BCI Capnocheck Plus User manual
-Capnocheck’
Plus
Service
Manual
BCI
International
W238
N1650
Rockwood
Drive
Waukesha,
Wi
53188-1199
Catalog
Number
1873
June
12,
1997
Version
2
©1997,
BCI
International
Table
of
Contents
Chapter
1:
Introduction
1-1
Warranty
dí
Service
InforMatiON......ococioonnorncnconracncnnnecnncoronenorrarcoonanonananin
conan
onorororenenecenen
oi
oras
1-1
Proprietary
Notice
................
…1-1
TLimited
Warranty
inner
…
1-1
Loaner Device
(DomesticSalesOnly)..............................
e
1-1
Service
SUPpport...........
iene
„12
About
This
MEantal
,sse
AA
1-2
À
Warnings,
Cautions,
and
Notes...
rr
sknne
1-2
Wamings.............................
..
1-2
CautiONS
иене
ини
ипититевлиилитилитишииииитинтилиниия
1-4
NA
emermere
senar
ramaaesereereseeesernen
1-4
Pneumatics
Cleaning
1-6
The
Pneumatics
consists
of
five
main
parts:...
„16
SA
1-6
Chapter
2:
Field
Service
Menu
2-1
Field
Service
Menu
Chapter
3:
Capnocheck?
Plus
Circuit
Description
3-1
Battery
Chareer
eee
zona
canini
onee
ze
iniezione
ione
3-1
System
Power
Supply
and
ON/OFF
Circuitry.
Microprocessor
Section
and
Address
Decoders...
na
Display
Controller...
ieri
Speaker
Volume
Controller.
...........
Extemal/O's.....................
Pump
and
Valve
Control...
rien
NA
II
AAA
can atara
tan
saanananads
3-6
Analog
Outputs
Controller.
„3-6
RS232
Controller.
...
3-6
Real
Time
Clock..
… 3-7
WachDogTimer..........................
eee
eee
meeereeseresezezen
3-7
Analog
SecttOn
uri
rie
eee
iii
3-7
CO;
Sensor
...
Pressure
SenSOT.
ii
3-8
FiO,Sensor....................
erener
sene
eeereraseraneseressrersenaaazn
3-8
Battery
Voltage
Level
.3-8
Signal
Dictionary
.
…
3-9
E
AAA
3-9
Chapter
4:
Oximeter
Board
(LOX)
Circuit
Description.
4-1
General
Description.
Power
Supply...
때
Isolated
Interface
and
Reset
Circuitry..…..........
sise
4-1
Capnocheck
Plus
Service
Manual
i
Table
of
Contents
Microprocessor
Circuit
and
Analog-to-Digital
Converter.
LED
Drive...
eee
ooo
ee
oo
eee
rene
re
oa
„42
Analog
Signal
Processing
nes
4-2
Signal
Dictionaly.............
vaa
aeeerenmrenesesearsesasasasaraamassanansennna
4-3
ο)
ο
μυ
μμ
μμ
rei
4-3
Chapter
5:
System
Testing
5-1
Test
Equipment
and
Tools
Required
eee
eeeeeeenenenen
5-1
Visual
Inspection
.
Power
ЗиррНе$
..........
чении
нинононининилинмиииншииаииваизииньиманонииининимевивининивипиинивиининиинитповитиитининияи
Main
Board
ssscessssereseecsesescesscasosecenseccesvacaesversessassssenseneesessseeseceneersesticavssssavennesee
LOX
Board...
Pneumatics
....
Inlet
Sample
Flow
..
Occlusion
Verifieaton
issues
5-2
Appendix
Appendix-1
Parts
LiSS
inner
Appendix-1
Assembly
Drawings
and
Schematics
ena
nnné
Appendix-1
di
Capnocheck
Plus
Service
Manual
Chapter
1:
introduction
Chapter
1:
Introduction
Warranty
&
Service
Information
Proprietary
Notice
Information
contained
in
this
document
is
copyrighted
by
BCI
International
and
may
not
be
duplicated
in
full
or
part
by
any
person
without
prior
written
approval
of
BCI
International.
Its
purpose
is
to
provide
the
user
with
adeguately
detailed
documentation
to
efficiently
install,
operate,
maintain
and
order
spare
parts
for
the
device
supplied.
Every
effort
has
been
made
to
keep
the
information
contained
in
this
document
current
and
accurate
as
of
the
date
of
publication
or
revision.
However,
no
guarantee
is
given
or
implied
that
the
document
is
error
free
or
that
it
is
accurate
with
regard
to
any
specification.
Limited
Warranty
BCI
International
warrants
each
new
device
to
be
free
from
defects
in
workmanship
and
materials
under
normal
use
and service
for
a
period
of
two
(2)
years
from
the
date
of
shipment,
and
reusable
oximetry
probes
for
a
period
of
one
(1)
year
from
shipment
(domestic
sales
only).
BCI
International's
sole
obligation
under
this
warranty
will
be
to
repair
or
replace,
at
its
option,
products
that
prove
to
be
defective
during
the
warranty
period.
The
foregoing
shall be
the
sole
warranty
remedy.
Except
as
set
forth
herein,
seller
makes
no
warranties,
either
expressed
or
implied,
including
the
implied
warranties
of
merchantability
and
fitness
for
a
particular
purpose.
No
warranty
is
provided
if
the
products
are
modified
without
the
express
written
consent
of
BCI
International,
and
seller
shall
not be
liable
in
any
event
for
incidental
or
consequential
damage.
This
warranty
is
not
assignable.
Loaner
Device
(Domestic
Sales
Only)
BCI
International
will
for
the
period
of
warranty
make
available
at
no
charge,
loaner
devices
if,
in
BCI
International's
opinion,
the
repair
of
the
customer's
device
would
require
an
unreasonable
period
of
time.
Capnocheck
Plus
Service
Manual
1-1
Chapter
1:
Introduction
Service
Support
Repairs
of
BC]
International's
devices
under
warranty
must
be
made
at
authorized
repair
centers.
If
the
device needs
repair,
contact
BCI
International's
service
department
or
your
local
distributor
to
request
a
customer
service
report
number
(CSR).
When
calling,
have
the
device’s
model
and
serial
number
ready.
NOTE:
Shipments
received
without
a
CSR
number
will
be
returned
to
sender.
If
you
need
to
ship
the
device,
pack
the
device
and
its
accessories
carefully
to
prevent
shipping
damage.
All
accessories
should
accompany
the
device.
BCI
International
Phone:
(414)
542-3100
W238
N1650
Rockwood
Drive
Toll-Free:
(800)
558-2345
Waukesha,
WI
53188-1199
Fax:
(414)
542-0718
E-mail
address:
bciinti@
execpc.com
About
This
Manual
This
manual
contains
circuit
descriptions,
voltage
and
waveform
test
points,
detailed
parts
lists,
and
circuit
diagrams
for
the
capnometer.
It is
intended
for
persons
trained
in
service,
maintenance,
and
repair
of
modern
medical
equipment.
Thorough
knowledge
of
this
equipment’s
operation
is
required
before
attempting
to
repair
this
equipment.
VAN
Warnings,
Cautions,
and
Notes
Warnings
KEYWORD
DEFINITION
WARNING
Tells
you
about
something
that
could
hurt
the
patient
or
hurt
the
operator.
CAUTION
Telis
you
about
something
that
could
damage
the
monitor.
NOTE
Tells
you
other
important
information.
WARNING:
Federal
law
(USA)
restricts
the
use
or
sale
of
this
device
by,
or
on
the
order
of,
a
physician.
WARNING:
Do
not
use
this
device
in
the
presence
of
flammable
anesthetics.
WARNING:
Do
not
autoclave, ethylene
oxide
sterilize,
or
immerse
in
liquid.
Unplug
before
cleaning
or
disinfecting.
1-2
Capnocheck
Plus
Service
Manual
Chapter
1:
Introduction
WARNING:
ELECTRICAL
SHOCK
HAZARD
when
cover
is
removed.
Do
not
remove
covers.
Refer
servicing
to
qualified
personnel.
WARNING:
Use
only
SpO2
probes
supplied
with,
or
specifically
intended
for
use
with,
this
device.
WARNING:
Do
not
use
this
device
in
the
presence
of
magnetic
resonance
imaging
(MR
or
MRI)
equipment.
WARNING:
Do
not
plug
the
monitor
into
an
outlet
controlled
by
a
wall
switch.
WARNING:
This
device
must
be
used
in
conjunction
with
clinical
signs
and
symptoms.
This
device
is
only
intended
to
be
an
adjunct
in
patient
assessment.
WARNING:
In
the
event
that
earth
ground
integrity
is
lost,
the
performance
of
this
device
and/or
other
devices
nearby
may
be
affected
due
to
excessive
RF
emissions.
WARNING:
Reposition
the
SpO,
probe
at
least
once
every
four
(4)
hours
or
as
needed
to
allow
the
patient's
skin
to
respire.
WARNING:
When
attaching
SpO2
probes
with
Microfoam®
!
tape,
do
not
stretch
the
tape
or
attach
the
tape
too
tightly.
Tape
applied
too
tightly
may
cause
inaccurate
readings
and
blisters on
the
patient's skin
(lack
of
skin
respiration,
not
heat,
causes
the
blisters).
WARNING:
The
displayed
message
FiO.
Ref
Err
indicates
a
factory
calibration
setting
is
incorrect.
Contact
your
authorized
repair
center.
WARNING:
Each
FiO,
cell
has
different
output
characteristics;
changing
the
FiO,
cell
without
calibrating
the
monitor
can
result
in
incorrect
displayed
FiO,
values.
The
incorrect
values
are
unpredictable
in
both
magnitude
and
direction,
possibly
resulting
in
hypoxic
FiO2
gas
mixtures
while
displaying
high
FiO.
values.
It
is
your
responsibility
to
properly
calibrate
the
monitor
after
changing
FiO,
cells.
WARNING:
When
connecting
this
monitor
to
any
instrument,
verify
proper
operation
before
clinical
use.
Refer
to
the
instrument’s
user
manual
for
full
instructions.
Accessory
equipment
connected
to
the
monitor’s
data
interface
must
be
certified
according
to
the
respective
IEC
standards,
i.e.,
IEC
950
for
data-processing
equipment
or
IEC
601-1
for
electromedical
equipment.
All
1
Microfoam®
is
a
registered
trademark
of
the
3M
Company.
Capnocheck
Plus
Service
Manual
1-3
Chapter
1:
introduction
Cautions
Notes
combinations
of
equipment
must
be
in
compliance
with
IEC
601-1-1
systems
requirements.
Anyone
connecting
additional
equipment
to
the
signal
input
port
or
signal
output
port
configures
a
medical
system,
and,
therefore,
is
responsible
that
the
system
complies
with
the
requirements
of
the
system
standard
IEC
601-1-1.
CAUTION:
Ensure
the
device’s
AC
rating
is
correct
for
the
AC
voltage
at
your
installation
site
before
using
the
monitor.
The
monitor’s
AC
rating
is
shown
on
the
external
power
supply.
If
the
rating
is
not
correct,
do
not
use
the
monitor;
contact
BCI
International’s
service
department
for
help.
CAUTION:
This
device
is
intended
for
use
by
persons
trained
in
professional
health
care.
The
operator
must
be
thoroughly
familiar
with
the
information
in
this
manual
before
using
the
monitor.
CAUTION:
Do
not
allow
water
or
any
other
liquid
to
spill
onto
the
monitor.
Unplug
the
external
power
supply
from
the
monitor
before
cleaning
or
disinfecting
the
monitor.
CAUTION:
Pressing
front
panel
keys
with
sharp
or
pointed
instruments
may
permanently
damage
the
keypad.
Press
front
panel
keys
only with
your
finger.
CAUTION:
Do
not
disassemble
unit,
not
user
serviceable.
Refer
to
qualified
service
personnel.
NOTE:
Dyes
introduced
into
the
bloodstream,
such
as
methylene
blue,
indocyanine
green,
indigo
carmine,
and
fluorescein,
may
cause
an
inability
to
determine
accurate
SpO,
readings.
NOTE:
Any
condition
that
restricts
blood
flow,
such
as
use
of
a
blood
pressure
cuff
or
extremes
in
systemic
vascular
resistance,
may
cause
an
inability
to
determine
accurate
pulse
and
SpO;
readings.
NOTE:
Operation
of
this
device
may
be
adversely
affected
in
the
presence
of
strong
EM
or
RF
sources,
such
as
electrosurgery
equipment.
NOTE:
Operation
of
this
device
may
be
adversely
affected
in
the
presence
of
computed
tomograph
(CT)
equipment.
1-4
Capnocheck
Plus
Service
Manual
Chapter
1:
Introduction
NOTE:
Significant
levels
of
dysfunctional
hemoglobins,
such
as
carboxyhemoglobin
or
methemoglobin,
will
affect
the
accuracy
of
the
SpO2
measurement.
NOTE:
SpO»
measurements
may
be
adversely
affected
in
the
presence
of
high
ambient
light.
If
necessary,
shield
the
probe
area
(with
a
surgical
towel,
for
example).
NOTE:
Remove
fingernail
polish
or
false
fingernails
before
applying
SpO2
probes.
Fingernail
polish
or
false
fingernails
may
cause
inaccurate
SpO2
readings.
NOTE:
Store
the
FiO:
cell
as
shipped
in
its
protective
wrapping,
until
it
is
ready
to
use.
This
maximizes
the
FiO,
cell’s
shelf
life.
NOTE:
Prolong
FiO}
cell
life
by
avoiding
high
O;
and
CO;
concentrations
when
it
is
not
in
use.
NOTE:
FiO,
Humidity
and
Pressure
Compensation:
Humidity
(i.e.
water
vapor)
is
not
an
interferent,
and
does
not
affect
the
FiO2
cell
accuracy.
Water
vapor
behaves
as
any
diluting
gas
and
reduces
the
oxygen
partial
pressure;
the
FiOz
cell
will
correctly
indicate
the
reduced
percent
FiOz.
However
when
calibrating
the
FiOz
celi,
the
humidity
of
the
calibration
gas
reduces
the
oxygen
partial
pressure,
it
is
for
this
reason
that
calibration
gas
must
be
dry.
For
example,
at
37°C,
water vapor
pressure
(PH20)
is
47
mmHg,
reducing
the
oxygen
partial
pressure
of
100%
oxygen
to
(760-47) 713
mmHg
and
results
in
an
oxygen
concentration
of
94%.
If
the
sensor
must
be
calibrated
with
humidified
oxygen,
then
if
the
calibration
gas
is
100%
humidified,
the
following
equation
provides
a
correction
factor
that
must
be
applied
to
all
FiO2
readings:
Peal
-
PH20
CH2o
=
一
一
一
(1)
Peal
In
addition,
if
the
pressure
of
the
calibrating
gas
(Pcal)
is
not
760
mmHg,
then
a
further
correction
can
be
made
according
to
the
following:
Peal
Cal
=
————
(2
760
mmHg
The
FiO,
cell
manufacturer
specifies
an
operating
pressure
(Psys)
range
of
+/-
200
mmHg
(+/-
4
psig).
The
FiO,
cell
response
is
proportional
to
oxygen
partial
pressure,
the
result
being
that
indicated
FiO,
can
be
corrected
for
the
difference
in
pressure
between
the
operating
system
and
the
calibrating
system
pressure.
The
correction
can
be
obtained
from
the
following
equation:
760
mmHg
csys
=
一
一
一
(8)
Psys
The
final
result
is
that
actual
FiO2
can
be
calculated
from
indicated
FiOg
by
combining
equations
1,
2
and
3:
FiOz
(actual)
=
FiOz
(indicated)
*
CH2O
*
Ccal
*
Csys
(4)
Capnocheck
Plus
Service
Manual
、 -
1-8
Chapter
1:
Introduction
Pneumatics
Cleaning
Cleaning
of
the
pneumatics
system
is
only
recommended
if
done
by
qualified
service
technicians.
Cleaning
of
the
pneumatics
is
generally
not
required
if
proper
filter
is
used
at
all
times.
However,
improper
use
of
the
device
or
use
under
very
harsh
conditions
may
warrant
periodic
cleaning.
The
Pneumatics
consists
of
five
main
parts:
Procedure:
*
Tubing
+
Sample
cell
(i.e.
CO;
bench)
+
Diaphragm
pump
*
Three-way
autozero
valve
+
Pressure
transducer
Each
of
the
above
parts
should
be
cleaned
independent
of
each
other.
For
example,
all
tubing
should
be
disconnected
from
components
before
cleaning.
Use
one
of
the
following
procedures,
whichever
is
most
appropriate:
For
tubing
and
diaphragm
pump:
1.
Pass
a
mild
detergent
through
to
remove
any
oily
residue
or
contaminants.
Flush
with
distilled
water
to
remove
the
detergent.
Flush
with
absolute
ethanol
to
remove
the
moisture.
Flush
with
dry
gas
to
evaporate
ethanol
and
dry
the
component
thoroughly.
5.
|
Make
sure
components
are
dry
before
reassembling.
Three-way
autozero
valve:
1.
Flush
with
dry
gas.
Do
not flush
with
alcohol
or
water.
Pressure
transducer
and
CO,
bench:
1.
If
contaminated
it
must
be
replaced
by
a
qualified
service
technician.
After
the
device
is
reassembled,
make
sure
to
check
for
proper
operation
and
flow
rate.
If
the
device
does
not
function
as
specified
refer
to
qualified
service
technicians
for
repair
or
replacement
of
pneumatics
components.
1-6
Capnocheck
Plus
Service
Manual
Chapter
2:
Field
Service
Menu
Chapter
2:
Field
Service
Menu
Some
factory
service
menu
options
can
also
be
set
through
the
Field
Service
menu
on
the
monitor.
To
access
the
field
service
menu,
power
up
the
unit
and
listen
for the
beep.
After
the
beep,
use
two
hands
to
momentarily
press
the
WAVE/TREND
and
MENU/ENTER
keys
at
the
same
time.
When
the
power
up
screen
goes
away,
press
MENU/ENTER
to
display
the
main menu.
Press
MENU/ENTER
again
to
select
“
menu,
Field
Service
Menu
”,
which
is
the
first
item
in
this
SERVICE
Date
Format:
Low
ETCO2
[nCO2=1
7"
RR=
18:
т
SpO2
Sensor
!|
%O2=
217
HR=1341
38
=Permanent
Silence:
Enabled
Trend
Sample:
Language:
English
[EXIT]
96,
[
VERIFY
]
4CO2
06.
12
sec/31
hr
USA
12/31/96
FIGURE
2.1:
FIELD
SERVICE
MENU
VERIFY
Permanent
Silence
Trend
Sample
NOTE:
This
takes
you
to
another
menu
which
shows
internal
capnograph
parameters.
”
means
alarms
can
be
silenced
indefinitely
by
pressing
and
holding
the
ALARM
SILENCE
key
for
3
seconds.
*
i"
means
indefinite
alarm
silence
is
not
allowed.
In
this
case,
only
2-minute
alarm
silence
is
available.
This
selects
the
basic
sample
time
for
trend
data
record
storage.
The
sample
time
determines
the
maximum
number
of
records
stored
and
consequently
the
maximum
storage
time.
i
=”
means
12
second
sample
time
for
31
hours
maximum
storage.
“
”
means
4
second sample
time
for
10
hours
maximum
storage.
lf
the
Trend
Sample
time
is
changed,
the
monitor
will
turn
off
after
quitting
the
Service
menu.
This
forces
the
monitor
to
reconfigure
memory
at
power
up.
Capnocheck
Plus
Service
Manual
Chapter
2:
Field
Service
Menu
Date
Format
Language
selects
a
date
format
of
month/day/year.
selects
a
European
date:
day/month/year.
Selects
the
language
for
all
displayed
text:
English,
French,
German,
Spanish,
or
Italian.
NOTE:
When
the
language
is
changed,
you
will
not
see
the
display
in
that
language
until
after
you
exit
the
Service
menu.
The
monitor
will
power
down
and
the
new
language
is
loaded
at
power
up.
Low
ETCO2
Bench
V
Bench
Temp
Bench
P
FiO2
ADC
BattV
inCO2=1
7
RR=
18:
т
%O2=
211
HR=1341
0.980
602
36mmHg
ΦΟΟ2
6
26.3
CO2
5.1%
728
ki
=
1016.0
0375
k2
=
3030.6
7.19
DIEXIT]
96,
FIGURE
2.2;
VERIFY
MENU
Bench
V
Bench
Temp
Bench
P
The
voltage
on
the
output
of
the
CO;
sensor
is
proportional
to
the
CO;
concentration.
During
troubleshooting
this
value
can
be
used
to
verify
whether
the
sensor
is
operational.
If
a
different
amount
of
CO;
is
passed
through
the
system,
the
*”
value
will
vary:
the
higher
the
CO:
value,
the
lower
the
7.”
Note:
All
benches
are
slightly
different.
Factory
calibration
compensates
for
the
difference.
Use“
“*”
as
a
relative
number
only.
The
temperature
of
the
CO:
sensor,
in
°C,
which
is
used
by
the
algorithm
to
compensate
for
temperature
dependency
of
the
sensor.
Because
of
the
heating
element
inside
the
bench,
expect
the
*
”
to
be
a
few
degrees
higher
than
ambient
temperature.
The
pressure
inside
the
bench
chamber
(in
mmHg).
Itis
measured
by
an
external
(from
CO,
bench)
pressure
sensor.
When
the
pump
is
running,
anticipate
this
value
to
be
below
the
ambient
pressure.
2-2
Capnocheck
Plus
Service
Manual
Fi0,
ADC
Batt
V
CO;
mmHg
CO2
%
k1,k2
Chapter
2:
Field
Service
Menu
The
FiO,
Analog-to-Digital
converter
reading
in
counts.
When
the
FiO.
sensor
is
not
plugged
in,
this
reading
must
be
close
to
zero.
If
the
FiO2
sensor
is
replaced
with
a
short,
this
value
is
around
350
counts.
If
the
FiO2
sensor
is
plugged
in,
this
value
will
increase
with
an
increase
in
O;
concentration.
The
voltage
on
the
battery
terminals
as
seen
by
the
system
Analog-to-Digital
converter.
If
the
battery
is
charging,
this
voltage
will
increase
to
more
than
7
V.
If
the
unit
is
running
on the
battery,
this
voltage
will
slowly
drop
from
6
to
5
V.
Current
CO,
reading
in
mmHg.
Current
CO:
reading
in
percent.
For
example,
if
10%
CO;
gas
is
supplied,
expect
to
see
a
value
in
the
range
of
9.6%
to
10.4%.
Calibration
constants.
These
numbers
reflect
the
CO,
curve:
CO,
concentration
vs.
CO,
sensor
voltage.
If
a
low/high
cal
has
been
done,
expect
to
see
slightly
different
kl
and
k2
values.
Capnocheck
Plus
Service
Manual
2-3
Chapter
3:
Capnocheck
Plus
Circuit
Description
Chapter
3:
Capnocheck®
Plus
Circuit
Description
Battery
Charger
The
battery
Charger
is
built
around
charging
controller
U17.
This
IC
controls
the
charging
current
in
both
fast
charge
and
trickle
charge
modes,
switching
from
fast
charge
mode
to
trickle
charge
mode
when
the
end
of
charge
condition
has
been
reached.
It
senses
charging
current
by
measuring
the
voltage
drop
across
current
sense
resistor
R63.
Thermistors
T3,
T4
and
the
thermistor
inside
battery
pack
in
combination
with
resistors
R59..R61
provide
temperature
control,
preventing
fast
charge
in
very
cold
or
very
hot
environments,
and,
also,
preventing
battery
from
overheating
during
fast
charge.
U17
controls
the
switch
mode
voltage
regulator
U18
using current
mirror
Q8-Q9.
This
completes
the
feedback
loop.
The
charging
indicator
circuitry
is
built
around
multivibrator
Q12-Q13.
Depending
on
the
FAST
control
signal
(U17,
pin
8),
the
green
LED
either
stays
lit
(in
trickle
charge
mode)
or
blinks
with
a
very
low
duty
factor
(in
the
fast
charge
mode).
System
Power
Supply
and
ON/OFF
Circuitry.
The
system
+5VDC
power
supply
is
built
around
a
low
drop
voltage
regulator
IC
U20.
MOSFET
transistor
O11
is
used
as
a
controlled
element.
Isolated
power
for the
Oximeter
Slave
Board
is
generated
by
the
DC-DC
voltage
converter
built
around
U21,
Q14
and
transformer
T5.
The
clock
signal
for
the
converter
is
the
microprocessor
clock
divided
by
the
freguency
divider
inside
Us.
The
Power
ON/OFF
circuitry
is
built
using
the
voltage
comparator
located
inside
the
“watch
dog
timer”
IC
U19.
When
the
STNBY/ON
key
is
pressed,
it
pulls
the
base
of
PNP
transistor
Q10
to
“ground”
through
resistor
R67.
Transistor
Q10
pulls
up
EN
(enable)
input
of
voltage
regulator
U20
turning
system
+5V
on.
From
then
the
high
voltage
level on
EN
input
is
maintained
by
the
VCC
voltage
through
resistors
R68
and
R69
until
power
is
off.
Capnocheck
Plus
Service
Manual
3-1
Chapter
3:
Capnocheck
Plus
Circuit
Description
There
are
several
conditions
which
can
power
down
the
Monitor.
If
the
STNBY/ON
key
is
pressed,
the
microprocessor
generates
a
/HALT
signal
which
pulls
down
the
PFI
input
of
the
voltage
comparator
inside
U19.
The
output
open
drain
signal,
/PFO,
goes
low
and
turns
off
U20
by
pulling
EN
low.
The
other
condition
for
turning
the
Monitor
off
is
a
low
battery.
The
battery
voltage
is
measured
by
the
resistor
divider
R65-R65.
If
this
voltage
is
lower
than
the
1.25VDC
threshold
of
the
internal
comparator
U19,
the
output
signal,
/PFO,
goes
low.
In
addition,
the
output
of
the
resistor
divider
is
connected
to
the
Analog-to-
Digital
converter,
and
is
read
by
the
microprocessor
to
give
an
early
warning
about low
battery
condition.
Microprocessor
Section
and
Address
Decoders
jee
Microprocessor
U1
is
a
Zilog
Z180.
Its
address
and
data
buses
are
connected
to
the
One
Time
Programmable
Read
Only
Memory
(OTP
ROM)
U2
and
Random
Access
Memory
(RAM)
U3.
A
Memory
Address
Decoder
is
implemented
in
the
Field
Programmable
Gate
Array
(FPGA)
U4.
The
following
drawing
shows
the
Memory
Address
Decoder
section
of
FPGA:
genres
a
on
creer:
|]
ler
ere
The
memory
address
map
is
shown
in
the
following
table:
Device
Address
Space
OTP
ROM
0..1FFFF
RAM
20000
..
23FFF
FPGA
U4
also
includes
a
RAM
Page
Selector
used
to
split
the
whole
RAM
area
into
pages,
which
can
be
accessed
by
the
microprocessor.
The
corresponding
section
of
FPGA
is
shown
on
the
following
drawing:
3-2
Capnocheck
Plus
Service
Manual
Chapter
3:
Capnocheck
Plus
Circuit
Description
The
Page
Selector
includes
a
Page
Register
-
a
five
bit
output
port,
in
which
the
microprocessor
stores
the
page
number.
Hence,
a
total
of
32
pages
exists.
The
total
RAM
size
is
128
kbytes,
each
page
is
4
kbytes
long.
The
Page
Selector
is
configured
such
that
the
first
three
pages
can
exist
as
“solid”
12
kbytes
of
memory,
which
allows
a
large
amount
of
data
to
be
located
in
continuous
memory.
RAM
Address
Space
RAM
Page
20000
..
20FFF
Page
0
21000
..
21FFF
Page1
22000
..
22FFF
Page
2
23000
..
23FFF
Pages
0..31
By
writing
a
page
number
into
the
Page
Register,
address
space
23000
..
23FFF
can
be
assigned
to
any
of
32
pages.
As
seen
from
the
table,
RAM
pages
0,
1
and
2
can
be
either
part
of
12kbytes
of
continuous
address
space,
or
can
be
selected
together
with
other
pages
to
reside
in
the
top
4kbytes
(address
23000
..
23FFF).
For
practical
reasons,
they
are
always
accessed
as
continuous
memory.
The
address
decoder
for
the
Input
/
Output
Interface
devices
is
implemented
in
FPGA
U4.
The
corresponding
section
of
FPGA
is
shown
on
the
following
drawing:
Capnocheck
Plus
Service
Manual
3-3
Chapter
3:
Capnocheck
Plus
Circuit
Description
The
I/O
address
space
is
divided
according
to
the
following
table:
VO
Address
Space
Device
0..1FFF
Used
by
Z180
for
internal
registers
2000..
3FFF
External
VO
4000
..
5FFF
RAM
Page
Register
6000
..
7FFF
Display
Select
8000
..
9FFF
Volume
Control
Select
A000
..
FFFF
Not
used
External
I/O
is
the
only
VO
select
available
outside
the
FPGA,
all
others
are
used
inside
the
chip.
Display
Controller.
Vacuum
Fluorescent
Display
Module
is
used
in
the
Monitor
to
display
graphical
and
numerical
information.
The
Display
has
its
own
controller
board
-
which
accepts
data
in
parallel
8-bit
format
in
the
form
of
Commands
(signal
AO
on
the
Display
communication
connector
J2
is
log.
1)
and
Data
(signal
AO
on
the
Display
communication
connector
J2
is
log.
0).
Bi-directional
data bus
buffer
US
is
used
to
pass
data
from
the
Display
board
to
the
microprocessor
and
from
the
microprocessor
to
the
Display
Board.
All
signals
to
control
U5
and
Display
Board
are
generated
inside
FPGA
U4:
ZUR
—
jr
一
LL...
3-4
Capnocheck
Plus
Service
Manual
Chapter
3:
Capnocheck
Plus
Circuit
Description
The
timing
diagrams
of
the
Display
Write
and
Read
Cycles
are
shown
on
the
schematic.
From
the
microprocessor’s
“point
of
view”,
the
Display
Board
represents
a
general
purpose
I/O
device,
controlled
using
signals
/CS
-
select,
[WR
-
write,
/RD
-
read
and
A0
-
Command/Data
select.
Signals
/DCS
and
DIR
control
the
bi-directional
buffer
and
prevent
any
possible
bus
conflicts
between
Display
Board,
buffer
and
microprocessor.
Speaker
Volume
Controller.
Speaker
Volume
Controller
is
located
in
FPGA
U4.
The
corresponding
fragment
of
FPGA
is
shown
on
the
following
drawing:
4.
608nH2
2.304MH=
1,152HHz
E7eKHz
{oad
ВЕЕТ
Srey
|:
code
Lag
RESET
UCS
loureur
The
volume
control
code
is
stored
by
the
microprocessor
into
a
four
bit
parallel
register.
Code
0
corresponds
to
the
lowest
volume,
code
F
-
to
the
highest.
Volume
control
circuitry
inside
FPGA
also
includes
a
binary
counter
which
divides
the
microprocessor
clock
frequency.
The
by-products
of
this
counter
are
the
clock
frequency
for
the
Analog
-
to
-
Digital
Converter
(signal
ADCCLK)
and
for
the
DC-DC
converter
(signal
PSCLK).
The
binary
code
from
the
divider
is
compared
with
the
number
stored
in
the
four
bit
parallel
register.
The
result
of
the
comparison
is
the
pulse
train
with
a
variable
duty
cycle
which
depends
on
the
number
stored
in
the
parallel
register.
If
the
number
equals
zero,
the
duty
factor
is
1/16,
if
the
number
equals
F,
the
duty
factor
is
1,
or
the
output
represents
constant
logical
“one”.
Then
the
signal
is
gated
with
the
TONE
signal
-
audio
frequency
signal
generated
by
the
microprocessor.
The
external
R-C
filter
converts
the
resulting
pulse
train
into
an
audio
frequency
signal,
the
amplitude
of
which
is
directly
proportional
to
the
number
stored
in
the
parallel
register.
Hence,
a
total
of 16
levels
of
volume,
plus
OFF,
can
be
achieved
with
this
circuitry.
Capnocheck
Plus
Service
Manual
3-5
Chapter
3:
Capnocheck
Plus
Circuit
Description
External
VO's
External
VO's
include
an
8
bit
input
buffer
and
a
14
bit
output
register.
The
input
buffer
allows
the
microprocessor
to
read
keyboard
signals
and
serial
data
streams
coming
from
the
Real
Time
Clock
(RTC)
IC,
Analog
-
to
-
Digital
Converter
(ADC)
and
CO2
Bench
internal
Electrically
Erasable
Programmable
Read
Only
Memory (EEPROM).
The
output
register
allows
the
microprocessor
to
control
LED’s,
keyboard
strobe
signals
and
all
other
peripheral
devices.
Pump
and
Valve
Control.
The
pump
and
valve
are
controlled
by
the
microprocessor
through
External
YO
output
register.
Dual
MOSFET
Q4
is
used
to
turn
pump
and
valve
on
and
off.
Speaker
Driver.
The
Speaker
Driver
is
built
around
operational
amplifier
U12A.
It
controls
the
speaker
driving
transistor
Q5.
The
input
signal
AUDIO
generated
by
FPGA
is
filtered
by
passive
R-C
filter
R25-C19-R26
to
restore
the
DC
component
of
the
AUDIO
signal,
which
is
then
amplified
by
U12A
and
Q5
circuitry
and
is
passed
to
the
speaker
through
connector
J6.
Analog
Outputs
Controller.
The
Analog
Outputs
Controller
is
built
around
Digital
-
to
-
Analog
converter
(DAC)
U9.
IC
U9
contains
three
independent
8-bit
(256
voltage
steps)
DAC’s
inside,
which
are
used
for
analog
output
channels
A, B
and
C.
U13A,
with
associated
resistors,
converts
the
2.5VDC
voltage
reference
output
into
a
1VDC
output used
as
a
reference
signal
for
analog
outputs.
The
output
of
the
first
internal
DAC
(signal
OUTA)
is
connected
through
an
ESD
protection
network
R33-C27
to
the
output
DB25
connector.
The
outputs
of
two
other
internal
DAC’s
are
not
internally
buffered
like
the
output
of
the
first
internal
DAC.
That
is
why
two
voltage
followers
U12B
and
U12C
are
used
as
buffers
between
DAC
and
output
connector.
The
DAC
is
controlled
by
the
microprocessor
using
synchronous
serial
communications.
RS232
Controller.
The
RS232
Controller
is
built
around
IC
U10,
which
is
used
to
convert
CMOS
voltage
levels
into
RS232
bipolar
voltage
levels.
U10
is
connected
directly
to
the
output
DB25
connector
through
ferrite
beads.
3-6
Capnocheck
Plus
Service
Manual
Table of contents
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