Ohmeda Infant Warmer Service manual

Important:

The information contained in this manual pertains only to

those models of products which are marketed by Ohmeda as of

the

effective

thereof. This manual was prepared for exclusive use by Ohmeda service personnel in light of their training and

experience and the availability to them of proper tools and

test equipment. Consequently, Ohmeda provides this manual

to its customers purely as a business convenience and for the customer's general information only without warranty of

the results with respect to any application of such

information.

circumstances

may be performed and the unique nature of each individual's

own experience,

customer

imply in any way that Ohmeda deems said individual to be

has

qualified

Moreover,

test and safety procedure or method, precaution, tool,

equipment or

or

unusual

or

additional

date

of

Furthermore,

under

capacity,

received

to

perform

it

should

device

circumstance

procedures

this

which

said

any

not

is

referred

manual

because

maintenance

or

the

of the

and

latest

wide

repair

and qualifications, the

information

such

be

maintenance

assumed

to

may not

or

warrant

requirements.

within,

that

from

or

every

or

or that

suggest

revision

variety

activities

fact

Ohmeda

repair

acceptable

of

that

does

not

service.

abnormal

different

This manual is subject to periodic review and customers are

cautioned to obtain and consult the latest revision thereof

and

suggestions are invited from

consideration

WARNING: After completing a repair of the Infant Warmer

System the appropriate calibration procedure must be

performed

operating

check

the information for future reference.

WARNING: After completing any portion of the calibration

and

adjustments

checkout procedure must be performed to make sure the Infant

Warmer

a

final

must

reference.

CAUTION: Servicing of this product in accordance with this

service manual should never be undertaken in the absence of

proper

this

understood.

be

service

to

condition.

and

System

electrical

performed.

tools,

by

make

leakage

procedure

is in

test

manual

Ohmeda

sure

current

with

the

Infant

In

additionafinal

test

for

proper

safety

Record

equipment and the

which

operating

check

the

is

clearly

our

these

periodic

Warmer

must

the

information

Infant

and

be

leakage

customers for

reviews.

System

is

electrical

performed.

Warmer

condition.

current

for

most

and

recent revision of

thoroughly

System

future

in

Record

In

addition

test

proper

safety

the

page

111

(^CAUTION:

throughout

procedure

observed. Use the static control

0175-2311-000) to help ensure that static charges are safely

conducted to ground and not through static sensitive

devices.

This document is not to be reproduced in any manner, nor are

the contents herein to be disclosed to anyone, without the

express authorization of the Ohmeda Product Service

Department, Madison, Wisconsin.

WARNING: Use of electrosurgical units or other electrical

field

Radiant Warmer

cables

WARNING: Use of electrosurgical units or other electrical

field radiating equipment can cause indirect heating of the

thermistor probe, by several tenths of a degree, through absorbed electrical energy. Operate the Infant Warmer

System in the Manual Mode

conditions are present.

This

in

radiating equipment can affect the operation of the

to

be

this

laid

static

control

manual.

manual,

system.

on

the

precaution

When

Do not allow excess electrosurgical

warmer

this

static

for

maximum safety when these

symbol

control

work

table.

symbol

appears

precautions

station (Part No.

appears

to

a ^&*

/tt^k'

^^

^1

page

iv

REPAIR

POLICY:

Note:

individual.

Do not use malfunctioning equipment. Make all necessary

repairs,

Ohmeda

equipment

accordance

To ensure

done by an authorized Ohmeda

this cannot be done, replacement and maintenance of those

parts listed in this manual may be undertaken by a

competent, trained individual having experience in the

repair of this type of equipment.

CAUTION: No repair should ever be undertaken or attempted

by anyone not having such qualifications.

Replace damaged parts

by Ohmeda. Then test the unit to ascertain that it complies

with the manufacturer's published specifications.

Service

or

have

Service

to

with

full

must

ensure

be

performed

the

equipment

Representative.

that

manufacturer's

reliability,

with

by

a

"Technically

serviced

After

it

is

functioning

published

have

components manufactured or sold

all

Service

by

an

repair test the

properly,

specifications.

repairs

Representative. If

and

Competent"

Authorized

service

in

Contact

assistance. If you send the unit to the Ohmeda Service

Center,

container,

letter

experienced

other than where

will

replacement

CAUTION:

extensive

convenience

test

trained by Ohmeda.

the

nearest

package it securely in the original shipping

if

possible,

with the unit

and

be

made

at

partfs)

Detailed

repairs

of

users

equipment,

Ohmeda

describing

the

repairs

Ohmeda's

plus

drawings

are

included

having

and

for

Service

and

ship

felt

warranty

current

a

reasonable

and

proper

service

it

in

Office

prepaid.

detail

for

any

necessary.

is

applicable,

list

procedures

herein

price

labor

for

solely

for

charge.

knowledge,

representatives

service

Enclose difficulties

In

all

cases,

repairs

the

more

for

the

tools,

and

specially

a

page

v

TECHNICAL

The procedures described in this service manual should be

performed

Maintenance

individuals

with

Genuine replacement parts manufactured or sold bv Ohmeda

must

Read completely through each step in every procedure before

starting the procedure; any exceptions may result in a failure to properly and safely complete the attempted

procedure.

Copvright 1987 bv Ohmeda, Ohmeda Drive, Madison, Wisconsin

53707-7550

DEFINITIONS

devices

be

COMPETENCE

by

should

who

of

used

trained

and

authorized

be

undertaken

haveageneral

this nature.

for all repairs.

personnel

only

by

knowledge

only.

competent

of

and

experience

Note:

point in the

Important:

used for greater emphasis.

CAUTION: A CAUTION statement is used when the possibility

of

WARNING:

injury

A

damage

to

note

provides

text.

An

Important

to the equipment

A WARNING statement is used when the possibility of

the

patient

additional

statement

exists.

or

the

operator

information

is

similar

exists.

to

to a

clarify

note

a

but

page

vi

PRECAUTIONS

Warnings:

After completing a repair of the Infant Warmer System the

appropriate calibration procedure must be performed to make

sure the Infant Warmer System is in proper operating

condition. In

leakage current test must be performed. Record the

information

addition

for

future

a final

reference.

electrical

safety

check

and

After

adjustments procedure for the Infant Warmer System the

checkout

Warmer System is in proper operating condition. In addition

a final electrical safety check and leakage current test

must

reference.

Use of

radiating

Warmer system. Do not allow excess electrosurgical cables

to

Use of electrosurgical units or other electrical field

radiating

thermistor

absorbed electrical

System

conditions are present.

If the bed

inches,

Overloading

unit.

completing

procedure

be

performed.

electrosurgical

equipment

be

laid

on

equipment

probe,

in

the

level

the

Infant

the

any

must

the

warmer

by

Manual

is

Warmer

shelves

portion of the

be performed to

Record

can

several

energy.

Mode

greater

the

units or

affect

table.

cause

tenths

Operate the Infant Warmer

for

than

information

the

indirect

maximum

System

can

affect

calibration

other

electrical field

operation

heating

ofadegree,

safety

or

less

will

not

the

stability

make

sure the Infant

for future

of the

when

than

operate

and

of

the

through

these

27

+/- 2

properly.

of

Radiant

the

Do

not

perform

occupies

Use

extreme

procedures, or while working on the 5000 Infant Warmer

System with power

does

Before any disassembly or repair disconnect the electrical

supply,

cylinders.

When

its

ever

side,

the

exist;

gas

lowering

use

the

Check-Out

Infant

care

be

while

connected.

certain

pipeline

or

two

people

Warmer

performing

to

observe

supply

lifting

for

page

Procedure

while

a

patient

System.

calibration

An electrical shock hazard

all

safety

connections

the

Infant

and

Warmer

and

precautions.

remove

System

safety.

vn

adjustment

any

gas

to

Whenever

procedure,

front).

and

attempting

injury

Observe all safety precautions to avoid electrical shock

hazard from high voltage.

the

unit

lay

it on

The

lamp-house

to

toarepair

must

the

be

laid

right

on

side

assembly

lay

the

unit

on

personordamage

its

side

(as

swings

the*left

to

the

forarepair

viewed

freely

side

from

to

could cause

equipment.

the

left

Never

is and

will

lubricant recommended (Order No. 0220-0091-300).

When replacing gauges, be sure to use identical pressure

rancres.

Do not use oil or oil bearing materials on or near the

regulator. Oils and greases oxidize readily and, in the

presence of oxygen, they will burn violently. All metallic parts of the regulator must be discarded if contaminated

with

Cautions

Servicing

manual

tools,

service manual which is clearly and thoroughly understood.

oil or

made

and

grease

burn

oil or grease.

should

test

grease

approved

oxidize

violently.

of

this

equipment

never

oxygen

for

readily,

Vac

product

be

undertaken

and

equipment

this

type

and

Kote*

in

accordance

the

most

in

is

in

unless

of

service

the

presence

the

oxygen

with

the

recent

a

lubricant

is

service

this

absence

revision

used.

of

oxygen,

service

of

that

Oils

proper

this

fify

This

^

this

in this manual, static control precautions MUST be observed.

Use

to help ensure that

ground

No repair should ever be undertaken or attempted by anyone

not having such qualifications.

Detailed

are included herein solely for the convenience of users

having

service representatives specially trained by

Insulation on the electrical wiring can deteriorate with

age.

power cord and all other electrical

Do not idle the elevating motor at the stop positions;

equipment damage

static

manual.

the

static

and

drawings

proper

Check

control

When

control

not

through

knowledge,

for

brittle

may

precaution

this

and

symbol

work

static

procedures

result.

charges

static

tools,

or

page

symbol

appears

station (Part No. 0175-2311-000)

sensitive

for

and

deteriorated

vin

appears

throughout

toaprocedure

devices.

more

test

wires.

extensive

equipment,

Ohmeda.

insulation

repairs

and

on the

for

Use the Static Control Work Station

to help

ground.

electrically

The back panel and display panel may drop down when the

bottom

the panels with tape before disassembly.

Disconnect the Infant Warmer System power cord and allow the

unit to cool before replacing the alarm light.

Disconnect the Infant Warmer System power cord and allow the

unit to

lamp normally operates at a high temperature.

ensure

The

cover

cool

that

static

Velostat

powered

mounting

before

replacing

charges

material

circuit

screws

is

boards

are removed. Be sure to secure

the

(Part

are

No.

safely

conductive.

on

it.

examination

0175-2311-000)

conducted

Do

not

light.

to

place

The

When

floor

Always

side

The

bed

Take

spring

lowering

for

check

(as

heater

access.

care

is

Depending

the

tension

For

caster.

lower

loaded.

safety

or

inspection

to

ensure

viewed

housing

to

from

ensure

released

on

the

position

column,

Use

have

at

lifting

does

that

or

that

the

not

the

repair,

you

front)

lock

the

carefully.

of

the

springs

care

when

least2people

Infant

use

lay

Warmer

two the

when

and

tension

the

upper

could

be

releasing

available

people unit

laying

pivots

on

the

column

System

on

the

to

hydraulic

to the

for

its

unit

the

in

relation

safety.

right

down.

left

heavilvorlightly

the

springs.

to

replace

for

system

to

a

page

ix

* »•

1/

FUNCTIONAL

DESCRIPTION

r

Figure

A.

POWER

This

System detailed

The

and

is

power

monitoring

provides

Also

that

microcontroller.

The

found

provides

control power HIGH

signal

device.

1-1.

SUPPLY

a

functional

Power

circuit

supply

power

supply

This

Ohmeda

BOARD

Supply

diagram.

board

of to

on

the

an

indicationofline

circuits

board

from

the

is

performed

5000

description

Board.

contains

line

the

board

voltage

control

is

for

each

are

functionally

control

Infant

Refer

devices.

board

a

line

board

with

Warmer

for

to

System

the

Infant

Fiaure

circuitry

The

and

the

voltage

identical

switching

an

opto-isolator

Warmer

8-1

for

the

board

display

sensing

magnitude

device

with

ON

the

so

a

control

also

board.

circuit

to

on

the

a

logic desired low/line

the

page

1-1

voltage

isolated

The

state

electro-mechanical relay contact connected in series with

the neutral to the solid state

switch

there is a component failure on the control board.

The regulator circuits provide a +5 vdc supply to the

display board and +5 vdc, and +9 vdc, supplies to the

control board. A NI-CAD battery supplies the 5 vdc supply and a de-rated 9 vdc supply for standby power, in the case

of a power loss. Standby power of 9 volts is used to

activate

provides power to the microcontroller and associated IC's

for memory retention purposes.

5

VOLT

circuits

(2500

heater

relay switching line

OFF

LEDS

is

the

transducer

can

volt

controlled

heater

dielectric).

interact

from

voltage.

if

the

solid

alarm,

but

the

relay.

while

remain

supply

state

electrically

board

There is also an

This is used to

relay

the 5

volt

with

fails

supply

a

solid

or

A nominal 8 vac is input to the power supply board at Jll

pins

control board via J12 pin capacitor

relav,

unregulated

supplv

of the relay circuit.

The

power

output

supply

should

of

millivolts.

LINE

A

secondaryisinput

rectifier

filtered

R3

at

nominal value

J12

A/D

3 and

opto-isolators,

must

output

to

voltage

be

500

ma.

VOLTAGE

voltage

is

preset

J12

Converter,

(U-13).

4.

Cll

provide

supply

beaminimum

of

regulator

drive

is,

measurable

between

The

SENSING

of

approximately

CRl

voltage

to

11

connects

The

digital

The

line

can

the

LED

is

within

4.8

maximum

to

and

capacitor

of

approximately12vdc.

produce

(TP-11)

for

the

to the

ADC

3711

frequency

2.

a

filtered

and

the

be

measured

of

VR2

displavs

at

TP-10

10%

and

5.2

allowable

the

board

an

when

unit.

(U6),

output

is

also

The

bridge

unregulated 8 vdc to the

regulator

at

7.32

is

11

C12

output

the

control

of

volts

nominally+5vdc

on

the

(J12,

of

volts

vac

line

The analog voltage signal at

via

the

nominal,

dc

ripple

from

at

Jll

provide

of

approximately

voltage

board

the

A/D

connected

rectifier CR2 and

VR2.

TP-1.

for

The

unregulated

proper

8

operation

and

display

12).

the

with

voltage

the

pins1and

a

full

and is

multiplexer,

converter

board.

When

the

output

a

maximum

is

transformer

2.

wave,

Variable

is

at

the

fed

is

to

supplies

voltage

150

resistor

0.6

MC14051B

the

vdc

The

load

Bridge

volts

into

input

^\

the

to

page

1-2

the

microcontroller

duration

variations

9

VOLT

The output of regulator VR3 is adjusted by R4 to provide 9.0

+/- 0.2 volts (TP12). This voltage is used for charging the

NI-CAD

vdc

standby

5

VOLT

of

power

in

STANDBY

battery,

regulator.

STANDBY

line

where

pulses

voltage.

and supplying the input voltage to the +5

the

to

measured

the

heater

value

to

determines

compensate

for

the

When

output of VR3 and through CR5 to provide 9.0 +/- 0.2 volts

to the input of VR4, and to J12 pin 3 (TP-12). In turn,

regulator VR4 outputs a voltage of 5.0 +/- 0.2 volts to J12

pin 14

millivolts.

If

NI-CAD battery maintains a de-rated output voltage of

approximately

provides input to VR4.

Note:

volts as the input voltage

HEATER

The

heater,amonitoring

heater in the event of a relay or system

line

power

The

heater

voltage

(TP-9)

loss

output

CONTROL

circuitry

is available, current flows from the

with a maximum

occurs

6.5

AND

volts

of

VR4

STATUS

with

to

only

consists

circuit,

ripple

the

unit

3 of

regulates

drops

of a

andarelay

voltage of

switched

J12

to

below

7.0

controller

ON,

(TP-12).

approximately

volts.

to

failure.

150

the

It

for

the

switch

7.2

also

OFF

volt

5.0

the

f^

The heater control circuit uses a solid state relay to

isolate

Operation

controls

the use of snubber sent to the heater control circuit from J12 pin 9 the output

of

the

signal

negative

microcontroller

first

This

the

line

of

differ

solid

of

the

voltage.

zero

provides

crossing

voltaqe

the

heater

only

state

heater

goes

zero

from

control

in

the

circuits.

relay

will

crosses

After

preceded

LOW,

the

heat

voltage

page

the

low

and

type

crossing

of

When a

not

the

zero

input

will

by

the

1-3

switch

voltage

other

circuits.

line

voltage

opto-isolator

logic

HIGH signal is

ON

until

potential

line

from

not

switch

negative

control

the

half

of

from

OFF

the

used

the

ac

a

until

cycle.

heater

and

the

switching.

percent

The

adjusts

ON.

voltage percentage

60

durations

heat

microcontroller

the

This

is

The

time

desired

number

provides

not

at

power

of

settings

heater

that

the

heater

(controllablein5%

also monitors the line

of

ac

heater

the

nominal

cycles

power

and

power pulses.

that

compensation.

value,

power

compensation

is

ON

depends

increments).

voltage

the

heater

the

combination

is

If

the

can

on

the

and

switched

line

of produce

The full

sample (through R

heater and provides rectified dc to the opto-isolator U3. If the heater is ON the dc output switches ON the LED in the

opto-isolator, except at voltage levels below the forward

bias voltaqe. When the LED is ON the transistor goes into

saturation causing the output at J12 pin 1 to go LOW (about

0.3 volts). When the heater is OFF the dc bridge output is in the region of zero potential and there is insufficient

forward bias voltage for the LED. This switches

transistor allowing capacitor CIO to charge and causes J12

pin 1 to go high (5 volts). When the

the LED switches the transistor ON

discharges.

the

charge/discharqe

The glitches are acceptable provided thev do not exceed the

trigger voltage of 1.4 volts for the 74LS132 on the Control

Board.

RELAY

wave

bridge rectifier CR6 takes a

13)

of the ac signal supplied to the

heater

again,

The

low

output

of

shows

the

capacitor

small

at

low

voltage

OFF

the

is switched ON

and the capacitor

glitches

every

caused

half

cycle.

by

s*\

The relav circuit is used to switch OFF the heater in the

event of a solid state relay or microcontroller failure.

Under

logic

input

relay

FET

the

signal

which

microprocessor.

A

minimum

relay

8 volt unregulated supply is 7.32 volts since the FET has an

internal

normal

HIGH,

from

coil

input

FET

at J12 pin 10

2.4

the

to

isaLOW

switches

isapart

voltage

coil.

Therefore

voltage drop of

conditions

volts

minimum.

control

energize

from

OFF

and

comes

of

a

logic/timing

of

7.2

the

board

and

close

the

from

volts

the

minimum

0.12

input

switchesONthe

control

relay

volts.

A

line

logic

from

HIGH

J12

signal

FET

the

relav

board',

contacts

Ul on the control board

circuit

is

required

allowable

contacts.

(0.5

open.

independent

to

energize

voltaqe

10

on

causing

volts

The

for

is

a

the

If the

max.)

of

the

page

1-4

MOTOR

The

or lower bed signals. When the raise bed or lower bed

switch

for pin

opto-isolater.

raise,

03

motor.

resistive

switching

and R18/C16 for lower bed signals. Note;

raised or lowered the heater control signal is inhibited,

stopping heater power to minimize the units total current

untii

UP/DOWN

bed

raise 5

for

the

CONTROL

up/down

is

selected

and raise,

U5

for

lower)

The motor is a combination inductive, capacitive and

load which

noise.

movement

the

J12

6

U2

pin3for

The

output

lower)

which then

triggers

requires

This

is

completed.

is

logic

for

of

switches

achieved

controlled

high

lower)

control

is

lower)

the

a

snubber

which

opto-isolator

triac

the

by

separate

signal

buffered

power's

gate

neutral

network to minimize

R21/C17

when

(04

supply

for

the bed is

by

(U6

raise

(J12

an an

for

raise

FET

raise,

for

bed

5

(U2

the

bed

ALARM

The alarm lights are controlled by a triac switching

voltage

less than 0.45 volts, this keeps the FET, triac driver, and

triac switched OFF. The triac acts as a switch to the line

voltage circuit, removing voltage from the load.

When the

volts

The

opto-isolator-driver

opto-isolator/driver

triac

lights

and does not have a snubber circuit in parallel with the

load.

OBSERVATION

LIGHTS

to the

minimum

FET

gate,

to

CONTROL

lamps

is

switches

switching

switch

LAMP

lamps.

should

output

ON

ON.

CONTROL

If the

be

switched

to

causing

(U8)

output

the

The

control

the

to

switch

drives

triac

alarm

lines

ON,

a

logic

corresponding

LED

of

the

on.

The

sufficient

(Q5)

light

ON

allowing

isaresistive

are

logic

HIGH

Ul,

current

the

of

line

LOW,

2.4

10

FET.

to

the

alarm

load

f0^

The

observation

line

The

and switches the control

observation lamp which is rated at 12 volts 50 watts.

voltage

FET

Ul

pin5buffers

to a

lamp

is

controlled

transformer

by

outputting

the

microprocessor

relay.

page

The 12 volts ac

1-5

a

relay

12

vac

control

which

to

powers

the

switches

lamp.

signal

the

B.

CONTROL

This is a functional description for the Infant Warmer

System

Figure

The control board contains electronic circuitry involved

with

and decision making functions of the Infant Warmer System.

The

8-bit microcontroller. The 8031

memory

8-bit

priority

and an on-chip oscillator with clock circuitry. The program

memory is stored in a 2764 64k bit (8k x 8), or a 27128 128K

bit

(74LS373) is connected to address inputs of the

permit the use of the bi-directional data bus port of the

microcontroller for addressing the EPROM and receiving

program instructions.

Four ICs with a network of precision resistors are used to

interface the microcontroller. The temperature sensor,

calibration resistors, or line voltage scaler are selected by an MC14051B 8 Channel Multiplexer. An LM-10 precision

reference with adjustable reference buffer, and on-board

operational amplifier

This is required bv the temperature measurement circuits and

the

expander

multiplexer and the A/D converter.

the

principle

parallel

(16k x 8)

ADC

BOARD

Control

8-2

measurement,

(RAM)of

nested

3711

is used to interface the

Board

in

Section8foradetailed

Part

No.

control,

IC

on

this

128

bytes,

ports,

two

board

32

16-bit

interrupt,

LTV

EPROM.

Analog

to Digital Converter. An 8243

An

furnishes

6600-0048-700.

circuit

computation,

is

the

8031

has:

I/O

lines

timers,

a

programmable

octal

a

an internal read/write

configured as

transparent

stable

microcontroller

Refer

diagram.

memory,

single

a

five

serial

reference

source

latch

EPROM

to

logic,

component,

four

two

I/O

port,

to

supply.

I/O

with

the

The control board is also equipped with several ICs that

form

timer,

transducer

also

Detailed paragraph

ANALOG

Temperatures are measured using a negative temperature

coefficient

resistance

signals

from a voltage divider network consisting of a 5.76k +/-

0.1% resistor in series with the temperature

voltage source for the measuring circuit is obtained from

the LM-10*s internal precision reference source of 200

the

solid

and

included

operation

is

TO

DIGITAL

inversely proportional to temperature are derived

state

the

audio

for

the

on

the

explained

CONVERTER

thermistor

values

and

relay

alarm

control

of

the

watchdog

tone

signals

circuits

in

the

that

generator.

and

board.

following

is

calibrated

interchangeability.

circuit,

its

driver

listed

sections.

watch-dog

The

in

the

for

specific

Analog

sensor.

audio

circuit

preceding

voltage

The

mv

are

page

1-6

amplified

the

LM-10.

adjustable

required

patient

networks

are used

25.0

unused.

A separate input to the control board A/D circuit comes from

the

board.

The outputs of all the voltage dividing networks are

connected to individual switch input terminals of

and

line

to

a

nominal

The

Op-amp

reference

by the A/D

probe,

on

for

37.9 degrees C. The third divider

voltage

there

the

control

calibration check

monitor

1.0

volts

portion

of

2.0

volts

converter,

are

three

board.

network

by

the

of

the

nominally,

U6.

other

points

In addition to the

voltage

Two

have

located

LM-10

of the A/D svstem at

reference

provides

which

divider

fixed

on

output

network

the

power

buffer

an

is

and

is

supplv

U13,

the

of

MC14051B Analog Multiplexer. The MC14051B contains eight

normally open switches with a common output terminal. The

common output of the MUX (pin

analog input (pin 9)of the A/D converter. The

microcontroller selects which sensor is to be measured by

toggling the control lines, pin 11(A), pin 10(B), and pin

9(C)

shows the digital codes used to select the individual

switches

of

the MUX via the 8243 #2, U5. The following table

of

the

MUX:

3)

is tied through R9 to the

13 14

15

12 01

05

02

04

rate

R4

3711

NO

•

calibration

line voltage monitor

unused

patient probe

unused

analog

is

frequency

and

may

400

will

set

C14.

vary

kHz

to

by

The

by

clock

take

digital

the

is

+/-

may

place

ON

SWITCHES

XO

XI

X2

X3

X4 X5

X6

X7

a

pulse

The

conversion

oscillator

components

is

not

U6.

With a

within

6)

of the MUX has no effect on

modulation

whose

critical

the

and

nominal

ADC

A B

0 0

0 1 0

0 1

1 0 1 0 1

1 1 0 1 1

INPUTS C

0

1

0

1

CONTROL

Note: Inhibit terminal (pin

the switch selection because it is tied LOW through R19

ohms).

The

ADC

3711,

conversion

frequency

determined

oscillator

from

measured

frequency,

at an approximate rate of 3 per second.

the

nominal 400 kHz. The oscillator frequency

on pin

U6,

uses

technique.

of

an

internal

by the

external

frequency

18

of

conversions

value value

(200

exact

15%

be

25C

37.9C

The ADC

with

the

inputs

3711

will output BCD data on demand in accordance

coded*digital

DO and

Dl,

pins

signals

20

and

page

applied

21

respectively.

1-7

to

the

digit

The

select

data

latch enable is tied

converter

#2

in

the digit select

will

be

conformance

output

to

inputs:

LOW,

to

the

following

therefore,

the

microcontroller

the BCD data of the A/D

through

codes

that

are

applied

8243

to

DO Dl

L L Digit 0 LSD

L H Digit 1 H L Digit 2 H H Digit 3 MSD

Note:

3, 4, 23

The ADC 3711 is continuously converting the analog voltage

present at its input to a number of counts between 0 and

3999 (BCD format). Therefore, the start conversion, input

at pin 7, and the conversion complete, output at pin 6, are

misnomered. The start conversion input only controls the

transfer

digital latches. The conversion complete output goes to a

logic LOW on the rising edge of the start conversion pulse

which is issued by the microcontroller. The conversion

complete will go to a logic HIGH sometime later when the new

The

and

of

magnitude

24.

information

of

SELECTED

the

selected

from

the

DIGIT

digit

internal

is

present

counter

to

at

the

pins

conversion information has been transferred to the display

latches. The start conversion pulse may occur at any time

in the conversion cycle because the microcontroller is

running asynchronously to the A/D

amount

maximum

conversion complete

msec.

of time

time

from

difference

the

pulses

start

between

in this application is about

to

clock.

finish

the

will

start

Therefore, the

vary.

conversion

The

and

300

The

operation

measurement

analog voltage

and

a

precision

the A/D converter

multiplexer.

source

unregulated output of the power transformer. Switch

selection

which

multiplexer.

The

signal

microcontroller

3711

output

transferred, the A/D converter toggles the conversion

complete

is

toggles

analog

in

which

latches.

output

individual

select

lines of the

of

circuits

signal

reference

For

obtained

is

software

the

voltage

four

then

BCD

digit BCD

sendsastart

starts

When all of the

line. The

digits

the

temperature

can

derived

through

the

line

from

controlled

A,

B,

is

converted

to

using

A/D

and

be

summarized

from

source

an

is

eight

voltage

the

rectified,

by

and C

format

update

converter.

input

in the ADC

(0

conversion

the

counts

microcontroller

coded

page

signals

1-8

line

voltage

as follows:

a voltage divider network

directed

channel

measurement,

filtered,

the

microcontroller

lines

to

3999

digital

to

analog

of the

3711

counts).

pulse

data

the

to a

to

and

the

in the

have been internally

then

to

the

reads

digit

The

input

of

voltage

digital

The

ADC

the

ADC

CALIBRATION

The A/D converter is calibrated by connecting a 5900 +/-

0.1% DIP

ohm

switch

resistor

on the

to

the

control

patient

board

probe

in

the

jack and following

placing

position:

the

Switch Switch

Switch

Potentiometer R44 on the until the elapsed time display

DIP switches in the given

#1 #2

#3

#4

OPEN OPEN

OPEN

CLOSED

(OFF) (OFF)

(OFF)

(ON)

control

reads

position,

board

is then adjusted

exactly

1122.

the patient temperature

With the

display will read out the actual patient temperature, even if it is outside of the normal range and the control

temperature display will read out the percent of nominal

line voltage.

During

system

switch

panel. After 2 seconds, the patient temperature display should read 25.0 and the control temperature display should

be 37.9. The elapsed timer should read the applied line voltage, expressed as a percentaqe of the nominal voltage,

+/-

operation, the calibration of the A/D conversion may

be checked by pressing and holding the hidden

located

2%.

above

the

ALARM

SILENCE

SWITCH

on

the

control

MICROCONTROLLER

The control system is

It

operates

at

a

clock

measuring the frequency at the Address Latch Enable

pin to be 1

EA pin is grounded which enables the 8031 to execute

instructions from an external memory device.

MHz

(ON

When the microcontroller

EPROM,

while

(Note:

the low order

the high order

Bit 6 is configured onlv to provide expansion

compatibilitv with a

pin goes HIGH allowing the

between

output

outputs'of

the EPROM to remain addressed by the microcontroller, and

return

Port

I/O

(CS)

the

goes

EPROM

LOW,

the

8

bits

1

of

the 8031 is

expanders.

line of the

the low

D

of

data

Bits

flip

first,

=

address address

fully

and

located

speed

0.33

performs

the

microcontroller.

order

flops

while

used

5-7

are

second,

in the

of

6MHz

usee

and

a

(8

bits)

(6

bits)

programmed

LS373

to appear transparent

address

within

using

to

communicate

the

only

connected

and third respective I/O

8031

and

can

OFF =

read

instruction

is output outputs

27128

is

LS373.

two

to

microcontroller.

be

verified

(ALE)

0.67

usee).

The

from

Port 0

from Port

EPROM).

After

latched

This

ports.

to

the

Chip

The

the

to the

allows

three

Select

ALE

8243

by

2.

ALE

page

1-9

expanders.

the

outputs

the

instruction

bit

4

transitions

Providing

activates

to

be

between

a

LOW

signal

the

corresponding

carried

HIGH

out

and

on

by

LOW.

one

an

and

IC.

8243

only

Bits

when

one

0-3

the

of

hold

enable

/*^'

^%

/

Port

control

transmit

serial

microcomputer

frequency

subroutines

T0/P3.4 sends serial data to the display driver while

connection

LINE

The

sinusoidal line voltage

The output of the circuit is used to clock the 4020B counter

(U9)

system software. The 1N4001 diode

the 8 vac (nominal) signal which is divided by potential divider R45/R16 and inputted to the Schmitt trigger NAND

gate

trigger will be inverted. Since the gate will not respond until the input exceeds 1.9 volts minimally, the duty cycle

of the output will be slightly more than 50%.

3

is

used to

system.

respectively),

interface chips so that communication to an external

interrupt

found

T1/P3.5

FREQUENCY

line

frequency

and to provide a low frequency clock source for the

(U8,

perform

Connections

is

possible.

line

within

provides

circuit

5)

With one line tied HIGH, the

remaining

3.0

are

used

Connection

that

the

system

clocking

converts

signal

and

in

is

used

into a

tasks

3.1,

conjunction

software.

to the

the

(CR1)

required

(receive

by the

and

with

INT0/P3.2

to

aid

driver.

60

or

square

half-wave rectifies

is

in

timing

Connection

50

Hz

wave

signal.

output

a

the

line

of the

HEATER

The HEATER STATUS function signals the microcontroller and the safety circuitry as to whether or not the heater is ON

or

HIGH

Small glitches appear when the heater is ON. Consult the

Functional Description of the power supply board for further explanation. The output of the NAND gate is inverted

because one input is tied HIGH.

HARDWARE

The 4020B 14 bit binary counter, U9, counts at a rate equal

to the line frequency and responds to the negative edge of

the

Schmitt trigger NAND gate, pin 6 of U8. The counter resets when the 74LS123 retriggerable one shot flip flop outputs a

OFF.

if

clock

STATUS

The input to the Schmitt trigger

the

heater

SOLID

pulse.

STATE

is

The

OFF

RELAY

clock

and

LOW

TEST

signal is

if

(U8,

the

heater

received

is ON.

from

13)

a

is

page

1-10

-f^"

HIGH

and

74LS123, U3, is HIGH at a time equal to

or

level

A

tied

after

pulse

LOW,

12304

on the Q

the

counter

counts

output

will

(Q5 = 16,

line.

reset

Q13

With CLR tied HIGH

=

when

4096,

(Q5)

B

of

the

+(Q13) +'Q14)

Q14

= 8192).

Approximately 6.19 usee, later the output of the one shot

will

return

to

its

initial

LOW

state.

Q13 and Q14 of the 4020B are tied to a 2 input AND gate

pins 1 and

8 counts Q4 of the counter qoes HIGH. Q4 is tied to the

2)

which will go HIGH after 12288 counts. After

(U2,

CLR

pin of D flip flop Ul. When CLEAR goes HIGH, the output of

Ql

(Ul

5)

is allowed to equal the input D on the next

positive edge of the clock pulse. Therefore the output at pin 5 will update after 9 counts. After 12288 counts

(3.4133

minutes

on 60Hz units, or 4.096

minutes

for 50Hz

units) the signal at the D input of the flip flop goes HIGH.

This signal is also input to the microcontroller through the

I/O expander

U4.

The software will then switch OFF the

heat. Nine counts later the HIGH input on D is clocked to

the output Q. The heater status (OFF-LOW, ON-HIGH) sent

from the Schmitt trigger NAND gate pin 11 of U8 is always

present at the

input

of U2 pin

5.

If the heater

is

still

ON

after 9 counts, the output of the AND qate pin 6 of U2 will

clock the second D flip

switch - Q goes

sets

off

the

HIGH

audio

alarm

safety relay causing the heater to switch

HEATER

STATUS

LED

flop.

and

The outputs of the flip

NOT

Q goes LOW. A

and drops

out

LOW

the

non-resettable

OFF.

on

NOT

flops

Q

A

heater

status

LED

is

located

on

the

control

board

for

troubleshooting. The LED can be seen through the rear of

the controller assembly

the

Schmitt

switches

the

LED

WATCHDOG

A

watch

trigger

ON causing the LED to emit

is

OFF.

TIMER

dog

timer

is

is"

used

cover.

HIGH,

to "check"

When the status line from

(heater

ON)

light.

that

the

transistor

If heat is

the

Q2

OFF,

microcontroller is working properly. After every cycle

through the system software the microcontroller sends a LOW

pulse'to the A input of

U3,

a

74LS123.

The RC network

connected to the RxCx and Cx pins create a time constant, t

=0.45xRxC=

0.263 seconds. If a pulse is not received

at the input before the time constant expires, the output

will go

due

to

LOW.

the

The high priority alarm will then be activated

microcontroller

failure.

Note

when

the

microcontroller detects a high priority alarm condition,

pulses to the watch dog circuit stop.

page

1-11

ALARM

The

TONE

alarm

GENERATOR

AND

CONTROL

circuit consists of an

CIRCUITS

alarm

tone

generator

and

control circuitry for high or low priority alarm conditions.

Under

inactive,(reset

LOW

a

no

PRIORITY

alarm

ALARM

condition

lines low).

the

7556

timers

are

both

Under normal operating conditions the input to U8 pin 9 is

HIGH.

a 1 Hz square wave is output to U8 pin

When

the microcontroller detects a low priority

9.

The timer

alarm

activates, causing a 2 kHz audio output. This results in a

one second ON, one second OFF audio alarm. The 2 kHz signal

of

is adjusted within +/- 100 Hz by R38. The volume

the audio alarm is adjusted by R37. This should be adjusted fully

CCW

for maximum volume.

HIGH

PRIORITY

ALARM

The high priority alarm is activated if the microcontroller

quits sending pulses to the watchdog timer. This occurs when a high priority alarm condition is detected or if the microcontroller fails. The high priority alarm is also

activated if the hardware solid state relay test circuitry

detects a failed solid state relay. Both timers become active with one timer feeding a 1 Hz signal to the control

line of the second. The 1 Megohm resistor changes the

output frequency of the second timer to produce a warbling effect (two tone alternating alarm). If high and

low

priority alarms are both ON, the output of the AND gate overrides the low priority signal, keeping both timers

active.

HEAT

CONTROL

ROUTINE

Proportional control of the heater power is obtained by

varying

delivered to the heater. To allow for line

the

number

of

full heat cycles of ac

current

voltage

compensation and still have at least 20 discreet levels of heat, a proportioning range of 0 to 60 full heat cycles is

used. In other words, at very low line voltages, 100% heat

will

of a possible maximum of

be output by

having

the heat ON for 60 full cycles

60.

Similarly, at this low line

out

voltage 90% heat is obtained by having the heat ON for 54

out

of

60

cycles.

page

1-12

In the "manual" mode of operation, the heat output is

determined by the bar-graph setting selected by the

operator. There are 20 steps on the bar-graph so each step

represents a 5% heat increment. To accomplish the desired compensation for line voltage variations, the maximum number

of

heat

of the power line voltage. For 115v nominal units, a line

voltage

number of heat cycles to 60. At greater than 125 volts the

maximum number of heat a possible

cycles

of

106

60.

is

calculated

volts

or

Therefore,

less

cycles

based

will

is limited to 40

on

the

increase

last

the

measurement

maximum

cycles

the number of cycles of current

out of

furnished to the heater in the manual mode is determined by

multiplying the maximum

line

voltage present by the

for

the

bar-graph setting. For example: assume the line voltage is

115v (maximum number of

setting is

30%;

the number of heat cycles to be output will

be 0.3 times 50 = 15

heat will be ON

for

sequence will continue until the

setting is changed on the

In the "servo" mode, the heater power is controlled by

cycles

cycles.

15

cycles

ON =

50)

and the bar-graph

Under these conditions the

and OFF

line

for

45

cycles,

voltage changes or the

bar-graph.

this

comparing the patient's skin temperature to the selected

value

control temperature and the patient temperature is referred

of

control

temperature. The

difference

between

the

to as "PTG"(patient temperature gradient). A positive PTG

indicates

a patient

is

cooler

than the

control

temperature

and a negative PTG occurs when the patient temperature is

higher than the control

and sign of the

find

converted to the appropriate number of bar-graph steps and

then the selected amount of heat is output by the same

process

the percent heat

used

in

PTG,

the

temperature.

Based on the magnitude

a software look-up table is used to

required.

manual

mode.

The percent heat is then

A hardware circuit is used to interrupt the microcontroller

once every cycle of the ac power line. During the interrupt

routine,

two

registers

are

decremented

to keep track of the

heater ON and OFF cycles. One register is used for counting

the number of cycles in one second

is loaded on

cycles to be output. A flag is set whenever this register

is

not

zero,

The

operation

output hardware are repeatedly tested during operation of

the warmer.

resistor directly across the heater terminals is used to

monitor heater

fed

into a Schmitt

ever}/

the

of

An

sixtieth count with the number of heat

heat

the

heat

opto-isolator

power.

trigger,

is

ON

only

control software

connected

The output of the opto-isolator is

which outputs directly to an

(60)

when

and another

this

with

flag

and

a series

is

the

register-

set.

heat

input port of the microcontroller. Therefore, the

microcontroller can verify if the heat is actually on when

it is supposed to be

be activated. Approximately every three

external hardware network (safety circuit) signals the

microcontroller

to

on.

switch

If

OFF

page

not,

the

1-13

a system

minutes,

heat.

This

fail

hardware

alarm will

an

also

monitors the output of the Schmitt trigger (heater status

line). If the heater power is not switched OFF after a short delay, the hardware circuit will de-energize the

"safety" relay to switch OFF heater power and also initiate

an alarm which cannot be silenced without switching the

power

OFF.

SERVICE

FEATURES

The electronic controller assembly is easily removed for

servicing or calibration. This controller contains all the

circuitry

and

components except for the heater,

alarm

lamps,

and observation lamps.

All indicators and the audio alarm are activated on power-up

for operator verification of proper display operation.

These can also be activated by depressing the alarm silence

switch

for

2

seconds.

In

addition

the

software

revision

number and the line frequency are displayed.

Test

points

on the printed

circuit

boards

are accessible

for

troubleshooting and calibration without removal of the

boards. In addition integrated circuits with 24 pins or

more have sockets to aid in troubleshooting and repair.

Software routines are built into the warmer to provide test

functions, to aid in troubleshooting, calibration, and

operation verification.

These

test routines are activated

using a DIP switch located on the control board. Some of

the test routines can be activated using the display panel.

Calibration may be verified on the controller display

without disassembly. A high calibration point and a low

calibration point are displayed when the service test switch

is pressed for 2 seconds.

Line voltage is monitored by the warmer and fluctuations of

+/- 10% from nominal voltage are compensated for so that

heat output is held constant. If the voltage exceeds +/-

17.5%

switches

SELF

from

TEST

nominal

off.

FUNCTIONS

an

alarm

is

activated

and

the

heater

The following text is a description of the self test

functions performed by the Infant

Warmer

System. If an

error results on any of the power-up or on-line tests then the error number will be displayed on the elapsed time

display in the format E

##.

The high priority alarm

page

1-14

(SYSTEM

Power

FAILURE

must

be

LED)

switched

will

OFF

be ON

to

and

reset

cannot

this

be silenced.

alarm.

POWER

UP

TESTING

On power up the following tests are performed.

1.

INSTRUCTION

TEST

(ERROR

#01)

Selected instructions are tested and verified operational.

2.

CHECKSUM

(ERROR

#04)

The hex values of Eprom locations from 0000 to 1FFD are

added together and a 2 byte sum is stored. Eprom locations 1FFE and 1FFF contain a 2 byte number which

when

3.

added

RAM

TEST

to

the

(ERROR

calculated

#05)

checksum

should

total

zero.

Rams 10 through 7F are tested with patterns of

00,FF,AA,

4.

TEST

and

PORT

55.

1

LINES

(ERROR

#06)

The port one I/O lines are tested to verify they

can

be

toggled.

NOTE:

At power up the software revision number is displayed

for 1 second in the elapsed time display, after the LED

segment

test.

ON

LINE

TESTING

The following tests are run during the normal operation of

the software. An error on any of these tests results in a

SYSTEM

1.

#03)

FAILURE

ADC

CALIBRATION

alarm.

TEST

(CAL

HIGH

ERROR

#02,

CAL

LOW

ERROR

Verifies that readings of the precision calibration

resistors are within 0.3 degrees of the nominal values.

These readings can be checked by depressing the hidden

switch on the display panel (located directly above the

alarm

silence

switch)

for

2

seconds.

After 2 seconds the displays should indicate as follows:

2.

Patient Control

HARDWARE

Temperature Temperature

SOLID

STATE

is 25.0 +/- 0.3 degrees. is 37.9 +/- 0.3 degrees.

RELAY

TEST

page

1-15

A circuit independent of the microcontroller monitors that

the micro can switch the heat OFF. Every 3 minutes 24

seconds in 60 Hz operation (4 minutes and 5 seconds for 50

Hz operation) a request is made to the micro to switch the

heat

OFF. If

the

heat does not go OFF, a

hardware

latch

is

latched and a relay contact is opened so there is no heat.

This verifies that the solid state relay is not shorted and

that

failure does

the

micro

is

still

not

display an error number because it is not

able

to

control

the

heat.

This

controlled by the micro but will cause the software solid

state relay test to fail when heat is called for by the

program.

3.

ADC

CONVERTER

NOT

CONVERTING

(ERROR

#07)

Verifies that the ADC conversion complete occurs within 1

second.

4.

SOFTWARE

SOLID

STATE

RELAY

TEST

(ERROR

#09)

The heater status line is checked to verify that the heat is

ON

when

the

micro

is switching it ON. This verifies that

the solid state relay is not failed open.

/^%~

5.

LINE

VOLTAGE

OUT

OF

RANGE

(ERROR

#10)

Verifies

that

the

line voltage is within the range of 82.6% to 117.4% of

nominal input voltage. (95v to 135v, for 115v units)

DIAGNOSTIC

TESTING

Diagnostic testing can be accessed by one of the following:

1.

Depressing and holding the APGAR TONES switch while

powering up unit. This causes the unit to cycle in the self

test loop until power is removed. See SELF TEST LOOP in

step

5.

2. Selecting one of the test positions on the 4 position

DIP

switch located on the control board.

Following

is a

description of the functions of the DIP positions:

a.

b.

SWITCHES

HARDWARE

ALL

OPEN

2,3,4,

SOLID

(OFF)

CLOSED

STATE

NORMAL

(ON)

RELAY

and

TEST

OPERATING

SWITCH

(0E)

POSITION

1

OPEN

(00).

(OFF)

This

test

mode

circuit.

can

be

The

used

heat

to test the

is

switched

hardware

ON

all

solid

the

state

time

relay

to

simulate a failed solid state relay. The elapsed time display will start at zero on power up and display the elapsed time. At about 3 minutes 24 seconds for 60Hz operation (4 minutes and 5 seconds for 50 Hz operation) a

page

1-16

failed solid state relay should be detected. The high

priority audio alarm should come ON and the heat should go

OFF.

The

heat

indicator

LED

located

on

the

control

board

should be checked to verify that the heat is OFF.

c.

The

SWITCHES

ADC

CALIBRATION

system

1,2,3,

OPEN

(08)

(OFF)

and

SWITCH

4

CLOSED

(ON)

displays the actual ADC counts on the elapsed

time display, the patient temperature on the patient display

even if outside of the normal displayed ranqe, and the % of

nominal line voltage on the control display. This position

is used for calibrating the analog to digital converter and

the line voltage compensation circuit.

d.

SWITCHES

ALARM

1,2,4

CALIBRATION

OPEN

(OFF)

(04)

and

SWITCH

3

CLOSED

(ON)

All segments of all LEDs are lit. The heater, overhead

alarm

lamps,

and the observation lamp are on. The audio

alarm emits a steady low priority alarm sound. The 2 kHz

alarm frequency can be adjusted using this mode.

e.

SWITCHES

SELF

TEST

ALL

LOOP

CLOSED

(OF)

(ON)

In this mode the unit cycles through a display test, checks

ADC calibration, cycles the heater, alarm lights, and

observation lights, and steps through the tests described in

power up testing. It also monitors the touch switches and

sounds the critical alarm while any switch is depressed. If

any error occurs the error number will be displayed on the

elapsed time display and the critical alarm will sound for

two seconds. The program will then continue to loop through

this test,

(OFF).

even

if the 4 DIP switches are

returned

to OPEN

If the test loop is entered on power up by depressing the

APGAR TONES switch the program will loop until an error is

detected. If an

the test

loop, elapsed time display, and the critical alarm will The power must be switched OFF to exit this

error

is

detected

the

unit

will

then

the error code will be displayed in the

sound.

mode.

stop

page

1-17

SELF

TEST

LOOP

The unit cycles in the following loop until the power is

removed.

Power

Instruction

up

tests

performed:

test

Check calibrate high

Check

Checksum

Ram

Test

calibrate

test

port

low

1 lines

Check if ADC is converting

(ERROR

(ERROR (ERROR

(ERROR

#01)

#02)

#03)

#04) #05)

#06)

#07)

page

1-18

Display loop test:

SEVEN

DISPLAY1

All All

All

All All All All

All

All All

The

Error

ERROR

SEG

l's 2's

3»S

4's 5's 6's 7's

8fs

9fs

0»s

OFF

unit

Codes

BAR

SEGMENTS

S

1,11

2,12

3,13

4,14

5,15

6,16 7,17

8,18 9,19

10,20

All

returns

DESCRIPTION

GRAPH

OFF

to

start

ALARM

Probe

Pat

Svs

Heater

Reset

Spare

All All All All All

of

temp

fail

OFF OFF OFF OFF OFF

self

LEDs

fail

OFF

timer

LED

test

MODE

Servo Servo

Servo

Manual

Apgar Apgar

Apqar

All

loop.

POSSIBLE

LEDs

OFF

HEATER

LIGHTS

ON

OFF ON

OFF

ON

OFF ON

OFF

ON

OFF OFF

CAUSE

&

#01 Instruction test fails Microprocessor 8031 failure

#02

Calibrate high

fails

ADC calibration

Cal high resistor failure

#03

Calibrate

low

fails

ADC

Cal

calibration

low

resistor

failure

#04 Checksum fails Eprom failure

Microprocessor 8031 failure

#05 Ram test fails Microprocessor 8031 failure #06 Port 1 lines I/O expander 8243 failure

Microprocessor 8031 failure

#07 ADC not converting A/D Converter ADC3711

Voltage Reference LM10

failure

I/O expander 8243 #2 failure

#08

#09

Not

Heat

used

not

controlled

Heater

failure

solid

state

relay

Microprocessor 8031 failure

#10

Line

voltage

out of

range

VQ1000J Power FET

Line

on

calibrated.

voltage

power

compensation

supply

(VI)

board

failure

not

pot

#P*N

page

1-19

C.

DISPLAY

BOARD

This

System Display Board Part No. 0631-5031-700. Refer to

Figure

The display board provides the interface between the

operator and the control

the unit, the patient

diagnostic

depressing

Operation

two

with the

conjunction with the LED

SWITCH

The I/O expander, Ul, is always enabled in the read mode

because

The

signal

bits)

transition of the PROG

is a

ICs:

functional

8-3

in

aid.

the

of

the

Section8foradetailed

The

various

the

display

8243

switches;

DECODING

its'

8243

sole

is

activated

on the Chip Select

is

latched

from

description

system.

statxis,

operator

switches

board

for

the

Infant

circuit

Warmer

diagram.

It displays the status of

and can also be used as a

controls

on

is

simplified

the

system

front

by

display.

with

the

use of

I/O expander which is used in conjunction

and

the

MM5451

(or

MM5450)

driver

used in

display.

purpose

by

the

pin.

is

to

detect

the

microcontroller

(CS)

input

line.

port

switch

depressions.

sending

A control word

2 on

the

HIGH

to LOW

The word is decoded as follows.

a LOW

(4

P23

INSTRUCTION

P22

0 0

1 1

0

1

0

1

CODE

Read

Write

OR AND

P21

0 0

0

1 1

P20

1 0

1

ADDRESS

As soon as the read instruction and the port address are

decoded the corresponding port lines are set to a HIGH

impedance

switched

respective

buffer.

terminates the read instruction and transfers information

back to port

HIGH

LED

The

the

DISPLAY

LED

displays

refresh rate of 60 synchronously with the clock

state

ON.

When

line

The

LOW

2.

8243

is

DRIVER

display,

are

multiplexed

and the

a

switches

to

input

switch

HIGH

buffers

is

depressed

LOW

and

is

transition

within

on

loaded

on

the

into

PROG

82

43 are

display,

the

input

line

When the microprocessor sets the CS line

disabled.

driver,

hertz.

U2,

controls

with a

duty

the

cycle

LED

of

Data is input to pin 22

(pin

21).

The first

displays.

20%

and a

"1"

bit

CODE

Port

the

The

4

5

6

7

page

1-20

f^

activates

the

driver

and

35

data

bits

will

follow.

After

the 35th bit is loaded the data is latched to provide direct

output. Note that a logic HIGH at the input switches the

output LOW and switches ON the LED connected to the output

(output is inverted).

BRIGHTNESS

ADJUST

R9 is used to adjust the output current from U2 and in turn change the brightness of the LEDs. R9 is adjusted to

produce

15ma).

MULTIPLEXING

3.30

+/-

0.10

volts

across

RIO

(3.3V

/

221

C6 is used to prevent oscillations at pin

OF

DISPLAYS

ohms

19.

=

Since there are not enough data bits to drive the entire display, the displays are divided into four sections. Bits

1-28 are

section.

1%

resistor

used

Bit

to supply the necessary information to each

29 is unused. Bit 30 is

which

is

used

for

calibration.

tied

to a 221

Bits

31-34

ohm

+/-

select which channel of the display is activated by switching ON a Darlington

transistor.

provides a large gain so that a small drive current will

sustain the large current draw from the LEDs.

The Darlington

A string of 35 zeroes are sent on the data line every fifth

update cycle. The driver has a serial input and does not

have a master reset. This string of zeroes resets the

driver in case an extra pulse was entered by a noise

spike.

The basic circuit for one LED segment consists of the 5 volt

LED

supply

a Darlington switch to enable the supply to the LED

(reduced to 4.3 volts by a series 1N4001 diode,)

group,

and the MM5451 driver to select a low voltage return for the

segment

(if

selected).

page

1-21

2/

SPECIFICATIONS

All specifications are

2.1

ELECTRICAL

POWER

REQUIREMENTS

0305-0404-910

0305-0404-911

0305-0404-912 0305-0404-913

subject

120

V

220

V

240

V

100

V

to change without notice

50/60

50/60 50/60

Hz

Hz Hz

Models

Models Models

115V

220V"

240V

95V

+/-

+/+/-

10% 10% 10%

10%

This model is designed to conform to IEC 601-1 requirements.

NOMINAL

HEATER

600

540

POWER

watts

OUTPUT

watts

CONSUMPTION

at

maximum

+/-

5% at

%power

maximum

setting.

%power

setting.

Average Energy at Mattress Level is 35 mw/cm2 at

Maximum

Peak

%

power

wavelength

setting

2.4

micron

at

100%

power.

6.6

3.7

3.3

8.2

amps

amps amps amps

RECOMMENDED

27

inches

WARNING: If

27

+/-

2

inches,

properly.

LINE

VOLTAGE

Input voltage is monitored and the heater drive output is

adjusted to compensate for variations of line voltage.

CIRCUIT

CHASSIS

BREAKER

Rated

Trip

Type:

Model:

LEAKAGE

Point: 9.4 5 amps

With

less

120V

240v

connection.

BED

LEVEL

+/-

the

bed

COMPENSATION

Current:

Manual

Airpax

CURRENT

the

ground

than

50

units

units)

2inches

level is

the

Infant

(All

except

7

amps

Resetting

Snapak

wire

microamperes

(100

microamperes

measured

from

the

greater

Warmer

lOOv

Minimum

open

or connected,

on

at

the

bottom

than

System

units)

100V

on

220v

patient

of

or less

will

and

probe

and

heater

not

module.

than

operate

With

less lOOv

the

than and

ground

less

120v

wire

than

units

open

90

(180

page

or connected,

microamperes

2-1

on

220v and 240v

metal

2.2

CONTROLLER

ELECTRONICS

Microprocessor based

Self test functions are performed at

power up and during normal operation.

surface.

units)

measured at an exposed

control

system.

POWER

CONTROL

Proportional heat control with zero

voltage switching to minimize radiated

and

EXAMINATION

Nominal illuminance output: 100 foot

candles

lamp life: 3,000 hours.

TEMPERATURE

Range:

Accuracy:

Resolution: +/- 0.1 degrees C Probe interchangeability: +/- 0.1 degrees C

Probe

ELAPSED

60 minute elapsed timer with hold mode

and

MANUAL

Manual

20 increments

conducted

TIMER

Apgar

MODE

LIGHT

at

SENSING

22-42

Model

mode

METHOD

center

+/-

Number:

tones.

heat

EMI.

of

SYSTEM

degrees

mattress.

C

Estimated

0.3 degrees C

LAO03

selector range: 0 to 540

(5%

per

step).

watts

in

SERVO

MODE

Servo control range 35.0 to 37.5 degrees C in

increments of 0.1 degrees

BED

HEIGHT

Control for raising and lowering the bed and

2.3

heater

ALARMS

assembly.

Multiple audio tones

1.

Operator

prompt

2. Alternating single tone

3.

Alternating

tone

two tone

page

C.

2-2

Ohmeda Infant Warmer Service manual

Specifications and Main Features

Frequently Asked Questions

User Manual