Datex-Ohmeda 3770, 3775 User manual

3770/3775 Pulse Oximeter

Service Manual

%SpO

2

♥

%SpO

2

2798

♥

2798

Not for continuous monitoring

6050-0004-915

Printed in USA

3770/3775 Pulse Oximeter

Service Manual

Important

This manual is subject to periodic review, update, and revision. Customers are
cautioned to verify that the information in this manual applies to the software and
hardware present in the equipment.

Attention! Consult the accompanying instructions before using this
device.

This device performs as described in this manual, and in accompanying labels
and inserts, when assembled, operated, maintained, and repaired in accordance
with the instructions provided.

This device must be cleaned and checked periodically. Do not use a defective
device. Parts that are broken, missing, plainly worn, distorted, or contaminated
should be replaced immediately. If repair or replacement become necessary,
request service advice from Datex-Ohmeda (information is listed on the back
cover). Do not repair this device or any of its parts other than in accordance with
written instructions provided by Datex-Ohmeda.

The user of this device shall have the sole responsibility for any malfunction that
results from improper use, faulty maintenance, improper repair, unauthorized
service, damage, or alteration by anyone other than Datex-Ohmeda.

The safety, reliability, and performance of this device can be assured only under
the following conditions:

• If it is used according to the accompanying operating instructions.

• If fittings, extensions, readjustments, changes, or repairs are carried out by

agents authorized by Datex-Ohmeda.

• If it is used in buildings having ground equalization wiring that complies with

relevant local standards and regulations.

Trademarks

Datex® and Ohmeda® are the property of Instrumentarium Corp. or its

subsidiaries.
FlexConnect is a trademark of Datex-Ohmeda, Inc.
Cidex is a registered trademark of Johnson & Johnson
Duracell is a trademark of Duracell, Inc.
Eveready is a trademark of Eveready Battery Company, Inc.
Formula 409 is a registered trademark of Clorox Company
Hewlet Packard is a registered trademark of Hewlett-Packard Co.
Kodak is a trademark of Eastman Kodak Company
Panasonic is a trademark of Panasonic Industries, Co.
Rayovac and Renewal are registered trademarks and Reusable Alkaline is a

trademark of Rayovac Corporation
Top Crest is a trademark of Safeway, Inc.
Windex is a registered trademark of The Drackett Company
All other product and company names are the property of their respective owners.

Text revised: May 2000

© 1997, 1999, 2000 Datex-Ohmeda, Inc. All rights reserved.

1/Overview

Related information...........................................................................................................1-1

Technical competence.....................................................................................................1-1

General description.....................................................................................................................................1 -2

Theory of operation.....................................................................................................................................1-2

Calibration............................................................................................................................................1-3

Functional components.............................................................................................................................1 -4

Digital board........................................................................................................................................1-5

80-pin board-to-board connector...................................................................1-5

Analog board.......................................................................................................................................1-6

Specifications..................................................................................................................................................1 -7

Electromagnetic effects.................................................................................................................1-7

Environment..........................................................................................................................1-7

EMC performance..............................................................................................................1-7

International Electrotechnical Commission (IEC) classifications.........................1-7

Compliance with standards.......................................................................................................1-8

Oximeter................................................................................................................................................1-8

Default settings.....................................................................................................................1-8

General......................................................................................................................................1-8

Visual displays and indicators.......................................................................1-8

Dimensions................................................................................................................1-8

Power............................................................................................................................1-9

Circuitry......................................................................................................................1-9

Sensor emitter wavelength ranges..............................................................1-9

(3775 only) Audio indicators...........................................................................1-9

SpO2...........................................................................................................................................1-9

Range............................................................................................................................1-9

Accuracy.....................................................................................................................1-9

Calibration.................................................................................................................1-9

Interfering substances.........................................................................................1-9

(3775 only) Alarm limits....................................................................................1-9

Pulse rate .................................................................................................................................1-9

Range............................................................................................................................1-9

Accuracy.....................................................................................................................1-9

Environmental................................................................................................................... 1-10

Operating................................................................................................................ 1-10

Storage...................................................................................................................... 1-10

Battery packs.................................................................................................................................... 1-10

AA battery pack ................................................................................................................ 1-10

Recommended brands.................................................................................... 1-11

NiCd rechargeable battery pack............................................................................. 1-11

Environmental—NiCd and AA................................................................................. 1-11

Operating................................................................................................................ 1-11

Storage...................................................................................................................... 1-11

Precautions....................................................................................................................................................1-12

Warnings............................................................................................................................................ 1-12

Handling............................................................................................................................... 1-12

Failure of operation........................................................................................................ 1-12

Explosion hazard.............................................................................................................. 1-12

Fire hazard.......................................................................................................................... 1-12

Contents

i

Contents

2/ Troubleshooting

3/Service Policy and Repair Procedures

Electrical shock and flammability hazard ........................................................ 1-12

Electrical shock hazard ................................................................................................ 1-13

Patient safety....................................................................................................................... 1-13

Operator safety.................................................................................................................. 1-13

Sensors................................................................................................................................... 1-13

Data validity........................................................................................................................ 1-13

Cautions.............................................................................................................................................. 1-14

Static sensitivity................................................................................................................ 1-14

Battery packs....................................................................................................................... 1-14

Cleaning................................................................................................................................ 1-14

HP printer............................................................................................................................ 1-14

Disposal.................................................................................................................................. 1-14

3770/3775 pulse oximeter.....................................................................................................................2-2

Printer..................................................................................................................................................................2-5

Battery charger monitoring station.....................................................................................................2-6

Battery charger (single)..............................................................................................................................2 -8

Service policy..................................................................................................................................................3 -1

Ordering parts and obtaining service..................................................................................3-1

Packaging and returning equipment....................................................................................3-2

Safety guidelines...........................................................................................................................................3 -2

Cleaning procedures...................................................................................................................................3 -3

Oximeter, battery packs, and battery chargers ...............................................................3-3

Sensors....................................................................................................................................................3-3

Inspecting the oximeter and replacing parts...............................................................................3-4

Disassembling the oximeter .......................................................................................................3-4

Replacing parts..................................................................................................................................3-5

Assembling the oximeter .............................................................................................................3-5

Checking normal operation....................................................................................................................3-7

4/Illustrated Parts

Service kits—3770 and 3775 oximeters.........................................................................................4-1

3775 oximeter assembly..........................................................................................................................4 -2

3775 assembly parts........................................................................................................................4-2

3775 assembly illustration...........................................................................................................4-3

3770 oximeter assembly..........................................................................................................................4 -4

3770 assembly parts........................................................................................................................4-4

3770 assembly illustration...........................................................................................................4-5

ii

1/Overview

This manual contains instructions for servicing the Datex-Ohmeda 3770 and 3775
Pulse Oximeters.

This chapter contains:

• A general description of the oximeter and its functional components.

• Oximeter and battery pack specifications.

• Precautions, including specific warnings and cautions, you must follow when

Related information

The content of this manual assumes you are familiar with how the unit operates.
For a detailed description of the unit’s components, key functions, and general
operating guidelines, see the Datex-Ohmeda 3770/3775P Pulse Oximeter User’s
Manual. General maintenance procedures contained in that manual, such as how
to replace batteries in the AA battery pack, are not repeated in this manual.

If you need to reference printed circuit board schematics and component lists,
purchase and refer to the information contained in the 3770/3775 PCA Drawings
Service Kit, REF 6050-0005-558.

You’ll find detailed instructions for servicing and repairing the battery charger
monitoring station in the Battery Charger Monitoring Station Service Manual (REF
6050-0003-861). If you need to replace fuses or change the voltage selection for the
monitoring station, refer to that manual.

servicing the oximeter.

Note: The NiCd and AA battery packs, the single-station battery charger, and the
Hewlett-Packard® (HP) printer are not serviceable accessories.

For information on sensor application and cleaning (reusable sensors only), see the
instructions for the sensor.

Technical competence

CAUTION: Only qualified service personnel should perform the procedures described in this manual.

Only Datex-Ohmeda service personnel or competent individuals who are
experienced with servicing medical devices of this nature should perform the
procedures described in this manual.

1-1

3770/3775 Pulse Oximeter Service Manual

General description

Two models of the oximeter are available: the 3770 and the 3775. Both oximeters
operate on power supplied by a battery pack. In addition, either oximeter, when a
nickel-cadmium (NiCd) battery pack is attached, can be positioned in the battery
charger monitoring station and operated using the station’s DC (from AC mains)
power supply.

• The 3770 oximeter is designed specifically for spot checking SpO

rate. It has no alarms or user-definable parameters and is not intended for
continuous monitoring.

• The 3775 oximeter is a full-featured model designed for spot checking in

addition to short- and long-term continuous SpO2 and pulse rate monitoring.
This model can print trend data, through an infrared link, to the optional
Hewlett-Packard® (HP) printer.

Note: Throughout this manual, components and features available on both
oximeter models and those found only on the 3775 oximeter are discussed. If you
are working on the 3770, references to components specific to the 3775 do not
apply.

Theory of operation

The oximeter uses a two-wavelength pulsatile system—red and infrared light—to
distinguish between oxygenated (O2Hb) and reduced (HHb) hemoglobin, each of
which absorbs different amounts of light emitted from the oximeter sensor. The
system then calculates the relative percentage of these two constituents and SpO2.

Variable absorption
(Due to arterial pulse)

Arterial blood absorption

Venous blood absorption

and pulse

2

1-2

Absorption

Other tissue absorption

Figure 1-1. Signal composite

Arterial blood pulsation at the test site modulates the transmission of the oximeter
sensor’s light. Since other fluids and tissues present generally don’t pulsate, they
don’t modulate the light passing through that location. The pulsatile portion of the
incoming signal is used to detect and isolate the reduction of light energy due to
arterial blood flow.

Time

1/Overview

1

(Red)

660 nm

)

0

x

Extinction (10

-1

-2
600 700 800 900 1000

Wavelength (nm)

Figure 1-2. Extinction vs. wavelength

The sensor’s photodetector converts the light, which is partially absorbed and
modulated as it passes through the tissue sample, into an electronic signal. Since
O2Hb and HHb allow different amounts of light to reach the photodetector at the
selected wavelengths, the electronic signal varies according to the light source that
is “on” and the oxygenation of the arterial hemoglobin. Analog and digital signal
processing then convert the light-intensity information into SpO2 and pulse rate
values for display on the monitor.

(Infrared)

940 nm

O2Hb

HHb

Calibration

Datex-Ohmeda pulse oximeters use two wavelength ranges, 650 nm to 665 nm and
930 nm to 950 nm, both with an average power of less than 1 mW. These wavelengths
are used to calculate the presence of oxyhemoglobin (O2Hb) and reduced hemoglobin
(HHb). A CO-oximeter typically uses four or more wavelengths of light and calculates
reduced hemoglobin (HHb), oxyhemoglobin (O2Hb), carboxyhemoglobin (COHb), and
methemoglobin (MetHb). Because of this, pulse oximetry readings and CO-oximetry
readings will differ in situations where a patient’s COHb or MetHb are increased.

Two different methods of calibration are currently used by oximeter manufacturers:
fractional and functional.

• The fractional saturation is determined by dividing the oxyhemoglobin by the

total hemoglobin, represented mathematically as

Fractional SpO2 = x 100 = x 100

O2Hb

Hb

TOTAL

O2Hb + HHb + COHb + MetHb

O2Hb

i.e., the percentage of the total amount of hemoglobin carrying oxygen.

• The functional saturation is represented mathematically as

Functional SpO2 = x 100 = x 100

Hb

O2Hb

- COHb - MetHb O2Hb + HHb

TOTAL

O2Hb

i.e., the percentage of hemoglobin capable of carrying oxygen that is carrying
oxygen.

1-3

3770/3775 Pulse Oximeter Service Manual

The calculation of SpO2 assumes 1.6% carboxyhemoglobin (COHb), 0.4%
methemoglobin (MetHb), and no other pigments. Appreciable variation from
these values will influence SpO2 accuracy. These values are based on the Datex­Ohmeda Pulse Oximeter Empirical Calibration Study.

The 3700/3775 uses the fractional calibration method.

Functional components

Figure 1-3 illustrates the relationship between each functional component.

Battery pack/

AC adapter

Power

Return

Temperature

Battery monitor

board

Analog boardDigital board

Power supplyOn/Off

Signal pathDigital core

Figure 1-3. System block diagram

A complete oximetry system requires digital and analog processing. The digital
board provides signal acquisition, numerical processing, and user interface for the
oximeter. The analog board amplifies and conditions the biological signal. The
digital board then samples the conditioned signal, performs the oximetry
algorithm, and displays the results on numeric and graphic LED displays.

The user interface features an eight-character dot-addressable LED display, a
24-segment LED driver, a variable frequency audio driver, and (for the printer
option) an infrared wireless transmitter.

Sensor

1-4

Digital board

1/Overview

The core processing of the digital board is provided by a 16-bit processor,
nonvolatile FLASH memory, semivolatile SRAM, and a Real Time Clock. For
signal acquisition, it has an A-to-D converter (which is internal to the processor),
I/O ports for timing and control, and an 8-bit D-to-A converter.

On/Off

Power control

(Reset control)

Ambient light

detection

Rotary encoder

and

pushbuttons

Code memory

Data memory

Address

decode

Processor

Analog

Signal

Path

Timing

Analog board

80-pin

connector

Programmable

interval

timer (PIT)

Real-time

clock

Alphanumeric

LED display

LED driver

(bargraph, low

battery, alarm bar)

Peripheral

I/O (PPI)

Audio tone

generator

I.R.

wireless

transmitter

Digital-to-analog

converter (DAC)

Figure 1-4. Digital system block diagram.

80-pin board-to-board connector

The 80-pin board-to-board connector interfaces with the analog board and contains
signals shared by both boards: power supplies, rotary encoder signals, oximetry
timing and control, and many ground connections.

1-5

3770/3775 Pulse Oximeter Service Manual

Analog board

The analog board provides the oximetry analog signal processing, sensor LED
drive, detection of interfering signals, housekeeping and fault monitoring, standby
and operational power, power switching, and battery interface. It also provides
structural support for the digital board and the battery contacts. It contains
attachments for the sensor connector, rotary encoder, and serial port. It also
provides the grounding system for the case shield with EMC capacitors to shunt
high-frequency currents.

VCC

UPS

-V

-PROBE

D

I

G

I

T

A

L

B
O
A
R
D

>

INTDET-

AVG DRV

VREF

LEDDRV

LOBAT

AMUX

INTF

MUX 0-3 , MUX 3-

ACA - ACC

VERN

RED

IR

RLT

IRLT

DARK

DLT

PETE

DISABLE

+VSW

REXPULSE

REXCHA

REXCHB

REXPB

OPERATE / TEST

TXD

RXD

GROUND*

A
N
A
L
O
G

5

B
O
A
R
D

<

>

<

GROUND

<

DETECTOR

DET RETURN*

IR CATHODS

RED CATHODE

ANODES*

PROBE ID

ID RETURN

VBATT

BATMON

BATTERY RETURN*

GROUND*
GROUND*

REXPULSE

REXCHA
REXCHB

REXPB

SERIAL PORT

Sensor

Battery

assembly

Rotary

encoder

*Essential grounds

1-6

Figure 1-5. Analog board and digital board system

Note: The rotary encoder is installed on the 3775 analog board only; in all other
respects the 3770 and 3775 analog boards and their components are identical.

Specifications

Electromagnetic effects

1/Overview

Unless otherwise indicated, all specifications are nominal and are subject to
change without notice. Unless otherwise indicated, the specifications below apply
to both oximeters.

The 3770 or the 3775 when used with a LR6 (AA) battery pack, a NiCd battery
pack, or a NiCd battery pack in a battery charger monitoring station are referred
to as the “system” for EMC purposes.

• Indications that the system is experiencing electromagnetic interference

include:

• Variations in the display (pleth bar does not correlate to physiological signals).

• Sudden increases or decreases in the signal strength indicator that do not

correlate to physiological condition of the patient.

• PROBE? messages that are not resolved by the instructions found in the

3770/3775 Pulse Oximeter User’s

•

T

he display of “rolling dots” when a valid physiological signal is present.

Manua.

This interference may be intermittent and careful correlation between the effect
and its possible source is important. The system will not display any of these
indications if it is used within its intended electromagnetic environment.

Environment

Suitable for use in the environment described in IEC/EN 60601-1-2 (1993).

EMC performance

The system complies with the requirements of IEC/EN 60601-1-2 (Electromagnetic
compatibility - Requirements and tests). The following basic EMC standards were
applied to verify conformance.

Emissions: IEC/EN 55011 Group I, Class B (1997)

Immunity: IEC/EN 61000-4-2 (1995), 8 kV air, 3kV contact

IEC/EN 61000-4-3 (1995), 3 V/m
IEC/EN 61000-4-4 (1995), 2 kV power, 1kV I/O
IEC/EN 61000-4-5(1995), 2 kV line to earth, 1 kV line to line

International Electrotechnical Commission (IEC) classifications

The oximeter complies with the requirements of IEC/EN 60601-1 (1988) Part 1:
General requirements for safety of medical electrical equipment:

Degree of protection against electric shock: Type BF applied part

IPX3

Type of protection against electric shock: Internally powered equipment/Class II

Mode of operation: Continuous

Degree of protection against ingress of liquids: Sprayproof (IEC/EN 60529)

1-7

3770/3775 Pulse Oximeter Service Manual

Compliance with standards

The presence on the device of any symbol described below indicates compliance
with the standard represented by that symbol.

Medical Device Directive 93/42/EEC of the European Union for a

0197

class I (with a measuring function), IIa, IIb, or III device.

Medical electrical equipment classified with respect to electric
shock, fire, and mechanical hazards only, in accordance with the
Canadian Standards Association CAN/CSA C22.2 No. 601.1 (1990).

Medical electrical equipment classified with respect to electric
shock, fire, and mechanical hazards only, in accordance with
Underwriters Laboratories Inc. UL 2601-1 (1994).

Oximeter

Default settings

Each time you power on the oximeter the following system settings are in effect:

• Low-SpO

• High-SpO

• Alarm volume = On

• Pulse beat volume = Off

• SpO

Settings for time, date, and language are retained when the system is powered off
as long as a battery is in place.

alarm limit = 85

2

alarm limit = On

2

averaging interval = 12 seconds

2

1-8

General

Visual displays and indicators

The displayed SpO2 and pulse rate values are updated every second. The

plethysmographic waveform sweep is updated every 4 seconds.

Main display: 8-character alpha-numeric; green; variable intensity dependent on

ambient light conditions
Waveform display: 8 green LEDs
Signal strength indicator bar: 4 LEDs (1 dark green, 1 yellow green, 1 yellow, and

1 orange)
Low battery indicator: 1 orange LED
Alarm bar (3775 only): red
Display update interval: 0.5 seconds
Display hold interval: 12 seconds

Dimensions

Height: 18.54 cm (7.3 inches; 9.5 inches including FlexConnect™)
Width: 7.62 cm (3.0 in.)
Depth: 5.33 cm (2.1 in.)
Weight: 0.33 kg (9.6 oz.) without battery pack

Power

Typical consumption: 1.6 W
Typical current: 180 mAmps

Circuitry

Microprocessor controlled
Automatic self-test at power on
Automatic setting of default parameters (3775 only)
Automatic alarm messages
Automatic/continuous system diagnostics

Sensor emitter wavelength ranges

Red LED peak wavelength range: 650 to 665 nm
Infrared (IR) LED peak wavelength range: 930 to 950 nm
Average power: ≤ 1 mW

(3775 only) Audio indicators

Alarm volume: On (default) and off
Pulse rate volume: On and off (default)
Pitch modulation to reflect changing SpO2 levels
Alarm silence (120 seconds)
Low- and high-SpO2 out-of-limits alarm
Sensor condition alarms
System failure alarms

1/Overview

S p O

2

Range: 0 to 100%

Accuracy (±1 standard deviation)

80 to 100% ± 2%
60 to 79% ± 3%
Below 60% unspecified

Calibration: fractional

Interfering substances

Carboxyhemoglobin may erroneously increase readings. The level of increase is
approximately equal to the amount of carboxyhemoglobin present. Dyes, or
substances containing dyes, that change usual arterial pigmentation may cause
erroneous readings.

(3775 only) Alarm limits

Low = 60 to 99%
High = 61 to 100% and OFF

Pulse rate

Range 40 to 235 beats per minute

Accuracy ± 1.7% of current reading

(accuracy calculations assume a constant pulse rate)

1-9

3770/3775 Pulse Oximeter Service Manual

Environmental

Operating

Temperature: 0 to 50 ºC (32 to 122 ºF)
Humidity: 0 to 95% RH, noncondensing
Atmospheric pressure: 550 to 1,060 hPa (8 to 15.4 psia)
Vibration: Meets or exceeds:

Drop/shock: Meets or exceeds:

Storage

Temperature: –40 to 70 ºC (–40 to 158 ºF)
Humidity: 0 to 95% RH, noncondensing
Atmospheric pressure: 496 to 1,060 hPa (7.2 to 15.4 psia)
Vibration: Meets or exceeds:

Drop/shock: Meets or exceeds:

ASTM 4728, (Method C)
MIL-STD-810E, Method 514.4, Section I.3.4.3
IEC/EN 60068-2-37

IEC/EN 60068-2-32 (Procedure 1)
MIL-STD 810E, Method 516.4, Section I.3.6

ASTM 4728, (Method C)
MIL-STD-810E, Method 514.4, Section I.3.4.3

IEC/EN 60068-2-32 (Procedure 1)
MIL-STD 810E, Method 516.4, Section I-3.6

Battery packs

The operation time depends on the monitoring technizue (long monitoring cycles
or short, spot-checks).

AA battery pack

Weight: 0.12 kg (4.4 oz.) without cells; 0.26 kg (9.3 oz.) with cells.

Capacity, operation time, charge time, and life cycle depend on the battery cell.

Figure 1-6. AA battery life cycles

Battery type Life expectancy in hours

05101520

Alkaline (8 to 15 hours)

Rechargeable alkaline (2.5 to 8 hours)

Lithium (10 to 20 hours)

Carbon (2 to 4.5 hours)

1-10

Low battery indicator LED lights depending on the battery cell, as follows:

Alkaline <2.5 hours

Alkaline rechargeable <1 hour

Carbon <2 hours

Lithium <1 hour

Recommended brands

Alkaline Lithium Carbon

Duracell ™ Eveready Eveready
Eveready™ Rayovac
Kodak™
Panasonic™
Rayovac®, including

rechargeable "Renewal®"

Top Crest™

NiCd rechargeable battery pack

Weight: 0.43 kg (12.5 oz.)
Power: 9.6 V, sealed nickel-cadmium (8 cells)
Capacity: 1.4 A-hours
Operation time: 8 hours
Charge time: 2 hours
Life cycle: 1 year (500 cycles)

Low battery indicator LED illuminates when battery usage time is at or below

15 minutes.

~

1/Overview

Environmental—NiCd and AA

Operating

Temperature: 0 to 50º C (32 to 122 ºF) – NiCd

0 to 40º C (32 to 104 ºF) – AA
Humidity: 0 to 95% RH, noncondensing
Atmospheric pressure: 550 to 1,060 hPa (8 to 15.4 psia)
Vibration: Meets or exceeds:

ASTM 4728 (Method C)

MIL-STD-810E, Method 514.4, Section I.3.4.3

IEC/EN 60068-2-37
Drop/shock: Meets or exceeds:

IEC/EN 60068-2-32 (Procedure 1)

(NiCd) MIL-STD 810E, Method 516.4, Section I-3.6

Storage

Temperature: –40 to 50 ºC (–40 to +122 ºF)
Humidity: 0 to 65% RH (±20%) noncondensing
Atmospheric pressure: 496 to 1,060 hPa (7.2 to 15.4 psia)
Vibration: Meets or exceeds:

ASTM 4728 (Method C)

MIL-STD-810E, Method 514.4, Section I.3.4.3
Drop: Meets or exceeds:

IEC/EN 60068-2-32 (Procedure 1)

1-11

3770/3775 Pulse Oximeter Service Manual

Precautions

Two types of precautions appear in this manual: warnings and cautions.

• A WARNING indicates a potentially harmful situation that may cause injury to a

patient or operator.

• A CAUTION indicates a condition that may lead to equipment damage or

malfunction.

Read this section fully and carefully before using or servicing the oximeter and its
accessories.

Warnings

Handling

Handle the oximeter and its accessories with care. Improper handling can cause
damage or inaccurate operation of these devices.

Failure of operation

If the oximeter fails to respond as described, do not use it until qualified personnel
have corrected the situation or the unit has been serviced.

Explosion hazard

Do not use the oximeter, printer, or battery charger in the presence of flammable
anesthetics or other flammable substances in combination with air, an oxygen­enriched environment, or nitrous oxide.

Use only a 3770/3775 battery pack as part of the oximeter.

Cadmium is a hazardous substance. Do not incinerate or burn a NiCd battery
pack. Dispose of a battery pack through an approved hazardous material disposal
facility or by returning it to Datex-Ohmeda for reclamation.

Use only a Datex-Ohmeda battery charger to recharge or condition a Datex-Ohmeda
NiCd battery pack. Do not use a Datex-Ohmeda battery charger to recharge or
condition a NiCd battery pack that is not made by Datex-Ohmeda.

Do not expose a battery pack to any temperature that is hotter than you can
tolerate to touch.

Fire hazard

To protect against fire hazard, replace the fuses in the battery charger only with
fuses of the same type and local line voltage rating.

Electrical shock and flammability hazard

Before cleaning or servicing the oximeter, always turn it off.

1-12

Before cleaning or servicing the printer, always turn it off and disconnect the
power cord from the AC mains power supply.

Before cleaning or servicing the battery charger, always disconnect the power cord
from the AC mains power supply.

1/Overview

Electrical shock hazard

To protect yourself from possible electric discharge when the cover of the unit is
removed and the unit is receiving power, avoid contact with internal components.

Do not attempt to repair the printer, battery pack, or single-station battery charger.
They are not serviceable parts.

The battery charger must be properly grounded.

• Insert the three-connector plug on the power cord into a three-wire, grounded

hospital-grade receptacle only. If a three-wire receptacle is not available, a
qualified electrician must install one in accordance with the governing
electrical code.

• Never remove the grounding connector from the power plug. The power cord

and plug must be intact and undamaged.

• Do not use extension cords or adapters.

Patient safety

Never test or perform maintenance on equipment while it is being used to
monitor a patient.

Operator safety

Do not handle hot or leaking battery packs or batteries.

Sensors

Discard a damaged sensor immediately. Do not repair a damaged sensor or use a
sensor repaired by others.

To prevent injury or equipment damage, use only Datex-Ohmeda oximeter sensors
approved for use with this oximeter. For complete information about the safe and
appropriate use of a sensor, consult the instructions for that sensor.

Data validity

To prevent erroneous readings, do not use an inflated blood pressure cuff or
arterial blood pressure measurement device on the same limb as the oximeter
sensor.

Interfering substances, excessive ambient light, excessive motion, low perfusion,
low signal strength, incorrect sensor placement, or electrical interference at the
sensor site can result in the display of inaccurate SpO2 data.

1-13

3770/3775 Pulse Oximeter Service Manual

Cautions

US Federal and Canadian laws restrict this device to sale by or on the order of a
licensed medical practitioner.

Only qualified service personnel should perform the procedures in this manual.

Static sensitivity

Internal electronic components are susceptible to damage by electrostatic
discharge. To avoid damage when disassembling the monitor, observe the
standard precautions and procedures for handling static-sensitive components.

Battery packs

To prevent battery pack damage,

• Never attempt to take a battery pack apart. Access only the battery

compartment for replacing batteries in the AA battery pack.

• Never attempt to replace a cell in the NiCd battery pack. The set of eight cells

is matched for capacity and improper operation could occur.

• Do not put a battery pack where it can be short-circuited by contact with

metal objects, such as in a pocket with keys.

• Use only batteries recommended by Datex-Ohmeda in the LR6(AA) battery pack.

Service diagnostic mode is to be used by Datex-Ohmeda service personnel only.

Cleaning

Do not autoclave, pressure sterilize, or gas sterilize the oximeter, printer, battery
pack, or battery charger.

Use cleaning solution sparingly. Do not immerse the oximeter, printer, battery
pack, or battery charger in liquid. Excessive solution can flow into the device and
cause damage to internal components.

When cleaning the display lens, do not use abrasive cleaning compounds or other
materials that could damage the lens.

Do not use petroleum-based solutions or solutions containing acetone, ethanol,
freon, trichloroethylene, or harsh solvents to clean the oximeter, printer, battery
pack, battery charger, or the protective covering on these devices. These
substances attack the devices’ materials and device failure may result.

When cleaning reusable oximeter sensors, follow all warnings and cautions stated
in the sensor user instructions.

Disposable sensors are intended for single patient use only.

HP printer

To avoid damage to the printer, use only an AC adapter recommended by and
available from Datex-Ohmeda.

1-14

Disposal

When the oximeter has reached the end of its useful life, dispose of it in
accordance with local procedures and regulations.

2/Troubleshooting

This chapter contains:

• Tables containing messages that may be displayed on the oximeter and

conditions that may occur while using the oximeter.

• A list of the possible causes for the message or condition.

• Recommended actions for responding to the message or to correct the

condition. These actions include troubleshooting procedures to help you
determine what needs to be done to correct the condition.

The tables in this chapter include the instruction to swap boards. This means you
should replace one board at a time with a like board you know is functioning
correctly to determine which board has failed. In most cases you are instructed to
start with a specific board.

Also included in the tables are references to possible failure points. This
information suggests component areas on a specific board that may have caused
the malfunction. To repair the unit, always replace the board. Do not attempt to
repair the board at the component level.

2-1

3770/3775 Pulse Oximeter Service Manual

3770/3775 pulse oximeter

Message Cause(s) Recommended action(s)

BOOTCODE The unit failed the power-on

sequence of diagnostics.

PRINT <XX

(3775 only)

PROBE? The sensor is not attached or not

Trend is printing to the printer.
XX represents the amount of
time remaining (in minutes) to
complete printing.

properly applied.

Replace the digital board. See chapter 3.

No action required.

Attach the sensor.

SERVICE

(alternates repeatedly
with an error
code/type message)

The sensor is not connected to
the oximeter.

The sensor is not compatible
with the oximeter.

The sensor has failed.

The system or one of its
components has failed.

Check the sensor site; make sure the
sensor is properly applied. Connect
the sensor cable to the sensor
connector on the oximeter.

Use a Datex-Ohmeda sensor that is
compatible with the 3770/3775
oximeters.

Use another sensor.

If the PROBE? message is continuous,

check the wiring contacts between the
sensor connector and the analog board.

If the condition persists, swap boards,
starting with the analog board. Replace
the failed board. See chapter 3.

Possible failure points:

Analog board: Analog path
Digital board: A/D converter

Note: If this message occurs during
printing, power the oximeter off and

then on. If you can’t restart printing
and the message appears again, see
below.

Swap boards and replace the failed
board. See chapter 3.

2-2

3770/3775 pulse oximeter (continued)

Condition Cause(s) Recommended action(s)

No display. Unit not receiving power.

Make sure a battery pack is correctly
inserted in the oximeter and press the
on/off button on the front panel of the
oximeter.

2/Troubleshooting

Oximeter alpha­numeric display
switches on/off
continually.

Displayed SpO2 value
flashes.

Low battery light
flashes every three
seconds.

NiCd battery pack needs
recharging or
AA pack needs new batteries.

If using the battery charger to
power the oximeter, the NiCd
battery pack’s contacts are not in
contact with the power contacts
in the battery charger.

Faulty battery pack.

Defective components on analog
or digital board.

The low SpO2 or high SpO
alarm limit has been violated.

This alert indicates that not
much full-power time remains on
the batteries.

2

Insert a charged battery pack.

Make sure the oximeter is inserted
correctly in the battery charger. A beep
sounds when correct contact is made.

If the condition persists, swap boards,
starting with the analog board. Replace
the failed board. See chapter 3.

Install a known functioning, fully
charged battery pack. If the new
battery pack corrects the condition,
discard and recycle the failed pack.

If the condition persists, swap boards,
starting with the analog board. Replace
the failed board. See chapter 3.

Possible failure points:

Analog board: Power supplies

Digital board: Power on reset (POR)

Flashing ceases when the alarm
condition is cleared. Make sure the
alarm limit is within the high and low
limits.

Remove the battery pack and replace it
with a new, fully charged NiCd pack or
AA pack with new batteries.

NiCd pack only—Recharge the battery
pack by itself or by placing it, together
with the oximeter, into the battery
charger.

Waveform bar LEDs
and signal strength
indicator darken, then
“rolling dots” appear in
the main display.

Loss of signal quality has
occurred. Low perfusion,
electrosurgery device, or other
interference has been detected.

Check sensor site.

Increase perfusion or relocate sensor.

Remove any device that may be
causing signal interference.

2-3

3770/3775 Pulse Oximeter Service Manual

3770/3775 pulse oximeter (continued)

Condition Cause(s) Recommended action(s)

Oximeter sounds a
constant tone.

(3775 only) Can’t access
menus.

Oximeter is not
functioning at all.

Oximeter component failure. Swap boards, starting with the digital

board. Replace the failed board. See
chapter 3.

Possible failure points:

Digital board:

Microprocessor
Speaker
External guard dog

Analog board:

Power

Faulty component or area on the
analog board.

Faulty battery pack. Install a known functioning, fully

Replace the analog board. See chapter 3.

Possible failure point:

Analog board:

Rotary encoder assembly

charged battery pack. If the new battery
pack corrects the condition, discard and
recycle the failed pack.

Possible failure points:

Analog board:

PETE
Power supplies

Digital board:

On/Off circuit;
Power on reset (POR)

2-4

Printer

Condition Cause(s) Recommended action(s)

Printer won’t print. Printer not powered on.

Make sure the printer AC adapter is
properly connected to the printer and
to the AC power supply. Slide the |/O
printer button to | (on).

2/Troubleshooting

Printer prints the
symbol that represents
lost information:

Prints repeatedly over
a single line.

Print head scans but
no characters are
printed.

Print head does not
move while unit is
powered on.

Red LED behind
printer IR window is
not lit when power is
on.

No data in the trend buffer.

Printer and oximeter are not
properly aligned; transmission is
not being received at the printer.

Printer malfunction.

Printer cannot print fast enough
to keep up with the data transfer
rate of the oximeter. The printer
battery power is running low.

Paper jam. Pull paper out and reload.

Printer malfunction: defective
print head assembly thermal
control.

Printer malfunction: jammed
print head assembly.

Batteries are dead.

No AC power.

No action required. No data to print.

Make sure the printer and oximeter are
properly positioned for infrared
transmission. See the 3770/3775 Pulse

Oximeter User’s Manual.

Replace the printer. If the new printer
corrects the condition, discard the
failed printer. The printer is not a
serviceable part.

If the condition persists, the oximeter is
malfunctioning. Swap boards, starting
with the digital board. Replace the
failed board. See chapter 3.

Install new batteries. Always use AC
power whenever possible.

Replace and dispose of the
malfunctioning printer. The printer is
not a serviceable part.

Replace and dispose of the
malfunctioning printer. The printer is
not a serviceable part.

Install new batteries.

Ensure that the AC adapter is plugged
into the printer and into the AC power
source.

Malfunctioning AC power
adapter.

Printer malfunction.

Check/replace the AC power adapter.

Replace and dispose of the
malfunctioning printer. The printer is
not a serviceable part.

2-5

3770/3775 Pulse Oximeter Service Manual

Battery charger monitoring station

Condition Cause(s) Recommended action(s)

Battery charge status
indicator is a steady
red light after a battery
pack is inserted.

Battery charge status
indicator is not lit after
battery pack is
inserted.

The NiCd battery pack is above
or below the allowable
temperature charging range.

Oximeter and/or NiCd battery
pack is not inserted into the
charger correctly.

The charger will automatically start
charging with a flashing green light
when the battery pack reaches the
proper range.

Reinsert the oximeter and/or NiCd
battery pack, aligning it so you can hear
a beep from the charger station and the
light is lit.

NiCd battery pack is not in
place on the oximeter and/or in
its slot in the monitoring station.

Voltage selected for the charger
does not match the available
local voltage.

NiCd battery pack is completely
dead.

Battery charge status
indicator is a steady
yellow light after a
battery pack is
inserted.

Battery charge status
indicator is a flashing
yellow light after a
battery pack is
inserted.

Green power light is on
but there is a
continuous beep.

Charger is “chirping.” Voltage selection drum in the

The NiCd battery pack is above
or below the allowable voltage
charging range.

The battery pack may be fully
charged already.

Charger is in conditioning
mode.

Faulty conditioning switch or
malfunctioning circuitry.

Voltage selection drum in the
power module is not set for
correct voltage.

power module is not set for
correct voltage.

Install a NiCd battery pack on the
oximeter and reinsert it.

Remove voltage selection drum and set
correctly. Refer to the Battery Charger

Monitoring Station Service Manual.

Replace NiCd battery pack with a new
one.

The charger will automatically start
charging with a flashing green light
when the battery pack reaches the
proper range.

Remove the battery pack from the
charger.

The charger will automatically start
charging with a flashing green light
when the discharge cycle is complete.

The monitoring station requires service.
Refer to the Battery Charger Monitoring

Station Service Manual.

Remove voltage selection drum and set
correctly. Refer to the Battery Charger

Monitoring Station Service Manual.

Remove voltage selection drum and set
correctly. Refer to the Battery Charger

Monitoring Station Service Manual.

2-6

Battery charger monitoring station (continued)

Condition Cause(s) Recommended action(s)

Green LED power
indicator is not lit.
Unit is not functioning.

Monitoring station is not
connected to AC power.

Ensure that the power cord is plugged
into the monitoring station and the AC
power source.

2/Troubleshooting

Charger is functioning
but slot not charging or
conditioning as
expected.

Fuse(s) are blown.

Voltage selection drum in the
power module is not set for
correct voltage.

Damaged contacts.

Damaged contacts.

If the LED stays at steady yellow
when charging batteries, the
battery pack may already be
fully charged.

Replace the fuse(s) in the power inlet
module. Refer to the Battery Charger

Monitoring Station Service Manual.

Remove the voltage selection drum and
set correctly. Refer to the Battery

Charger Monitoring Station Service
Manual.

Inspect the contacts.

If the fuses, voltage selection setting, and
contacts are not causing the condition,
open the charger and troubleshoot from
inside. Refer to the Battery Charger

Monitoring Station Service Manual.

Inspect the contacts. All four prongs
should protrude equally. If not, replace
the contacts. Refer to the Battery

Charger Monitoring Station Service
Manual.

No action is required.

Charger is not
functioning at all.

When conditioning batteries
and the LEDs don’t go to
flashing yellow, the conditioning
switch may be faulty.

Fuse(s) are blown or contacts
are damaged.

Voltage selection drum in the
power module is not set for
correct voltage.

Replace the conditioning switch. Refer
to the Battery Charger Monitoring

Station Service Manual.

Inspect the contacts. Replace the fuse(s)
in the power inlet module. Refer to the

Battery Charger Monitoring Station
Service Manual.

Remove the voltage selection drum and
set correctly. Refer to the Battery

Charger Monitoring Station Service
Manual.

If the condition persists, open the
charger and troubleshoot from inside.
Refer to the Battery Charger Monitoring

Station Service Manual.

2-7

3770/3775 Pulse Oximeter Service Manual

Battery charger (single)

Condition Cause(s) Recommended action(s)

Battery charger status
indicator is not lit after
a battery pack is
inserted.

NiCd battery pack is not
inserted correctly.

Damaged contacts.

Reinsert NiCd battery pack.

Inspect contacts. All three prongs
should protrude equally. If contacts are
broken, discard charger. The charger is
not a serviceable part.

Battery charger status
indicator is flashing
slowly after a battery
pack is installed.

Battery charger status
indicator is flashing
rapidly after a battery
pack is inserted.

Green power indicator
is not lit.

Green power indicator
is flashing.

Yellow LED is burned out.

Internal failure.

The NiCd battery pack is above
or below the allowable
temperature or voltage charging
range.

The battery pack may be fully
charged already.

Defective battery pack.

The battery pack may be fully
charged already.

Charger is not connected to AC
power.

Fuse(s) are blown.

The battery pack is defective. Remove and replace the battery pack.

Discard charger.

Discard charger.

The charger automatically starts
charging with a steady yellow light
when the battery pack reaches the
proper range.

Remove the battery pack from the
charger.

If the indicator continues to flash slowly,
replace the battery pack.

Remove the battery pack.

Ensure that the power cord is plugged
into the battery charger and the AC
power source.

Discard charger. The charger is not a
serviceable part.

2-8

3/Service Policy and Repair Procedures

This chapter contains:

• The Datex-Ohmeda service policy and the procedures to follow for obtaining

service.

• Safety procedures you must follow when handling equipment that may be

contaminated and when making repairs.

• Instructions for cleaning the oximeter, durable sensors, battery packs, and

battery chargers.

• Procedures for inspecting the oximeter and replacing these parts:
Alarm bar
Analog board
Bezels
Digital board
IR lens
Menu select wheel and label

• Instructions for checking the normal operation of the oximeter.

Service policy

Warranty repair and service must be performed by Datex-Ohmeda. When the
warranty is not applicable, repairs are made by Datex-Ohmeda at the current list
price for replacement parts plus a reasonable labor charge.

CAUTION: Only qualified service personnel should perform the procedures described in this manual.

Do not use malfunctioning equipment. Make all necessary repairs or have the
monitor repaired by a Datex-Ohmeda service representative. For all repairs, use
only genuine replacement parts and service kits sold by Datex-Ohmeda.

Ordering parts and obtaining service

Contact Datex-Ohmeda or your authorized service representative (see the back
cover of this manual) to order parts or for assistance.

3-1

3770/3775 Pulse Oximeter Service Manual

Packaging and returning equipment

If you are instructed to ship the monitor to Datex-Ohmeda or an authorized service
office for repair, follow these steps:

1. Clean the monitor. See Cleaning procedures later in this chapter.

Make sure the monitor is completely dry before you pack it for shipment.

2. Package the monitor carefully for shipment (in the original shipping container,

if possible). Enclose these items:

3. You may be required to include the following items (when you call for

assistance, verify the shipping requirements):

• A letter describing the problem in detail.

• Person (name, telephone or fax number, and country) to contact for

questions about necessary repairs.

• Ship to and Bill to information.

• Warranty information (a copy of the invoice or other applicable

documentation).

• Purchase order number to cover repairs (if out of warranty) or for tracking

purposes.

4. Ship the monitor as directed by your service office.

Safety guidelines

Read and follow each step of all test and repair procedures to ensure their proper
and safe completion. Give special attention to all WARNINGS and CAUTIONS.

WARNING: Patient safety. Never test or perform maintenance on the equipment while it is
being used to monitor a patient.

WARNING: Electrical shock and flammability hazard. Before cleaning or servicing the oximeter,
always turn it off.

Before you start any procedure that involves disassembly of the oximeter, be sure
to

• Power off and disconnect the unit from any power supply.

• Disconnect the sensor from the unit.

• Clean the unit (see below).

After repairs are complete, verify that the device is functioning correctly. See
Checking normal operation later in this chapter.

3-2

Cleaning procedures

Oximeter, battery packs, and battery chargers

CAUTIONS:

• Do not autoclave, pressure sterilize, or gas sterilize the oximeter, printer, battery pack, or

battery charger.

• Use cleaning solution sparingly. Do not immerse the oximeter, printer, battery pack, or battery

charger in liquid. Excessive solution can flow into the device and cause damage to internal
components.

• When cleaning the display lens, do not use abrasive cleaning compounds or other materials

that could damage the lens.

• Do not use petroleum-based solutions or solutions containing acetone, ethanol, freon,

trichloroethylene, or harsh solvents to clean the oximeter, printer, battery pack, battery
charger, or the protective covering on these devices. These substances attack the devices’
materials and device failure may result.

Cleaning agents

Warm water Hydrogen peroxide solution Cidex
Liquid soap/mild detergent Gluteraldehyde (4% or less) Windex
Mild chlorine bleach solution Isopropyl alcohol Formula 409

3/Service Policy and Repair Procedures

®

®

®

Sensors

Never Use:

Acetone * Butyl alcohol * Denatured ethanol * Freon * Trichloroethylene

WARNING: Electrical shock and flammability hazard. Before cleaning or servicing the oximeter,
always turn it off.

To clean the oximeter, power it off. Then, wipe it gently with a soft cloth
dampened with any of the cleaning agents listed above.

WARNING: Electric shock and flammability hazard. Before cleaning the battery charger,
always disconnect the power cord from the AC mains power supply.

Before cleaning the battery pack or battery charger, disconnect it from any power
supply. Then wipe it gently with a soft cloth dampened with any of the cleaning
agents listed above (do not spray the agent directly on any device).

To clean Datex-Ohmeda reusable oximeter sensors, follow the instructions
provided with the sensor.

CAUTION: When cleaning oximeter sensors, follow all warnings and cautions stated in the sensor
user instructions.

CAUTION: Disposable sensors are intended for single patient use only.

After cleaning a sensor, verify that it is functioning correctly. See Checking normal
operation later in this chapter.

3-3

3770/3775 Pulse Oximeter Service Manual

Inspecting the oximeter and replacing parts

Refer to chapter 4 for illustrations.

Follow the procedures in this section to inspect the oximeter for damage and
replace defective parts.

CAUTION: Static sensitivity. Internal electronic components are susceptible to damage by
electrostatic discharge. To avoid damage when disassembling the monitor, observe the standard
precautions and procedures for handling static-sensitive components.

Tools and equipment

• #1 Phillips screwdriver

• Clear silicone rubber adhesive sealant (Dow Corning RTV 3145)

Disassembling the oximeter

Important: As you disassemble the oximeter, carefully set aside each part you
plan to reinstall when you assemble the oximeter.

1. Turn off the oximeter and remove the battery pack.

2. Turn the oximeter face down and remove the four screws that secure the

bottom bezel to the top bezel.

3. Remove the bottom bezel.

4. Inspect the top and bottom bezels. If either bezel is damaged, replace it

during reassembly.

5. Inspect the interior for loose or broken parts and for foreign materials.

Remove foreign material and note those parts that need replacement.

6. Grasp the FlexConnect™ sensor connector and lift up to loosen it from the top

bezel.

7. 3770 oximeter: Lift out the board set.

8. 3775 oximeter:

• Remove the IR lens (plastic window).
Note: If the lens is held in place with sealant, remove the lens only if you

are replacing the lens and/or the top bezel or if the sealant is not intact.

• Turn the oximeter face up and gently pry off the menu select wheel.

• Remove the rotary encoder nut.

• Lift the top bezel off the board set.

9. To separate the analog and digital boards from each other, grasp the board set

near the horizontal center and pull gently but firmly.

3775 oximeter: Avoid stressing the ribbon cable and its connection to the analog
board. Do not flex the ribbon cable any more than absolutely necessary.

3-4

10. If you plan to replace the alarm bar or the top bezel, turn the bezel face up

and push the alarm bar through the bezel.

Replacing parts

When the oximeter is disassembled, you can replace any part listed below with a
new part as you assemble the oximeter:

• Alarm bar

• Analog board

• Bezels

• Digital board

• IR lens

• Menu select wheel and label

Assembling the oximeter

Important: During the manufacture of some 3770/3775 oximeters, a bead of
silicone sealant was applied to the IR window and sensor connector cutouts on
the top and bottom bezels (see Figures 3-1 and 3-2). The sealant was applied to
ensure the waterproof integrity of these oximeters.

You may need to reapply sealant during assembly if disassembly of the oximeter
results in loss of the original sealant or if the sealant is no longer intact. Follow
the instructions in this section to check the oximeter for the presence of sealant
and, if necessary, reapply sealant.

3/Service Policy and Repair Procedures

1. Make sure the rotary encoder, FlexConnect wires, the power on/off switch, the

alarm bar switch, all display and alphanumeric LEDs, and all other
component parts are securely in place on their respective boards.

2. If you separated the alarm bar and top bezel during disassembly, position the

alarm bar in the underside of the bezel, and press it into place.

3. Gently but firmly connect the analog and digital boards to each other.

4. Turn the top bezel face down. Place the board set into the top bezel with the

digital board facing down.

5. 3775 oximeter:

• Turn the oximeter face up.

• Place the rotary encoder nut on the rotary encoder and tighten it.

• Place the menu select wheel firmly on the encoder’s stem.

• Turn the oximeter face down.

6. Push the FlexConnect sensor connector firmly into position in the top bezel.

3-5

3770/3775 Pulse Oximeter Service Manual

7. Check the oximeter for the presence of sealant. If sealant is not present, go to

the next step.

• If the sealant on the top bezel is not intact, apply new clear silicone

rubber adhesive sealant (Dow Corning RTV 3145) to the top bezel above
the sensor connector. See Figure 3-1.

Figure 3-1. Applying sealant to the top bezel

• 3775 oximeter: Add sealant in the IR lens cutout on the top bezel, if necessary.

• If the sealant on the bottom bezel is not intact, add sealant to the sensor

connector cutouts. See Figure 3-2.

3-6

Figure 3-2. Applying sealant to the bottom bezel

• 3775 oximeter: Add sealant to the IR lens cutouts on the bottom bezel, if

necessary.

8. 3775 oximeter: Slide the IR lens into its slot on the top bezel.

9. Position the FlexConnect wires so that they will not be crushed between the

ground ring on the analog board and the conductive boss that extends from
the bezel.

10. Make sure there are no loose parts inside the top bezel. Then, place the

bottom bezel on the top bezel and install the screws that connect the bezels:

• For the 3770, use four 4-20 x 0.5L screws.

• For the 3775, use four 4-20 x 5/8L screws.

11. Check the operation of the oximeter. See Checking normal operation on the

next page.

Checking normal operation

1. Install a battery pack on the oximeter. Power on the oximeter.

3775 oximeter: No alarms sound for the first two minutes after powering on the

unit.

2. Verify that the low-battery light is not lit.

3. Plug the sensor cable into the sensor cable connector on the oximeter.

4. Place the sensor on a finger and wait until the SpO2 and pulse rate values

appear in the main display.

5. Unplug the sensor cable from the oximeter.

3770 oximeter: Verify that dashes (- - -) are displayed.
3775 oximeter: Verify that the PROBE? message appears on the main display.

6. Plug the sensor cable back into the oximeter and wait for monitoring data to

reappear on the main display.

7. Remove the sensor from the finger.

3770 oximeter: Verify that dashes (- - -) are displayed.
3775 oximeter: Verify that the PROBE? message appears on the main display.

8. Reattach the sensor to the finger.

9. Verify that the signal strength is good to adequate (green or yellow signal

strength indicator is illuminated).

For more information, see Data validity and signal strength in the 3770/3775

Pulse Oximeter User’s Manual.

3/Service Policy and Repair Procedures

3-7

3770/3775 Pulse Oximeter Service Manual

3-8

4/Illustrated Parts

This chapter contains a list of service kits, a list of parts, and assembly illustrations
for each oximeter.

Service kits—3770 and 3775 oximeters

Kit, PCA drawings..........................................................................................6050-0005-558

Includes board drawing, list of components, and
schematics for the analog and digital boards

Kit, “Not for continuous monitoring” labels....................................6050-0003-466

Danish, Finnish, French, German, Italian, Spanish, Swedish

Kit, analog board, tested, 3775...............................................................6050-0003-667

PCA, analog board, 3775
Spacer, foam 0.25 x 0.125 x 0.75 in. (2)
Spacer, foam 0.50 x 0.125 x 1.0 in.
Spacer, foam 0.75 x 0.25 x 1.0 in.

Kit, analog board, tested, 3770...............................................................6050-0003-486

PCA, analog board, 3770
Spacer, foam 0.25 x 0.125 x 0.75 in.
Spacer, foam 0.50 x 0.125 x 1.0 in.
Spacer, foam 0.75 x 0.25 x 1.0 in.

Kit, digital board, tested, 3775................................................................6050-0003-480

PCA, digital board, 3775

Kit, digital board, tested, 3770................................................................6050-0003-481

PCA, digital board, 3770

Kit, bezel, bottom, 3770/3775................................................................6050-0004-078

Kit, bezel, top, 3775......................................................................................6050-0002-889

Note: This kit does not include the alarm bar,

on/off label, or wheel assembly.

Kit, bezel, top, 3770......................................................................................6050-0002-886

Assembly, alarm bar, 3775.......................................................................6050-0002-600

Assembly, nut, bearing, 3775..................................................................6050-0002-888

On/Off Label, 3775......................................................................................6050-0002-593

Kit, wheel/label, 3775.................................................................................6050-0003-666

Assy, wheel
Wheel/select label

Kit, hardware, 3770/3775........................................................................6050-0003-780

Screw, tri-rnd, 4-20 x 0.5/8L (4)
Screw, tri-rnd, 4-20 x 0.5L (4)
Lens, IR

4-1

3770/3775 Pulse Oximeter Service Manual

3775 oximeter assembly (REF 6050-0002-601, Rev. P)

3775 assembly parts

Each item number listed below identifies a component in the assembly
illustration that follows.

Item Description

1 Assy, wheel, 3775
2 Assy, nut, bearing
3 Assy, top bezel, 3775
4 Assy, alarm bar
5 PCA, analog board, 3775

Includes: Rotary encoder switch
7 Lens, IR, 3775
9 Bezel, bottom

10 Label, serial port (not shown)
11 PCA, digital board, 3775

Includes: Speaker, 5 V, 0.354 inch diameter

13 Screw, tri-rnd, #4-20 x 5/8L, plastite (4)
14 Label, wheel/select
15 Label, on/off
16 Label, serial REF, 2.75 x 1.68 in. (not shown)
18 Spacer, foam, 0.25 x 0.125 x 0.75 in. (2)
19 Spacer, foam, 0.50 x 0.125 x 1.0 in.
20 Spacer, foam, 0.75 x 0.25 x 1.0 in.
21 O-ring seal 0.354 in. ID , .040 in. wall
25 Label, warranty void, 3770/3775

4-2

3775 assembly illustration

3770/3775 Pulse Oximeter Service Manual

14

1

SEE VIEW A

2

ALIGN SHAFT FLATS WITH

FLATS IN MOLDED WHEEL

VIEW A

SEE VIEW B

11

3

Datex-Ohmeda

15

7

4

18 (2X)

19

20

ITEM 4

BOTTOM VIEW

Datex-Ohmeda

TOP VIEW

VIEW B

ITEM 3

21

5

13 (4X)

9

SEE VIEW C

10 REF 16 REF 25 REF

VIEW C

4-3

3770/3775 Pulse Oximeter Service Manual

3770 oximeter assembly (REF 6050-0002-632, Rev. H)

3770 assembly parts

Each item number listed below identifies a component in the assembly
illustration that follows.

Item Description

1 Label, On/Off
2 Assy, top bezel, 3770
3 Spacer, foam, 0.25 x 0.125 x 0.75
4 PCA, digital, 3770
5 PCA, analog, 3770
6 Bezel, bottom
8 Screw, tri-rnd, #4-20 x 0.5L, plastite (4)

10 Label, serial port
16 Label, serial REF, 2.75 x 1.68 in. (not shown)
18 Spacer, foam, 0.50 x 0.125 x 1.0 in.
19 Spacer, foam, 0.75 x 0.25 x 1.0 in.
20 Label, use warning, 3770
24 Label, warranty void, 3770/3775

4-4

3770 assembly illustration

3770/3775 Pulse Oximeter Service Manual

24 REF

16 REF

10 REF

20

2

Datex-Ohmeda

4

5

1

3

18

19

VIEW A

8 (4X)

6

SEE VIEW A

4-5

3770/3775 Pulse Oximeter Service Manual

4-6

1315 West Century Drive

Louisville CO 80027-9560 USA

1 303 666 7001

Corporate Office

Datex-Ohmeda Division
Instrumentarium Corp.
PO Box 900
FIN-00031 Helsinki, Finland
Tel [phone]
Fax [phone]

Asia/Pacific

China

Datex-Ohmeda Pte. Ltd.
Room B416, COFCO Plaza
8 Jianguomennei Avenue
Beijing 100005, PR China
Tel [phone]
Fax [phone]

Datex-Ohmeda Pte. Ltd.
Room 1708, Yunlong Mansion
No. 122 Luoguo Street
Chengdu 610017, PR China
Tel [phone]
Fax [phone]

Datex-Ohmeda Pte. Ltd.
Room 1602, GIE Tower
403 Huan Shi Dong Road
Guangzhou 510095, PR China
Tel [phone]
Fax [phone]

Datex-Ohmeda Pte. Ltd.
Room 2509, Lippo Plaza
No. 222 Huaihai Road (M)
Shanghai 200021, PR China
Tel [phone]
Fax [phone]

Datex-Ohmeda Pte. Ltd.
Room 809, Truroll Plaza
Wusheng Road
Wuhan 430033, PR China
Tel [phone]
Fax [phone]

India

Datex-Ohmeda (India) Pvt. Ltd.
Block EP & GP, Sector V
Plot XI-16, Salt Lake City
Calcutta 700091, India
Tel [phone]
Fax [phone]

Indonesia

Datex-Ohmeda Pte. Ltd.
Wisma Danamon Aetna Life 19th Fl.
Jin. Jend Sudirman Kav. 45-46
Jakarta 12930, Indonesia
Tel [phone]
Fax [phone]

Japan

Datex-Ohmeda K. K.
TRC Annex 9F
6-1-1 Heiwajima, Ohta-ku
Tokyo 143-0006, Japan
Tel [phone]
Fax [phone]

Datex-Ohmeda K. K.
Technical Center
TRC A Bldg. AE 4-8
6-1-1 Heiwajima, Ohta-ku
Tokyo 143-0006, Japan
Tel [phone]
Fax [phone]

Korea

Datex-Ohmeda Pte. Ltd.
10th Floor, Sam Sung Building
36–1, Yoido-Dong,
Youngdeungpo-Ku
Seoul, Korea
Tel [phone]
Fax [phone]

Malaysia

Datex-Ohmeda Pte. Ltd.
Level 2 Bangunan O’Connor
13 Jalan 223
46100 Petaling Jaya
Selangor, W. Malaysia
Tel [phone]
Fax [phone]

Singapore

Datex-Ohmeda Pte. Ltd.
152 Beach Road #12–05/07
Gateway East
Singapore 189721
Tel [phone]
Fax [phone]

Taiwan & Philippines

Datex-Ohmeda Pte. Ltd.
2nd Floor, No. 85
Chien-Kuo North Road, Sec. 2
Taipei, Taiwan
Republic of China
Tel [phone]
Fax [phone]

Thailand

Datex-Ohmeda Pte. Ltd.
12th Floor (Unit F)
Grand Amarin Tower
1550 New Petchburi Road
Makasan, Rajathevi
Bangkok 10320, Thailand
Tel [phone]
Fax [phone]

Vietnam

Datex-Ohmeda Pte. Ltd.
522G Nguyen Tri Phuong St.
Ho Chi Minh City, Dist. 10
Vietnam
Tel [phone]
Fax [phone]

Australia

Datex-Ohmeda Pty. Ltd.
Units 1 & 2
149 Arthur Street
PO Box 356
Homebush NSW 2140
Australia
Tel [phone]
Fax [phone]

Europe

France

Datex-Ohmeda S. A. S
Parc de Pissaloup, BP 10
8 Avenue Jean d’Alembert
F-78191 Trappes-Cedex, France
Tel [phone]
Fax [phone]

Datex-Ohmeda S. A. S
17 rue Jean-Elysée Dupuy
F-69410 Champagne au

Mont d’Or, France
Tel [phone]
Fax [phone]

Germany

Datex-Ohmeda GmbH
Auf der Hohe 49
Gewerbehof 49
D-47059 Duisburg, Germany
Tel [phone]
Fax [phone]

Italy

Datex-Ohmeda S. p. A.
Via Cassanese 100
20090 Segrate
Milan, Italy
Tel [phone]
Fax [phone]

Netherlands

Datex-Ohmeda B. V.
Kantemarsweg 18
Post Box 22
3870 CA Hoevelaken
Netherlands
Tel [phone]
Fax [phone]

Spain

Datex-Ohmeda S. L.
C/Manuel Tovar 26
28034 Madrid, Spain
Tel [phone]
Fax [phone]

United Kingdom

Datex-Ohmeda Ltd.
Ohmeda House
71 Great North Road
Hatfield Hertfordshire
AL9 5EN England
Tel [phone]
Fax [phone]

Latin America,
Caribbean

Datex-Ohmeda Latin America
10685 N. Kendall Drive
Miami FL 33176, USA
Tel [phone]
Fax [phone]

Middle East

Datex-Ohmeda
Middle East Operations
PO Box 5527
Dubai, United Arab Emirates
Tel [phone]
Fax [phone]

North America

Canada

Datex-Ohmeda (Canada) Inc.
1093 Meyerside Drive, Unit 2
Mississauga, Ontario
L5T 1J6 , Canada
Tel [phone]
Tel [phone]
Fax [phone]

United States

Customer Service

Datex-Ohmeda, Inc.
Ohmeda Drive
PO Box 7550
Madison WI 53707-7550, USA
Tel [phone]
Fax [phone]

Technical Support

Datex-Ohmeda, Inc.
Three Highwood Drive
Tewksbury MA 01876, USA
Tel [phone]

Equipment Service Center

Datex-Ohmeda, Inc.
1315 West Century Drive
Louisville Co 80027-9560, USA
Tel [phone]

Sales and Service

Datex-Ohmeda, Inc.
Three Highwood Drive
Tewksbury MA 01876, USA
Tel [phone]
Fax [phone]

1/00 (388/F)