by the generator to which it is connected. Ensure that the two patient return electrodes do not touch.

Connecting the CUSA Handpiece with CEM Nosecone

Warning

Electric Shock Hazard

• Do not connect wet accessories to the generator.

• Ensure that all accessories and adapters are correctly connected and that no

metal is exposed.

CEM indicator illuminates green

If you choose to use a monopolar footswitch, you must connect it to the Monopolar 1 Footswitch

CUSA handpiece with CEM nosecone

Patient return electrode

Connect to CUSA system

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Setting Up the Generator

Setting the Output Power

Caution

Set power levels to the lowest setting before testing an accessory.

When you use the CUSA handpiece with CEM nosecone for ultrasonic electrosurgery, only Low cut or Desiccate 1 coag are available when you activate the handpiece.

To verify or change the Low cut power setting:

To increase the power, press the yellow up arrow ( ∆ ) button. To decrease the power, press the yellow down arrow ( ∇ ) button. The maximum cut power is 100 watts.

To verify or change the Desiccate 1 coag power setting:

To increase the power, press the blue up arrow ( ∆ ) button. To decrease the power, press the blue down arrow ( ∇ ) button. The maximum coag power is 70 watts.

Simultaneous Coag with a CUSA System

To use a CUSA handpiece with CEM nosecone for simultaneous coag, connect the handpiece to the Monopolar 1/CEM Instrument receptacle. Then connect a monopolar instrument to the Monopolar 2 Instrument receptacle. During simultaneous coag, only Desiccate coag is available; the maximum power is limited to 70 watts.

Setup, Tests, and Adjustments

Changing the Mode

Verify the selected mode with the surgeon. You cannot change the mode while the generator is activated.

To change the mode, press the desired bipolar, cut, or coag mode button. The indicator above that button illuminates green. You can activate only one mode at a time.

When you change modes within a function (bipolar, cut, coag), the power setting remains the same unless it exceeds the maximum for the new mode. In that case, it reverts to the maximum for the new mode. For example, if you set the power to 250 watts for Pure cut, when you select Blend, the power setting changes to 200 watts, the maximum for Blend. If, however, you set the power to 65 watts in Desiccate, when you select Fulgurate, the power setting does not change because it falls within that mode’s range.

Changing the Power Setting

Verify the power settings for the selected mode with the surgeon. You can change the power setting when the generator is on, including when it is activated.

To increase the power, press the up arrow (∆) button for the selected mode.

Force FX-8C Service Manual 5-11

Setting Up the Generator

To decrease the power, press the down arrow (∇) button for the selected mode.

When you press and release the power button, the power changes by one setting (1, 5, or 10 watts), based on the settings available for the selected mode. The available power settings are listed in Section 3, Technical Speciﬁcations.

To reach the maximum or minimum power setting for the selected mode, press and hold the up arrow (∆) or down arrow (∇) button. The setting changes slowly at ﬁrst, then more rapidly. Release the button when the desired setting is displayed. If you try to set the power above the maximum setting or below the minimum setting for the selected mode, a tone sounds.

Activating the Surgical Instrument

Notice

Do not activate the generator until the forceps have made contact with the patient. Product damage may occur.

To activate a handswitching instrument, use the controls on the instrument or on the appropriate footswitch. To activate a footswitching instrument, you must use a footswitch.

To reduce the possibility of alternate site burns that may be caused by RF leakage currents, avoid unnecessary and prolonged activation of the generator.

If you use bipolar output when a return electrode is applied to the patient, the return electrode circuit is deactivated automatically to eliminate the possibility of current dispersal.

Table 5-1. Activation Indicators

Handswitching Footswitching Activation Indicator

Bipolar Close forceps tines ﬁrmly Press pedal Activation tone sounds – Bipolar

indicator illuminates blue

Monopolar Press Cut or Coag button

or Close forceps tines ﬁrmly

CUSA handpiece with CEM nosecone

Press Cut or Coag button on CEM nosecone

Press Cut or Coag pedal Activation tone sounds – Cut indicator

illuminates yellow or Coag indicator illuminates blue

Press Cut or Coag pedal Activation tone sounds – Cut indicator

illuminates yellow or Coag indicator illuminates blue – CEM indicator on front panel illuminates green when handpiece is properly connected

5-12 Force FX-8C Service Manual

Periodic Safety Check

Important

When testing RF equipment, follow these test procedures to duplicate manufacturer test data. Keep test leads to the minimum length usable; lead inductance and stray capacitance can adversely affect readings. Carefully select suitable ground points to avoid ground loop error in measurements.

The accuracy of most RF instruments is approximately 1–5% of full scale. Using uncompensated scope probes causes large errors when measuring high voltage RF waveforms.

Setup, Tests, and Adjustments

Perform the following safety check every six months to verify that the generator is functioning properly. Record the test results for reference in future tests. If the generator fails to meet any of the checks, refer to Section 6, Troubleshooting.

Warning

Electric Shock Hazard When taking measurements or troubleshooting the generator, take appropriate precautions, such as using isolated tools and equipment, using the “one hand rule,” etc.

Electric Shock Hazard Do not touch any exposed wiring or conductive surfaces while the generator is disassembled and energized. Never wear a grounding strap when working on an energized generator.

Caution

Here is a summary of safety checks:

• Inspect the generator and accessories

• Inspect the internal components

• Test the generator

• Verify REM function

• Conﬁrm outputs

• Check leakage current and ground resistance.

Recommended Test Equipment

• Digital voltmeter—Fluke 77 or 87, or equivalent

• True RMS voltmeter—Fluke 8920, or equivalent

• Oscilloscope—Tektronix 2445, or equivalent

• Leakage current tester—Use UL load device or commercially available leakage tester

• Leakage table—per IEC 601-2-2, Figure 104

• 100, 200, 300, 500 ohm, all 250 watt, 1% tolerance, noninductive (Dale NH-250 or equivalent).

Force FX-8C Service Manual 5-13

Periodic Safety Check

Inspecting the Generator and Accessories

Equipment required:

• Bipolar footswitch or monopolar footswitch

• Bipolar instrument cords (handswitching and footswitching)

• Monopolar instrument cords (handswitching and footswitching). Turn off the generator, and disconnect the power cord from the wall

receptacle.

Rear Panel

1. Check the rear panel footswitch receptacles for obstructions or

damage. Check for a secure ﬁt by inserting the bipolar footswitch or monopolar footswitch connector into the appropriate receptacle.

2. Remove the fuse and verify correct voltage and current rating. Refer to

Performance Characteristics in Section 3.

If either connection is loose, replace the footswitch board assembly. Refer to Footswitch Board Replacement in Section 7.

Front Panel

1. Check the Footswitch receptacle for obstructions or damage. Check for

a secure ﬁt by inserting the monopolar footswitch connector into the receptacle.

If the connection is loose, replace the receptacle. Refer to Front Panel Footswitch Receptacle Replacement in Section 7.

2. Check the Bipolar Instrument receptacle for obstructions or damage.

Insert the bipolar instrument connector (footswitching and handswitching) into the appropriate receptacle to verify a secure ﬁt.

If the connection is loose, replace the front panel assembly. Refer to Front Panel Replacement in Section 7.

3. Check the monopolar instrument receptacles for obstructions or

damage. Insert the monopolar instrument connector (footswitching and handswitching) into the appropriate receptacle to verify a secure ﬁt.

If any of the connections are loose, replace the front panel assembly. Refer to Front Panel Replacement in Section 7.

4. Check the Patient Return Electrode receptacle for a broken pin or an

obstruction. If the receptacle is damaged or obstructed, replace the front panel assembly. Refer to Front Panel Replacement in Section 7.

5-14 Force FX-8C Service Manual

Periodic Safety Check

Footswitch

1. Remove the footswitch from the generator.

2. Disassemble the footswitch connector. Inspect the connector for

damage or corrosion.

3. Reassemble the footswitch connector.

4. Inspect the footswitch for damage.

5. Reconnect the footswitch to the generator.

Power Cord

1. Remove the power cord from the unit and ensure that it is unplugged

from the wall receptacle.

2. Inspect the power cord for damage.

3. Reconnect the power cord to the generator and wall receptacle.

Inspecting the Internal Components

Equipment required:

• Phillips screwdriver.

Setup, Tests, and Adjustments

Caution

1. Turn off the generator.

2. Loosen the ﬁve screws that secure the cover to the chassis. Lift the

cover off the chassis. Set the cover aside for reinstallation.

3. Verify that all connectors are ﬁrmly seated.

4. Inspect each board for damaged components, wires, cracks, and

corrosion.

• If you ﬁnd evidence of damage on the Control board, Display

board, or Footswitch board, replace the board. Refer to Control

Board Replacement, Display Board Replacement, or Footswitch Board Replacement in Section 7.

• If you ﬁnd evidence of damage on the Power Supply/RF board,

replace the board only if the damage is severe. Refer to Power Supply/RF Board Replacement in Section 7.

5. Reinstall the cover on the generator. Position the cover above the

chassis and slide it down. Tighten the ﬁve screws that secure the cover to the chassis.

Force FX-8C Service Manual 5-15

Periodic Safety Check

Important

If the coag mode has been optionally changed to default to Desiccate or Spray, that corresponding indicator illuminates after the self-test is performed successfully

Testing the Generator

Turning on the generator initiates an internal self-test to verify the calibration. The self-test also checks the operation of the speaker, all indicators, and the displays.

Warning

Use the generator only if the self-test has been completed as described. Otherwise, inaccurate power outputs may result.

1. Turn on the generator by pressing the front panel On (|) switch. Verify

the following:

• All visual indicators and displays on the front panel illuminate.

• Activation tones sound to verify that the speaker is working properly.

If the self-test is successful, a tone sounds. Verify the following:

• Indicators above the default mode buttons (Standard bipolar, Pure cut, and Fulgurate coag) illuminate green.

• Each display shows a power setting of one watt.

• The REM Alarm indicator illuminates red.

If you removed and/or replaced the battery, alarm number 212 may appear in the Cut display when you turn on the generator. If this happens, calibrate the generator.

5-16 Force FX-8C Service Manual

Valleylab Force FX-8C User manual

Specifications and Main Features

Frequently Asked Questions

User Manual