Novametrix 515B, 515C User manual
Model 515B
and
Model 515C
Service Manual
Pulse Oximeter
This manual covers Model 515B (Cat. No. 6500-00) and Model 515C (Cat. No. 6550-00)
November 15, 1995
Catalog No. 6500-90-01/6550-90-01
Novametrix Medical Systems Inc. Wallingford, Connecticut, U.S.A. 06492.
Copyright 1995. All rights reserved. No part of this manual may be reproduced
without the written permission of Novametrix Medical Systems Inc. Printed in U.S.A.
R
Revision History
19-May-95 Release at revision 00.
15-Nov-95 Updated, revision 01.
Rev. 01 Model 515B/C Service Manual
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Model 515B/C Service Manual Rev. 01
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Guarantee
Equipment manufactured or distributed by Novametrix Medical Systems Inc., is fully
guaranteed, covering materials and workmanship, for a period of one year from the date of
shipment, except for certain disposable products and products with stated guaran tees other th an
one year. Novametrix reserves the right to perform guarantee service(s) at its fac tory, at an
authorized repair station, or at the customer’s installation.
Novametrix’ obligations under this guarantee are limited to repairs, or at Novametrix’ option,
replacement of any defective parts of our equipment, except fus es, batteries, and cal ibration
gasses, without charge, if said defects occur during normal service.
Claims for damages during shipment must be filed promptly with the transportation company.
All correspondence concerning the equipment must specify both the model name and number,
and the serial number as it appears on the equipment.
Improper use, mishandling, tampering with, or operation of the equipment without following
specific operating instructions will v oid this g uarantee and r elease Nov ametrix from any further
guarantee obligations.
Service Department
For factory repair service, call toll free
1-800-243-3444
In Connecticut, call Collect (203) 265-7701
Telex 956-054
Facsimile (203) 284-0753
Caution: Federal (U.S.A.) law restricts this device to sale, distrib ution, or u se by or on the order
of a licensed medical practitioner.
Copyright 1995, Novametrix Medical Systems Inc. This document contains information
which is proprietary and the property of Novametrix Medical Systems Inc ., and may not be
reproduced, stored in a retrieval system, translated, transcribed, or transmitted, in any form, or
by any means, without prior explicit written permission fro m No vametrix Medical Systems Inc.
Rev. 01 Model 515B/C Service Manual
v
Service Policy
Novametrix Medical Systems Inc. will provide Warranty Service Support to its customers
within 48 hours of receiving a telephone request for technical support. This 48 hour period
begins once a service request is placed through the Factory Technical Support Department in
W allingford, Connecticu t. Nov ametrix provides factory direct technical support to its customers
through a technical support group located in Wallingford, Connecticut and company service
representatives located throughout the United States. All Technical Support for Novametrix
products is provided “Factory Direct”.
Novametrix p rov ides 24 hour a day techn ical supp ort accessibility via telephone numbers (800 )
243-3444 or (203) 265-7 701. After ho urs technical supp ort requests (before 8:00 AM and after
5:00 PM Eastern Time) will be responded to promptly by the Technical Support On-Call staff.
It is suggested that any person calling in for technical support have the inoperative equipment
available for preliminary troubleshoo ting as well as product identif ication. No v ametrix reserv es
the right to repair or replace any product found to be defective during the warranty period.
Repair may be provided in the form of replacement exchange parts or accessories, on-site
technical repair assistance or complete system exchanges. Repairs provided due to product
abuse or misuse will be considered “non-warranty” and invoiced at the prevailing service rate.
Any replaced defective material is expected to be returned to Novametrix within 10 days of
being provided in order to avoid additional charges. Exchanged material should be returned
promptly and directly to Nov ametrix using the retur n paperwor k and shipp ing label(s) pro vided.
Transferring return materials to local sales or dealer represent atives does not absolve return
responsibility.
Novametrix manufactures equipment that is generally “user se rviceable” and can us ually be
repaired with the replacement of a plug-in electro-mechan ical assembly by the clinical end user.
When repair parts are provided, the recipient can call into Novametrix for on-line replacement
assistance and repair assurance. In the event a replacement part requires increased technica l
capability, Technical Support may request Biomedical assistance, provide on-site technical
support or complete replacement equ ipment. If the custom er requires the retur n of their original
product, the exchange material will be considered “loaner material” and exchanged again after
the customer equipment is repaired.
Novametrix pro motes customer participation in warr anty repairs should the y become necessary .
This program allows for customer training and a smooth transition into self-maintenance after
warranty, which can provide substantial cost savings on repairs throughout the product’s life.
The Novametrix Techn ical Suppor t Department can pro vide technical prod uct support at a le vel
appropriate to most customers protocol and budget requirements. Please contact the Technical
Support Group at Novametrix for additional information.
Additional Novametrix Technical Support Programs
• Focus Series Technical Training Seminars
• Test Equipment and Test Kits
• Service Contract / Part Insurance Plans
• On-Site Technical Support
• 24 hr. telephone support
• “Demand Services”
Flat rate parts-exchange,
Flat rate return for repair
Time and Material,
Full warranty, discounted replacement sensors
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Model 515B/C Service Manual Rev. 01
C
Contents
1 Description .................................................................................................... 1
1.1 Trademark Acknowledgments ...................................................................1
2 Patient Safety ................................................................................................3
2.1 Indications and Usage ..................................... .... ........................ .... ..... .....3
2.2 Warnings ................................................................................................... 4
2.3 Cautions ....................................................................................................5
3 Front and Rear Panel Illustrations .................... .... ..... ..... ....................... .....7
4 Summary of Operation .................................................................................9
4.1 Turning the monitor ON/OFF ................................................................ .....9
4.2 Displays .....................................................................................................9
4.3 Adjusting Alert Limits .................................................................................9
4.4 Adjusting Volume Levels .........................................................................10
4.5 Muting Alerts ............................................................................................10
4.6 Contrast ...................................................................................................10
5 Electronic Theory of Operation .................................................................11
5.1 2532/2725 Power Supply Board ..............................................................11
5.1.1 AC Mains and Battery Operation Overview ..............................................................11
5.1.2 AC Mains Operation ..................................................................................................11
5.2 Main Board ..............................................................................................12
5.2.1 Power On/Off Control Circuitry ..................................................................................12
5.2.2 Power Supplies and Voltage References ..................................................................13
5.2.3 Sensor LED Drive Circuits ........................................................................................13
5.2.4 Sensor Photodiode Return Path ...............................................................................13
5.2.5 20-Bit Analog-to-Digital Convertor Self Calibration ...................................................14
5.2.6 20-B it Ana lo g-to-Dig ita l Conversion ............................... ....... ....................................14
5.2.7 Sensor Status Decoding and Conversion .................................................................15
5.2.8 Front End Timing Signals ..........................................................................................15
5.2.9 Sensor Status Parameters ........................................................................................16
5.2.10 Serial I/O Controller ...................................................................................................17
5.2.11 Microprocessor and Memory .....................................................................................18
5.2.12 Decoding ................................................................................................................... 18
5.2.13 Microprocessor Supervisor ......................................................... ..............................19
5.2.14 System Output Ports .................................................................................................19
5.2.15 Displays ............................. ................... .......................... .................... .......................2 0
5.2.16 Audio Drive Circuitry .................................................................................................20
5.2.17 Keypanel and Configuration Header .........................................................................21
5.2.18 Graphics Display .......................................................................................................21
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vii
6 Maintenance ................................................................................................ 23
6.1 Cleaning and Sterilization ........................................................................23
6.1.1 Mon itor ..................................................... .................................................................23
6.1.2 SpO
6.1.3 SpO
6.1.4 Y-S trip Ta pes and Foam Wraps ................................. ....... ...... ....... ...... ....................23
6.1.5 Ea r Cli ps ..................................... ....... ...... ...... ....... ...... ....................................... ....... 23
Finger Sensor ..................................................................................................23
2
Y-Sensor ......................................................................................................... 23
2
6.2 Battery Maintenance ................................................................................24
6.3 Replacing AC Mains Fuses .....................................................................24
6.3.1 Assemblies with the earlier Power Entry Modules .................................................... 25
6.3.2 Assemblies with the newer Power Entry Module ...................................................... 25
6.4 Changing AC Mains Voltage ..................... .... ........................ .... ..... ..... ....26
6.4.1 Assemblies with the earlier Power Entry Module ......................................................26
6.4.2 Assemblies with the newer Power Entry Module ...................................................... 27
6.5 Assembly Exchanges ..............................................................................29
6.5.1 Internal Assemblies ...................................................................................................29
6.5.2 Main Board/Keypanel Assembly ...............................................................................29
6.5.3 Power supply assembly ............................................................................................ 29
6.5.4 Replacing the internal battery ...................................................................................29
6.6 Changing System Software ......................................... ............................29
7 Troubleshooting ..........................................................................................31
8 Functional Test ...........................................................................................33
8.1 Equipment require d ................ ..... .... ..... ....................... ..... ..... .... ..............33
8.2 Functional Test ........................................................................................34
9 Electronic Tests ..........................................................................................37
9.1 Assembly Tests .......................................................................................37
9.1.1 Equipment Required .................................................................................................37
9.1.2 Power Supply ............................................................................................................37
9.1.3 Main Board ................................................................................................................38
9.2 Accuracy Test ..........................................................................................40
9.2.1 Equipment Required .................................................................................................40
9.2.2 Test ...... ................................................................. ....................................................40
10 Specifications ..............................................................................................43
10.1 Pulse Oximeter ........................................................................................43
10.1.1 Principle of Operation ...............................................................................................43
10.1.2 SpO
10.1.3 Pulse Rate ................................................................................................................ 43
10.1.4 Se nsors .............................................. ............................................. ..........................43
10.1.5 Pl eth ysmo gram (Mode l 515C onl y) .... ...... ...... ....................................... ....... ...... ....... 43
(Oxygen Saturation) ....................................................... ................................. 43
2
10.2 General Specifications .............................................................................43
10.2.1 Al erts ..................................... ................................ ....................................... .............43
10.2.2 Display ...................................................................................................................... 44
10.2.3 Ph ysical ............. ............. ............. ............. ...... ............. ............. ............. ....... ............. 44
10.2.4 Electrical ................................................................................................................... 44
11 Accesories ................................................................................................... 45
12 Parts Lists ....................................................................................................49
12.1 Model 515C .............................................................................................49
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Model 515B/C Service Manual Rev. 01
12.2 Model 515B ..............................................................................................53
12.3 Common Assemblies to both Models 515B & 515C ................................59
13 Schematics and Assembly Drawings ........................................................63
Rev. 01 Model 515B/C Service Manual
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Model 515B/C Service Manual Rev. 01
1
Description
This manual is written for personnel who service and/or maintain the No vametrix Model 515B
or 515C Pulse Oximeter. The Model 515B/C provides reliable continuous measurement,
display, and alerts for oxygen saturation (SpO
from its rechargeable internal battery or from the AC Mains.
The Model 515B/C measures oxygen saturation using sensors that contain red and infrared (66 0
and 940 nanometer) light sources, called LEDs. The light e nergy from each LED is beamed
through a sample cell—a pulsating vascular bed, the patient’s finger or toe for example. The
remaining light energy not absorbed by the sample cell reaches a light receptor in the sensor,
called a photodiode. Oxygen saturated blood absorbs different amounts of light at each
wavelength as compared to unsaturated blood. Therefore, the amount of light absorbed by the
blood in each pulse can be used to calculate oxygen saturation.
The Model 515B/C is calibrated to display “functional” saturation. This differs from the
“fractional” saturation value displayed by most co-oximeters. Functional saturation is defined
as:
Functional Saturation =
= Percentage of hemoglobin saturated with oxygen
HbO
2
COHb = Percentage of carboxyhemoglobin
METHb = Percentage of methemoglobin
) and pulse rate. The monitor can be powered
2
HbO
2
100 - (COHb + METHb)
This can be considered to re present the amount of oxyhem oglobin as a percentage of the
hemoglobin that can be oxygenated. Dysfunctional hemoglobins (COHb and METHb) are not
included in the measurement of functional saturation.
Pulse Rate is calculated by measuring the time interval between peaks of the infrared light
waveform. The inverse of this measurement is displayed as pulse rate.
The oxygen saturation and pulse rate values are upda ted once each second. Presence of a pulse
is indicated visibly by a b ar graph display, a plethysmogram graphic disp lay (Models 515C
only), and audibly by a “beep.”
The Model 515B/C must be used in conjunction with Su perBright™ Sensors. These sensors
have an 8700 series part number (e.g., 8776 or 8791).
1.1
Rev. 01 Model 515B/C Service Manual
Trademark Acknowledgments
SuperBright, Y-STRIP and Y-SENSOR are trademarks of Novametrix Medical Systems Inc.
1
1
Description
Trademark Acknowledgments
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2
Model 515B/C Service Manual Rev. 01
2
Patient Safety
Pulse oximetry is a non-invasive method of monitoring the oxygen saturation of arterial blood.
Pulse oximeters display oxygen saturation of functional hemo globin an d ther efor e the accuracy
may be interfered with by carboxyhemoglobin or other dyshemoglobins present in significant
concentrations. Oxygen saturation monitoring is intended to be used in a variety of clinical
situations, including, but not limited to respiratory therapy, anesthesia, intensive care, and
emergency.
The Model 515B/C Pulse Oximeter has electrically isolated inputs. Patient leakage current
flowing from the instrument to ground is limited to less than 10 µA at 120 V, 60 Hz. Patient
isolation is greater than 10 MΩ, 2500 V rms at 60 Hz. For maximum patient and operator safety ,
the following procedures are recommended;
• Failure of Operation: If the monitor fails to respond as described, do not use until the
situation has been corrected by qualified personnel.
• Keep the Model 515B/C and its accessories clean.
• Do not operate the Model 515B/C when it is wet due to spills or condensation.
• Do not operate the Model 515B/C
• Connect the line cord only to a grounded hospital grade outlet. Th e Model 515B/C should
be connected to the same electrical circuit as other equipment in use on the patient.
Outlets on the same circuit can be identified by the hospital’s engineering department.
if it appears to have been dropped or damaged.
2.1
Indications and Usage
The Model 515B/C is intended to be used for monitoring functional oxygen satur ation and pulse
rate in circumstances where it is desirable to monitor patient oxygenation. The monitor is
designed to monitor all patients including adult, pediatric, and neonatal. The Model 515B/C is
not intended for any other purpose.
NOTE: Components of this product and its associated accessories which may have patient
contact are free of latex.
Rev. 01 Model 515B/C Service Manual
3
2
Patient Safety
Warnings
2.2
!
Warnings
• Explosion Hazard: Do NOT use the Model 515B/C in the presence of flammab le
anesthetics. Use of this instrument in such an environment may present an explosion
hazard.
• Electrical Shock Hazard: Always turn the ox imeter off, and remov e the AC power cord
before cleaning it. Do NOT use a damaged sensor or one with exp osed electrical contacts.
Refer servicing to qualified service personnel.
• Patient Safety: Extreme care should be exercised with neonates to assure continued
circulation distal to the sensor site after application.
• Failure of Operation: If the oximeter fails to respond as described, do not use it until
the situation has been corrected by qualified personnel.
• Data Validity: The Pulse Oximeter should NOT be used as a substitute for an ECG
monitor. The oximeter’s Pulse Rate display reflects the pulsatile flow found at the patient
extremity connected to the sensor. This rate can be affected by many factors and may
occasionally be “frozen.”
• Care should be exercised to assure continued peripheral perfusion distal to the SpO
sensor site after application.
• Data Validity: Do NOT attach a sensor distal to a blood pressure cuff. Valid data
CANNOT be processed when the cuff is inflated. Attach the sensor to the limb opposite
to the site used for the blood pressure cuff.
• Data Validity: Inaccurate SpO
of the following:
• Do Not apply Y-Sensor tapes or wraps so tightly that circulation is restricted. Inspect site
often for adequate circulation - at least once every four hours. When applying sensors
take note of patient’s physiological condition. For example, burn patients may exhibit
more sensitivity to heat and pressure and therefore additional consideration such as more
frequent site checks may be appropriate.
Warning
Indicates a potentially harmful condition
that can lead to personal injury.
2
and/or Pulse Rate measurements can be caused by any
2
• Incorrect application or use of a sensor
• Significant levels of dysfunctional hemoglobins such as
carboxyhemoglobin or methemoglobin
• Significant levels of indocyanine green, methylene blue, or other
intravascular dyes
• Exposure to excessive illumination such as surgical lamps - especially ones with
a xenon light source, or direct sunlight
• Excessive patient movement, venous pulsations.
• Electrosurgical interference.
4
Model 515B/C Service Manual Rev. 01
Cautions
Patient Safety
2
2.3
Cautions
Caution
Indicates a condition that may lead to
equipment damage or malfunction.
• Do not operate the Model 515B/C when it is wet due to spills or condensation.
• Do not operate the Model 515B/C if it appears to have been dropped or damaged.
• Never sterilize or immerse the monitor in liquids.
• Do not sterilize or immerse sensors except as directed in this manual.
• Excessive tension should not be applied to the sensor cable.
• Do not store the monitor or sensors at temperatures less than 14 °F (-10 °C) or greater
than 131 °F (55 °C).
• Do not operate the monitor or sensors at temperatures less than 50 °F (10 °C) or greater
than 104 °F (40 °C).
• Federal (U.S.A.) law restricts this device to sale, distribution, or use by or on the order
of a licensed medical practitioner.
• Do not stretch the finger sensor open beyond the limit for which it was designed.
Overstretching the pulse oximeter finger sensor can damage the sensor and potentially
affect pulse oximeter readings. Overstretching can be prevented: avoid opening the
sensor by any means other than squeezing the grips; DO NOT force the sensor onto large
objects such as a bedrail.
Rev. 01 Model 515B/C Service Manual
5
2
Patient Safety
Cautions
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Model 515B/C Service Manual Rev. 01
3
Front and Rear Panel Illustrations
WAVEFORM DISPLAY ON MODEL 515C ONLY
POWER button - Press to turn the monitor
on or off.
Audio key - Press to toggle two minute
silence, and reset alert conditions (when
active). Press and hold for audio disable.
Pulse Key - Sets pulse rate alert limits when
used with the keys. Press and hold
to set auto alert limits.
SpO
key - Sets saturation alert limits when
2
used with the keys. Press and hold
to set auto alert limits.
ALERT BAR
SENSOR INPUT
AC indicator - Green when the monitor is
connected to AC power and rear panel
power entry module switch is set to “|”
(ON). Also indicates the battery is charging.
Battery icon - Green when operating on ba ttery with a charged battery, orange when
battery power is diminished, flashes red
when battery power is at a critical low.
Finger probe icon -Flashes red when no
probe connected or probe off patient. Red
for any sensor errors.
Hand icon - Yellow when monitor is searching for valid signal and data is being held.
Increase/decrease keys - Press to set pulse
and alert audio level. Sets alert limits when
used in conjunction with SpO
keys. Press and hold to control graph ics display contrast on Models 515C (Model 515B
does not have graphics display option).
Saturation and pulse rate displays - Saturation and pulse rate values will appear. Status
messages will appear if necessary, see
“Troubleshooting ” on p age 31. Arrows indicate alert status or that alerts are being set.
Rev. 01 Model 515B/C Service Manual
and Pulse
2
Audio disabled icon - Flashes yellow when
the audio has been disabled.
Two minute silence indictor - Illuminates
yellow when the audio has been muted for
two minutes.
Signal bar - Pulses with respect to monitored pulse rate. Amplitude corresponds to
signal strength.
7
3
Front and Rear Panel Illustrations
EARLIER REAR PANEL
Ground stud - Use to connect monitor’ s chassis to earth
ground.
Rear panel power switch - Set to “|” allows AC mains
to power monitor, set to “O” switches A C main s p ower
off.
Voltage select/fuse comp artment - Sets mains operating
voltage and houses mains fuses.
Power cord entry - P lug power co rd into this recep tacle.
Use only hospital grade three wire plugs for connection
via supplied power cord.
NEWER REAR PANEL
Ground stud - Use to connect monitor’ s chassis to earth
ground.
Voltage select/fuse comp artment - Sets mains operating
voltage and houses mains fuses.
Rear panel power switch - Set to “|” allows AC mains
to power monitor , set to “O” switches AC mains power
off.
Power cord entry - P lug power co rd into this recep tacle.
Use only hospital grade three wire plugs for connection
via supplied power cord.
8
Model 515B/C Service Manual Rev. 01
4
Summary of Operation
This section gives a brief description of the operation of the Model 515B/C monitor. For more
detailed information refer to the Model 515B/C User’ s Manual (Cat. No. 6500-23/65 50- 23).
4.1
4.2
Turning the monitor ON/OFF
The key controls powering the monitor on and off. To charge the battery from AC mains
ensure that the power cord is connected and plu gged into a hospital grade three prong outlet. Set
the rear panel power switch to | (ON). Che ck that the front panel icon is gree n, this
indicates that AC mains power i s connected to the monitor and chargin g the internal battery . The
monitor will operate on its internal battery power when the rear panel power switch is set to O
(OFF), or if the power cord is removed.
When operating on a fully charged battery the icon on the front panel will turn green. As
the battery charge dimini shes and reaches a low le vel the icon will turn orange. When the battery
has reached a critical low the icon will flash red . If AC mains po wer is not connected at this time
to power the unit and rechar ge the battery, the monitor will flash a red icon, emit an alarm
tone, then shut itself off.
Displays
When a sensor is connected to the monitor and detecting pulsatile data the SpO2 and pulse rate
values will appear in their respective displays. The signal bar will pulse in accordance to the
pulse rate, and on Model 515C, the graphics display will show a plethysmogram (the wa v eform
will travel from left to right).
The and indicate conditions regarding sensor activity; poor signal, probe not
connected, etc. Refer to the User’s Manual for more detailed information (Cat. No. 6500-23/
6550-23).
4.3
Rev. 01 Model 515B/C Service Manual
Adjusting Alert Limits
The Model 515B/C can have its alert limits manually adjusted, or automatically adjusted1. To
manually set the alert limits press eithe r for SpO
Pressing the appropriate key once will allow adjustment of the high limit using the up/down
arrow keys. Pr essing the same button twice will allow adjustment of the lo wer aler t limit. If the
key is pressed a third time the m onitor will exit the alert limits setting mode and retur n to normal
operation and displays.
For example: Press once, use to adjust upper alert limit. Press again, use
to adjust lower alert limit. Press a third time to exit alert limits mode, or wait
for 10 seconds.
1. For automatically set alert limits the monitor must first have acquired valid data on which to base the limits on for a specified amount of time.
2
limits, or for pulse rate limits.
2
9
4
Summary of Operation
Adjusting Volume Levels
T o acti v ate auto alert limits press and hold either the k ey f or saturation, or the k ey for
pulse rate. The monitor will temporarily display the new upper, then lower limits on the
saturation or pulse rate display, depending upon which limits were set, then return to normal
operating mode.
4.4
4.5
4.6
Adjusting Volume Le vel s
Both pulse beep and alert volume can be separatel y adjusted. To adjust the pulse beep press
, “Pul” will appear in the SpO
through 7. To adjust the alert volume press , “Alr” appears in the SpO
to adjust the alert volume level from 1 through 7.
NOTE: When the monitor is sounding an alert (with audible alerts enabled - not
illuminated), the keys will control the alert volume only.
display, use to adjust the volume level from 0
2
display, use
2
Muting Alerts
The key controls two minute audio muting, audible alert disable, and alert acknowledge.
Pressing will activate the two minute audible alert mute. Press and hold until
illuminates to activate audible alert disable. Pressing again will cancel either the two
minute mute or the audio disable (which ever is active). Press to acknowledge and reset
alert conditions.
Contrast
Press and hold the key to vary the contrast of the graphics display ( on Model 51 5C only ).
The SpO
the keys to vary the contrast. The moni tor will return to norm al operating mode ten
seconds after the last key depression.
display will show “Con” to indicate that the monitor is in contrast adjust mode. Use
2
2. There is a ten second time-out counter that starts each time the SpO2 or pulse key is pressed. When the counter times-out
the monitor will return to its normal operating mode.
10
Model 515B/C Service Manual Rev. 01
5
Electroni c Theory of Operation
The electronic theory of operation of the Model 515B/C Pulse Oximeter is detailed in the
subsections below. Refer to Section 13, Schematics and Assembly Drawings, on page 63 for
schematics and assembly prints.
5.1
2532/2725 Power Supply Board
The Power Supply Board co ntains the circuitry needed to char ge the battery from th e A C Mains
(line voltage). The monitor may be supplied with either the 2532 or the 2725 power supply
board. The 2532 board is manufactured with thru-hole components while the 2725 is mostly
surface mount technology. The circuitry is identical therefore the theory of operation that
follows applies to both assemblies.
5.1.1
AC Mains and Battery Operation Overview
The Model 515B/C is powered from its internal 12 v olt battery that is charg ed when the monitor
is connected to the A C line. The g reen (sine wave shaped) fron t p anel indicator illuminates
when the line cord is connected and the rear pan el po wer switch is in th e “|” (On) p osition. This
indicates that AC Mains power is charging the battery.
If AC mains power is removed by unplugging the line cord, or setting the rear panel power
switch to the “0” (Off) position, the monitor will operate for up to eight hours from its internal
12 volt lead-acid battery on a full charge. As the battery voltage runs low ( ≈11.5 volts), the
(battery icon) on the front panel will turn orange. At this point, the AC Mains should be
reconnected to charge the battery.
If the monitor continues to be powered from a battery in a low voltage situation, at
approximately 10.5 volts, a continuous alarm sounds for sixty seconds while the battery
indicator will flash red. A “bAt” and “Lo” message will appear in the SpO
displays respectively. If this alarm is ignored, the monitor will shut down . The A C mains sho uld
be connected to the monitor to recharge the battery before this occurs.
and pulse rate
2
5.1.2
Rev. 01 Model 515B/C Service Manual
AC Mains Operation
Reference the Overall Wiring Diagram. The AC Mains voltage enters the monitor at the rear
panel Power Entry Module (PEM10 1). This device contains a built in RFI power line filter, a
double-pole single-throw switch that opens and closes both AC input lines, fuses, and an input
voltage selection key.
The filtered, switched, and fused output of the Power Entry Module is fed to the primary coils
of the system transformer, T301. Reference the Power Supply schematic 2532-03 or 2725-03.
The secondary output from T301 is rectified by D1 (bridge rectifier) and filtered by C1. The
(loaded) DC voltage at this point is approximately 20 volts.
The 20 volts DC is fed to the battery charging regulator IC1 (pin 5) through Q1. Biasing for Q1
is accomplished by D2, R1, and R2 when A C po wer is applied. When running on battery po wer ,
11
5
Electronic Theory of Operation
Q1 is biased off by R1, R2, and D3. This prevents the battery from trying to power the battery
charger regulator.
The output of switching regulator IC1 pin4 is rectified and filtered by D4, C4, and L1, then fed
to the battery through current sense resistor R3 and fuse F302, to J302 pin 1 (VBAT+). The
battery float charge voltage is maintained at 13.2 volts ex cept for f ast char ge that is re gulated at
14.4 volts. The output is also monitored for over current conditions. These parameters are
controlled by IC3 and associated circuitry. When the battery charge current exceeds a preset
limit, IC3 pin 7 goes high w hich biases Q2 on, this i n turn shorts out R12 which affects the
feedback control (FB) to IC1 (pin 1). With R12 shorted out, the control resistors R14 and R13
set the output voltage to 14.4 volts. When the charge current lowers, IC3 pin 7 goes low which
biases Q2 off, this puts R12 back into the feedback con trol which no w consists of R12, R13 and
R14; setting the voltage to 13.2 volts. When more than the maximum charge current flows
through R3, IC3 pin 1 shorts IC1 pin 2 to ground, that shuts IC1 o ff until its ne xt switching cycle.
When the current reaches a safe level IC3 pin 1 allows IC1 to remain on.
Main Board
5.2
Main Board
5.2.1
The 2721 or 2723 Main Board contains all the analog and digital circuitry that controls the
sensor, front panel display, and user interface. The isolated power supplies, microprocessor,
analog circuits, and memory are all contained on this board . The 2722 or 272 4 ver sion contains
the graphics display for model 515C, otherwise the circuitry is identical. Units with the newer
2723 (for Model 515B) or 2 724 (Model 515C) board can be identified with an “X” in the serial
number suffix.
Power On/Off Control Circuitry
When connected to the AC line (front panel AC icon illuminates green) the internal battery is
charging, this occurs whether or not the monitor itself is turned on. The monitor is powered on
by pressing the front panel power key, pressing this key while the monitor is on will shut it off.
The actual turning off is contro lled b y the pr ocessor, this enables the processor to control when
the power is removed to avoid corrupting RAM contents (e.g. turning power off while writing
to, or reading from RAM).
Power enters the main board through J404, see page 4 on schematic. When the monitor is
connected to the AC mains power, the LINEST voltage will be high indicating that AC line
power is available and charging the battery. The LINEST line will bias the green LED D16 on
through current limiter R28 (see page 2 on schematic). This LED illuminates the AC indicator
icon on the front panel. When the monitor is running off of its internal battery (no AC mains
power av ailab le), the V B ATTERY line will be supplying power for the monito r. This will cause
D17 to be reverse biased (LINEST low, VBATTERY @ battery voltage) and no voltage will
appear at LINEST, therefore D16 will be biased off.
When the front panel power key is pressed VBATT biases Q8 on through R31, R97, and D18.
When Q8 is on, VBATT biases Q10 on thro ugh R9 1 and R92, this in turn powers IC17, a pulse
width modulated switching power supply. The LEDPWR supply is generated by IC17, Q11,
D32, T1 and filtered by C59-C63 (C89 added on 2723/2724 board). The voltages used by the
main board are all derived from the LEDPWR supply.
When the monitor is on and the front panel power key is pressed (to turn the monitor of f), IC10
pin 12 will go low (se e page 1 on schema tic). This will drive the ou tput of IC8 pin 8
(PWRNMI*) low when the KEYS* line is brought low by the processor (IC1 pin 9). The
PWRNMI* line drives the NMI line of the processor , when this line is brought lo w the processor
will bring the PWROFF line high thr ough IC14 pin 12. When the PWROFF line is high, Q13
will turn on, this in turn sets the PFI input (pin 4) of IC4 low. This will set the PWROFF* line
12
Model 515B/C Service Manual Rev. 01
Main Board
Electronic Theory of Operation
IC4 pin 5 low, biasing Q2 on (page 4 on schematic). W i th Q2 on, Q8 and Q1 0 will be biased of f,
shutting down IC17 which turns the monitor off.
5
5.2.2
5.2.3
Power Supplies and Voltage References
See page 4 on schematic. The 5 vol t supply VDD is re gulated b y IC18 , a lo w dropout re g ulator.
The -VA supply is generated by IC19 from the LEDPWR supply. This supply is synchronized
to front end timing signals by the SYNC line via C82, R127, R120, D35, and Q7. Without this
synchronization, ailiasing frequencies m ay interfere with sensor measureme nts. The +VA
supply is drawn from the LEDPWR line through filter coil L2.
The LEDSRC supply , used by the sensor LEDs, is regulated by IC20. Fuse F201 protects against
over current conditions. This supply is connected to the sensor‘s LED anodes when a sensor is
connected.
See page 3 on schematic. A -5 volt, and a 2.5 volt reference (VREF2.5) are needed for the 8 bit
D/A conv erter I C31 , the A/D co nverter IC26, and for the 20 bit A/D converters IC23 and IC24.
The 2.5 volt reference is generated by IC29 from the +VA supply. The output of IC29 pin 6
(VREF2.5) feeds the input of inverting amplifier IC30a. The output of IC30 a drives the base of
Q12 which creates a low impedance -5 v olt source -V5 at i ts emitter. The -5 volt source is used
by the eight channel multiplexor IC25, t he 20 bit A/D converters IC23, IC24, and the eight bit
D/A converter IC31.
Sensor LED Drive Circuits
Each LED (one red and one infrared) in the sensor is driven separately. Since the circuitry is
similar only one channel will be discussed, the corresponding co mponents for the other chan nel
will appear in brackets. See page 3 on schematic.
The VLED voltage is used b y b oth chan nel’s drive circuitry. When IC31 is enabled b y the WR*
and DA CCS* lines, the processor programs a voltage b y inserting a particu lar v alue on the data
lines D0-D7. This voltage appears at the output of IC30b pin 7 and is labelled as VLED.
When the REDLED* [IRLED*] line is low Q3 [Q4] will turn off, this allo ws the VLED volta ge,
divided by R48 [R46 ] and R47 [ R49 ], to dr ive the non-inverting inp ut of I C27 a [IC27b ]. Wh en
IC27a [IC27b] output is high, Q6 pins 3, 4, 5, 6 [1, 2, 7, 8] will turn on, this pulls current through
the sensor LED from the LEDSRC supply (fed to the sensor from J403 pin 1). When the
REDLED* [IRLED*] line is high, the input of IC27a [IC27b] is brought to ground potential
because Q3 [Q4] is biased on. This shuts Q6 off resulting in no current flow through the LED.
5.2.4
Sensor Photodiode Return Path
Light, from the sensor’s Red or Infrared LED, shines through the pulsating vas cular bed (the
patient’s finger, toe, etc.) placed between the LEDs and the photodiode. Some of this light
emerges from the tissue and impinges on the photodiode, causing the photodiode to conduct
current. See page 3 on schematic. IC21b pins 5-7 are set up as a differential amplifier that
converts this input current to a voltage at the amplifier output. The sensors are wired such that
photodiode current produces a positive v o ltag e at IC21b pin 7
The voltage at IC21b pin 7 is presented to an analog switch IC28b p in 6. This switch is
controlled at pin8 by INSIG*
except if the monitor is in a Probe Off Patient condition or is undergoing its self-test at system
power up. The switch IC28c pins 9- 11, contro lled from SIGND*
1. The Model 515B/C uses SuperBright™ sensors (part number 87xx series). If a non-SuperBright™ (Novametrix part number 86xx series) sensor is connected, IC4b p in 7 will go negative.
(Input Signal), and will be closed (IC28b pins 6 and 7 connected)
1
.
(Signal Ground), will be open
Rev. 01 Model 515B/C Service Manual
13
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