Valleylab Force 4 User manual

FORCE 4

SERVICE MANUAL

110V

EFFECTIVITY DATE: May 1, 1985

VALLEYLAB PART NUMBER A 945 100 054 A

PRINTED IN USA

VALLEYLAB, INC. 5920 LONGBOW DRIVE, P.O. BOX 9015, BOULDER, COLORADO 80301

303 530-2300

TWX 910-940-2514

TABLE OF CONTENTS

SECTION PAGE

1.	INTRODUCTION	1
2.	INSTALLATION	2
3.	DESCRIPTION OF CONTROLS & INDICATORS	4
4.	MONOPOLAR AND BIPOLAR ELECTROSURGICAL	13
	CONFIGURATIONS AND ACCESSORIES
5.	TECHNICAL SPECIFICATIONS	15
6.	CIRCUIT DESCRIPTION	21
7.	TESTING PROCEDURE	43
8.	TROUBLESHOOTING	50
9.	ASSEMBLIES AND SCHEMATICS	76
10.	PARTS LIST	116
11.	WARRANTY	135

LIST OF ILLUSTRATIONS

FIGURE	PAGE

1	FORCE 4 INDICATORS AND OUTPUTS ON FRONT PANEL			4
2	FORCE 4 CONTROL KEYBOARD ON FRONT PANEL			8
3	FORCE 4 REAR PANEL CONTROLS AND CONNECTORS			11
4	OUTPUT POWER VS LOAD -		MONOPOLAR	18
5	OUTPUT POWER VS LOAD -		BIPOLAR	19
6	OUTPUT VOLTAGE VS CONTROL SETTING			20
7	BLOCK DIAGRAM -	BIPOLAR STAGE		27
8	TIMING WAVEFORMS	- CLOCK/CONTROL BOARD		35
9	BLOCK DIAGRAM -	CONTROL MODULE		36
10	OUTPUT POWER SUPPLY TIMING DIAGRAM			41
11	FORCE 4 BLOCK SCHEMATIC			42
12	MONOPOLAR OUTPUT WAVEFORMS			68
13	BIPOLAR OUTPUT WAVEFORMS			70
14	TROUBLESHOOTING WAVEFORMS			72
15	FORCE 4 COMPONENT/CONNECTOR LOCATIONS-TOP VIEW			77
16	FORCE 4 COMPONENT/CONNECTOR LOCATIONS-SIDE VIEW			78
17	SYSTEM INTERCONNECT SCHEMATIC			98
18	PCB INTERCONNECT LIST			80
19/20	CPU BOARD ASSEMBLY/SCHEMATIC			81
21/22	OUTPUT BOARD ASSEEMBLY/SCHEMATIC			84
23/24	INTERFACE BOARD ASSEMBLY/SCHEMATIC			86
25/26	BIPOLAR OUTPUT BOARD ASSEMBLY/SCHEMATIC			88
27/28	BIPOLAR CONTROLLER BOARD ASSEMBLY/SCHEMATIC			90
29/30	CLOCK/CONTROL BOARD ASSEMBLY/SCHEMATIC			92
31/32	SENSE BOARD ASSEMBLY/SCHEMATIC			94
33/34	DRIVER BOARD ASSEMBLY/SCHEMATIC			96
35/36	STRIPLINE BOARD ASSEMBLY/SCHEMATIC			98
37/38	MONOPOLAR DISPLAY BOARD ASSEMBLY/SCHEMATIC			100
39/40	BIPOLAR DISPLAY BOARD ASSEMBLY/SCHEMATIC			102
41/42	SPEAKER BOARD ASSEMBLY/SCHEMATIC			104
43/44	POWER SUPPLY OUTPUT BOARD ASSEMBLY/SCHEMATIC			106
45/46	POWER SUPPLY CONTROLLER BOARD ASSEMBLY/SCHEMATIC			108
47/48	MONOPOLAR KEYBOARD/SCHEMATIC			110
49/50	BIPOLAR KEYBOARD/SCHEMATIC			112
51/52	POWER SUPPLY MODULE/SCHEMATIC			114
LIST OF TABLES
TABLE				PAGE
	INPUT & OUTPUT LINES -		BIPOLAR CONTROL	29
	SIGNALS ON CPU BOARD			32

11

SECTION 1

INTRODUCTION

This Service Manual covers the installation and basic service instructions for the Valleylab Model FORCE 4 Electrosurgical Generator. Also included are sections covering the Technical Specifications, Circuit Descriptions and the Testing and Troubleshooting of the Generator. Detailed instructions in the use of electrosurgery is beyond the scope of this manual and the reader is directed to the Operator's Instruction Manual provided by Valleylab.

Valleylab, its dealers and representatives reserve the right to make changes in equipment built and/or sold by them at any time without incurring any obligation to make the same or similar changes on equipment previously built

and/or sold by them.

SECTION 2

INSTALLATION

INSTALLING THE FORCE 4

The compact size of the FORCE 4 system allows a variety of installations. The unit may be placed on the mounting cart available from Valleylab, or on any

convenient and sturdy table or cart.

At high power settings considerable power is dissipated within the unit and it is important that the vents on the rear and sides remain unobstructed for proper cooling. For this reason the FORCE 4 should not be installed in a closely fitting cabinet or cart which might restrict the free circulation of air. Under continuous use for extended periods of time, it is normal for the

top and rear panel to feel warm to the touch.

POWER FOR THE FORCE 4

90 - 140 VAC, 50 - 60 Hz

The FORCE 4 is designed to operate over an unusually wide range of input voltages with essentially perfect output regulation. This means that in case of brownouts or power surges the output of the FORCE 4 will always remain constant. The FORCE 4 is normally supplied for operation on 120 volts AC

(nominal).

PROPER GROUNDING

An important consideration in assuring patient safety while using electrical equipment is proper grounding. The ground wire in the power cable is connected to the generator chassis and insures that no dangerous currents will flow from the cabinet of the unit in the event of an internal electrical

failure.

Undesirable 60 Hz leakage currents are also affected by the polarization of the input 60 Hz power to the unit. It is the responsibility of the user to assure proper grounding and polarity in the power outlets furnishing power to

the FORCE 4.

POWER PLUGS FOR THE FORCE 4

Unless an explosion-proof connector is specified, the 110 volt FORCE 4 is equipped with an approved hospital duty three-prong connector. This connector meets all requirements for safe grounding. Its purpose should not be defeated by using extension cords or 3-prong to 2-prong adapters. The connector should be periodically disassembled and inspected by qualified maintenance personnel.

220 volt AC versions of the FORCE 4 are shipped with a standard U.S.A. 220

volt	tandem blade connector of equivalent quality and construction to the
Hospital Grade 110 volt connector. At present			there are no Hospital				Grade	220
volt	connectors and we do not have	access	to	all	the	various	220	volt
connectors used in other countries.		The Valleylab			representative		in	your
country will equip your FORCE 4 with		the proper		connector		for your	operating

room .

ROUTINE MAINTENANCE AND INSPECTIONS

The solid-state design of the FORCE 4 assures virtually maintenance-free use.

Maintenance is limited to periodic inspections. Repair should be limited to repairing cords and replacing accessories. Should breakage or wear occur to the cord it should be replaced. Proper handling will minimize repair and replacement problems. Cords should always be grasped by the plugs. DO NOT

PULL ON THE CORD ITSELF.

We recommend that the FORCE 4 be inspected by the hospital engineer twice a year. This Service Manual describes the recommended inspection and check-out procedures. For major repairs the FORCE 4 can be returned to Valleylab or your Valleylab representative. If desired, Valleylab will supply any parts or

information needed to repair the FORCE 4.

SECTION 3

DESCRIPTION OF CONTROLS AND INDICATORS

6)(16H9Y8)(7b) (11) (10

mrumi <

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com rawcii

iTVW
• •	•
ACCCSSORT	ITCH	s2	2
MICR08IPOU R	MONOPOLAR

1,2 Microbipolar Power

4,5 Monopolar Power - Cut

6-9 Alarm and Mode Indicators

10,11 Monopolar Power - Coag

12 REM connector

13,14 Monopolar Output Jacks

3 Bipolar Output Jacks

15Audio Volume

16Remote Power Change Indicator

FIGURE 1

THE FORCE 4 INDICATORS AND OUTPUTS ON THE FRONT PANEL

A. FRONT PANEL INDICATORS AND OUTPUTS (SEE FIG. 1)

1. BIPOLAR OUTPUT ACTIVE INDICATOR

The word 'WATTS' will be illuminated when useful output power is available at the Microbipolar Output Jack (3). Absence of illumination when the generator is keyed in the bipolar mode may indicate generator malfunction.

2. BIPOLAR POWER READOUT

This digital LED display is visible when the generator is in the ready mode (2, Fig. 2). The number displayed predicts the level of bipolar power, in watts, which will be delivered to a 100 ohm load when the

generator is keyed in the bipolar mode.

3. BIPOLAR ACTIVE RECEPTACLE

This receptacle will accept the three prong active bipolar accessories and will be keyed by the handswitch. It will also accept two prong active accessories and the bipolar generator is then keyed by the foot switch when the bipolar foot switch button, (18, Fig. 2), is pressed.

4. MONOPOLAR CUT OUTPUT ACTIVE INDICATOR

The backlit word 'WATTS' will be visible when the generator is keyed in the cut mode and useful output power is available at either of the monopolar output jacks (13) and (14). Absence of illumination when the generator is keyed indicates a malfunction.

5. MONOPOLAR CUT POWER READOUT

This digital LED display is visible when the generator is in the ready mode (2, Fig. 2). The number displayed predicts the level of monopolar cut power, in watts, which will be delivered to a 300 ohm load when the generator is keyed in the monopolar cut mode.

6. ALERT INDICATOR

This LED lamp is on whenever the generator is disabled by an alarm condition. The audio alarm will sound twice when this lamp goes on.

7. MODE INDICATOR LAMPS

A. One of four CUT mode indicators is illuminated to show the CUT power waveform. The mode may be changed by pressing one of the four mode selector push buttons (9,10,11,12; Fig. 2)

Pure:		750 kHz sinusoid
Blend 1:		50% duty	cycle,	750 kHz	sinusoid
Blend	2:	25% duty cycle,		750 kHz	sinusoid
Blend	3:	25% duty	cycle,	750 kHz sinusoid plus inductive discharge

pulses.

B. One of two COAG mode indicators is illuminated to show the COAG power

waveform. Select by pushing one of the mode selector push buttons

(15,16; Fig. 3)

SPRAY COAG: 31 kHz inductive discharge

SOFT COAG: 22 kHz inductive discharge

C. One of two bipolar power mode indicators is illuminated to show the bipolar output power versus load impedance characteristics. Selection is by the push buttons (5,6; Fig. 2).

STANDARD: Output power at 50 and 200 ohm loads is 1/2 of the power at a

100 ohm load.

PRECISE: Output power at a 200 ohm load is 1/4 of the 100 ohm output

power.

8. RETURN FAULT INDICATOR

This LED illuminates if the FORCE 4 is keyed without a proper patient electrode connection, producing a situation where a significant proportion

of the RF current returns to the generator by some path other than the

patient connector ( 12 ). The FORCE 4 is disabled so long as the indicator

is on. The audio alarm will sound twice when the alert is first detected.

The alarm can be cleared by releasing the hand or footswitch and then

rekeying	the unit.	•
9. REM FAULT	INDICATOR	(Return Electrode Monitor)

This LED illuminates when the patient electrode contact monitor senses an

alarm condition. For a single-section patient electrode the alarm condition is a resistance greater than 16 ohms between the pins of the

patient electrode connector			( 12	).	For a dual-section	patient		electrode
the	alarm condition is a resistance outside the range of					5 - 135 ohms or a
30%	increase in	resistance.	The audio alarm will sound				twice	when	the
alarm is first		detected.	The	alarm	is cleared when	the	resistance		is

lowered and is within the acceptance range.

10. MONOPOLAR COAG OUTPUT ACTIVE INDICATOR

The backlit word 'WATTS" will be visible when the generator is keyed in the coagulation mode and useful output power is available at either of the monopolar output jacks (13) and (14). Absence of illumination when the

generator is keyed may indicate a malfunction.

12. MONOPOLAR COAGULATION POWER READOUT

This digital LED display is visible when the generator is in the ready mode (2, Fig. 2). The number displayed predicts the level of monopolar coagulation power, in watts, which will be delivered to a 300 ohm load

when the generator is keyed in the monopolar coagulation mode.

12.PATIENT RETURN ELECTRODE RECEPTACLE

This 2 pin receptacle accepts the patient return electrode connector used

in monopolar procedures.

A pin on the patient electrode connector

actuates a switch within the receptacle to indicate the use of the dualsection patient electrode used for contact area (REM) monitoring.

13. MONOPOLAR ACTIVE RECEPTACLE - HAND OR FOOTSWITCH

This receptacle will accept three-prong handswitching active accessories

(Valleylab LectroSwitch) or standard one-prong active accessories. This output can be activated by the footswitch when the monopolar footswitch button (17, Fig. 2) is pressed or by the handswitching accessory. Cut mode or coagulation mode power may be keyed at this receptacle.

14. MONOPOLAR ACTIVE RECEPTACLE - HANDSWITCH

This receptacle will accept the three-prong handswitching active accessories. This output is activated only by the handswitch and will have no power available if the generator is keyed by the footswitch. Cut mode or coagulation mode power may be keyed at this receptacle.

15. AUDIO VOLUME CONTROL

The volume of the cut and coag audio tones produced when the generator is keyed may be adjusted with this 4-position slide switch. Pull the switch forward to increase the volume, push it back to decrease the volume. The volume of the 'bong' produced by alarm conditions is not adjustable.

16. REMOTE INDICATOR

This lamp will be illuminated and the audio will 'bong' once when the remote power change feature is activated at the handswitching accessory.

When the lamp is on, remote power changes can occur. The lamp is turned off by switching to standby (1, Fig. 3).

3-6 Bipolar Controls

7-12 Monopolar CUT controls

1,2 Standby, Ready Mode Selectors

17,18 Footswitch Keying Selectors

13,16 Monopolar COAG controls

FIGURE 2

THE SSE4 CONTROL KEYBOARD ON THE FRONT PANEL

8

B.FRONT PANEL KEYBOARD CONTROLS (SEE FIGURE 2)

1. STANDBY MODE SELECTOR

In this mode the generator cannot be keyed and the audio alerts are suppressed. Prior power level settings are retained but the displays will be blank. The generator is in standby when power is first applied.

2. READY MODE SELECTOR

Pressing this button places the generator in service with outputs and

alarms fully active.

3. BIPOLAR POWER INCREASE BUTTON

This button increases the bipolar power readout. A single push will raise the power by one watt. Holding the button down continuously will cause the display to increase continuously to 70 watts maximum.

4. BIPOLAR POWER DECREASE BUTTON

Pressing this button decreases the bipolar power display by one watt per push, or continuously if the button is held down.

5. STANDARD MODE SELECTOR

Pressing this button will select the Standard Bipolar mode.

6. PRECISE MODE SELECTOR

Pressing this button will select the Precise Bipolar mode.

7. MONOPOLAR CUT POWER INCREASE BUTTON

This button increases the monopolar cut power readout. A single push will increase the power by one watt, and holding the button down will increase

the display to the mode maximum.

8. MONOPOLAR CUT POWER DECREASE BUTTON

Pressing this button decreases the monopolar cut mode power display by one watt per push, or continuously if the button is held down.

9. CUT MODE SELECTOR - PURE CUT

Pressing this button will select a continuous sinewave cut waveform output.

10. CUT MODE SELECTOR - BLEND 1

Pressing this button will select a 50% duty cycle sinewave cut waveform

output.

11. CUT MODE SELECTOR - BLEND 2

Pressing	this	button	selects	a cut mode waveform of	25%	duty cycle
sinewave	for moderate hemostasis.
12. CUT MODE SELECTOR - BLEND 3
Pressing	this	button	selects a	cut mode output waveform	of	25% sinewave

plus inductive discharge. This is the cut waveform producing maximum

hemostasis.

13. MONOPOLAR COAGULATION POWER INCREASE BUTTON

This button increases the monopolar coagulation power display. A single push will raise the power by one watt, and holding the button down will

cause a continuous increase.

14. MONOPOLAR COAGULATION POWER DECREASE BUTTON

This button decreases the coagulation power display by one watt per push, or continuously when it is held down.

15. COAG MODE SELECTOR - SPRAY COAG

Pressing this button will select an inductive discharge with a 31 KHz repetition rate coagulation waveform.

16. COAG MODE SELECTOR - SOFT COAG

Pressing this button will select a coagulation waveform with inductive discharge at a lower repetition rate (22 KHz).

17. FOOTSWITCH SELECTOR - MONOPOLAR

Pressing this button places the monopolar output under footswitch keying

control .

18. FOOTSWITCH SELECTOR - BIPOLAR

Pressing this button places the bipolar output under footswitch control.

10

MONOPOLAR

FOOTSWITCH

21 21 A

0

©

BIPOLAR

FOOTSWITCH

Wiring Diagrams

A	footswitch			A	1
				D		/^"CT*\
				CUT /	COAG/
	D Ao	OU		f	f	AfOOV
C\o		OJ B		C		W	B	B"
				B
				^7 CASE
B	Monopolar Handswitch					DOWN
		^		r
ACTIVE					O-i
						in
		i	;
						i COAG
	COAG	=*<>		;REMOTE
	cut	=t^7			O-l.m		CUT
C	Bipolar			IPUR CHNG	UP.ACT1VATE
			JJandswitch L&C.CE5S.0B.Y			!
			o	ASWITCH			SWITCH
ACTIVE ( °				O jACTIVE
			°
				J SWITCH

FIGURE 3

THE FORCE 4 REAR PANEL CONTROLS AND CONNECTORS

1

Th CAS

ACTIVE

ACTIVE

ACTIVE

11

REAR PANEL CONTROLS AND CONNECTORS (SEE FIG. 3)

1. FOOTSWITCH RECEPTACLE-MONOPOLAR/BIPOLAR

This 4-pin	MS-type receptacle accepts the two-treadle footswitch
connector.	The wiring diagram is shown in Fig. 3.A.

2. POWER SWITCH

This power switch includes a circuit breaker. Press the toggle upward to apply power and down to shut power off.

3. POWER CORD

The line cord is terminated in a grounded 3-pin plug and should be connected to a properly phased, grounded receptacle.

4. FOOTSWITCH RECEPTACLE-BIPOLAR

This three-pin MS-type receptacle accepts the single-treadle footswitch

connector.

12

SECTION 4

MONOPOLAR AND BIPOLAR

ELBCTROSURGICAL CONFIGURATIONS

& ACCESSORIES

The FORCE 4 features three separate outputs which may be activated. Two of these outputs are used primarily in monopolar configurations. The MONOPOLAR

HANDSWITCH output is designed for use with either switching forceps or a switching pencil. The MONOPOLAR ACCESSORY output is designed for use with switching accessories or it can be activated by the footswitch. The third output is a reduced power BIPOLAR output which may be used with switching or nonswitching bipolar accessories and may he activated by either the switching accessory or by the footswitch.

MONOPOLAR CONFIGURATION

Monopolar Accessories

The FORCE	4 has a	radio frequency (RF) grounded	output.	In	monopolar
operation,	the radio	frequency current passes from	the active		accessory,

through the patient, and returns to the generator via a patient plate which contacts the patient's skin.

The Valleylab hand-switching accessories plug into the three banana pin jacks on either the "Handswitch" or "Accessory" receptacles. All three pins are

"active" since there are only low, switching voltages between the pins.

Models E4001 and E4002 coagulation forceps also plug into either monopolar receptacle. The standard active "accessory" jack will accept the plugs of most standard accessories directly or through an appropriate adapter. The footswitch then controls the current flow to the accessory. Both the Model

E6008 and E6009 footswitches are designed for operating room use and are connected to the FORCE 4 by means of a four-pin footswitch receptacle on the

back panel of the generator.

The E6008 footswitch pedals activate the

generator in CUT/BLEND or COAG as needed. The E6009 activates the Force 4 in

Bipolar only. The FORCE 4 has an override circuit to insure that only COAG is activated in the event that both pedals are pushed simultaneously. The FORCE 4 has an "intrinsically safe" footswitch circuit. This means that the switching currents are too low to cause a spark even in the most dangerous mixture of flammable gas and oxygen. To qualify as intrinsically safe, the spark energy which occurs at the switch contacts must be less than 1 millijoule. The energy present in the FORCE 4 switching circuits is about

1/5000 of the amount considered a conservative limit for safe, opencontact

operation.

The Patient Return Electrode

In a monopolar configuration, a return electrode is used to limit the current

densities to a safe level.

13

An accepted standard for gelled plate or foil electrodes is 1.5 watts per square centimeter of return electrode area or roughly 9 or 10 square inches per hundred watts of generator output. (NFPA Bulletin No. 76CM, Part II.)

A delicate procedure which uses low power settings requires only a few square inches. Gelled foam pad electrodes, and conductive adhesive electrodes such as Valleylab Model E7503, 5, 6, 7 have come into common usage and with proper adherance to manufacturer's instructions, they can be an effective and safe method of providing the return connection. The FORCE 4 is an RF grounded system with a return fault circuit which continuously monitors the flow of electrosurgical current in the patient circuit and the power distribution ground. The circuit prevents FORCE 4 operation if the proportion of current returning through ground is excessive and thus provides a high degree of safety from patient burns under common fault conditions.

BIPOLAR CONFIGURATION

Bipolar Accessories

The most common bipolar instruments are forceps, the jaws of which are connected to the BIPOLAR output jacks. In bipolar operation the current flow is limited to the tissue which is grasped by the jaws. The FORCE 4 BIPOLAR output operates at lower power levels than the MONOPOLAR output and has impedance characteristics optimized for desiccation. This means faster coagulation at a given power setting and an automatic reduction of output power when the coagulation is complete.

14

SECTION 5

FORCE 4 TECHNICAL SPECIFICATIONS

OUTPUT WAVEFORM

CUT	750 kHz sinusoid

BLEND 1 750 kHz bursts of sinusoid at 50% duty cycle recurring at 31 kHz.

BLEND 2 750 kHz bursts of sinusoid at 25% duty cycle recurring at 31 kHz.

BLEND 3

750 kHz

bursts

of

sinusoid at

25%

duty

cycle

plus

inductive

discharge

damped

sinusoidal

bursts,

all

bursts

recurring at

31

kHz. Power is adjusted so that the sinusoid bursts account for 75%

of the power into a 300 ohm load and the damped sinusoid bursts

account for the remainder.

SPRAY COAG

750 kHz

damped

sinusoidal

hursts

with a

repetition

frequency

of

31 kHz.

SOFT COAG

750 kHz

damped

sinusoidal

bursts

with

a

repetition

frequency

of

22 KHz.

MICROBIPOLAR

750 kHz

sinusoid,

unmodulated

OUTPUT CHARACTERISTICS

Maximum

Rated

Maximum Power

Crest

Factor

(open circuit)

Load

(at Rated Load)

At Rated Load

Mode

P-P Voltage

(Ohms)

(Watts)

+10%

CUT

2500

300

300

+

20

1.9 § 100W

BLEND 1

2800

300

250

+

20

2.6 6 100W

BLEND

2

3000

300

200

+

20

3.7 6 100W

BLEND

3

3400

300

200

+

20

4.4 6 100W

SPRAY COAG

9000

300

120 +

10

9.0 § 50W

SOFT COAG

9000

300

60+5

13.0 <? 30W

MICROBIPOLAR

400

100

70

+

8

1.6 § 40W

Microbipolar

has selectable

output

characteristics:

power

approximately

proportional to I/R or I/R2 (Standard or Precise).

POWER READOUTS

Three L.E.D. displays (for coag, cut and microbipolar) indicate output power.

Power readouts agree with actual power into rated load to within +_ 10% or 5

watts, whichever is greater.

15

LOW FREQUENCY LEAKAGE (50/60 Hertz)

Source current, patient leads, all outputs tied together.

Normal polarity, intact chassis ground, less than 2.0uA

Normal polarity, ground open, less than 30uA

Reverse polarity, ground open, less than 30uA

Sink current, 140 volts applied, all inputs, less than 150uA

HIGH FREQUENCY RISK PARAMETERS

Bipolar RF leakage current, 40 pf output to ground: 150 mA rms.

Trip capacitance (mid power setting)

Normal sensitivity: 130 +_ 15 pf

A trip defeats output for a period of one second +_ 10%. Under typical

conditions, a trip occurs in 0.15 seconds.

Patient to chassis voltage, after 40 pf accessory capacitance, less than 60 V

rms .

Return Electrode Monitor (REM)

Measurement Frequency 140 kHz +_ 5

Measurement Current 1.5 mA +_ 0.5

Acceptable resistance ranges:

Effective RF pad resistance 6-30 ohms.

Dual area mode 5-135 ohms

Single area mode less than 20 ohms

Mode selected automatically by return electrode connector. Outside acceptance range generator will be shut down and fault warning given. If resistance increases by more than 30% the generator will be shut down and an alarm given.

COOLING

Natural convection cooled. No fan.

CONTROL PANEL

The control panel is a flat sealed	unit	with	no	openings thus preventing
fluids from entering the system.
INDICATORS
The RF indicators for COAG, CUT, and	MBP	will	be	illuminated only when RF

power is available at unit output connections. In addition to the digital

L.E.D.s, two indicator lamps are used with COAG to indicate either the normal or fulgurate modes. Four indicator lamps are used with CUT to indicate either

Pure	Cut or three available Blend modes, Bl,					B2,	or B3.	Two indicator lamps
are used with MBP to indicate either Standard or							Precise	power characteris
tics.	REM	has a	"fault"	indicator	light that gives an intermittant 800 Hz
tone	for	fault	warning.	There is	also a return fault indicator light.
Monopolar and bipolar lamps indicate					footswitch	function.

16

AUDIO VOLUME

Mode indicator tones: 65 dba at 1 meter, maximum

Adjustable external volume control.

REM fault tone is 65 dba at 1 meter min. Not externally adjustable.

FOOTSWITCH LOGIC

Front panel touch buttons select monopolar standard output or bipolar output.

Footswitch function starts in the monopolar mode.

Depression of both

footswitch pedals selects COAG mode.

OUTPUT POWER ADJUSTMENT

When an "up" button located on the instrument control panel is actuated, the power of that function is increased. When a "down" button is actuated, the

power of that function is decreased.

The operator can view the L.E.D.

display for power level while adjusting it to the desired level. Power levels

will range from 1 watt to a set maximum.

INPUT POWER SOURCE

Nominal voltage 120 volts rms

Regulation range 95-140 volts rms

Operation range 80-140 volts rms

Frequency 45-64 Hertz

CURRENT: Idle: 0.4 amperes maximum

Cut: 10 amperes maximum

Coag: 4 amperes maximum

Bipolar 3 amperes maximum

POWER: Idle: 50 watts maximum

Cut: 900 watts maximum

Coag: 375 watts maximum

LINE REGULATION

Between 90 and 140 volts input, output power into a nominal load will vary no

more than 2% or 2 watts.

WEIGHT: 38 lb, 17 kg.

SIZE:

6 X 13 X 22 inches, 15 X 33 X 56 cm.

Specifications subject to change without notice.

17

300

200

CO

l

c

Ul

o a.

100

100

200

500

1000

2000

RESISTANCE/OHMS

FIGURE 4

OUTPUT POWER VS LOAD - MONOPOLAR OUTPUT

18

70

aPRECISE

MBP

56

•STANDARD MBP

CO

1 42

C

UJ

$

O

Ql

28

*

14

I

10

20

50

100

150

200

500

100

RESISTANCE/OHMS

FIGURE 5

OUTPUT POWER VS LOAD - BIPOLAR OUTPUT

19

BIPOLAR

400

300

<

UJ

g

O

<.

z°-

UJ 0. o

200

100

n

10

20

30

40

50

60

70

CONTROL SETTING

MONOPOLAR

0,000

COAG

8000

6000

4000

BLEND 3

2000

CUT

0

MODE

MAXIMUM

CONTROL SETTING

FIGURE 6

OUTPUT VOLTAGE VS CONTROL SETTING

20

SECTION 6

CIRCUIT DESCRIPTIONS

POWER SUPPLY MODULE

The FORCE 4 power supply module generates the regulated and isolated DC power required by the generator circuitry. It also contains two load resistors; R2,

across the output transformer primary and R3 which discharges								the output		peak
detector	capacitors.		There are	four	supplies:	+5V,	-5V,	+15V	and	high
voltage.	There	are four returns:		analog, digital,		high	voltage and		chassis;
all connected		together	at pins	1-4 of	the Controller		PCB.	Transformer Tl

drives the three low voltage supplies and transformer T2 supplies the high

voltage. The large circuit board is the controller and the small circuit board has the high voltage output components. The output board and its four transistors mounted on the large heatsink are connected directly to the line; use extreme caution when probing the board.

5V Supply

The -5V supply originates on the Supply Module. Input power is passed through

Tl, and rectified by CR2.	The rectified AC is filtered by C2, C3 and
regulated by Ul.
+5V Supply

This is a switching supply with 15V input and 5V output. U2 is a comparator

which provides overvoltage				protection by firing SCR01 to clamp					the		output.
L07 is the 60 microhenry switching buck inductor, operating									at	a	nearly
constant	current	equal	to	the load	current.	When	Q04	is on,	the	inductor
current	increases	and	when	Q04 is	off CR03	holds	the	input	side		of the

inductor at -0. 7v and the inductor current decreases. The duty cycle of Q04 is controlled by U01 which has an internal oscillator running at about 25 kHz. The 5v output is divided down by R13, R14 and compared to an internal reference of 1.25V to enable the output and turn on Q04. A second comparator shuts down the oscillator when pin 14 drops 0.33 volts below pin 13. The maximum output duty cycle is 50% and regulation is accomplished by gating the

oscillator to lower duty cycles.

+15V Supply

This regulator uses a buck inductor with pass device Q01 and catch diode CR01. The output voltage is divided down by R34, R35, and R37 and compared to a zener diode CR02 voltage divided by R27, R38. When the output is less than the reference, comparator U05 turns on the pass device via Q02, Q03. With the pass device on, current increases in LI, the 0.75 mH inductor, until the output exceeds the reference. At this time, the pass device is shut off and the inductor current passes through CR01. Note that U05 is wired as a schmidt trigger with hysteresis. This regulator controls the output voltage and ripple, and runs at varying frequency and duty cycles as the load is varied.

21

Ancillary circuits provide over voltage protection, current limiting and detection of loss of the -5V supply. CR06 is the over voltage sensor and SCR2 is the output crowbar. U06 is the comparator which shuts off the supply when current through the sense resistors R05, R06 exceeds the limit adjusted by

R33. CR05 and Q07 shut off the +15V supply when the -5V supply goes below -3

volts .

High Voltage Supply

This supply is an off-line pulse width modulated push-pull switching type. DC input is provided by CR5 and CR3 in the module and fed to the primary center tap of T2. Transistors Q1901, Q1902, Q1903 and Q1904 conduct alternately to produce variable width AC pulses at the secondary. The output is rectified by bridge CR4 and smoothed by inductor L2 and capacitors C1103, C1104 and C1105 which are located on the St ripline PCB. The negative side of these capacitors has its own return wire, labeled the high voltage return. Inductor L2 acts as a current source under low duty cycle conditions and a bridge CR4 performs the catch diode function. Drive for Q1901, Q1902, Q1903 and Q1904 is supplied

from	transformer T1901 on the output		PCA.	The tapped		winding		and	diodes
CR1901, CR1902 prevent		saturation of the	transistors.
Drive	pulses are generated by an astable U09 divided by					2 in U04 to ensure
equal	pulse widths in	a 2 phase drive.	The	U04	outputs	are	logically		ANDed
with	the U09 output,	to eliminate overlap		in	time and	with	the	output of

U08/1, the pulse width controller. The variable width pulses are amplified by Q05, Q06 to drive the primary of T1901. Pulse width control by U08/1 uses C25, the astable capacitor, and its ramp waveform. The ramp is compared with a slowly varying error voltage and the output drive is enabled when the ramp voltage is less than the error voltage. (See page 41.)

The error voltage is the amplified and integrated difference		between Vs, the
set point voltage generated in the Clock/Control PCB,	and	the	actual	high
voltage output taken from the high voltage bus. U07/1	compares		the set	point

and actual voltages and its binary output is integrated by U07/2 with a 15 millisecond time constant due to R41, C22. R61 is the comparison calibration.

Several protection circuits are provided for the supply. The error voltage is set below zero, disabling the ramp comparator, by U07/13 and U07/14 when the ready signal from the CPU PCB is high, indicating a standby condition.

U08/2 disables	the output AND gates when the +5 volt supply is lost.	U08/13
is the current	limit comparator. The output current is sampled by	R07 and

when U08/11 is pulled below U08/10 the comparator latches low and disables the output AND gates. R62 is the current limit calibration.

22

INTERFACE PRINTED CIRCUIT ASSEMBLY

The function of the interface printed circuit assembly is to perform the measurement and control functions which link the monopolar output circuitry of the FORCE A Electrosurgical unit with the microcomputer control. The sections of circuitry which are contained in this assembly are the output networks, return fault monitor, lamp enable circuit, keying isolating circuit, and the

return electrode monitor (REM).

This assembly contains components which are connected to the output terminals of the electrosurgical unit and they are at high voltage with respect to ground during operation of the FORCE 4. Use extreme caution when making measurements on or handling this assembly during operation.

The purpose of the output networks are to connect the output transformers located on the stripline assembly with the output jacks located on the front

panel.	These networks provide the	necessary	series capacitors	for the
monopolar outputs (for example C102),		and provide the interconnection modes
for other assembly modules. Physical		spacings	of approximately 1	centimeter

are provided between components of this module and other modules. It is important that these spacings be maintained for continued safe operation of

the FORCE 4 generator.

Components C110 and R112 serve to provide a grounding link to the return electrode. These components have high impedance to line frequency voltages,

however,	they have	low impedance to radio	frequency current so that typically
patient	to ground	voltages are under 30	volts rms. C116 provides a small

amount of radio frequency current at the output mode and out of phase with typical currents in that mode so that patient to ground voltage is minimized.

Transformers T101, T103, and T104 provide the interface between the output networks and the return fault monitor. T101 isolates against high voltages present on the FORCE 4 monopolar actives and it is important that insulation in this transformer be maintained. T101 is balanced in response with respect to T103 for proper return fault operation.

The return fault monitor provides a	current summing	function between		the
active and return currents flowing in the monopolar output.			A voltage
corresponding with this current sum	is compared with	a reference	which	is

dependent upon the radio frequency voltage in the activated monopolar output circuit. If the sum exceeds a pre-determined level an alert is asserted and further electrosurgical operation is inhibitied. This function assures that

harmful alternate return current will not be present during the use of the

FORCE 4 generator. Active and return currents are summed in opposite sign in

the CR106 network. Higher active current than return causes disabling.

Further, C117, C118, and C140 operating through the CR106 network provide an output voltage dependent reference which when summed with the other currents causes a bias opposite from the direction of trip. The above circuit function causes tripping to be approximately related to a given level of impedance between the active electrode and ground for a specified load condition between

active and return.

23

Adjustment of this level of impedance between active and ground is provided

through C140. The net voltage developed within the CR106 network is measured

as it appears across R125 by comparator U110. Whenever the voltage exceeds a fixed reference dependant upon the five volt supply the comparator places an output at J101-19.

The indicator lamps on the FORCE 4 front panel which indicate activation in

either the cutting or the coagulation modes are enabled by the presence of

radio frequency power available from the output amplifier. The provisions for

this on the interface board are as follows: current is coupled from the

output amplifier via C124 to CR105 and CR104, rectified, limited by CR108,

filtered by CI25 and detected in U109. A signal indicating the presence of RF

power is coupled to the controller through J101-16.

Activation switching components located on the active accessory handles are

capacitively coupled to the electrosurgical active output. To prevent

excessive radio frequency leakage currents these switching components must be allowed to float independent of grounded circuitry. Q103-106 driving T102

provide isolated 6 volt supplies. R143-147 and R149-152 provide well-defined

input	voltages	to comparators in U101 and 102 which are dependent upon the
keying	switch	states.	The output of	the comparators is fed through
optoisolators to		output	from the Interface	PCB.

The Interface PCB contains the circuitry necessary to support the FORCE 4's function of verifying acceptable return electrode impedance conditions. L101,

a matched capacitor and U103 form an oscillator which produces 140 kilohertz

square waves at the output pins 6 and 8 of U105. These signals appear as symmetrically injected currents into the tuned network comprised by T105, C113

and C114. Voltages present across the tuned network are detected by U107 also

using the outputs from U105. The voltages present across Clll and C112 are

dependent upon the resistive loading across the return electrode outputs J105

- 3 and J105 - 4. The components in the oscillator and load tuned networks

have matched temperature drift characteristics by virtue of similar inductor

and capacitor temperature coefficients. The outputs of U105 pins 6 and 8 have

fast	edges and are exactly opposing	in phase. These	two conditions	assure
that	the monitoring circuitry will	have repeatable	response to	return

electrode resistance and also that the detected outputs will be independent of

coupled electrosurgical currents. The detected outputs are amplified by differential amplifier U108 and a range adjustment is provided by R118. The analog signal representing the measured value of return electrode impedance is present on J101 pin 19, calibrated to 5 volts at 150 ohms.

The following characteristics of the Interface PCB		affect the safety of the
FORCE 4:	1) insulation; 2) creepage distances;	3) component values; 4)
component	types; 5) component location. Any service	operation affecting these

characteristics should be performed with care so that none of the critical

characteristics are altered.

24

BIPOLAR OUTPUT

The bipolar output stage is a high efficiency, low impedance RF generator which functions independently of the monopolar system in the FORCE 4. It will deliver a maximum power of 70 watts into a nominal load impedance of 70 to 100 hms . Two modes are provided which differ only in the power output at high

load impedance.

In STANDARD mode, the power output decreases from 70 watts at 100 ohms to ahout 35 watts at 200 ohms, while the power output in PRECISE mode would decrease to about 20 watts. Figure 4 is a plot of output power vs load for

the bipolar output.

Figure 5 is a block diagram of the bipolar stage. The major blocks are 1) The

RF output stage, 2) The switching power supply which modulates the DC voltage

supplied to the RF stage from 0 to 100 volts to control output power, 3) The control microprocessor which takes operator commands (keying, mode and power level) as inputs, measures voltage and current at the output, and adjusts the power supply for correct power output.

Figure 22 is a schematic diagram of the bipolar output board. The functional blocks of the output board are 1) The switching power supply, 2) The RF driver circuitry, 3) The switching output stage, 4) Voltage and current sensors, 5)

Handswitching circuit.

The switching power supply consists of the controller, U201, the switching

transistors Q201, Q203 and Q204, and the filter L201 and C201. When the generator is keyed in the bipolar mode, +100 volts is present at HV. The switching supply regulates this to a voltage from 0 to 100 volts, determined by the feedback voltage AFB. By comparing AFB with the scaled DC voltage at DCSEN, the controller adjusts the width of the drive pulses applied to the emitter of Q204. If the DC voltage is too low, (AFB DCSEN) the pulse width

is increased.

Current drawn through Q204 is applied to the base of Q203, whose collector current becomes the drive for Q201. The switched current through Q201 is filtered by L201 and C201, and fed back through the divider R215 - R216 to the controller. CR202 is a freewheeling diode which supplies the current for L201

after Q201 is turned off.

The RF driver circuitry develops the 750KHz to drive the output FET. U206 is

a binary divider which receives the 6MHz from the bipolar control board and divides by eight to give a precise 750KHz square wave. Two gates of U207 gate

the 750KHz to Q210 when key (NOT) is low, Q210 amplifies the drive to 12 volts

and Q207-Q208 supply the high transient currents to drive the power FET.

The power FET Q203 is

operated in switched

mode

at 750KHz

with a

50%

duty

cycle. L202 is

the RF

choke,

and supplies DC to the

FET.

C205,

C206,

and

T202

form

the

output

filter

stage, which

is

designed to

minimize power

dissipation

in

the FET

by maintaining low voltage at

turn on and turn off.

T202

has a third winding which

is used to sense the RF

voltage.

C207 and C208

are

blocking capacitors

which,

along with T202, provide

redundant

DC isolation

at the output.

25

The sense winding on T202 develops a voltage proportional to the voltage at the output. This voltage is rectified and filtered by CR208 and C227. The maximum voltage appearing on C227 is about 35 volts. R246 and trimpot R247

scale this down so that 128V of RF will appear as 5VDC at the output of

amplifier U204. The RF sense voltage is also applied to comparator U203 which

pulls the lamp enable line (LE(NOT)) low if RF voltage is present.

Current sense transformer T201 has a turn ratio of 20:1 so that current

flowing in the load appears across trimpot R228, decreased by a factor of 20.

The voltage across R228 is filtered by the combination of R227 and C228 and buffered by U204 to become the current sense output, ISEN. This is adjusted

to 1 volt » 250MA of load current.

The function of the handswitching circuit is to place a low voltage at HSDS

(NOT) only when a low is present at SAMPLE (NOT) and the handswitching contact

RF out (3) is electrically connected to the active output RF out (2).

The isolated handswitching circuitry consists of a free running oscillator, isolation transformer T203, optoisolators OPI-201, 202, comparator U205, and

resistor network HY201.

The free running oscillator Q209 runs at abut 150 KHz. Energy is coupled through T203, rectified and filtered to become the isolated DC voltage +5A.

Referring to the schematic, note that the voltage at PIN 2 of U210 is +1.2V when J202, Pin 3 is open, and +2.4V if J202, Pin 3 is connected to J202, Pin 2. Also the voltage at non-inverting input PIN 3 is 3.0 volts if PIN 7 (the

output	of the	second comparator) is high and 1.8 volts if it is						low. PIN 7 is
held low only		when	SAMPLE (NOT)	is low,	which	causes the	first	comparator	to
switch	states	and	follow the	closure	of the	handswitch.	Thus, OPI-201		has

current through the diode and asserts HSDS (NOT) only if the handswitch is

closed and SAMPLE(NOT) is low.

26

UNREGULATED

DC

VOLTAGE

SWITCHING

REGULATED

POWER

3

	SUPPIY
to
	a
a	POWER
s
1
Co	hi
	NJ
p	FOOTSWITCH -
CO
g	NOMINAL
	POWER

REGULATED DC		750KHZ
0-100V		RF POWER	750KHZ RF
HIGH EFFICIENCY		VOLTAGE.
		CURRENT	FORCEPS
RF GENERATOR		SENSORS
	1	2
	i i
SUPPLY CONTROL	RF GENERATOR

ENABLE

RF VOLTAGE

MICROPROCESSOR

RF CURRENT

CONTROLLER

4