GE Corometrics 170 Service manual

Corometrics®170 Series

SERVICE MANUAL MANUAL P/N 2000947-004 REV. C

Corometrics® 170 Series

SERVICE MANUAL MANUAL P/N 2000947-004 REV. C

GUARANTEE

All equipment sold by GE Medical Systems Information Technologies, is fully guaranteed as to
materials and workmanship for a period of 1 year. Information Technologies reserves the right to
perform guarantee service operations in its own factory, at an authorized repair station, or in the
customer’s installation.

Our obligation under this guarantee is limited to repairing, or, at our option, replacing any
defective parts of our equipment, except fuses or batteries, without charge, if such defects occur in
normal service.

Claims for damage in shipment should be filed promptly with the transportation company. All
correspondence covering the instrument should specify the model and serial numbers.

GE Medical Systems Information Technologies
A GE Medical Systems Company

GE Medical Systems Information Technologies will make available on request such circuit
diagrams, component diagrams, component parts lists, descriptions, calibration instructions, or
other information which will assist the users or appropriately qualified technical personnel to
repair those parts of the equipment which are classified by GE Medical Systems Information
Technologies as repairable. Refer to the service manual for further information.

!

CAUTION: In the United States of America, Federal Law restricts this device to sale by or

on the order of a physician.

Corometrics and Marquette are registered trademarks of GE Medical Systems Information Technologies. GE is a registered
trademark of General Electric Company. All other product and brand names are trademarks or registered trademarks of their
respective companies. ©2002-2004 GE Medical Systems Information Technologies. All rights reserved. No part of this
manual may be reproduced without the permission of GE Medical Systems Information Technologies.

Contents

1 Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1

General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

Definitions of Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3

Monitor Contraindications, Warnings, and Precautions . . . . . . . . . . . . . . . . . . . . 1-4

Equipment Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-9

2 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1

Indications for Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2

Monitoring Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3

Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4

About Your Monitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5

3 Controls, Indicators, and Connectors . . . . . . . . . . . . . . . 3-1

Front Panel Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2

Front Panel Displays and Indicators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6

Front Panel Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-8

Strip Chart Recorder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-12

Rear Panel Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-14

4 Setup Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1

Loading Strip Chart Paper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2

Turning the Monitor On . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-7

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Monitor Self-Test Routines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-8

Customizing the Monitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-10

Quick Reference Card . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-18

Flasher Software Utility Upgrade . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-20

5 Theory of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1

Functional Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2

Main Board Theory of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-17

FECG/IUP Board Theory of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-36

6 Functional Checkout Procedure . . . . . . . . . . . . . . . . . . . 6-1

Equipment Required . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-2

General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-3

Monitor Self-Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-4

Front Panel Pushbutton Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-5

Connecting the Simulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-6

FECG Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-7

Legplate Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-12

Ultrasound Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-13

Fetal Movement Detection Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-16

Ultrasound Transducer Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-18

Uterine Activity Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-19

Tocotransducer Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-21

Strain Gauge Transducer Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-22

Pattern Memory Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-23

Dual Heart Rate Test (Non-Pattern) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-24

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Alarm Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-28

7 Serviceable Assemblies . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1

General Anti-Static Handling Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-2

Transducer Plug Replacement Kits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-3

Nautilus Transducer Cable Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-15

Removing the Monitor Top Cover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-19

Tocotransducer Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-20

Nautilus Ultrasound Transducer Top Cover Replacement . . . . . . . . . . . . . . . . . 7-30

Nautilus Transducer Reassembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-32

Testing a Repaired Transducer (TOCO or US) . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-34

Replacing the Main Board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-35

Replacing the FECG/IUP Board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-36

Replacing the Membrane Switch Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-37

Replacing a Front Panel Connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-40

Servicing the Recorder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-41

Boot ROM Error Codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-49

8 Peripheral Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1

Remote Marks Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-2

Telemetry Connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-3

RS-232 Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-4

9 Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-1

Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-2

Preventative Maintenance Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-5

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10 Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-1

General Monitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-2

Operating Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-3

Strip Chart Recorder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-4

11 Parts Lists . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-1

2000268-188, Model 171 Final Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-2

2000268-189, Model 172 Final Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-5

2001972-037, Model 173 Final Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-8

2001972-038, Model 174 Final Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-11

2264AAX, Button-Style Nautilus Tocotranducer Assembly Parts List . . . . . . . 11-14

5700GAX, Button-Style Nautilus Ultrasound Transducer Assembly Parts List 11-15

5700KAX, Loop-Style Nautilus Ultrasound Transducer Assembly Parts List . 11-16

2264DAX, Loop-Style Nautilus Tocotransducer Assembly Parts List (5-ft cord) 11-17

1509AAO/BAO, Qwik Connect Plus Legplate Assembly Parts List . . . . . . . . . 11-18

Block Diagrams. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-19

8 Corometrics 170 Series Revision C

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Chapter 1

!

Safety 1

The information presented in this section is important for the safety of both the
patient and operator and also serves to enhance equipment reliability. This chapter
describes how the terms Danger, Warning, Caution, Important, and Note are used
throughout the manual. In addition, standard equipment symbols are defined.

This section includes the following important information:

General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

Definitions of Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3

Monitor Contraindications, Warnings, and Precautions . . . . . . . . . . 1-4

Equipment Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-9

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Safety: General Information

General Information

General Use

If the monitor is cold to the touch or below ambient temperature, allow it to stabilize
before use.

To ensure patient safety, use only parts and accessories manufactured or
recommended by GE Medical Systems Information Technologies. Parts and
accessories used shall meet the requirements of EN60601.1.1.

Disposable devices are intended for single use only. They should not be reused.

Periodically, and whenever the integrity of the monitor is in doubt, test all functions.

Refer to the “Maternal/Fetal Monitoring Operator’s Manual” for information
concerning the limitations of internal and external fetal heart rate monitoring
techniques.

Responsibility of the Manufacturer

GE is responsible for the effects on safety, reliability, and performance if:

 assembly operations, extensions, readjustments, modifications, or repairs are

carried out by persons authorized by GE;

 the electrical installation of the relevant room complies with the requirements of

appropriate regulations; and

 the monitor is used in accordance with the instructions of use.

Responsibility of the User

This device is intended for use by clinical professionals who are expected to know
the medical procedures, practices, and terminology required to monitor obstetrical
patients. This manual documents all possible parameters available in the 170 Series
of monitors. It is the responsibility of each hospital to ensure that the Labor and
Delivery staff is trained in all aspects of the selected model.

The 170 Series Monitor is designed to assist the perinatal staff by providing
information regarding the clinical status of the fetus during labor. The monitor does
not replace observation and evaluation of the mother and fetus at regular intervals,
by a qualified care provider, who will make diagnoses and decide on treatments or
interventions. Visual assessment of the monitor display and strip chart must be
combined with knowledge of patient history and risk factors to properly care for the
mother and fetus.

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Safety: Definitions of Terminology

Definitions of Terminology

Six types of special notices are used throughout this manual. They are: Danger,
Warning, Caution, Contraindication, Important, and Note. The warnings and
cautions in this Safety section relate to the equipment in general and apply to all
aspects of the monitor. Be sure to read the other chapters because there are
additional warnings and cautions which relate to specific features of the monitor.

When grouped, warnings and cautions are listed alphabetically and do not imply any
order of importance.

Danger

Warning

Table 1-1. Definitions of Terminology

A DANGER notice indicates an imminently
hazardous situation which, if not avoided, will result
in death or serious injury.

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

Caution

Contraindication

Important

Note

A CAUTION indicates a potentially hazardous
situation which, if not avoided, may result in minor
or moderate injury. Cautions are also used to
avoid damage to equipment.

A CONTRAINDICATION describes any special
symptom or circumstance that renders the use of a
remedy or the carrying out of a procedure
inadvisable, usually because of a risk.

An IMPORTANT notice indicates an emphasized
note. It is something you should be particularly
aware of; something not readily apparent.

A NOTE indicates a particular point of information;
something on which to focus your attention.

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Safety: Monitor Contraindications, Warnings, and Precautions

Monitor Contraindications, Warnings, and Precautions

Warnings

WARNINGS

ACCIDENTAL SPILLS—In the event that fluids are accidentally
spilled on the monitor, take the monitor out of operation and
inspect for damage.

APPLICATION—This monitor is not designed for direct cardiac
connection.

CONDUCTIVE CONNECTIONS—Avoid making any
conductive connections to applied parts (patient connection)
which are likely to degrade safety.

CONDUCTIVE PARTS—Ensure that the conductive parts of the
lead electrodes and associated connectors do not contact other
conductive parts including earth.

DEFIBRILLATION—During defibrillation, all personnel must
avoid contact with the patient and monitor to avoid a dangerous
shock hazard. In addition, proper placement of the paddles in
relation to the electrodes is required to minimize harm to the
patient.

ELECTRICAL SHOCK—To reduce the risk of electrical shock,
do not remove monitor cover. Refer servicing to qualified
personnel.

ELECTROMAGNETIC INTERFERENCE—Be aware that
strong electromagnetic fields may interfere with monitor
operation. Interference prevents the clear reception of signals by
the monitor. If the hospital is close to a strong transmitter such as
TV, AM or FM radio, police or fire stations, a HAM radio
operator, an airport, or cellular phone, their signals could be
picked up as signals by the monitor. If you feel interference is
affecting the monitor, contact your Service Representative to
check the monitor in your environment. Refer to page 1-8 for
additional information.

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Safety: Monitor Contraindications, Warnings, and Precautions

WARNINGS

ELECTROSURGERY—The monitor is not designed for use with
high-frequency surgical devices. In addition, measurements may
be affected in the presence of strong electromagnetic sources such
as electrosurgery equipment.

EXPLOSION HAZARD—Do not use this equipment in the
presence of flammable anesthetics or inside an oxygen tent.

GROUNDING—Do not defeat the three-wire grounding feature
of the power cord by means of adaptors, plug modifications, or
other methods. A dangerous shock hazard to both patient and
operator may result.

INSTRUCTIONS—For continued and safe use of this equipment,
it is necessary to follow all listed instructions. However, the
instructions provided in this manual in no way supersede
established medical procedures concerning patient care. The
monitor does not replace observation and evaluation of the
patient, at regular intervals, by a qualified care provider who will
make diagnoses and decide on treatments and interventions.

INTERFACING OTHER EQUIPMENT—Monitoring equipment
must be interfaced with other types of medical equipment by
qualified biomedical engineering personnel. Be certain to consult
manufacturers’ specifications to maintain safe operation.

LEAKAGE CURRENT TEST—The interconnection of auxiliary
equipment with this device may increase the total leakage current.
When interfacing with other equipment, a test for leakage current
must be performed by qualified biomedical engineering personnel
before using with patients. Serious injury or death could result if
the leakage current exceeds applicable standards. The use of
accessory equipment not complying with the equivalent safety
requirements of this equipment may lead to a reduced level of
safety of the resulting system. Consideration relating to the
choice shall include: use of the accessory in the patient vicinity;
and evidence that the safety certification of the accessory has been
performed in accordance with the appropriate EN60601.1 and/or
EN60601.1.1 harmonized national standard.

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Safety: Monitor Contraindications, Warnings, and Precautions

WARNINGS

LINE ISOLATION MONITOR TRANSIENTS—Line isolation
monitor transients may resemble actual cardiac waveforms, and
thus cause incorrect heart rate determinations and alarm activation
(or inhibition).

STRANGULATION—Make sure all patient cables, leadwires,
and tubing are positioned away from the patient’s head to
minimize the risk of accidental strangulation.

WATER BIRTHS—Do not use the monitor to directly monitor
patients during water births, in whirlpool or submersion water
baths, during showers, or in any other situation where the mother
is immersed in water. Doing so may result in electrical shock
hazard.

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Cautions

Safety: Monitor Contraindications, Warnings, and Precautions

CAUTIONS

ANNUAL SERVICING—For continued safety and performance
of the monitor, it is recommended that the calibration, accuracy,
and electrical safety of the monitor be verified on an annual basis
by an GE Service Representative.

DAILY TESTING—It is essential that the monitor and
accessories be inspected every day. It is recommended practice to
initiate the monitor’s self-test feature at the beginning of each
monitoring session; follow the instructions in “Chapter 4, Setup

Procedures”.

ENVIRONMENT—The performance of the monitor has not been
tested in certain areas, such as x-ray and imaging suites. The
monitor is not recommended for use in these environments.

PERFORMANCE—Report all problems experienced with the
monitor. If the monitor is not working properly, contact your
Service Representative for service. The monitor should not be
used if it is not working properly.

PINCHING—Keep fingers clear of the paper roller because the
roller could pinch your fingers.

TRAPPING—Keep hands, hair, jewelry, and loose clothing away
from the paper roller because the roller could trap these items.

TRIPPING—Arrange monitoring equipment so that cords and
cables do not present a tripping hazard.

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Safety: Monitor Contraindications, Warnings, and Precautions

Electromagnetic Interference

This device has been tested and found to comply with the limits for medical devices
to the IEC 601-1-2:1993, EN60601-1-2:1994, Medical Device Directive 93/42/EEC.
These limits are designed to provide reasonable protection against harmful
interference in a typical medical installation.

However, because of the proliferation of radio-frequency transmitting equipment
and other sources of electrical noise in the health-care and home environments (for
example, cellular phones, mobile two-way radios, electrical appliances), it is
possible that high levels of such interference due to close proximity or strength of a
source, may result in disruption of performance of this device.

This equipment generates, uses, and can radiate radio frequency energy and, if not
installed and used in accordance with these instructions, may cause harmful
interference with other devices in the vicinity. Disruption or interference may be
evidenced by erratic readings, cessation of operation, or incorrect functioning. If this
occurs, the site of use should be surveyed to determine the source of this disruption,
and actions taken to eliminate the source.

The user is encouraged to try to correct the interference by one or more of the
following measures:

 Turn equipment in the vicinity off and on to isolate the offending equipment.

 Reorient or relocate the other receiving device.

 Increase the separation between the interfering equipment and this equipment.

 If assistance is required, contact your GE Service Representative.

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Equipment Symbols

The following is a list of symbols used on products manufactured by GE. Some
symbols may not appear on your unit.

Safety: Equipment Symbols

Table 1-2. Equipment Symbols

!

ATTENTION: Consult accompanying documents.

TYPE B EQUIPMENT. Type B equipment is
suitable for intentional external and internal
application to the patient, excluding direct cardiac
application.

TYPE BF EQUIPMENT.
suitable for intentional external and internal
application to the patient, excluding direct cardiac
application. Type BF equipment has an F-type
applied part.

TYPE CF EQUIPMENT. Type CF equipment is
suitable for intentional external and internal
application to the patient, including direct cardiac
application. Type CF equipment has an F-type
applied part.

ALTERNATING CURRENT (AC).

EQUIPOTENTIALITY.

ON/STANDBY: button toggles between full power
and standby.

Type BF equipment is

CAUTION

AC MAINS—The On/Standby switch does not disconnect the
monitor from AC mains power. To completely remove power, you
must disconnect the power cord from the AC wall outlet.

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For your notes

Safety: Equipment Symbols

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Chapter 2

Introduction 2

This section lists the indications for use for monitors in the 170 Series as well as
provides an explanation of the different patient monitoring modalities.

This section summarizes the clinical applications of monitors in the 170 Series:

Indications for Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2

Monitoring Methods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3

Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4

About Your Monitor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5

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Indications for Use

Models 171 and 172

Models 171 and 172 Fetal Monitors are indicated for use in the monitoring of the
fetus during the antepartum period as well as throughout labor and delivery. Each
monitor also has an optional monitoring mode to detect fetal body movements.

Models 173 and 174

Models 173 and 174 Fetal Monitors are indicated for use in the monitoring of the
fetus throughout labor and delivery. Each monitor also has an optional monitoring
mode to detect fetal body movements.

Introduction: Indications for Use

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Introduction: Monitoring Methods

Monitoring Methods

The following is a summary of all the clinical monitoring methods found in the 170
Series.

Fetal Heart Rate

External Method, Pulsed Doppler Ultrasound

Ultrasound monitoring is available on all 170 Series Monitors. Models 171 and 173
provide a single ultrasound channel, while Models 172 and 174 provide two
ultrasound channels.

Fetal heart rate can be measured externally using pulsed Doppler Ultrasound. A
transducer placed on the mother’s abdomen is used to direct an ultrasonic beam
toward the fetal heart and to sense Doppler shifted echoes created by moving cardiac
structures. A patented autocorrelation process is used to determine the timing of
successive cardiac cycles. The resulting fetal heart rate (FHR) pattern is recorded on
the strip chart paper and the FHR appears on the digital display.

Internal Method, Direct Fetal Electrocardiogram (FECG)

FECG is available on Models 173 and 174 only. The Model 173 provides a
dedicated FECG connector. The Model 174 provides a combi-connector which can
be used for either FECG or US.

FECG signals are obtained via a spiral electrode attached to the fetal presenting part.
FHR is computed on a beat-to-beat basis using the R-to-R time interval of the QRS
complexes. The instantaneous FHR pattern is printed on the strip chart paper and
the FHR appears on the digital display.

Maternal Uterine Activity

External Method, Tocotransducer (TOCO)

Maternal uterine activity is measured externally using a tocotransducer (toco).
Relative pressure within the uterus is measured using a tocotransducer attached to
the mother’s abdomen in the area of the uterine fundus. The readings are plotted on
the strip chart paper in a relative scale from 0 to 100 as well as shown on the digital
display. All 170 Series Monitors provide external uterine activity monitoring.

Internal Method, Intrauterine Pressure Catheter and Strain Gauge (IUP)

IUP is available on Models 173 and 174 only.

Intrauterine pressure is measured using a transcervical catheter. The pressure trend
is plotted over the range of 0 to 100 mmHg and the readings appear on the digital
display.

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Features

Introduction: Features

The 170 Series is a family of fetal monitors offering various combinations of
modalities to suit your institution’s needs. Each monitor boasts the following
qualities:

 The strip chart recorder is a quiet, easy-to-load, high resolution thermal array

printer. The recorder prints continuous trends and alphanumeric data on one
strip chart.

 Automatic mode selection is provided simply by inserting the appropriate

transducer plug into the front panel receptacle.

 Wide beam ultrasound transducer provides an advanced level of system

performance.

 Transducer connectors are easy-to-use, color-coded, and durable.

 Frequently-used functions are controlled by front panel buttons—including

audio volume, uterine activity reference, alarm silence, event mark, paper
advance, and user setup controls.

 The ultrasound mode provides clean accurate traces with few “dropouts”

because of a patented autocorrelation processing.

 Fetal heart rate alarm limits are user-defined, with pre-set defaults.

 Alarm silencing is controlled by a front panel pushbutton—colored for easy

recognition.

 Fetal heart rate alarm conditions have both audible and visual indications. The

audible indicator can be silenced on an alarm-by-alarm basis.

 Two RS-232C ports provide interfacing to external devices.

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About Your Monitor

This manual describes all monitors in the 170 Series; therefore some sections may
not apply to your model monitor. Refer to Table 2-1.

Model 171

The Model 171 Antepartum Fetal Monitor provides singleton ultrasound and
external uterine activity monitoring.

Model 172

The Model 172 Antepartum Fetal Monitor provides dual ultrasound and external
uterine activity monitoring.

Model 173

The Model 173 Intrapartum Monitor provides dual heart rate monitoring using
FECG and ultrasound. The monitor also provides external uterine activity
monitoring using a tocotransducer or internal monitoring using an intrauterine
pressure catheter (IUPC).

Introduction: About Your Monitor

Model 174

The Model 174 Intrapartum Monitor provides dual heart rate monitoring using
FECG/ultrasound or dual ultrasound. The monitor also provides external uterine
activity monitoring using a tocotransducer or internal monitoring using an IUPC.

Table 2-1. Summary of Features

Feature 171 172 173 174

External uterine activity (TOCO) 9999

Internal uterine activity (IUPC) 99

Ultrasound

Dual ultrasound 99

FECG

Fetal heart rate alarms 9999

Fetal movement detection (optional) 9999

Heartbeat coincidence 999

Fetal heart rate offset 999

a

a

a

The Model 174 has a combi-connector for the primary FHR that can be used for either US or FECG.

9999

99

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For your notes

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Chapter 3

Controls, Indicators, and Connectors

This section describes all possible controls, indicators, and connectors in the 170
Series.

This section contains the following information:

Front Panel Controls. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2

Front Panel Displays and Indicators. . . . . . . . . . . . . . . . . . . . . . . . . . 3-6

Front Panel Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-8

Strip Chart Recorder. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-12

Rear Panel Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-14

3

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Controls, Indicators, and Connectors: Front Panel Controls

Front Panel Controls

Figure 3-1. Front Panel Controls (Model 172 shown)

Table 3-1. Front Panel Controls

Symbol Name

Power

Record

Paper Advance

Mark/Offset

Setup

Volume

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Controls, Indicators, and Connectors: Front Panel Controls

Table 3-1. Front Panel Controls

Power Button and Indicator

Pressing the blue Power button turns the monitor on and illuminates the green
indicator to the left of the button. Pressing the button again puts the monitor in
standby and extinguishes the indicator.

Record Button and Indicator

Pressing the Record pushbutton activates the recorder, provided paper is installed;
the amber indicator illuminates to the left of the button. Pressing the button again
turns the recorder off and extinguishes the indicator.

UA Reference

Alarm Silence

Paper Advance Button

Pressing the Paper Advance button causes the recorder to advance chart paper at a
rate of 40 cm/min for as long as the button is pressed. If the recorder is on, twenty
seconds after the button is released, the recorder prints the time, date, active trends
legends, and chart speed.

Mark/Offset Button

The Mark/Offset button is a multifunction button:

Mark

Briefly pressing the button prints an event mark on the bottom two lines of the
heart rate grid.

Offset (Models 172, 173, and 174 Only)

When the heart rate offset mode is enabled, pressing and holding the Mark/Offset
button for at least two seconds shifts the secondary FHR trend +20 BPM for
visibility purposes. You will hear a “beep” for confirmation. Refer to the “170

Series Operator’s Manual” for more information.

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Controls, Indicators, and Connectors: Front Panel Controls

Setup Button

Volume Buttons

Model 171

Models 172, 173, and 174

Pressing and holding this button while the monitor is on enters a user setup mode for
configuring the monitor.

Pressing and holding this button during power up enters a service setup mode.

Refer to “Chapter 4, Setup Procedures” for instructions.

The Volume buttons are used to raise ( ) and lower ( ) the volume of the audio
signals emitted by the speaker. The volume buttons are also used during setup.

This monitor has two volume buttons used to control the ultrasound audio.

These monitors have four volume buttons. The left pair controls the audio signals
for the mode shown in the primary FHR display; likewise, the right pair of buttons
controls the audio for the mode shown in the secondary FHR display.

Setup Mode

When the monitor is in setup mode (user or service), the volume buttons change: the
setting or value shown in the FHR display; or the monitor feature code shown in the
UA display. (For Models 172, 173, and 174, only the leftmost volume controls are
active during setup mode.)

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Controls, Indicators, and Connectors: Front Panel Controls

UA Reference Button

The UA Reference button is used to set the uterine activity pressure reference. This
button is also used during setup.

Setting a Baseline for External Monitoring (Tocotransducer)

Briefly pressing the UA Reference button sets the pressure baseline at a preset
default. The monitor is shipped from the factory with a default setting of 10 relative
units. Qualified service personnel can access a service screen to set the default to 5,
10, 15, 20, or 25 relative units.

Pressing this button for more than two seconds causes the uterine activity reference
value to override the default setting and cycle through all available selections: 5, 10,
15, 20, or 25 relative units, starting at the default setting—until the button is
released. While the button is held down, the strip chart tracing remains unchanged.
Once the button is released, the recorder trace takes on this new value. This value is
stored as the new baseline for the currently measured uterine activity signal.

Setting a Baseline for Internal Monitoring (IUPC)

Pressing the UA Reference button sets the pressure baseline at 0 mmHg.

Setup Mode

Alarm Silence Button

NOTE: IUPC monitoring is only available on Models 173 and 174.

When the monitor is in setup mode, the UA Reference button selects the active
display. Pressing the button alternates between the UA display (which shows a
monitor feature code) and the FHR display (which shows the setting or value for the
selected feature code). When the UA display is active, the ± sign lights. When the
FHR display is active, the heartbeat indicator lights.

This button is yellow for easy recognition. Pressing the Alarm Silence button
removes the audible indication of an individual fetal heart rate alarm.

NOTE: Silencing an alarm does not affect the visual indications.

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Controls, Indicators, and Connectors: Front Panel Displays and Indicators

Front Panel Displays and Indicators

Fetal Heart Rate Display(s) and Indicator(s)

FHR Display

A three-digit yellow numeric display indicates the fetal heart rate in beats per
minute. The value flashes during an alarm condition.

Heartbeat Indicator

A yellow heart shaped indicator flashes with each detected valid heartbeat for the
fetal heart.

Primary Versus Secondary (Models 172, 173, and 174 only)

Refer to Table 3-2 for a summary of display positions relative to connectors.

Uterine Activity Display

This green three-digit display indicates the uterine activity values.

Tocotransducer

If uterine activity is measured using a tocotransducer, the uterine activity value
displays in relative units. A plus sign flashes when the uterine activity value
exceeds the strip chart range of 100 relative units.

IUP (Models 173 and 174 Only)

If uterine activity is measured using an intrauterine pressure catheter or a strain
gauge pressure transducer, the uterine activity value displays in mmHg.

.

Table 3-2. Display/Connector Summary

Monitor Model 171 Model 172 Model 173 Model 174

Mode US TOCO US1 US2 TOCO US FECG

Display

1 2

TOCO

or

IUP

US1

or

FECG

US2

TOCO

or

IUP

Connector

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2

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Controls, Indicators, and Connectors: Front Panel Displays and Indicators

Alarms Disabled Indicator

Audio Alarm Indicator

Active Patient Alarms

Resolved Patient Alarms

Signal Quality Alarms

This yellow indicator illuminates when all alarms have been disabled. The indicator
is unlit when alarms are enabled. Refer to “Chapter 4, Setup Procedures” for
information on enabling/disabling alarms.

For active patient alarms, this yellow indicator flashes; it continues to flash even if
the alarm is silenced.

For resolved patient alarms, the indicator continues to flash until you silence the
alarm. This ensures that the alarm is acknowledged by a clinician.

For signal quality alarms, the indicator flashes during an active alarm and turns off
as soon as the condition is resolved. The indicator is unaffected by silencing the
audio alarm.

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Controls, Indicators, and Connectors: Front Panel Connectors

Front Panel Connectors

Model 171 Connectors

Ultrasound Connector

The ultrasound connector1 is a blue, round receptacle mechanically keyed to accept
only a Corometrics ultrasound transducer plug. The fetal heart rate derived from
this transducer shows in the fetal heart rate display.

Figure 3-2. Model 171 Connectors

Uterine Activity Connector

The uterine activity connector is a white, round receptacle mechanically keyed to
accept a Corometrics tocotransducer. The uterine activity value obtained from this
transducer shows in the uterine activity display.

1

If the Model 171 is interfaced to a clinical information system (CIS), be aware that the CIS may be
designed to alarm when there is no fetal heart rate signal. Therefore it is recommended that you
unplug the ultrasound transducer from the monitor, when not in use, to eliminate false alarms.

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Controls, Indicators, and Connectors: Front Panel Connectors

Model 172 Connectors

1

2

Primary Ultrasound Connector

Secondary Ultrasound Connector

Uterine Activity Connector

1

Figure 3-3. Model 172 Connectors

The primary ultrasound connector1 is a blue, round receptacle mechanically keyed
to accept only a Corometrics ultrasound transducer plug. The fetal heart rate derived
from this transducer shows in the primary fetal heart rate display.

The secondary ultrasound connector1 is a blue, round receptacle identical to the
primary ultrasound connector described above. The fetal heart rate derived from
this connector displays in the secondary fetal heart rate display.

The uterine activity connector is a white, round receptacle mechanically keyed to
accept a Corometrics tocotransducer. The uterine activity value obtained from this
transducer shows in the uterine activity display.

2

1

If the Model 172 is interfaced to a clinical information system (CIS), be aware that the CIS may be
designed to alarm when there is no fetal heart rate signal. Therefore it is recommended that you
unplug the ultrasound transducer(s) from the monitor, when not in use, to eliminate false alarms.

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Controls, Indicators, and Connectors: Front Panel Connectors

Model 173 Connectors

Ultrasound Connector

Figure 3-4. Model 173 Connectors

The ultrasound connector1 is a blue, round receptacle mechanically keyed to accept
only a Corometrics ultrasound transducer plug. The fetal heart rate derived from
this transducer shows in the primary fetal heart display.

FECG Connector

The FECG connector1 is a dark grey, round receptacle mechanically keyed to
accept a Corometrics FECG cable/legplate plug. The fetal heart rate derived from
the spiral electrode displays in the secondary fetal heart rate display.

Uterine Activity Connector

The uterine activity connector is a white, round receptacle mechanically keyed to
accept a Corometrics tocotransducer, a Corometrics strain gauge transducer plug, or
any intrauterine pressure catheter with compatible cable plug. The uterine activity
value obtained from this transducer shows in the uterine activity display.

1

If the Model 173 is interfaced to a clinical information system (CIS), be aware that the CIS may be
designed to alarm when there is no fetal heart rate signal. Therefore it is recommended that you
unplug the ultrasound and/or FECG transducers from the monitor, when not in use, to eliminate false
alarms.

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Controls, Indicators, and Connectors: Front Panel Connectors

Model 174 Connectors

Combi-Connector (Primary Ultrasound or FECG)

Figure 3-5. Model 174 Connectors

The combi-connector is a blue connector1 with a dark grey inner center. This round
receptacle is mechanically keyed to accept only a Corometrics ultrasound transducer
plug or a Corometrics FECG cable/legplate plug. The fetal heart rate derived from
this transducer or cable/legplate shows in the primary fetal heart display.

IMPORTANT

COMBI-CONNECTOR—The combi-connector can be used for
monitoring ultrasound or FECG depending on what you plug in
(US transducer or FECG cable/legplate). When used in
conjunction with the secondary ultrasound connector, you have
the option of monitoring twins using dual US or FECG/US.

Secondary Ultrasound Connector

The secondary ultrasound connector1 is a blue, round receptacle mechanically
keyed to accept only a Corometrics ultrasound transducer plug. The fetal heart rate
derived from this connector shows in the secondary fetal heart rate display.

Uterine Activity Connector

The uterine activity connector is a white, round receptacle mechanically keyed to
accept a Corometrics tocotransducer, a Corometrics strain gauge transducer plug, or
any intrauterine pressure catheter with compatible cable plug. The uterine activity
value obtained from this transducer shows in the uterine activity display.

1

If the Model 174 is interfaced to a clinical information system (CIS), be aware that the CIS may be
designed to alarm when there is no fetal heart rate signal. Therefore it is recommended that you
unplug the ultrasound and/or FECG transducers from the monitor, when not in use, to eliminate false
alarms.

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Controls, Indicators, and Connectors: Strip Chart Recorder

Strip Chart Recorder

4305AAO

bpm

150

180

210

240

FHR

30

60

90

120

8

12

10

Figure 3-6. Strip Chart Recorder

UA

kPa

0

426

Heart Rate Grid

The strip chart recorder is located on the right side of the front panel. Latches on
each side of the recorder open the paper drawer.

Two styles of paper are available: 30-240 BPM scale and 50-210 BPM scale.

Refer to “Chapter 4, Setup Procedures” for instructions on loading strip chart paper
into the recorder.

One or two fetal heart rate trends print in the top (or left) grid of the strip chart
paper—depending on your model monitor and the active modalities.

If only one fetal heart rate is being monitored, the FHR trend is printed in black. If
twins are being monitored, the primary trend is printed in plain black while the
secondary trend is bolded.

Refer to the “170 Series Operator’s Manual” for additional information about fetal
heart rate trends and annotations.

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Controls, Indicators, and Connectors: Strip Chart Recorder

Uterine Activity Grid

Annotation Area

The uterine activity trend prints in black on the bottom (or right) grid of the strip
chart paper.

Refer to the “170 Series Operator’s Manual” for more information about uterine
activity trends and annotations.

An annotation area is provided between the fetal heart rate and uterine activity grids.

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Controls, Indicators, and Connectors: Rear Panel Connectors

Rear Panel Connectors

CONNECT TO:

GE MEDICAL SYSTEMS

REF 7714AAT ONLY

Figure 3-7. Rear Panel Connectors

RS232 RS232

12

Power Supply Connector

This is the receptacle for the AC adapter, P/N 7714AAT only. A line cord connects
from the other end of the adapter to an AC wall outlet. The connector is labeled

CONNECT TO GE MEDICAL SYSTEMS REF 7714AAT ONLY. The power supply is a

universal AC-to-DC converter which can accept an AC input in the range 100–230
VAC. The converter supplies a regulated 12 Vdc to the monitor.

Remote Mark Connector

This connector is provided for attaching an optional Corometrics Model 146 Fetal
Acoustic Stimulator (FAST). The annotation
the Model 146 is used.

Remote Mark Connector

This connector is provided for attaching an optional Corometrics Remote Event
Marker. This accessory annotates the strip chart recorder paper with a marker which
can be configured as one of the following:

The monitor is factory set to use the annotation. Refer to the “Chapter 4, Setup

Procedures” for information about selecting the annotation.

prints on the strip chart each time

: This annotation is commonly used to record an “event.”

FM

: This annotation is commonly used as an indication that the mother has

perceived fetal movement.

FM

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Controls, Indicators, and Connectors: Rear Panel Connectors

Nurse Call Interface

RS-232C Connectors

This connector is intended for future interfacing to a standard Nurse Call System.

Two RS-232C connectors are provided for interfacing to peripheral equipment such
as:

 a maternal non-invasive blood pressure monitor

 a central information system that uses Hewlett-Packard’s Digital Series

Interface Protocol

Contact your Service Representative for more information.

CAUTION

NON-DESTRUCTIVE VOLTAGE—The maximum non­destructive voltage that may be applied to the rear panel
connectors is 0 V. Do not attempt to connect cables to these
connectors without contacting your Biomedical Engineering
Department or Service Representative. This is to ensure the
connectors comply with leakage-current requirements of one of
the following applicable standards: Underwriters Laboratories
UL-2601.1, Canadian Standards Associations CSA 22.2 No. 125,
or International Electrotechnical Commission EN60601.1.

Telemetry Connector

This high-density 15-pin connector is intended for future interfacing to the receiver
of a Corometrics telemetry system. Contact your Service Representative for more
information.

IMPORTANT

TELEMETRY—For proper operation when using a telemetry
system, disconnect all transducers from the front panel of the 170
Series Monitor. Refer to the operator’s manual for your telemetry
system for more information.

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For your notes

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Chapter 4

Setup Procedures 4

This section contains information about configuring a 170 Series Monitor to meet
the individual needs of your clinic or hospital. Use of the monitor will vary
according to the accessories attached to it, the clinical applications in which it is
used, and the personal preferences of the users.

This chapter lists all available user setup options in the monitor and provides step­by-step instructions for making selections:

Loading Strip Chart Paper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2

Turning the Monitor On . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-7

Recorder Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-9

Customizing the Monitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-10

Printing a Summary of Configuration Settings . . . . . . . . . . . . . . . . 4-17

Quick Reference Card . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-18

Flasher Software Utility Upgrade . . . . . . . . . . . . . . . . . . . . . . . . . . 4-20

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Setup Procedures: Loading Strip Chart Paper

Loading Strip Chart Paper

The required paper for use with the 170 Series Monitor is:

 catalog number (REF) 4305AAO/CAO

(HR scale of 30–240 BPM); or

 catalog number (REF) 4305BAO/DAO

(HR scale of 50–210 BPM).

CAUTIONS

LOADING PAPER—The instructions for loading paper into a
120 or 170 Series Monitor are different than the instructions for
loading paper into other Corometrics monitors with which you
may be familiar. Improper loading can cause paper jams. Follow
the instructions carefully.

PAPER TYPE—Do not use non-Corometrics paper or paper
designed for use with other Corometrics monitors. Using paper
other than catalog number (REF) 4305AAO/BAO/CAO/DAO:
may produce inferior print quality; could result in permanent
damage to the recorder’s print head; and may void your warranty.

STORAGE/TRANSPORT—Paper should be installed in the
monitor’s strip chart recorder at all times. This reduces particle
build up on the printhead and facilitates opening the recorder door.

To protect against paper jams, the 170 Series recorder contains a paper-loading
sensor which detects if the paper has been incorrectly loaded. When the recorder
detects a paper-load–error condition:

 the recorder will not print;

 the Record indicator flashes on and off every second; and

 three short beeps (low tones) sound every three seconds at a fixed volume.

The most likely cause of a paper-load–error condition is that you loaded the paper
with the black squares facing up. The correct method is to load the paper with the
black squares down, as explained later in this section.

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Setup Procedures: Loading Strip Chart Paper

To install Corometrics catalog number (REF) 4305AAO/BAO/CAO/DAO chart
paper in the 170 Series Monitor, follow these steps:

CAUTION

LOADING PAPER—Paper loading instructions for a 170 or 120
Series Monitor are different than other Corometrics monitors with
which you may be familiar.

1. Press on each side of the paper drawer to release the drawer latches.

Figure 4-1. Releasing the Drawer Latches

2. Slide the paper drawer out toward you.

Figure 4-2. Opening the Paper Drawer

3. Remove the plastic wrapper from the paper and discard.

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Setup Procedures: Loading Strip Chart Paper

4. Fan the pack of Z-fold paper on all sides to loosen any folds and to ensure
proper feed of the paper throughout the recorder.

Figure 4-3. Fanning the Paper

5. Hold the package of paper so that:

 the black squares are on the bottom of the pack; and

 the Information Technologies name and page numbers are on the left side

of the pack.

NOTE: The black squares indicate the end of the recorder paper. When the black

squares appear, the strip chart recorder has approximately 20 minutes of
paper remaining, when running at a speed of 3 cm/min.

Figure 4-4. Orienting the Paper

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Setup Procedures: Loading Strip Chart Paper

6. Unfold two sheets from the top of the pack so that they extend toward you.

Figure 4-5. Creating a Paper Leader

7. Place the pack in the drawer so that the pack is laying flat in the bottom of the
paper tray.

Figure 4-6. Inserting the Paper

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Pull paper
leader taut

Remaining paper

lays flat in drawer

Setup Procedures: Loading Strip Chart Paper

8. Pull the paper leader taut at an angle between remaining pack and the paper
guides. The balance of the paper pack should stay flat in the drawer as shown in

Figure 4-7. (The paper guides are shown in Figure 4-8.)

Figure 4-7. Paper Drawer Side Cutaway View

9. Slide the drawer closed by exerting even pressure on both sides of the drawer.
Avoid skewing the drawer in its tracks. (The pre-printed vertical lines on the
paper should be parallel to the printhead.) You will hear a click when the
drawer is locked in place.

Paper Guide

90

60

30

Printhead

12

10

8

6

4

2

A

U

a

kP

0

Paper Guide

bpm

240

210

180

R
H
F

150

O
A

5A

430

120

Figure 4-8. Closing the Paper Drawer

IMPORTANT

PAPER—Paper should always be installed in the monitor. The
monitor runs a self-test routine each time it is powered on; part of
this routine includes a recorder test.

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Setup Procedures: Turning the Monitor On

Turning the Monitor On

The 170 Series uses a universal AC-to-DC converter which accepts an AC input in
the range 100–230 VAC. The converter supplies a regulated 12 Vdc to the 170
Series Monitor.

1. Connect the AC adapter into the power supply connector labeled:

GE MEDICAL SYSTEMS REF 7714AAT ONLY

Figure 4-9. Connecting the AC Adapter

2. Connect one end of the detachable line cord to the AC adapter; connect the
other end into a hospital grade grounded wall outlet.

.

CONNECT TO

3. Press the monitor’s
illuminates. A self-test routine automatically runs. Read "Monitor Self-Test

Routines" on the next page.

Power button . The green indicator next to the button

Figure 4-10. Turning the Monitor On

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Setup Procedures: Monitor Self-Test Routines

Monitor Self-Test Routines

NOTE: Ensure paper is installed in the recorder in order to verify a successful

recorder test.

Each 170 Series Monitor contains a self-test routine which checks the internal
circuitry of the monitor, the displays and indicators, and the strip chart recorder.
The self-test routine is automatically initiated each time you turn on the monitor.

CAUTION

SELF-TEST FAILURE—If there is any problem with the self-test
routine, turn off the monitor and remove it from operation. Notify
your Biomedical Engineering Department or Service
Representative.

After completion of a successful self-test routine, the monitor is ready for use.

NOTE: If the recorder was off at the time the monitor was turned off, the test

routine will turn the recorder on, then turn it off after the tests are complete.
If the recorder was on at the time the monitor was turned off, the tests will
be performed and the recorder will remain on.

Table 4-1. Summary of Self-Test Routines

Test Description What to Verify

Display/Indicator Test: All displays and indicators

illuminate.

Internal Test: The internal circuitry of the monitor is
verified.

Recorder Test: The following message prints on the
strip chart paper: TEST: ARE ALL DOTS PRINTED?
Three continuous lines are drawn across the strip chart
recorder paper, testing the integrity of the printhead.
See Figure 4-11.

Ensure all indicators and each segment of the displays
illuminate throughout the entire self-test routine.

Make sure the monitor performs the recorder test. If
there is a problem with the internal circuitry, the recorder
test will not be performed.

Ensure that the lines are printed in the correct positions
on the paper. Verify that the lines are continuous and no
gaps appear on the traces.

4-8 170 Series Monitor Revision C

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Setup Procedures: Monitor Self-Test Routines

HR Scale

4305CAO

GE MEDICAL SYSTEMS

PAGES
REMAING

30-240

TEST: ARE
ALL DOTS
PRINTED?

12

10

8

6

FHR

240

210

180

150

120

90

60

30

bpm

41153

100

75

50

4

2

kPa

0

Figure 4-11. Recorder Test

25

0

UA mm Hg

Revision C 170 Series Monitor 4-9

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Setup Procedures: Customizing the Monitor

Customizing the Monitor

User Setup Mode

The monitor includes a user setup mode where you can:

 enable/disable alarm functionality

 set the high alarm limit for the fetal heart rate

 set the low alarm limit for the fetal heart rate

 set the alarm volume

 set the time and date

Service Setup Mode

The monitor includes a service setup mode where you can access all user setup
modes as well as the following:

 enable/disable fetal movement detection

(if purchased and installed)

 select the language for printing on the strip chart paper

 set the chart speed

 select the paper scale

 choose a communication mode for each rear panel communications port

 set the baud rate for each communications port

 select the remote mark annotation style

 enable/disable fetal heart rate offset

(Models 172, 173, and 174 only)

 enable/disable ECG artifact elimination

(Models 173 and 174 only)

 enable/disable heartbeat coincidence

(Models 172, 173, and 174 only)

 set the default UA reference value

 perform a recorder alignment test

 print the software version number along with a summary of all current

configuration settings

4-10 170 Series Monitor Revision C

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EXAMPLE

Setup Procedures: Customizing the Monitor

Setting or value for
selected feature (e.g.
FHR Alarms On or 180
BPM High Alarm Limit).

Monitor Feature Code
(e.g. FHR Alarms or
High Alarm Limit).

Press to enter the

1

user setup mode.

Use

2

3

4

( ) to select
feature code 2FHR
High Alarm Limit.
See Table 4-2.

Press

to switch
displays. The
heartbeat indicator
lights.

Use ( ) to change
the value to 185
BPM. See Table
4-2.

21

21

Press
between displays.

21

Use ( or ) to
change the number.

21

( or ) to

Use
change the number.

to switch

Press to switch between displays.
Repeat steps to change other settings.

Press

5

to switch
displays again. The
± sign lights. (Repeat
steps 2 to 5 .)

21

NOTE: For Models 172, 173, and 174, use the leftmost set of volume controls.

Figure 4-12. Setup Mode Summary (Model 172 shown)

Revision C 170 Series Monitor 4-11

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Setup Procedures: Customizing the Monitor

You can enter the user setup mode during an active monitoring session. The fetal
heart rate and uterine activity trends print without interruption and the FHR tones
remain audible; however you will be unable to see the heart rate and uterine activity
values on the display while in the user setup mode.

You can only enter the service setup mode from a power off state.

NOTE: If an alarm occurs while in user setup mode, the heart rate display will not

flash; however, the alarm indicator flashes and the audio alarm sounds.
As soon as you exit the setup mode, the affected display flashes to indicate
the alarm condition.

1. Enter the appropriate mode, user or service, as follows:

User: To enter the user mode:

 Press the monitor’s Power button to turn on the monitor. Wait until

the monitor completes the self-test routine and enters the normal operating
mode.

 Press and hold the Setup button , for three seconds, to enter the user

setup mode.

Service: To enter the service mode:

 Press and hold the Setup button

 Press and hold the blue Power button .

 Release both buttons. The service mode is now activated.

2. Use the

UA Reference button to toggle between the setup code (shown in

the UA display) and the setting or value (shown in the primary FHR display).
The UA display is active when the
active when the heartbeat indicator

3. Use the

Volume buttons to increase ( ) or decrease ( ) the code,

± qualifier illuminates; the FHR display is

() illuminates.

value, or setting shown in the active display. Refer to Table 4-2 (user codes) or

Table 4-3 (service codes). (For Models 172, 173, and 174, use the leftmost set

of volume controls.)

4. Repeat steps 2 and 3 until all settings are configured.

5. Press the

Setup button to exit the setup mode. Exiting the user setup

mode returns to the monitoring mode; exiting the service setup mode turns the
monitor to standby.

4-12 170 Series Monitor Revision C

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Setup Procedures: Customizing the Monitor

NOTE: If you press the

Power button to exit the setup mode (user or service)

any changes you made will not be stored in memory.

NOTE: You must exit by pressing the

Setup button in order for changes to

take effect.

NOTE: If an alarm is in progress when you exit the user setup mode, any changes

to an alarm setting do not take effect until the alarm condition is resolved.

Table 4-2 lists the available settings for the user setup mode. Table 4-3 lists the

available settings for the service setup mode. Table 4-4 provides a summary of the
factory default settings for both the user and service setup options.

Revision C 170 Series Monitor 4-13

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Setup Procedures: Customizing the Monitor

Table 4-2. Summary of User Setup Codes

Code

(UA Display)

Code Description

Setting or Value

(Primary FHR Display)

1

FHR Alarms

0 = off (disabled)
1 = on (enabled)

2 FHR High Alarm Limit 140–210 (BPM, in increments of 5 BPM)

3 FHR Low Alarm Limit 50–140 (BPM, in increments of 5 BPM)

4 FHR Alarm Volume 2–10

10 Minutes (time setting) 0–59 (minutes)

11 Hours (time setting) 0–23 (hours)

12 Day of Month (date setting) 1–31 (day)

13 Month (date setting) 1–12 (month)

14 Year (date setting) 00–99 (year)

4-14 170 Series Monitor Revision C

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Setup Procedures: Customizing the Monitor

Table 4-3. Summary of Service Setup Codes

Code (UA Display)

Code # Code Description

Setting Or Value

(Primary FHR Display)

20 ECG artifact elimination (173, 174 only) 0 = off; 1 = on

21 heartbeat coincidence (172, 173, 174 only) 0 = off; 1 = on

22 fetal movement enable/disable

1 = on (if option installed)

0 = off

0 = English; 1 = Spanish; 2 = German;

23 language

3 = French; 4 = Japanese; 5 = Italian;

6 = Swedish; 7 = Dutch; 8 = Portuguese;

9 = Chinese

24 chart speed 1= 1; 2 = 2; 3 = 3 (cm/min)

25 paper scale 0 = 30–240; 1 = 50–210 (BPM)

0 = HP; 1 = HP w/notes;

30, 40 communications mode (port 1, 2)

2 = ext BP; 3 = factory test; 4 = ext. FSpO

5 = 115 update; 6 = 115 transmit/receive

3

31, 41 baud rate (port 1, 2)

00; 600; 1200; 2400;

48

00; 9600; 19200; 38400

50 remote mark annotation style 0 = FM; 1 = arrow

2;

51 future use (Japanese units only) 0 = off; 1 = on

52 fetal heart rate offset enable/disable 0 = off; 1 = 10 minute auto-revert; 2 = on

53 UA reference default 5, 10, 15, 20, 25 (relative units)

100 recorder alignment 0–255

Revision C 170 Series Monitor 4-15

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Setup Procedures: Customizing the Monitor

Table 4-4. Summary of Factory Defaults

Setup Option Factory Default Hospital/Clinic Setting

FHR Alarms on

FHR High Alarm Limit 160 BPM

FHR Low Alarm Limit 120 BPM

FHR Alarm Volume 5

Eastern Standard Time or Daylight-

Time/Date

Saving Time—whichever is

applicable

*ECG Artifact Elimination

(Models 173 and 174 only)

*Heartbeat Coincidence

(Models 172, 173, and 174 only)

*Fetal Movement Detection

(if purchased and installed)

*Language

*Recorder Speed

*Paper Scale

*RS-232 Port 1

Communications Mode

*RS-232 Port 1

Baud Rate

*RS-232 Port 2

Communications Mode

*RS-232 Port 2

Baud Rate

off

off

on

set according to shipping

destination

United States: 3 cm/min

International: 1 cm/min

United States: 30–240 BPM

International: 50–210 BPM

HP

1200

ext. BP

600

*Remote Mark Annotation

*HR Offset

(Models 172, 173, and 174 only)

on with 10-minute auto-revert

FM

on ( )

*UA Reference 10 relative units

* = service setup mode

4-16 170 Series Monitor Revision C

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Setup Procedures: Customizing the Monitor

Printing a Summary of Configuration Settings

To print the software version number and a summary of configuration settings on
the strip chart paper:

NOTE: You can only enter the service setup mode from a power off state.

1. Enter the service mode:

 Press and hold the Setup button

 Press and hold the blue Power button .

 Release both buttons. The service mode is now activated.

2. Press the

Record button . Figure 4-13 shows a sample printout.

Figure 4-13. Configuration Summary Printout

Revision C 170 Series Monitor 4-17

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Setup Procedures: Quick Reference Card

Quick Reference Card

Your monitor was shipped with a Quick Reference Card in the appropriate language.
The front side lists the user setup codes while the reverse lists the service setup
codes. The card is laminated and comes with hook and loop adhesives to attach to
your monitor.

A copy of this card is included on the following page if you wish to make additional
copies for training. Additional Quick Reference Cards can be purchased by calling
one of the numbers listed in the front of this manual. Table 4-5 provides a summary
of the Quick Reference Card re-order numbers:

Table 4-5. 170 Series Quick Reference Card

Language Document Part Number

English 2003024-001

Chinese 2003024-002

Dutch 2003024-003

French 2003024-004

German 2003024-005

Italian 2003024-006

Japanese 2003024-007

Portuguese 2003024-008

Spanish 2003024-009

Swedish 2003024-010

Polish 2003024-011

Greek 2003024-013

Russian 2003024-014

Czechoslovakian 2003024-015

4-18 170 Series Monitor Revision C

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Setup Procedures: Quick Reference Card

Revision C 170 Series Monitor 4-19

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Setup Procedures: Flasher Software Utility Upgrade

Flasher Software Utility Upgrade

The Corometrics Flasher is a software utility program which uses one of the
monitor’s RS-232 serial ports to upgrade to a newer software release; or to install a
purchased option such as fetal movement detection. Each Flasher disk contains the
software upgrade for one-time use only. (In other words, you need an individual
Flasher disk for each monitor being upgraded.) Table 4-6 lists the Flasher kits
available for the 170 Series.

Table 4-6. Flasher Kits

Kit Description Catalog Number

Fetal Movement Detection
Feature Addition

Software Upgrade to Version 3.2x
which includes the following
features:

 Heartbeat coincidence
 Portuguese/Chinese languages

(1701BAO only)

 Communications interface to

external FSpO2 monitors

 Communications support of 115

Update and 115 Transmit/
Receive protocols

1700AAO

1701AAO (English language units)

1701BAO (non-English language units)

4-20 170 Series Monitor Revision C

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Chapter 5

Theory of Operation 5

This section of the manual contains the electronic theory of operation for the 170
Series Monitor. When possible, references are made to the appropriate schematic
contained in “Chapter 11, Parts Lists” of this manual

Throughout this chapter, signal names ending with an asterisk (*) are active low.

This chapter contains the following information:

Functional Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2

Main Board Theory of Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . 5-17

FECG/IUP Board Theory of Operation . . . . . . . . . . . . . . . . . . . . . . 5-36

Revision C 170 Series Monitor 5-1

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Theory of Operation: Functional Overview

Functional Overview

For all 170 Series Monitors, the Main Board controls the majority of the 170 Series
functionality including:

 antepartum (US, TOCO) front ends and connector(s)

 uterine activity front end and connector

 seven-segment displays

 user-interface buttons

 peripheral device communications

 processing

For Models 173 and 174, a separate FECG/IUP Board controls:

 intrapartum front ends

 isolation for analog signals

Figure 5-1 provides an overview of the system architecture. Table 5-1 through
Table 5-17 provide pinouts for each of the external connectors and the internal main

board harness connectors. Figure 5-2 through Figure 5-9 provide illustrations of the
front and rear panel connectors.

Display Board

Membrane

Switch Panel

Speaker

Cable

Display

Speaker

Cable

Cable

Membrane

Cable

Printhead

Cable

Sensor

MAIN BOARD

Figure 5-1. Overview of System Architecture

RECORDER MODULE

Printhead and Sensors

5-2 170 Series Monitor Revision C

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Theory of Operation: Functional Overview

Table 5-1. Main Power Connector

Pin Number Description

1 +12 Vdc Input

2 Negative Input

3 Shield

1

2

3

Figure 5-2. Main Power Connector

Revision C 170 Series Monitor 5-3

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Theory of Operation: Functional Overview

Table 5-2. Recorder Printhead Connector

Signal Type

Pin Number Signal Name

(Relative To Recorder

Signal Description

Board)

1 +24V Input +24 Volts for Recorder

2 +24V Input +24 Volts for Recorder

3 +24V Input +24 Volts for Recorder

4 +24V Input +24 Volts for Recorder

5 HGND Input Ground for +24V

6 HGND Input Ground for +24V

7 HGND Input Ground for +24v

8 HGND Input Ground for +24V

9 HGND Input Ground for +24V

10 +5v Input +5V for Logic

11 NC No Connection

12 NC No Connection

13 STB0* Input Head Strobe 0

14 STB1* Input Head Strobe 1

15 STB2* Input Head Strobe 2

16 STB3* Input Head Strobe 3

17 BSCK Input Head Serial Clock (3.07 MHz)

18 LD* Input Head Load Line

19 PDATA Input Head Serial Data

20 NC No Connection

* Active low.

5-4 170 Series Monitor Revision C

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Theory of Operation: Functional Overview

Table 5-3. Recorder Motor Connector

Signal Type

Pin Number Signal Name

(Relative to

Signal Description

Main board)

1 NC No Connection

2 P3 Output Motor Phase 3

3 P4 Output Motor Phase 4

4 +5VM Output +5 Volts for Motor

5 NC No Connection

6 P2 Output Motor Phase 2

7 P1 Output Motor Phase 1

8 +5VM Output +5 Volts for Motor

Table 5-4. Recorder Sensor Connector

Signal Type

Pin Number Signal Name

(Relative to

Signal Description

Main board)

1 NC No Connection

2 MISCOL Input Paper Misload Sensor Collector

3 MISLED Output Paper Misload Sensor LED Voltage

4 GND Output Ground for Sensor

5 NC No Connection

6 OUTCOL Input Paper Out Sensor Collector

7 OUTLED Output Paper Out Sensor LED Voltage

8 GND Output Ground for Sensor

9 DOOR Input Door Switch Input

10 GND Output Ground for Door Switch

Revision C 170 Series Monitor 5-5

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Theory of Operation: Functional Overview

Table 5-5. RS-232 Connector 1

Pin Number Signal Name Signal Description

1 +5V 200 mA Fused

2 RTS Request to Send Output from Monitor

3 RXD Receive Data Input to Monitor

4 GND Signal Ground

5 GND Signal Ground

6 TXD Transmit Data Output from Monitor

7 CTS Clear to Send Input to Monitor

8 +5V 200 mA Fused

Table 5-6. RS-232 Connector 2

Pin Number Signal Name Signal Description

1 GND Signal Ground

2 RTS Request to Send Output from Monitor

3 RXD Receive Data Input to Monitor

4 GND Signal Ground

5 GND Signal Ground

6 TXD Transmit Data Output from Monitor

7 CTS Clear to Send Input to Monitor

8 GND Signal Ground

1

2

3456

78

Figure 5-3. RJ-45 Connector (facing the rear panel from the outside)

5-6 170 Series Monitor Revision C

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Theory of Operation: Functional Overview

Table 5-7. Speaker Connector

Pin Number Signal Name Signal Description

1 SPKR-LO Speaker Low Side Connection

2 SPKR-HI Speaker High Side Connection

Table 5-8. Remote Mark Connectors

(Remote Event Marker and Fetal Acoustic Stimulator)

Pin Number Signal Name Signal Description

1 Tip Remote Event Marker or Fetal Acoustic Stimulator

2 Shunt No Connection

3 NC No Connection

4 Sleeve Ground

1

2

3

4

Figure 5-4. Remote Mark Connectors

Revision C 170 Series Monitor 5-7

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Theory of Operation: Functional Overview

Table 5-9. Ultrasound Connector(s)

Pin # Signal Name Signal Description

1 NC No Connection

2 NC No Connection

3 GND Chassis Ground

4 XMIT/RCV SHIELD Shield for Transmit/Receive

5 XMIT/RCV Transmit/Receive

6 NC No Connection

7 NC No Connection

8 NC No Connection

9 GND Chassis Ground

10 NC No Connection

11 U/S ENABLE* Enable for Ultrasound Channel

12 GND Chassis Ground

* Active low.

879

56

1

8

9

7

12

6

1

10

11

5

23

101112

4

2

3

4

Figure 5-5. US Connector(s) (facing the front panel from the outside)

5-8 170 Series Monitor Revision C

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Theory of Operation: Functional Overview

Table 5-10. FECG Connector (Model 173)

Pin # Signal Name Signal Description

1 NC No Connection

2 FECGEN* Enable for FECG Channel

3 GND Chassis Ground

4 NC No Connection

5 NC No Connection

6 LA Left Arm

7 RA Right Arm

8 SHIELD Shield

9 NC No Connection

10 NC No Connection

11 NC No Connection

12 RL Right Leg

* Active low.

879

56

8

9

7

12

6

1

1

10

11

5

23

101112

4

2

3

4

Figure 5-6. FECG Connector (facing the front panel from the outside)

Revision C 170 Series Monitor 5-9

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Theory of Operation: Functional Overview

Table 5-11. Ultrasound/FECG Combi-Connector (Model 174)

Pin # Signal Name Signal Description

1 NC No Connection

2 FECGEN* Enable for FECG Channel

3 ISOGND Isolated Ground

4 XMIT/RCV SHIELD Shield for Transmit/Receive (isolated ground)

5 XMIT/RCV Transmit/Receive (isolated ground)

6 LA Left Arm

7 RA Right Arm

8 SHIELD Shield (isolated ground)

9 NC No Connection

10 NC No Connection

11 U/S ENABLE* Enable for Ultrasound Channel

12 RL Right Leg

* Active low.

879

56

8

9

7

12

6

1

1

10

11

5

23

101112

4

2

3

4

Figure 5-7. US/FECG Combi-Connector (facing the front panel from the outside)

5-10 170 Series Monitor Revision C

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Theory of Operation: Functional Overview

Table 5-12. Uterine Activity Connector

Pin# Signal Name Signal Description

1 +PRESSURE Positive Input to Pressure Amplifier

2 –PRESSURE Negative Input to Pressure Amplifier

3 NC No Connection

4

+4 VOLT

EXCITATION

+4 Volt Reference

5 NC No Connection

6

GND

(EXCITATION REF)

+4 Volt Reference Ground

7 UA SHIELD Shield

8 NC No Connection

9 NC No Connection

10 NC No Connection

11

NC (171/172)

IUP ENABLE (173/174)

No Connection (171/172)

Mode Enable for IUP (173/174)

12 TOCO ENABLE * Mode Enable for TOCO

* Active low.

879

56

8

9

7

12

6

1

5

23

1

101112

4

2

10

3

11

4

Figure 5-8. Uterine Activity Connector (facing the front panel from the outside)

Revision C 170 Series Monitor 5-11

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Theory of Operation: Functional Overview

Table 5-13. Telemetry Connector

Signal Type

Pin Number Signal Name

(Relative To Main

Signal Description

Board)

1 TMARK/ Input Telemetry Mark Line (active low)

2 TELPR/ Input Telemetry Present (active low)

3

NC (171/172)

TECGEN/ (173)

Input

No Connection (171/172)

Telemetry FECG Enable (173/174)

4 NC No Connection

5

NC (171/172)

TECG (173)

Input

No Connection (171/172)

Telemetry FECG (173/174)

6 TTOCO Input Telemetry TOCO

7 AGND Output Analog Ground

8 TELMAUDIO Input Telemetry US Audio

9 DGND Output Digital Ground

10 NC No Connection

11 TTOCOEN/ Input Telemetry TOCO Enable

12 TUSEN/ Input Telemetry US Enable

13

NC (171/172)

TIUPEN/ (173)

Input

No Connection (171/172)

Telemetry IUP Enable (173/174)

14 NC No Connection

15 NC No Connection

54

3

21

10 9 8 7 6

15 14 13

12

11

Figure 5-9. Telemetry Connector (facing the rear panel from the outside)

5-12 170 Series Monitor Revision C

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Theory of Operation: Functional Overview

Table 5-14. Display Interface (J18)

Signal Type

Pin Number Signal Name

(Relative To Main

Signal Description

Board)

1 D6 Output Main Board Data Bit 6

2 D5 Output Main Board Data Bit 5

3 D7 Output Main Board Data Bit 7

4 DISPLCS* Output Not Used

5 A0 Output Telemetry ECG (173/174)

6 D4 Output Main Board Data Bit 4

7 D1 Output Main Board Data Bit 1

8 D0 Output Main Board Data Bit 0

9 D2 Output Main Board Data Bit 2

10 D3 Output Main Board Data Bit 3

11 SEGA Output Segment A for Pressure ±1 LED

12 SEGB Output Segment B for Pressure ±1 LED

13 SEGC Output Segment C for Pressure ±1 LED

14 SEGD Output Segment D for Pressure ±1 LED

15 +5V Output +5 Volts for LEDs

16 GND Output Ground for LEDs

Revision C 170 Series Monitor 5-13

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Theory of Operation: Functional Overview

Table 5-15. Membrane Switch Panel Interface (J19)

Signal Type

Pin Number Signal Name

(Relative To Main

Signal Description

Board)

1 UAREF* Input UA Ref Switch Input

2 PWRANODE Output Power Indicator LED Anode

3 REC* Input Recorder On Switch Input

4 NC Output No Connection

5 MARK* Input Mark Switch Input

7 PADV* Input Paper Advance Switch Input

6 GND Output Ground

8 RECANODE Output Recorder on LED Anode

9 VOLDN* Input Volume Down Channel 1 Switch Input

10 CANCEL Input Alarm Cancel Switch Input

11 VOLUP* Input Volume Up Channel 1 Switch Input

12 VOLDN2* Input Volume Down Channel 2 Switch Input

13 PWRSWITCH Input Power Switch Input

14 VOLUP2* Input Volume Up Channel 2 Switch Input

15 GND Output Ground for LEDS and Switches

16 MENU Input Menu Switch Input

* Active low.

5-14 170 Series Monitor Revision C

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Theory of Operation: Functional Overview

Table 5-16. FECG/UA Option Interface Part One (J16), Models 173/174 Only

Signal Type

Pin Number Signal Name

(Relative To Main

Signal Description

Board)

1 +12V Output +12 V for FECG Isolated Power Supply

2 GND Output +12 V Ground

3 +5V Output +5 V Supply

4 +7.5V Output +7.5 V Supply

5 2.5VREF Output 2.5 V Reference

6 IUPEN* Input IUP Enable Output

7 +3.3VANA Output +3.3 V for Analog

8 144KC Output 144 KHz for Isolated Power Supply

9 –3.3VANA Output –3.3 V for Analog

10 AGND Output Analog Ground

11 FECGOUT Input FECG Analog Output

12 PRESSOUT Input Pressure Analog Output

13 FECGEN* Input FECG Enable (Active Low)

14 NC (171/172/173)

CLEAR* (174)

—

Output

No Connection (171/172/173)

Clear (Model 174)

15 TOCOEN* Input TOCO Enable

16 NC — No Connection

* Active low.

Revision C 170 Series Monitor 5-15

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Theory of Operation: Functional Overview

Table 5-17. FECG/UA Option Interface Part Two (J15), Models 173/174 Only

Signal Type

Pin Number Signal Name

(Relative To Main

Signal Description

Board)

1 RA Output Right Arm Input from Patient Connector

2 LA Output Left Arm Input from Patient Connector

3 RL Input Right Leg Drive Signal from FECG/IUP Board

4 SHIELDF Output Isolated Shield

5 –PRESS Output UA Channel Negative Input

6 +PRESS Output UA Channel Positive Input

7 ISO4V Input Isolated 4 V Reference

8 ECGEN* Output Enable for FECG Cable

9 4VISOGND Input Isolated 4 V Reference Ground

10 PEN* Output Isolated IUP Enable

11 NC — No Connection

12 ENTOCO* Output Isolated TOCO Enable

* Active low.

5-16 170 Series Monitor Revision C

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Theory of Operation: Main Board Theory of Operation

Main Board Theory of Operation

Figure 5-10 provides a block diagram of the Main Board in the 170 Series Monitor.

The board number varies according to the particular model in the series as
summarized in Table 5-18.

Table 5-18. Main Board Variations

170 Series Model Main Board FRU Number Ultrasound Channels FECG/IUP Board Mount

Model 171 2000244 Single No

Model 172 15269 Dual No

Model 173 2000324 Single Yes

Model 174 2000952 Dual Yes

Revision C 170 Series Monitor 5-17

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Theory of Operation: Main Board Theory of Operation

Audio Module

 Audio amplifier
 Ultrasound volume controls
 ECG/alarm-tone volume

control

Display Interface

 Data buffers
 ESD protection

Ultrasound Module

 Ultrasound transmitter
 Control logic PAL
 Pin diode switches, pre-

amplifier, and demodulator
 Ultrasound envelope filters
 Ultrasound envelope

detector
 Audio frequency doubler

and filters
 Fetal movement bandpass

filters
 Telemetry multiplexor
 A/D converter
 Local voltage regulators

Status/Switch Input Module

 Front panel switch input

buffers

 Rear panel, recorder, and

front-end status buffers

 Motor control latches
 Head control latches
 Status input buffers
 Printhead serial data link

Processing Block

 System processor
 System flash memory
 System boot flash memory
 System RAM
 System address decoder

PAL

 System battery RAM with

real-time clock

Interface to

FECG/UA Board

(173/174)

System Power Supply

 Pre-regulators
 +5 V regulators
 ±3.3 V regulators
 +7.5 V regulators (173/174)
 +24 V regulators
 +11 V regulators (173/174)

Communications Module

 Quad async UART
 RS-232 transceivers

Recorder Interface

Uterine Activity Module

 Pressure differential

amplifier
 +4 V reference
 A/D converter

+12 V input

Figure 5-10. Main Board Block Diagram

5-18 170 Series Monitor Revision C

2000947-004

Processing Block

Theory of Operation: Main Board Theory of Operation

The processing block consists of the processor, system memory, battery RAM (with
real time clock), and address decoder PAL. Figure 5-11 provides a block diagram of
the processing block.

System Boot Flash Memory

(128k x 8)

Battery RAM with

Real Time Clock

(8k x 8)

System SDRAM Memory

(1M x 32 standard)

SH3 Processor

System Flash Memory

 512k x 32 standard
 512k x 32 optional

12.288 MHz Crystal

System Control/Address Decoder PAL

 Address decoding
 Recorder control latch and head

protection timer
 SPI chip select and clock control
 Recorder serial interface

to peripheral devices

Figure 5-11. Processing Circuitry Block Diagram

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Theory of Operation: Main Board Theory of Operation

The processor (U1) is an Hitachi SH3 used with a 32-bit data bus and 24-bit address
bus. Series 100
address, data bus and output lines. The series resistors limit transient response
resulting in better EMI performance. Pull-up resistors prevent these lines from
floating if the processor enters sleep mode which tri-states these lines. Crystal X2 is
the main crystal for the processor running at 12.288 MHz. Mode lines which the
CPU examines at power up are pulled up and down to set the CPU to mode 4. This
allows the CPU to run internally at either X2 x 1 (12.288 MHz) or X2 x 4 (49.152
MHz). The external bus and SYSCLK run at the X1 frequency. Crystal X1 is for the
processor’s real-time clock. The real-time clock is not used; however, in addition to
time/date, it can be used to process interrupts for exiting sleep mode. A MAX809
reset IC (U2) monitors 3 V backup power to hold RESET* low during power up
from the AC line cord and or the DC power cable. Power-up reset using the power
button is accomplished through an external RC circuit (R544 and C285) for a
shorter on reset time.

Four AMD AM29LV800B 8 Mb flash memory parts (U23–U26) are used to provide
4 MB of data storage and non-volatile program memory. The flash parts are
arranged in pairs to allow 32-bit data access. Separate write enable lines allow
access to individual 16-bit words, if required. Chip selects for each flash pair are
controlled by the programmable array logic device (PAL) U4 and are memory
mapped to make all 4 MB appear as a single area of memory.

Ω resistors and 100 kΩ pull-up resistors are provided for all

The system RAM consists of two Hitachi HM5216165 16-Mb SDRAMs (U27,
U28). The processor provides all of the DRAM support signals (RAS, CAS, etc.).
A 32-bit data bus is used and 8- and 16-bit access are supported.

An AT29LV010A 1 Mb flash memory part (U29) is used as a boot ROM. The
processor begins execution from this area of memory (Area 0 / CS0*). An 8-bit data
bus is used.

A battery RAM, with real-time clock MT48T18 (U31), provides the clock and 8k x
8 data storage function for parameters, error logs, etc. Transceiver U30 buffers and
voltage translates data from the 5 V battery RAM.

The PAL (U4) provides the address decoding for the system flash memory, UART,
battery RAM, display, input buffers, and recorder control latches. The PAL also
contains latches which allow control of the printhead, serial peripheral interface
(SPI) chip selects, telemetry, and fetal movement signal controls. PAL U4 also
provides the parallel-to-serial conversion for the printhead data. The PFAIL and
software enable bits are used to disable battery RAM writes. Figure 5-12 provides a
block diagram of the PAL.

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Processor
Address/Data
and Control

Theory of Operation: Main Board Theory of Operation

System Flash ROM

Decoder Bank 1

System Flash ROM

Decoder Bank 2

Recorder Control

Decoder and Latch

 Head strobes
 Head supply control
 Head protection

Recorder Control

Latch Decoder

Motor phase latches

General Decoder and Latch

 SPI (serial peripheral

interface) chip selects

 Front-end/telemetry control

Battery RAM/RTC Decoder

Status Port Decoder

 Front panel buttons
 Recorder status

Display Decoder

UART Decoder

Recorder Printhead

Data Shift Register

Figure 5-12. PAL Block Diagram

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Theory of Operation: Main Board Theory of Operation

Display Interface Module

The display interface consists of a data buffer (U14) for D0–D7 which interfaces to
the ICM7228A seven-segment LED driver IC (U1 on the display board), and D flip­flop U3 which drives the ±1 UA segments through Q1–Q4 transistors. Data lines
have 100 Ω series resistors (R524–R531) which help to reduce emissions. A diode
clamp device (U18) on the data bus is a used to protect against ESD to the display
area. Figure 5-13 provides a block diagram of the display interface module.

to Data Bus

Chip Select and Address

to Data Bus

Latch

Figure 5-13. Display Module Interface Block Diagram

Status/Switch Input Module

The status/switch input module consists of buffers U15 and U16 and series/parallel
elements for protection against ESD. The monitor membrane switch panel provides
11 switch closures to ground which are fed to 100 kΩ pull up resistors and through
10 kΩ series elements. Buffers U14 and U15 are further protected by capacitors to
ground and diode clamp devices U17 and U22. Two LEDs are present on the
membrane switch panel: the power LED is driven by +5 V through resistor R350;
the recorder LED is driven from PAL U4 through buffer U6 and resistor R351.

Figure 5-14 provides a block diagram of the status/switch input module.

Data Buffer

Transistor Drivers

for Pressure

± Display

10

Display Board

4

Membrane Switch Inputs

Data

Buffers

to Data Bus

Recorder Status Inputs

Figure 5-14. Status/Switch Input Module Block Diagram

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Theory of Operation: Main Board Theory of Operation

Communications Module

The communications section consists of quad UART U21 and RS-232 transceivers
U19 and U20. The baud rate frequencies are generated from crystal X3 (3.6864
MHz). Two of the RS-232 channels are used for external communications while the
remaining two provide spare internal channels. Each channel has four ports for
RTS/CTS/general input-output. Both external channels support the RTS/CTS lines.
Transceivers U19 and U20 convert the UART 3 V digital communications lines to
RS-232 levels (±7 V typically) for transmission; and ±7 V RS-232 levels to 3 V
levels for reception. RJ-45 connectors J7 and J8 provide center connection
compatibility to the 6-pin RJ-11 connectors found on the 120 Series Maternal/Fetal
Monitors. The 170 Series uses the larger 8-pin connectors to provide fused power
for future interfacing. Each channel has shunt 1000 pF shunt capacitors for
emissions, 100 Ω series resistors, and clamp devices D6 and D7 for ESD protection.

Figure 5-15 provides a block diagram of the communications module.

to Data Bus

RS-232 Line
Transceivers

(Channel 1)

RS-232 Line
Transceivers

QUAD UART

Miscellaneous Inputs

Miscellaneous Outputs

(Channel 2)

Figure 5-15. Communications Module Block Diagram

TXD, RTS,
RXD, CTS

TXD, RTS,
RXD, CTS

to Rear Panel

to Rear Panel

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Theory of Operation: Main Board Theory of Operation

Recorder Interface Module

The recorder interface consists of motor control, paper status logic, and printhead
control logic. The motor control consists of latch U3, buffer U6, and FET transistors
Q5–Q8. The four phase signals are generated by the processor using U3. These
phases are translated to 5 V and buffered by U6 to drive the FETs which in turn
drive the unipolar motor. Clamp diodes are used to limit the inductive spike
generated when the switches open. The paper status logic consists of paper out and
paper misload optical sensor interface circuitry as well as a door switch interface.
The paper status logic consists of dual digital potentiometer U9, resistors R216 and
R217 for LED drive to the paper out sensor, and R219 and R220 for LED drive to
the paper misload sensor. The digital potentiometer connects to the collector of the
sensor transistor and becomes the variable pull-up. These signals (MISCOIL and
OUTCOIL) are further processed by the analog-to-digital converter to determine the
correct threshold for the two sensors. Clamp device U8 is used for ESD protection.
The door switch input is a switch closure to ground and is read by the processor
through buffer U15. The printhead interface consists of PAL U4 which contains the
printhead control latch, head protection circuitry, and printhead shift register. The
printhead control latch contains the four strobes for the printhead sections, the
printhead load line, and the printhead power supply enable line. The printhead
protection timer consists of a four-bit counter which uses a 2 kHz clock [Usmode,
U4 (pin 35)] to count off six clocks. The counter is enabled when any one of the
four processor-latched strobes is active. After six counts of any active strobe (3 ms),
the counter disables all four output strobes and turns off the +24 V head supply. The
circuit resets when the processor-latched strobes return to an inactive state. The
power fail control line input U4 (pin 76) is also a form of protection which turns off
all strobes and the power supply when the +12 V drops to about 10 V. The
printhead shift register consists of an 8-bit shift register which clocks out D7 first
and clock counters which allow eight clocks to be output for every processor write
to the register. The clock counter also provides a done status bit (BUSY*) which
goes high after all eight bits are shifted out. This status bit is read through the
UART spare port line U21 (pin 28).

Figure 5-16 provides a block diagram of the recorder interface.

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Theory of Operation: Main Board Theory of Operation

to Data Bus

Motor Control Latch

Status Read Buffer

from PAL Device

Printhead Control Latch

Printhead Protection Circuitry

Printhead Data

Shift Register

to Motor

Paper Status Lines

to Printhead
 strobes

 load line
 clock
 data

Figure 5-16. Recorder Interface Block Diagram

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Ultrasound Module

Overview

Isolation Transformer

Theory of Operation: Main Board Theory of Operation

Model 171 and Model 173 Monitors contain a single ultrasound channel board.
Model 172 and Model 174 Monitors contain a dual ultrasound channel board.
The theory contained in this section references the dual ultrasound board but is
applicable to the single ultrasound board as well.

The ultrasound circuitry is a dual channel pulsed Doppler system with Channel 1
and Channel 2. Each channel generates a 1.151 MHz (center frequency) pulsed
carrier signal. This signal carrier causes the crystals in the transducer to emit
ultrasonic waves. When these sound waves enter the maternal abdomen, they
create echoes when encountering an interface between tissues of differing
acoustic impedance. If the interface is moving either toward or away from the
ultrasound transducer, the frequency of the reflected sound differs from the
frequency sent from the transducer.

Model 174 Monitors have an isolation transformer for US Channel 1 signals
since the connector is shared with the FECG Channel.

Ultrasound Transducer

When the reflected sound wave is received by the transducer crystals, it is
converted to an electrical signal. After being amplified, detected, and filtered,
this signal is split into two paths: ultrasound audio and ultrasound envelope. The
audio signal is amplified for driving the speaker, while the ultrasound envelope is
processed for heart rate data.

The center frequency of the transmitted carrier is 1.151 MHz with a pulse
repetition frequency of 2 kHz (single or dual use).

When both ultrasound channels are being used, Channel 1 completes a transmit/
receive cycle while Channel 2 is muted; then Channel 2 completes a transmit/
receive cycle while Channel 1 is muted.

Programmable Array Logic (PAL)

All functions of the pulsed Doppler ultrasound circuit are controlled by a PAL
U50. Integrated circuit U48 latches the transmit and demodulator signals to
prevent race conditions and phase jitter caused by the PAL U50.

Table 5-19 provides a summary of PAL outputs. Figure 5-17 provides a block

diagram of the ultrasound module.

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Theory of Operation: Main Board Theory of Operation

Table 5-19. PAL Outputs

Pin Number Signal Name Signal Description

1 TRANS_BURST Operates the Ultrasound Transmitter.

2 DET_BURST1 Activates the Demodulator.

18 575KC Synchronizes the Power Supplies

19 USMODE Signals the Processor that the

US Channel is Active

21 PIN1 Selects Channel 1 Transducer

22 PIN2 Selects Channel 2 Transducer

42 CH2 Selects CH2 Track and Hold Circuit

43 CH1 Selects CH1 Track and Hold Circuit

US Channel 1

Isolation

Transformer

(174 only)

Transmitter

US Channel 2

Demultiplexor

Telemetry Audio

Input Pin

Diode Switching

CH2

CH1

Telemetry

Switch

Telemetry

Switch

Pre-Amplifier Demodulator

Main

Filter

CH2

AGC

Main
Filter
CH1

Fetal Movement

Detection Filter

Envelope

Detector

Envelope

Detector

CH2

CH1

to Data Bus

A/D

Control Lines

Figure 5-17. Ultrasound Module Block Diagram

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Ultrasound Oscillator

Pin Diode Circuitry

Theory of Operation: Main Board Theory of Operation

Internal gates located in integrated circuit U50, X4, and associated components
comprise a crystal-controlled oscillator running at 4.604 MHz. The inverted output
of this oscillator is the clock that is used to clock latch U48; therefore changes at the
outputs of U50 are not clocked out of U48 until one-half clock cycle later. The
system runs at a frequency of 2 kHz [(4.604 MHz/1151)/2=2 kHz] and the time for
each transmission and reception is 250 µs [(1/2000)/2=250 µs]. The signal
TRANS_BURST is a square wave at a frequency of 1.151 MHz. It is initiated four
clock cycles after the internal reset of the binary counter within U50 used to decode
the signals used by the ultrasound system and continues 428 clock cycles. The
signal DET_BURST1 is also a square waves at a frequency of 1.151 MHz. This
signal is output 640 clock cycles after reset, and continues up to 1020 clock cycles.

The signals PIN1 and PIN2, from PAL U50, turn on the appropriate switches of U47
so as to bias pin diodes D21 and D22 on; this in turn provides a low impedance path
for the Channel 1 transducer to the ultrasound transmitter and preamplifier. Diodes
D23 and D24 are biased off, providing a high impedance path to the ultrasound
transmitter and preamplifier for the Channel 2 transducer. The opposite of the above
is true when the Channel 2 transducer is activated.

Transmission/Reception

Integrated circuits U53, U54, and U55 are voltage regulators used to provide stable,
low-noise power supplies for the ultrasound receiver and transmitter. Transistor
Q11, inductor L1, and capacitor C208 form the ultrasound transmitter. Q11 is
driven by the signal TRANS_BURST. Inductor L2 and capacitors C209, C210, and
CV1 provide tuning for the transmitter output. The transmitter has a nominal output
impedance of 30 Ω, and can typically drive 4 V peak-to-peak into a 20 Ω load.

Transistors Q12, Q13, and Q14, and associated components, form the preamplifier.
Capacitors C213, C215, C229, and C216 provide power supply rejection for the
preamplifier. Inductor L3, along with capacitors C211 and C212, form a series
resonant tank circuit. This tank circuit provides a low impedance path for the
received signals from the transducer, and a voltage gain of approximately 28 dB.
The typical input impedance to this tank circuit is 30 Ωs.

Transistors Q12 and Q13 form a cascode amplifier. Transistor Q13 is a dual n­channel field effect transistor connected in parallel. This parallel connection
provides an improvement of 3 dB in signal-to-noise ratio due to the gain doubling
and the noise adding in quadrature. Inductor L4 and capacitors C214 and CV3 form
a parallel resonant tank circuit with an impedance of approximately 17 kΩs. The
shunt impedance of resistors R388, R389, R390, R391, and R392 effectively lower
this impedance to 3.6 kΩ. The gain of the preamplifier is approximately 19 dB and
is defined by:

Rl/((1/(2*gm))+R386)= 3.6k/((1/.002)+200)

Transistor Q14 and transformer T1 provide a differential output for the preamplifier.
Diode D19 provides protection for Q13 and removes the low impedance tank circuit
L3 and C211, and C212 during transmission by shunting L3. Diode D20 provides
overload recovery for the preamplifier and voltage limiting to the demodulator
through Q14 and T1.

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Theory of Operation: Main Board Theory of Operation

U43 is a quad-switched capacitor integrated circuit configured as a balanced ring
demodulator. Its analog inputs are connected to the differential outputs of the pre­amplifier at the secondary of T1. The switches within the device are actuated by the
signal DET_BURST1.

The two analog outputs of U43 drive the difference amplifier U44 and its associated
components. Integrated circuit U45 switches the output of the difference amplifier
U44 (pin 14) to the track-and-hold circuit of either Channel 1 or Channel 2.

The track-and-hold circuit for Channel 1 is comprised of components R408, C225,
and buffer amplifier U46 (pin 7). The track-and-hold circuit for Channel 2 is
comprised of components R409, C226 and buffer amplifier U46 (pin1).

The track-and-hold circuits retain the amplitude of the last value from the previous
demodulator activation. If this method were not employed, the system gain would
have to be twice as high since it is a time sampled system. The samples must be
integrated over time (averaged) to produce the desired output. In summary, this
method improves the signal-to-noise ratio of the system.

Since the DET signal is driven at the same frequency as the transmitted signal, any
return signal of the same frequency will be averaged and produce either 0 V or a dc
offset at the output of the demodulator; this is not seen by the main filter driven by
the demodulator since it is AC coupled by capacitors C253 and C262. Therefore, a
difference frequency (Doppler shift frequency) must be present to produce an output
from the demodulator. The output of the track-and-hold circuit of Channel 1 at U46
(pin 7) is switched to the Channel 1 main filter through U39 (pin 11) to U39 (pins 6
and 10).

Telemetry (if present) is switched to the Channel 1 main filter through U39 (pin 7)
to U39 (pins 6 and 10). Telemetry FECG (if present) is switched by U39 (pin 3) to
U39 (pins 2 and 15) to the analog-to-digital converter. The main filter is a band-pass
amplifier. Its 3 dB points are 120 Hz and 300 Hz, respectively. The bandwidth
slopes are greater than 40 dB/octave. The maximum gain of the filter is 46 dB with
peaking of approximately 48 dB at 250 Hz. The nominal gain in the system is
approximately 36 dB and is controlled by R454. The Channel 1 main filter is
comprised of U51 and associated components.

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Filtering

Theory of Operation: Main Board Theory of Operation

The main filter is a band-pass amplifier with 3 dB points at 120 Hz and 300 Hz,
respectively. The band width slopes are greater than 40 dB/octave. The maximum
gain of the filter is 46 dB with peaking of approximately 48 dB at 250 Hz. The
nominal gain in the system is approximately 36 dB and is controlled by R454. The
Channel 1 main filter is comprised of U51 and associated components.

The output of the track-and-hold circuit of Channel 2 at U46 (pin 1) is connected
directly to the Channel 2 main filter. The main filter is a band-pass amplifier with 3
dB points are 120 Hz and 300 Hz, respectively. The band width slopes are greater
than 40 dB/octave. The maximum gain of the filter is 46 dB with peaking of
approximately 48 dB at 250 Hz. The nominal gain in the system is approximately
36 dB and is controlled by R467. The Channel 2 main filter is comprised of U52
and associated components. Integrated circuit U40 switches the output of either the
Channel 1 demodulator, the Channel 2 demodulator, or telemetry audio to the fetal
movement band-pass filter. This filter has a gain of 3.5 and corner frequencies of
15 Hz. and 39 Hz, respectively. It is comprised of U41 and associated components.
The output of the fetal movement filter is input to the analog-to-digital converter.

The output of the main filters are input to U10 through capacitors C44 and C45. The
input impedance of these inputs is 10 kΩ, thus producing a high-pass filter at 72 Hz.
A tone is also one of the inputs to U10 through a high-pass filter at 15 Hz and a gain
reduction of –21 dB. The components comprising the filter are C47 and R223. U10
is a quad digital potentiometer with 255 step producing a gain range from 0 to
–48 dB. It is controlled by the serial peripheral interface (SPI) system bus.

Ultrasound Audio

Ultrasound audio (Channel 1 and Channel 2) is output on U10 (pin 8) and U10 (pin

4), respectively. These outputs are buffered by U11 (pin 7) and U11 (pin 8),
respectively. The buffered outputs are high-pass filtered at 80 Hz by C57/R236 and
C58/R237. They are then half-wave rectified by U13 (pin 8) and its associated
components. The output of the rectifier is band-pass filtered from 43 to 260 Hz at a
gain of 7.3 by U13 (pin 1) and its associated components. This effectively doubles
the frequency which is necessary because the transducer operates at a low RF
frequency (1.151 MHz); and the frequencies produced from the fetal heart would not
produce acceptable audio quality.

The output of U13 (pin 1) is input to summing amplifier U11 (pin 14). The tone
output of U10 (pin 18) is also summed by U11 (pin 14) which is a low-pass filter at
2600 Hz with a slope of –12dB/octave. The output of U11 (pin 14) is high-pass
filtered at 72 Hz by C52/R231 to the audio power amplifier.

The audio power amplifier U12 is a bridge type configuration with a gain of 2.5 and
capable of delivering 1.5 W of power into 8 Ω. Figure 5-18 provides block diagram
of the audio module.

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Theory of Operation: Main Board Theory of Operation

Tone Bit

Digital

Potentiometers

for Volume

Channel 1

US Audio

Channel 2

US Audio

Serial Clock and Data

Control (x3)

Ultrasound Envelopes

Summing

Amplifier

Summing

Amplifier

Ultrasound

Audio

Doubler

Bridge

Amplifier

Figure 5-18. Audio Module Block Diagram

The outputs of the main filters are also input to U32 and U35. The input to U35 is
through high-pass filters at 63 Hz. The high pass components for Channel 1 and
Channel 2 are C154/R338 and C159/R357, respectively. The output of the main
filters are also input to U32; this integrated circuit, in conjunction with U35, forms
an AGC (automatic gain control) circuit for both ultrasound channels.

Each of these AGC circuit has a maximum gain of 200 with a dynamic range of 46
dB. Each of the AGC outputs are high-pass filtered by
C169/R343 at 90 Hz with a gain of one, then input to a half-wave detector U36 (pin

7) with a gain of 1.47. The output of the detector circuits are low-pass filtered by
U36 (pin 1)at 20 Hz at gain of ten.

These envelopes are then input to the analog-to-digital converter U38. Other inputs
to the analog-to-digital converter are the telemetry TOCO signal. This signal is
scaled and offset to provide –100 to +400 relative UA units.

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Uterine Activity

Pressure

Pressure

Theory of Operation: Main Board Theory of Operation

Integrated circuit U33, with a gain of 200, and U34 (pin 7), with a gain of 1.25,
provide a total gain of 250 for the on-board tocotransducer pressure channel. The
output of U34 (pin 7) is offset +0.5 V, providing a dynamic range of –80 to +400
relative units. Each relative unit represents 20 µV at the input of U33 through
resistors R318 and R320.

Integrated circuit U42, and its associated components, comprise a charge pump that
converts the +3.3 V to –3.3 V. U38 (pin 11) and U34 (pin 1) comprise a 2.5 V
reference voltage. U71 (pin 7) provides a reference voltage which is half the 2.5 V
reference, called VREF/2. Integrated circuit U56 (pin 7), and associated
components, provides the +4 V required for the tocotransducer.

Figure 5-19 provides a block diagram of the antepartum uterine activity section.

Differential

Amplifier

Gain

Stage

Telemetry TOCO

A/D

to Data Bus

+4 V Reference

Figure 5-19. Antepartum UA Module Block Diagram

+4 V

Reference

Amplifier

+2.5 V

Reference

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Power Supplies

Theory of Operation: Main Board Theory of Operation

Integrated circuit U60 is a voltage comparator that senses that the power has been
removed, and inhibits battery RAM access and recorder printing when the supply
drops to approximately 10 V.

Integrated circuit U58 forms an R-S flip-flop. U58 (pin 6) is set high when the

Power button is pressed. Q19 collector also goes to a logic 1 whenever the Power

button is pressed. When U58 (pin 6) is pulled high, it enables the SYNC signal at
U59 (pin 4) which is inverted by U59 (pin 3) to reach all the switching power
supplies. The sync frequency is 575 kHz and is derived, and hence synchronized to
the ultrasound system. U62 and its associated components comprise a buck
converter with an output voltage of +5.8 V. This is used as the pre-regulator for
linear regulators U65, U66, U68, and U69. U65 provides the system +5 V. U66
provides the +5 V for the recorder motor. U67 provides the +5 V for the audio
amplifier. U68 provides +3.3 V for the analog circuitry. U69 provides the +3.3 V for
the digital circuitry. U61, and its associated components, comprise a linear regulator
with an output voltage of +7.5 V. This is used as the pre-regulator for the linear
regulator U55 which provides the +6 V for the ultrasound front end; it also powers
U53 which provides the –6 V and powers U56 which is used to generate the +4 V
for the tocotransducer circuitry. U64, and its associated components, comprise a
boost converter with an output voltage of +24 V.

Integrated circuit U70, under microprocessor control, is used to control the +24 V
for the recorder printhead. The +24 V output is current limited by Q20, Q21, and
associated components. The power output is limited to 17 W.

Figure 5-20 provides a block diagram of the power supply section.

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Theory of Operation: Main Board Theory of Operation

Power Status Comparator

5 V Linear Regulator

for Audio

5 V Linear Regulator

for Motor

5 V Linear Regulator

for Digital Logic

+12 V
Input

Switching Pre-Regulator

+7.5 V Linear Pre-Regulator

Switching Regulator for
Recorder

 +24 V
 Shutdown digital control
 Sync input from ultrasound

timing

Low Power +3.3 V Regulator

3.3 V Linear Regulator
for Digital Logic

3.3 V Linear Regulator
for Analog Circuitry

6 V

for

Ultrasound

+6 V

for

Ultrasound

+5 V

for

Ultrasound

from Power Switch

Power Off Control

Power Switch Flip-Flop

Switching Regulator Shutdown

Figure 5-20. Power Supply Section Block Diagram

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Theory of Operation: Main Board Theory of Operation

FECG/IUP Board Interface

J16 and J15 provide the interface to the FECG/IUP Board. J15 is patient isolated.

FECG

Connector

Pressure

Connector

Telemetry

Connector

RA, LA, RL

±PRESS

4V REF

Telemetry

FECG In

IUP

12-Bit A/D

FECG/IUP

Board

Figure 5-21. FECG/IUP Board Interface Block Diagram

FECG

Telemetry

FECG Out

Telemetry

Switch

Converter

to Data Bus

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Theory of Operation: FECG/IUP Board Theory of Operation

FECG/IUP Board Theory of Operation

Isolated Power Supply

Patient isolation for the FECG and the IUP catheter is accomplished by providing
floating power supplies to power the FECG and IUP front end electronics.
Integrated circuit U12 provides non-overlapping drive signals to dual FET U9 which
in turn drives the primary of transformer T1. Resistor R94 and capacitor C12
provide dampening for the primary of T1 so as to limit the voltage at the drains of
U9 to a level below their breakdown voltage. The frequency at which the primary of
T1 is switched is 35968.75 Hz which is derived by dividing the signal 144 kHz by
four. The actual frequency of this signal is 143875 Hz and is derived from the PAL
U50 in the ultrasound circuit. Thus the transformer switching frequency is
synchronized to the ultrasound circuit. The secondary of transformer T1 drives
rectifiers D9 and D10. These rectifiers are filtered by C8 and C10 for the positive
power supply, and by C9 and C11 for the negative power supply. Integrated circuit
U3 and its associated components provide a regulated positive voltage (+10 V for
Model 173; +9.3 V for Model 174), while integrated circuit U4 provide a regulated
negative voltage (–10 V for Model 173; –9.3 V for Model 174). Integrated circuit
U1 is a positive precision 2.5 volt reference. The output of U1 is input to the non
inverting input of amplifier U2 (pin 3). The output of this amplifier U2 (pin 1) drives
the emitter follower Q1. The gain of the amplifier-emitter follower is 1.6 and is set
by resistors R3 and R4. The output of Q1 emitter is 4 V (1.6 x 2.5). This voltage is
used to power either an IUP transducer or tocotransducer. Resistor R1 in the
collector of Q1 is used to sense the current drain from other manufacturers of IUP
transducers who don't have an IUP enable associated with them. When the voltage at
the junction of resistors R36 and R37 falls below 1.164 V
(4 mA) the output of the voltage comparator U16 (pin 8) switches from a high state
to a low state, which in turn causes transistor Q3 to turn on and transfer the IUP
enable across the isolated barrier. This signal is named IUPEN*. However If a
tocotransducer is present, this signal is ignored. Transistor Q3 can also be turned on
by the signal PEN*.

For Model 173 and 174 Monitors, integrated circuit U33 and associated components
provide regulation of the power supplied to the FECG/IUP Board circuitry (+12 V
for Model 173; +11.6 V for Model 174).

For a Model 174 only, the CLEAR signal synchronizes the counter in the PAL; this
in effect stops the power supply during the receive cycle of the ultrasound process
for noise reduction purposes.

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Pressure Channel

Theory of Operation: FECG/IUP Board Theory of Operation

The input to the pressure channel is to resistors R9 and R10 with the signal names of
–PRESS and +PRESS respectively. Resistors R9 through R12 and capacitors C16
through C18 provide RF filtering, and in conjunction with diode limiters D1 and D2,
provide protection from electro-static discharge.Instrumentation amplifier U5
provides a gain of 248 which is given by (49.4E3/R13)+1. The output of U5 which
is inverting with respect to the signal –PRESS, drives the inverting amplifier U6 (pin

1). This amplifier has a gain of –4.99 and rolls off at approximately 32 Hz. The
output of U6 (pin 1) drives U6 (pin 5) with a division of two formed by resistors R18
and R19. The operation of this amplifier is best understood if analyzed from its
quiesent condition of no input signal. Under this condition U6 (pin 5) is at zero
volts, therefore U6 (pin 6) must also be at zero volts. This forces a quiesent current
of 75 µA through R20. This current is produced by U6 (pin 7) driving the LED that
illuminates the photodiode at U10 (pins 3 and 4) which is the feedback path. The
LED also illuminates the photodiode at U10 (pins 5 and 6) which are on the non­isolated side. The current transfer ratio of this photodiode with respect to the
photodiode on U10 (pins 3 and 4) is 0.85 to 1.05. The tocotransducer and the IUP
transducer have the transfer function of 5µV/UA-Unit/Volt-excitation. Therefore
since the excitation voltage is 4 V, the input voltage is 0.002V/100UA-Units. This
corresponds to 2.475 V at U6 (pin 1) and 1.2375 Vat U6 (pin 5). This causes a delta
current of 9.3 µA through R20, which is also transferred across the barrier with the
same transfer ratio of 0.85 to 1.05. This current is input to U13 (pin 6) through R32.
Potentiometer R25 sets the gain at U13 (pin 8) to 0.5 V/100UA-Units. Potentiometer
R30 sets the initial offset voltage to +0.5 V. The output amplifier U13 (pin 8) is a
unity gain amplifier with 3 poles of filtering with its 3 dB frequency of 3 Hz. Since
the system analog-to-digital converter has an input range of 0 to 2.5 V, the dynamic
range is from –100 to +400UA-Units.

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FECG Channel

Theory of Operation: FECG/IUP Board Theory of Operation

The input to the FECG channel is two resistors R42 and R43 with the signal names
of RA and LA respectively. Resistors R42, R43, R45, and R462 and capacitors C38
through C40 provide RF filtering, and in conjunction with diode limiters D3 through
D6 provide protection from electro-static discharge. Resistors R40, R41, and R44
cause amplifier U7 to saturate when the FECG cable is not connected to a fetus.
This disables the FECG channel from counting noise and flashing LEDs and causing
tones to be generated by the speaker. Instrumentation amplifier U7 provides a gain
of 13.7 which is given by (49.4E3/R54)+1. Amplifier U2 (pins 5, 6, and 7) is an
integrator which has high gain at DC with reducing gain as frequency increases.

Amplifier U2 (pin 7) drives amplifier U2 (pin8). Amplifier U2 (pin 8) is non­inverting and is patient protected in the event of a failure of this device. The two
sections of U2 provide the right leg drive circuit. The right leg drive is a feedback
circuit that provides drive in the opposite polarity to a common mode voltage. Its
purpose is to cancel DC offset from the electrode, and to help reject 50 and 60 Hz
components. The output of U7, which is inverting with respect to the signal RA,
drives the non-inverting amplifier U2 (pin 12) through a high-pass filter of 10 Hz.
Resistor R58 and diode D7 provide voltage limiting at U2 (pin 12). This amplifier
has a gain of 22.5 and rolls off at approximately 224 Hz. The output of U2 (pin 14)
drives U8 (pin 3) through R64. Resistor R64 and diode D8 provide voltage limiting
at U8 (pin 3). This amplifier has a gain of 22.5 and rolls off at approximately 224
Hz. The composite bandwidth and gain at this point is from 10 Hz to 320 Hz with a
gain of 6936. The output of U8 (pin 1) drives amplifier U8 (pin 5) with a division of
10/11 formed by resistors R67 and R68. The operation of this amplifier is best
understood if analyzed from its quiesent condition of no input signal. Under this
condition U8 (pin 5) is at zero volts, therefore U8 (pin 6) must also be at zero volts.
This forces a quiesent current of 75 µA through R69. This current is produced by U8
(pin 7) driving the LED that illuminates the photodiode at U11 (pins 3 and 4) which
is the feedback path. The LED also illuminates the photodiode at U11 (pins 5 and 6)
which are on the un-isolated side. The current transfer ratio of this photodiode, with
respect to the photodiode, on U11 (pins 3 and 4) is 0.85 to 1.05. The input voltage
required to drive U8 (pin 1) to either of its power supply limits is approximately
±1.44 mV peak. This corresponds to approximately ±5 V at U8 (pin 1) for ±0.72 mV
input, and ±4.55 V at U8 (pin 5). This causes a delta current of 34.2 µA through
R69, which is also transferred across the barrier with the same transfer ratio of 0.85
to 1.05. This current is input to U15 (pin 3) with resistor R75 being the load resistor
that produces a voltage proportional to the current transferred to it. Amplifier U15
(pin 7) produces an offset voltage of –1.97 V. The quiesent current of 75 µA flowing
through R75 will produce a voltage of approximately +1.25 V at U15 (pin 3). A

0.72 mV signal peak-to-peak at the input will produce approximately 1.26 V at U15
(pin 1). Thus ±1.44 mV at the input will produce ±2.52 V at U15 (pin 8). Amplifier
U15 (pin 14) is a non-inverting amplifier with a gain of one. It also provides 3
sections of high-pass filtering at 25 Hz. Amplifier U15 (pin 8) is a non-inverting
amplifier with a gain of one. It also provides 3 sections of low-pass filtering at 90
Hz.

Mode Enables

The FECG enable ties resistor R87 to the floating ground when the FECG cable is
attached. This causes approximately 4.5 mA to flow in the LED of opto-coupler
U17. The current transfer function of the coupler is 19% typically which causes 860
µA to flow in the photo-transistor of U17 in turn causing R103 to be pulled to

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Theory of Operation: FECG/IUP Board Theory of Operation

ground on the non-floating side of the barrier. It is then sensed by the system
microprocessor.

The IUP enable ties resistor R97 to the floating ground when the IUP transducer
cable is attached. This causes approximately 4.5 mA to flow in the LED of opto­coupler U17. The current transfer function of the coupler is 19% typically which
causes 860 µA to flow in the photo-transistor of U17 in turn causing R104 to be
pulled to ground on the non-floating side of the barrier. It is then sensed by the
system microprocessor. The tocotransducer enable ties resistor R100 to the floating
ground when the IUP transducer cable is attached. This causes approximately 4.5
mA to flow in the LED of opto-coupler U17. The current transfer function of the
coupler is 19% typically which causes 860 µA to flow in the photo-transistor of
U17in turn causing R105 to be pulled to ground on the non-floating side of the
barrier. It is then sensed by the system microprocessor.

For a Model 174 only, the ultrasound enable ties resistor R109 to the RL when the
ultrasound cable is attached. This causes approximately 4.5 mA to flow in the LED
of opto-coupler U17. The current transfer function of the coupler is 19% typically
which causes 860 µA to flow in the photo-transistor of U17 in turn causing P16 (pin

6) to be pulled to ground on the non-floating side of the barrier. It is then sensed by
the system microprocessor. In summary, the US1 enable isolated one channel of US
from the Main Board along with a mode enable from the FECG/IUP Board.

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Theory of Operation: FECG/IUP Board Theory of Operation

To Main Board Front End
FECG/IUP Connector

Isolated Side
Connector

RA

LA

RL

PRESS

+PRESS

4 V

FECGEN

 FECG Low Noise

Differential
Amplifier with

Protection Circuitry
 RL Drive Circuitry
 High-Pass Filter

Pressure Differential

Amplifier with

Protection Circuitry

 +4 V Reference
 IUP Detection

Circuitry

To TOCO Enable

Optical

Isolation

Optical

Isolation

To Main Board A/D

Converter for Processing

Unisolated Side

Connector

Filtering

and Gain

Stages

 Gain and Offset

Adjustments

 Filtering Stages

FECGEN

IUPEN

TOCOEN

US1EN (174 only)

Model Line Optical

Isolation for FECG,
IUP, US1 (174 only)

and TOCO

Isolated

Supplies

IUPEN

TOCOEN

US1EN (174 only)

+12 V (173); +11.6 V (174)

Isolated Power

Supply

Q, Q*

Figure 5-22. FECG/IUP Board Block Diagram

144 KHz (173 only)

Power Supply

Control PAL

174 Only

144 KHz

CLEAR*

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