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SERVICE MANUAL - Frank`s Hospital Workshop

1. BTN_PWR RST 5 RAMEN L B PHOTOT LU 150K TxD cal o2 Do EXD 2N39045 VAN v Sern Sem BTN SHIFT REDLEDIAV P2 6 TWUP DN tll MEMBRANE SWITCH CONNECTOR SCOPE PROBE GROUND Tess ADDHS 24 27 23 PADDR gt 1 USE J2 PINS FOR TEST POINTS OF VCC RAW 10V RAW 5V PLACE BY Ua PIN 36 STATIC SERIAL INTERFACE Note Populate U12 with 8Kx8 143101 or 32Kx8 143102 ven CLINICAL SERIAL DATA CONNECTOR TP26 FACTORY TEST NOTES POGO DATA CONTACTS 1 ALL CAPACITORS ARE 10 50V 1206 PACKAGE UNLESS OTHERWISE NOTED ALL RESISTORS ARE 1 1 8W 1206 PACKAGE LCD BOARD INTERFACE UNLESS OTHERWISE NOTED vec UNUSED GATES LEDDIS Note To populate 05 with 64Kx16 143003 or 128Kx16 143010 parts do not populate location J4 1 To populate 05 with 256Kx16 143011 171259 populate SAMPRED OW FSAMPRED Lep_uaGHT HOT g HOTOD O U AMN pwm rsAMPIR BUMGTBOS EXTERNAL OUTPUT PORT bes OUT FIRLED AV CYYYA iRLED AV ELNITTHOU
2. FO 3 LCD PCB Schematic Diagram sese FO 4 Front Panel Keypad Schematic Diagram FO 5 Troubleshooting Guide sse 4 2 NPB 40 Error Codes ssssssssseseeeeeenene nnne enne ene 4 5 SECTION 1 INTRODUCTION 1 1 Manual Overview 1 2 Equipment Description 1 1 MANUAL OVERVIEW This manual contains information for servicing the NPB 40 handheld pulse oximeter Only qualified service personnel should service this product Before servicing the NPB 40 read the operator s manual carefully for a thorough understanding of how to operate the 40 1 2 EQUIPMENT DESCRIPTION The Ndlcor Puritan Bennett NPB 40 handheld pulse oximeter is used for noninvasive spot check measurement of functional oxygen saturation of arterial hemoglobin SpO2 and pulse rate measured by the SpO2 sensor The 40 is for attended monitoring only and must be used in the continuous presence of a qualified healthcare provider The NPB 40 can be used on adult pediatric and neonatal patients It can be used in mobile environments when protected from excessive moisture such as direct rainfall The NPB 40 is powered by four AA cell alkaline batteries An external Hewlett Packard H P82240B printer can be used with the NPB 40 to printout readings stored in the NPB 40 memory This printer is available from Nellcor Puritan Bennett The NPB 40 h
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4. eese nennen 1 1 12 Equipment Description 1 1 Section 2 Routine Maintenance sss 2 1 2 4 Maintenance Overview seen 2 1 2 2 Battery Maintenance sese nnn 2 1 2 2 1 Battery 2 1 2 2 2 Battery Disposal emn 2 2 2 3 Gleanihig c oni tere eH uer ae oes 2 2 Section 3 Performance Verification sss 3 1 3 1 Performance Verification esse 3 1 Section 4 Troubleshooting sss eee 4 1 43 Introductions macte e regna 4 1 42 Who Should Perform esse 4 1 43 Repair Level 1 sse 4 1 44 Howto Use This Section ss seen 4 1 45 Obtaining Replacement Parts 4 1 4 6 Troubleshooting Guide sss 4 2 Section 5 Disassembly Guide eena 5 1 ST JntrodUctiOri s oie rct ret n petu 5 1 52 System Disassembly and Reassembly 5 1 Section 6 Spare Parts sse nennen 6 1 6 1 Introducti riz uio ete 6 1 Section 7 Packing for
5. 619 e 629 808 IEY z Sell Bm E il E 872 094 4 HI OD LER ER REI NELLCOR PURITAN BENNETT TOP SIDE NPB 40 LCD m m 014 mg We 664075 CSU 694 4 I ME mm mm e CIN BIN B EH HH e N I e 5 85415 954 020 910 dm cm ELLE c e 22 21 GYI moe SQ Ww 49 9 0 5 eo UU LEO 674 89 Tc RII Lu 1 e TOP SIDE BOTTOM SIDE Figure S4 2 LCD PCB Parts Locator Diagram 034315 FOS S5 3 POWER ENTRY POWER SUPPLY CIRCUIT ADDRESS DECODING R22 0 75A SELF RESETTING FUSE BATS L DEoo LPE 4841 EXOUTEN ua 2 6 2 TE Ve VAR I 220 MBRS130 ss n vec o GND NER NEAR T1 PIN 2 2 4 a 1373 SG or SEPARATE VIAS CURRENT 10v TO GROUND PLANE z243 FOR PINS 6 amp 7
6. 7 1 7 1 General sese enne 7 1 7 2 Packing NPB 40 in Original Carton 7 1 7 3 Packing in a Different Carton sse 7 1 Section 8 Specifications sss enne 8 1 8i Performance steer e eS 8 1 82 Electrical eere uim 8 2 83 Environitmi rital ttt ter ei cente ku xu 8 2 8 4 Physical io te 8 3 Technical Supplement sss S 1 St Introductionis soe nett eee at S 1 S2 Pulse Oximetry Principles of Operation 5 1 521 Overview 1 nennen rne 5 1 S22 Functional Versus Fractional 5 1 523 Measured versus Calculated Saturation 5 2 532 Circuit AralyslS uie te ende a 5 2 531 X Overall Unit Block Diagram Analysis 5 3 53 2 PCB Theory of 5 5 53 3 LCD PCB Theory of Operation 5 11 S4 Schematic Diagrams 5 17 Table of Contents LIST OF FIGURES LIST OF TABLES 1 1 2 1 3 1 3 3 3 4 5 1 5 2 5 4 6 1 7 1 52 1 53 1 53 2 5
7. AN ROMEN ene 0000 DFFF Power Supply Feedback 7aHncios vec MBRS130 xps 19 ADDHO 18 WR 36 ADDAS 15 ADDR E Ves 14 ADDES E VERDE ADS 38 ADDR6 ANGND TZ ADUH7 E 8 ACHO Po 0 vec ACH1 PO 1 X AcHz Po 2 AcHa Po 3 ACH4 Po 4 ACHs Po S ACHe Po 6 ACGH7 PO 7 BAT VOLT L cia T LEDDIS POWER SWITCH CIRCUIT BERD PWT woke PBRST P1 0 e TEST POINTS E rw IE mm P1 4 PWM2 ADODO Ana 37 ADDRTS S eoo P1 5 BREQ NRH BHE H Pi6 is 20 16 ADDAI E ADDHZ Srest ADE Py HOLD SaLis AbbHiz ADDHS Sips orraa 9 SaLi4 ADDHis ADDHa __ ADS READY 15 ADDR Eao o 1 ADDHe __ 456 NMI W b7 o g BUSWIDTH Tq oc ADDHS Orpaz ADS 4 jreas Eom o Hei TAHOSTS NADoHii Oribaa o _ 012 0 2 0 auum P2 1 RXD ADDHi4 Drpaz ADIT P2 2 EXTINT EADDHIS or 2 PZA TARST Ye is USED ONLY IF RE TES IS NOT AVAILABLE
8. 22 vee Sease SESS Seaisg 22 ves SEGao Seaan 2 Seas 42 CDao53S e a ize Lepcor TP11 sEaa2 SEG12 x sEaas SEG11 g 421 LMC6044S SEG12g o TPS SEGa4 SEG108 3245 NE sEaas SEGS cas SEG46 SEGs 52647 Sear 2 Rot Seca Seas SEGae Seas E SEGso iu SEG51 SEG3 sEas2 SEG2 B8 7K_0 1 TPS E Ex SEGS53 sEG1 REDLED AV NJUSGASZE _ 9 42v N 092015 BYPASS Ui2c Uia U3A TP23 i E 592015 E H POWER ENTRY 12 TE Yo VIN usB b 15 zo 3 21 vss CDa4o5ss 2Ns906S WA o u12B8 DG201S LMC6044S as 2N39045 1N914S 5 20v Raz o 7343 100K u14ac Vv V 7 LCD BACKLIGHT IR PRINTER LINK RAW 10V vec 2 9 viz 779 TP26 mce044s I una 15 gt gt gt U14D LTE 302 74HCoaa t LED DRIVE
9. 3 bpm that the pulse amplitude indicator is displaying properly that the SpO 2 indicator is displaying 81 2 96 that a pulse beep can be heard and that the PULSE SEARCH indicator is off Press the Shift key followed by the Display Light Beep On Off key Verify that the SHIFT indicator illuminates when the Shift key is pressed then verify that the pulse beep stops and the SHIFT indicator extinguishes when the Display Light B eep On Off key is pressed Press the Shift key followed by the Display Light Beep On Off key and verify that the pulse beep can be heard again at a low level 12 13 14 15 16 17 18 19 20 Section 3 Performance Verification Press the Shift key followed by the Display Light Beep On Off key and verify that the pulse beep can again be heard again at a higher level Press and releasethe Display Light Beep On Off key on the front panel keypad and verify that the LCD backlight comes on remains on and the LCD is adequately illuminated Press the Display Light Beep On Off key on the front panel keypad and verify that the LCD backlight is off Set the following SRC 2 control as indicated LOCAL REMOTE RCAL REMOTE On the 40 verify that the PULSE SEARCH indicator illuminates after a few seconds and that the number 0 is displayed in the SpO296 and pulse rate displays Set the following SRC 2 control as indicated LOCAL RCAL LOCAL On the NPB 40 verify th
10. NELLCOR SERVICE MANUAL NPB 40 Handheld Pulse Oximeter Caution Federal law U S restricts this device to sale by or on the order of a physician To contact Nellcor Puritan Bennett s representative In the United States call 1 800 635 5267 or 12 925 463 4000 outside of the United States call your local Nellcor Puritan Bennett representative 0123 2001 Nellcor Puritan Bennett Inc All rights reserved 036048D 0601 Nellcor Puritan Bennett Inc 4280 Hacienda Drive Pleasanton CA 94588 USA Telephone Toll Free 1 800 NELLCOR Tyco Healthcare UK LTD Fareham Road Gosport PO13 OAS Tel 44 1329 224000 To obtain information about a warranty if any for this product contact Nellcor Puritan Bennett Technical Services Department or your local Nellcor Puritan Bennett representative Notice Purchase of this instrument confers no express or implied license under any Nellcor Puritan Bennett patent to use the instrument with any sensor that is not manufactured or licensed by Nellcor Puritan Bennett Oxisensor is a trademark of Nellcor Puritan Bennett Inc Covered by one or more of the following U S Patents and foreign equivalents 4 621 643 4 653 498 4 700 708 4 770 179 4 869 254 4 928 692 4 934 372 5 078 136 5 351 685 5 368 026 and Re 35 122 TABLE OF CONTENTS List of Figures List of Tables Section 1 Introd ction e enda 1 1 1 314 Manual
11. U 12D The RDC and REDDC arethen filtered and input to the microprocessor on the CPU PCB 3 3 4 2 AC Variable Gain Control Circuits The AC modulations are amplified by U 12A red and 12B IR and superimposed on the baseline voltages present at the output of U 12D IR and 12C red The amplification is handled by means of the SPDT analog multiplexing switch U 13 within the feedback loop which increases gain as PWMOis increased The and REDAC are then filtered and input to the microprocessor on the CPU PCB LS1 a piezo ceramic sounder is the audio output device Due toits low drive current of 2 mA maximum no drive circuitry is needed and is driven directly from the external output port It is differentially driven with 2 square waves 180 degrees out of phase The drive frequency is approximately 1480 Hz or 740 Hz and is generated by the CPU LS1 is differentially driven to obtain maximum audible volume Technical Supplement S3 3 6 Display Control Circuitry TheLCD CE LCD CLK and LCD DATA from external output port U9 and LCD EN from the microprocessor on the CPU PCB are connected tothe LCD drivelC U1 U1 in turn drives the individual segments of the LCD The microprocessor drives LCD CE and LCD EN high connected tothe U1 CE and INH inputs respectively At that time data on the LCD DATA lineis clocked into U1 by the LCD CLK line U1 then decodes the data input and turns the proper segments on or off on the L
12. are found 43 Section 4 Troubleshooting Table 4 1 Troubleshooting Guide Continued ProbableCause Corrective Action ____ morekeys CPU PCB has failed Replacethe CPU PCB with on the front panel known good PCB keypad does not work Continued One or more An LCD PCB Inspect the LCD PCB display segments component has components and circuit board does not work failed for cracking burning or damage and replace the LCD PCB if any are found Flex circuit between Inspect the flex circuit between LCD and LCD PCB theLCD and theL CD PCB has has come loose come loose and replace the LCD PCB if loose ee known good PCB Beeper does not The beeper has been Turn the beeper back on beep for pulse turned off or its indication or no volume is turned sound can be heard down too low to hear from the beeper The holes for the Clear the holes for the beeper on beeper on the back of the back of the NPB 40 the NPB 40 are blocked The external output Replacethe CPU PCB with port on the CPU PCB known good PCB has failed Replacethe LCD PCB with a LCD PCB has failed known good PCB Pulse rate or SpO2 The SpO2 sensor is Connect the SpO2 sensor to the valueis not not connected NPB 40 displayed and the properly unit is on Replace the SpO2 sensor with failed known good SpO2 sensor Replacethe LCD PCB with a LCD PCB has failed known good PCB Replace the CPU PCB wi
13. Failurein the 1 Replace the sensor microprocessor analog to digital 2 Replace the CPU PCB with a converter on the CPU known good PCB PCB 150EEE Failure of the Replace the CPU PCB with microprocessor on known good PCB the CPU PCB on the CPU PCB known good PCB on the CPU PCB known good PCB Failurein the Replace the CPU PCB with microprocessor O known good PCB ports on the CPU PCB 154EEE Failure of the Replacethe CPU PCB with a watchdog circuit on known good the CPU PCB 155 Failure of the Replacethe CPU PCB with a memory on the CPU known good PCB when storing an event or when printing 4 5 This page intentionally left blank SECTION 5 DISASSEMBLY GUIDE 5 1 Introduction 5 2 System Disassembly and Reassembly 5 1 INTRODUCTION TheNPB 40 can be disassembled into five assemblies Case top front panel keypad Case bottom CPU PCB LCD PCB Battery compartment door Note Some spare parts you receive will have a business reply card attached When you receive these spare parts please fill out and return the business reply card The only tool you will need to disassemble or reassemble the NPB 40 is a Number 1 medium Phillips head screwdriver Caution Observe E SD electrostatic discharge precautions when disassembling and reassembling the NPB 40 and when handling any of the components of the NPB 40 5 2 SYSTEM DISASSEMBLY AND REASSEMBLY Use the following proce
14. Type of Protection Internally Powered Degree of Protection TypeBF Enclosure Degree Protection Class IPX1 Mode of Operation Continuous 8 3 This page intentionally left blank TECHNICAL SUPPLEMENT 1 Introduction S2 Pulse Oximetry Principles of Operation S3 Circuit Analysis S4 Schematic Diagrams 1 INTRODUCTION This Technical Supplement provides a description of the principles of pulse oximetry a block diagram level theory of operation discussion and a schematic level theory of operation discussion Part locator diagrams and schematic diagrams are located at the end of this section as fold out drawings These diagrams can be folded out for review while reading the theory of operation S2 PULSE OXIMETRY PRINCIPLES OF OPERATION S2 1 Overview The NPB 40 is based on the principles of spectrophotometry and optical plethysmography Optical plethysmography uses light absorption technology to reproduce waveforms produced by pulsatile blood The changes that occur in the absorption of light dueto vascular bed changes are reproduced by the pulse oxi meter as plethysmographic wave forms Spectrophotometry uses various wavelengths of light to qualitatively measure light absorption through given substances Many times each second the NPB 40 passes red and infrared light into the sensor site and determines absorption The measurements that are taken during the arterial pulse reflect absorption by arterial blood nonpulsatile b
15. ADO 19 BEEP 2 eaor 35 T5 BEEP T RDZ 7 Teo K 16 H DLED AV ZERO L 15 4 Lco ce da LCD Pw FOFF ON COON orron T 12 roD LGHT m BLM31B06 vec T4HGS74S Figure S4 3 CPU PCB Schematic Diagram 034310 FOS S5 5 uisa 7 LCD DRIVER LCD FLEXTAIL Ut 62 Lepcoma 9 1 SEG SEG2 seas2m S 5 5 5 SEGS5 SEG49 lA 74 g SEG SEGazm 81 SEGA season SEGS SEG4Sm 10 11 s SEG11 SEG43 12 SEG12 SEG42 13 SEG13 SEG41 12 SEGA 15 BYPASS 15 Stace 16 ne Seas M 15 s 38 Sease OFF ON co Seassg zo 60 52225 21 a saurin SERA ZZ SEGS2R 281 SAMPRED LCD CLK 8 4 SEG23 SEG31 5 SEGSoR 25 SEG29B 25 Leo DATA 621 SEG26 8 27 SEG 55 gt SEG2om 28 m IRLED AV LOD EN Seez SEG2SB 20 SEG24m 81 a ZERO SEG Season 22 mer oS Sess 522228 58 a REDDO 22 250 RED CHANNEL Eie 2 38 SS SEGse seis 37 5 7 SEG178
16. An analog switch sets the mean signal value to the mean of the A D converter range and the AC modulation is superimposed on that DC level Then each AC signal is amplified and filtered to eliminate residual effects of the PWM modulations Finally these two signals are input to the CPU A D converter S 12 Technical Supplement The relationship between these subsections is shown in the LCD PCB block diagram Figure S3 3 To from CPU PCB Raw 10 Vdc Power 410Vdc conditionin Raw 5 Vdc 9 5 Vdc V ref Printer IR LED Printer LED signal LCD light enable LCD backlight e Red channel IR channel Beeper drive Analog sensor signal Analog circuit control signals 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 T 1 1 I LCD clock 1 LCD 1 LCD data driver LCD LCD enable 1 1 1 I 1 1 1 1 T 1 1 1 1 1 1 1 1 1 1 1 1 Sensor D connector To from patient sensor LED drive RSENS Photodiode Figure S3 3 LCD PCB Block Diagram S3 3 1 Sensor Output LED Control The SpO2 analog circuitry provides control of the red and IR LEDs such that the received signals are within the dynamic range of the input amplifier Because excessive current to the LEDs will induce changes in their spectral output it is sometimes necessary to increase the received signal channel gain To that point the CPU
17. RESISTORS ARE 1 1 8W 1206 PACKAGE UNLESS OTHERWISE NOTED Figure S4 4 LCD PCB Schematic Diagram 034314 FOS S5 7 Figure S4 5 Keypad Schematic Diagram FOS S5 9
18. for interrupt input The CPU receives one external interrupt signal PHOTOI S 7 Technical Supplement 3 2 2 CPU Memory S 8 P2 0 and P2 1 are configured as a standard asynchronous serial transmitter and receiver for a factory serial interface P2 5 P1 3 and P1 4 are configured as pulse width modulator outputs They are used with outputs from P 1 6 and P2 6 to control gains within the SpO2 analog section S3 2 1 1 Address Demultiplexing 010 and 011 aretransparent latches that latch the address portion of the AD bus data on the falling edge of ALE the outputs are always enabled The outputs of U 10 and U11 are always the address portion of the AD bus S3 2 1 2 Address Decoding The CPU has a 64 K byte address range of O0 FFFF RAM EPROM and 1 0 ports sharethis space The address decoding circuit splits up this space and output enable lines tothe RAM EPROM and external output ports When address lines A13 A14 A15 are all high the output of U 7C goes low enabling the RAM and generates the active low enable signal RAMEN L This occurs for the 8K address range of E 000 F FFF U8 is used to generate the output port active low enable signal EXOUTEN L When address lines A15 A14 A11 and 10 are high and A13 is low U8 becomes enabled With U8 enabled the Y 3 output is set low The output to go low is selected by pins A B and C They form a 3 bit binary number with pin C being the most significant bit So when
19. high This enables the power supply circuits which then generate the operating voltages for the N PB 40 The Q not output of U 1B is applied to U4 analog to digital converter input P0 6 through a battery voltage sensing circuit consisting of U2B R14 R17 and C14 When the battery voltage drops below 3 6 Vdc as measured by U4 the PWR DOWN line at U4 output HSO3 goes high and turns on Q2 which clears flip flop U1B and the PWR ON signal at the Q output goes low and turns off the power supply circuits When the NPB 40 is turned on the D input of U 1B is low See Power Supply Feedback Circuitry When On Off key on the front panel keypad is pressed the BTN PWR lineis grounded and theresultant high going pulse from U2A toggles the CLK input of U 1B and the low D input logic level is transferred to the Q output This sets the Q output and the PWR ON signal low which turns off the power supply circuits S3 2 5 Serial Interface S3 2 6 Printer Control Technical Supplement S3 2 4 4 Power Supply Circuits When the PWR ON signal at the S S input of U3 is high U3 generates a square wave signal that drives the primary winding of transformer T1 The three secondary windings of T1 are rectified and filtered to provide RAW 10V VCC 45Vdc and RAW 5V The VCC signal is resistor divided by R9 and R12 for a feedback voltage that U 3 must see to continue operating VCC is used on the CPU and theL CD PCBs for operating circuit power RAW HLOV and R
20. left as shown in Figure 5 2 J3 Figure 5 2 Top Case Removal 5 2 Section 5 Disassembly Guide Caution Failure to unlock connector J 3 on the CPU PCB before attempting to remove the front panel flex circuit could damage the flex circuit 5 Unlock connector J 3 on the CPU PCB as shown in Figure 5 3 and pull the front panel keypad flex circuit out of J 3 Note When reassembling the NPB 40 be sure to lock J after you insert the front panel keypad flex circuit SeeFigure 5 3 Unlock J3 Lock Lock 4 Figure 5 3 Unlocking CPU PCB Connector J3 Note The battery connectors spring assemblies at the bottom of the CPU PCB are held in slots in the battery compartment In the next step observe how these connectors are engaged in these slots when you remove the CPU PCB with the LCD PCB and make sure the battery connectors are inserted back in these slots when you reassemble the N PB 40 6 Lift the CPU PCB and the LCD PCB together and remove them from the case bottom 7 Toseparate the CPU PCB and the LCD PCB grasp the CPU PCB in one hand and the LCD PCB in the other Rotate the ends of the two PCBs as shown in figure 5 4 until the two assemblies separate at the connectors J 1 and J 2 Figure 5 4 Separating LCD PCB from CPU PCB Note When reassembling the NPB 40 be sure to align all 20 pins of both J 1 and J 2 on the CPU PCB with all 20 sockets of J 1 and J 2 the LCD PCB before pressing t
21. not pressed If incorrect replace case top If all keys function correctly replace CPU PCB Caution Unlock J 3 before attempting to remove flex circuit conductor Flex circuit between Inspect the flex circuit between front panel CPU the front panel and the CPU PCB is disconnected PCB and reconnect if loose A CPU PCB Inspect the CPU PCB component has components and circuit board failed for cracking burning or damage and replace the CPU PCB if any arefound If any failed components are observed replace CPU PCB known good PCB One or more keys Thefront panel Open the 40 disconnect the front panel keypad is defective the case top from on the CPU keypad does not PCB and connect an ohmmeter work lead to the flex circuit conductor for J 3 pin 3 Refer tothe front panel schematic diagram and individually connect the other ohmmeter lead to each conductor for the other keys Observe a short when the key is pressed and an open when not pressed If incorrect replace case top If correct replacethe CPU PCB Caution Unlock J 3 before attempting to remove flex circuit conductor Flex circuit between Inspect the flex circuit between front panel CPU the front panel and the CPU PCB is disconnected PCB and reconnect if loose A CPU PCB Inspect the CPU PCB component has components and circuit board failed for cracking burning or damage Continued on next and replace the CPU PCB if any
22. the combined AC and DC signal from exceeding an acceptable input voltage from the A D converter S3 3 3 1 Variable Gain Circuits Thetwo variable gain circuits are functionally equivalent The gain of each circuit is contingent upon the signal s received level and is controlled to bring each signal to approximately 3 5 V Each circuit uses an amplifier and one switch in thetriple SPDT analog multiplexing unit U9 The gain in each of the circuits is accomplished by means of a feedback loop which includes one of the SPDT switches in U9 The PWMs control whether the feedback loop is connected to ground or to the amplifier output The feedback is then averaged by C17 R27 red and C20 R26 IR The higher the value of PWM2 the greater the IR gain the higher the value of PWM 1 the greater the red gain 5 15 Technical Supplement 3 3 4 AC Ranging 3 3 5 Audio Output 5 16 53 3 3 2 Filtering Circuits These circuits consist of two cascaded second order filters with a break frequency of 10 Hz Diodes CR1 CR2 for the red channel CR4 CR3 for the IR channel connected to VREF and ground at the positive inputs of the second amplifiers maintain the voltage output within the range of the A D converter In order to achieve a specified level of oxygen saturation measurement and to still use a standard type combined CPU and A D converter the DC offset is subtracted from each signal Because the DC portion of the signal can be on the ord
23. the following guidelines for battery replacement and battery disposal as a minimum 2 2 4 Battery Replacement Caution The NPB 40 could be damaged by batteries that are left unused in the unit and begin to leak Never store the NPB 40 with the batteries installed for a prolonged period of time NPB 40 batteries should be replaced whenever a low battery indication is observed on the unit Remove the batteries if you will be storing the NPB 40 for longer than one month Refer Figure 2 1 for replacing the batteries Note For easier battery installation insert the negative end of the battery first when installing each battery Section 2 Routine Maintenance Figure 2 1 NPB 40 Battery Installation 2 2 2 Battery Disposal When NPB 40 batteries have been replaced dispose of the old batteries Always follow local ordinances when disposing of the NP B 40 batteries Warning Never dispose of NPB 40 batteries by burning The batteries could explode in fire and cause serious personal injury 2 3 CLEANING Caution Do not immerse the 40 or accessories in liquid or use caustic or abrasive cleaners To dean the NPB 40 dampen a soft cloth with a commercial nonabrasive cleaner and wipe the unit with the cloth 22 SECTION 3 PERFORMANCE VERIFICATION 3 1 Performance Verification 3 1 PERFORMANCE VERIFICATION The performance of the NPB 40 can be verified using the following procedure Before performing this procedu
24. ti mes 13 1 ms the CPU will drive RESET low resetting the entire unit The reset output by the CPU is only 16 state times long 3 2 us The CPU has the ability to dynamically switch the data bus width based on the BUSWIDTH input pin A low on BUSWIDTH tells the CPU to access memory only 8 bits at a time When accessing the static RAM BUSWIDTH is low automatically reading the 8 bit wide RAM Since BUSWIDTH is connected to the active low RAM enable line RAM EN L all other memory and mapped 1 0 are read or written 16 bits at a time Eight analog inputs are measured by the CPU Input from the SpO2 analog section on the LCD PCB includes AC and DC signals for the oxi meter sensor red and infrared channels and the sensor calibration resistor RSENS The battery voltage and reference voltage from the LCD PCB are also measured The CPU is configured as follows Decoded ADO and generate separate WR write strobes for the low and high bytes of a word The signal WR WRL is thelow byte write strobe A standard address latch enable ALE is generated and used 504 and HSO5 are configured as outputs The HSO is used to generate stable timing control signals to the SpO2 analog section display and printer driver External control pins P2 2 P2 3 and 2 4 are configured to monitor front panel keyboard keys Store Data Print Display Light Beep On Off and Shift keys respectively Pins HSIO is configured
25. 3 3 54 1 54 2 54 3 54 4 54 5 4 1 NPB 40 Handheld Pulse 1 1 NPB 40 Front esee 1 2 NPB 40 Battery Installation see 2 2 NPB 40 Self Test Front Panel Display 3 1 Printer Interface sse 3 3 Typical Average Data Print 3 4 Typical Data Print Out sse 3 5 Typical Error Code Display esee 4 2 Opening the NPB 40 Case 1 esses 5 2 Top Case 1 seen nennen rnnt 5 2 Unlocking CPU PCB Connector J3 5 3 Separating LCD PCB from CPU 5 3 NPB 40 Expanded View sss sse 6 2 Repacking the NPB 40 eene emen 7 2 Oxyhemoglobin Dissociation Curve 5 2 NPB 40 Block Diagram 84 CPU PCB Block Diagram sss 5 6 LCD PCB Block seen 5 12 CPU PCB Parts Locator FO 1 LCD PCB Parts Locator Diagram FO 2 CPU PCB Schematic Diagram
26. AW 5V are supplied to the LCD PCB for backlight power and for power conditioning for the SpO2 analog circuits Theserial interface is only used for factory test purposes and is not at the RS 232 level neither is it electrically isolated and therefore cannot be used outside of the factory The serial data port J 5 is a TTL level serial interface RXD and TXD are configured as a standard asynchronous serial transmitter and receiver at 19 2 Kbaud with 1 stop bit 8 data bits and no parity The serial interface can operate in full duplex mode If no external serial data device is connected R19 pulls the RXD input high which prevents the input from floating when it is not being used Microprocessor U4 provides a drive signal IR OUT at HSO5 that controls an infrared LED on the LCD PCB which is used to interface with an external printer S3 2 7 External VCC Monitor and Watchdog Timer The external VCC monitor and watchdog timer circuit consists of U 6 and associated components U6 provides two functions If the VCC input voltage drops below 4 0 Vdc U6 will drivethe RST L linelow which resets microprocessor U 4 U6 also periodically receives the WD RST pulse output from U4 If U6 does not receive the WD RST signal at least every 500 ms it will drive the RST L line low which resets 04 533 LCD PCB Theory of Operation Refer to Figure S3 3 for the LCD PCB block diagram and to Figure S4 4 for the LCD PCB schematic diagram in the following de
27. CD The INH inhibit input of U1 is held low by resistor R9 until the line is driven high by the LCD EN signal from microprocessor on the CPU PCB This assures that the display is blanked until it is under microprocessor control Should the microprocessor be reset the LCD EN line goes toa floating state R9 then pulls the INH input to U1 low and the display is blanked 53 3 7 Power Conditioning Circuitry Unfiltered positive RAW 10V and negative RAW 5V voltages from the CPU PCB are applied to the power conditioning circuit RAW 10V is filtered by a circuit consisting of R6 C1 and C2 to provide a clean and stable 10 V dc operating voltage for LCD PCB SpO2 analog and other circuits Likewise 5 is filtered by a circuit consisting of R11 C8 and C10 to provide a dean and stable 5 V dc operating voltage for the LCD PCB circuits A filtered 5Vdc VCC from the CPU PCB is also used as VCC by circuits on the LCD PCB 53 3 8 Analog Reference Voltage RAW 10V from the CPU PCB is applied to a filter consisting of R7 and C6 to create VIN that is used by voltage converter U2 to create VREF U2 provides an accurate regulated voltage that is used as the reference voltage for the A D inside the microprocessor U4 the CPU PCB Filtering is provided by C7 C9 and R12 The voltage output VREF is 5 Vdc 3 3 9 LCD Backlighting RAW 10V from the CPU is used as power for the LCD backlight The LCD backlight consists of LEDs DS1 t
28. DATA CE LCD LCD enable driver 1 Printer LED signal Printer interface Analog sensor voltage reference Vrei Analog sensor signal Sensor Analog circuit control signal circuits l Figure S3 2 CPU PCB Block Diagram S 6 53 2 1 CPU Technical Supplement Thelntel 80C196K C CPU is a 16 bit microprocessor with built in peripherals induding a serial port watchdog timer A D converter with an 8 input analog multiplexer three pulse width modulators two 16 bit counter ti mers up to 481 0 lines and a high speed 1 0 subsystem The CPU is capable of running up to 16 MHz but it is run at 10 MHz for decreased power consumption All unused inputs are tied to either Vcc or ground through resistors this prevents unused inputs floating to any voltage and causing excess power drain The READY input pin is tied high thereby disabling wait state generation all bus accesses are zero wait state The EA pin is tied low to enable addressing of the external EPROM When the power supply is first switched on by the power control circuit the watchdog reset circuit holds the CPU RESET pin low for at least 20 ms then allows the internal pull up resistor to bring it high this assures a good CPU reset An internal watchdog timer is enabled and runs continuously The watchdog timer provides a means of recovering from a software upset caused by ESD EMI etc If the software does not dear the timer at least every 64K state
29. EAR Fer 250 n2 2 2 Taa usc REDLED AV gt CONNECT ae 2Ns906S 10V TO AGND WITH 5 565 SEPARATE 4 2439045 5 L ues DG201s 1 vec mao Lri0138 10 0K oss b vr AA1101 Y AATIOTW Qn 4 mesases a n E CD4osss pru nw A Uuiic u11B LCD LiGHT D 201s DG201s s i 5 5 os o e E IF RED L1 BLM31B06 i CPU INTERFACE 1 OFF ON Y Vos TP17 1N914S LEDDIS Rss R51 10 0 10 0K 2439043 1 6 04K 0 196 Che 1N914S B DAG v IRAC RAW 10V gt PWMO LEDDIS PHOTO AGND and DGND for usa connected together on CPU board BOSS HOLES RIB LT1013S LEFT SIDE RIGHT SIDE 241 SAMPRED PHOTO ER 2 RSENS SAMPIR IR OUT IR RED E IRLED AV TO CASE EMI PAINT LCD LIGHT 7 LCD EN BEEP 2 NOTES LCD CE 8 11 BEEP 1 LCD DATA LCD CLK 1 ALL CAPACITORS ARE 10 50V 1206 PACKAGE REDLED AVI ZERO L UNLESS OTHERWISE NOTED PWM1 OFF ON ALL
30. M and a 64K x 16 EPROM Display control The CPU provides drive and control signals for the LCD driver and display on the LCD PCB Audio output drive Drives piezoelectric ceramic beeper on the LCD PCB for audio output Printer drive The CPU provides a printer drive signal that is applied to an IR LED on theL CD PCB Power supply Power control circuitry The NPB 40 receives power from 4 AA cell batteries The power control circuitry discontinues power to the unit when the batteries no longer reliable 5 5 Technical Supplement Battery power From front panel keypad On off key Shift key l Display light beep on off key Store data print key VCC monitor and watchdog reset circuit 10MHz clock circuit Power switch circuit Power shut off control Battery power Power on feedback Power supply circuit Battery voltage sense 0 12 9 15 ADDR ADDR o To LCD 1 Raw 10 5Vde VCC 5 Vdc To CPU PCB circuits EPROM enable decoding Address latch Microprocessor AD 0 7 External output enable dcc To from LCD PCB Beeper drive Beeper output port LCD light enable LCD LCD CLK backlight
31. MPRED and SAMPIR which are both active low control SPST analog switches in U3A and U3C respectively Switch U3A is closed to sample the red signal switch is dosed to sample the IR signal The sampling rate for both switches is 10 kHz Switching is coordinated with the LED transmission so that the IR and red signals are each sampled twice per cyde that is once when the LED is off signal inverted and once when the LED is on signal not inverted The filtering circuit that follows has a long time constant thereby acting as an averaging circuit If the instantaneous average photocurrent DC offset is excessive and U5B cannot bringit to VREF the PHOTOI linetothe CPU HSIO is activated This action is an indication of excess ambient light into the photosensor or the occurrence of excess noise in the input circuit It also serves as a warning tothe instrument that the sensor signal may be contaminated and causes the software to send an error message The separated IR and red signals are amplified so that their DC values are within the range of the A D converter Because the received I R and red signals are typically at different current levels the signal gain circuits provide independent amplification for each signal as needed The gain in these circuits is adjusted by means of the PWM lines After the IR and red signals are amplified they are filtered to improve the signal to noise ratio and clamped to a reference voltage to prevent
32. PB 40 consists of three main functional components the front panel keyboard the CPU PCB and the LCD PCB as follows CPU PCB contains the CPU power supply circuitry support memory circuits sensor circuits for battery voltage a serial data port LCD backlight control pulsatile beeper drive circuits and some display control circuits LCD PCB contains the SpO2 analog circuitry and interface to the external sensor the power conditioning circuitry the LCD display and display driver circuits the interface circuitry for the printer which is not used unless a printer is present the LCD backlight and audio output hardware Front Panel Keyboard contains four membrane switches and a line common to all four switches This assembly connects to the CPU PCB by a flex circuit Refer to Figure 53 1 for this NPB 40 block diagram The CPU PCB and the LCD PCB are each described in more detail in later paragraphs 5 3 Technical Supplement The 40 is powered by four AA size replaceable alkaline batteries A dc voltage in the range of 3 6 to 6 Vdc is provided over the life of these batteries When the voltage from these batteries drops to a level toolow to operate the NPB 40 the unit will shut itself off At that time the batteries must be replaced Thefront panel keypad contains four keys that provide discrete signals that are monitored by the microprocessor on the CPU PCB Refer to Figure 54 5 for a schemati
33. U uses address line AO for low high byte selection and is not used as a normal address line The CPU can only address 64K x 8 bytes or 32K x 16 bytes Pin A15 of U5 is tied low always selecting the lower half of the EPROM Signal ROMEN L is then used to enable the EPROM for the proper memory area The output port external to the CPU consists of an octal D latch U9 The output of U9 is always enabled The output bits of U9 control the beeper output the LCD backlight and the LCD display drive signals 53 2 3 Standard User Controls The standard user controls consist of four momentary push button switches on the front panel keypad These keys are metal dome membrane contact switches The front panel switches Store Data Print Display Light Beep On Off and Shift are connected to the microprocessor U4 input lines P2 2 P2 3 and P2 4 and are normally pulled to the high state by R10 R8 and R18 Whenever one of these keys is pressed the U4 input lineis pulled low The switch contacts are debounced in software The fourth front panel switch On Off is connected to the power switch described Power Supply Power Control Circuitry 53 2 4 Power Supply Power Control Circuitry The power supply and power control circuitry consists of the following primary elements Batteries Four 1 5 V alkaline AA size batteries provide 3 6 6 power Power entry circuit Components protect the B 40 from damage if batteries ar
34. address line A12 is high WR active low and RD inactive high a binary 3 is produced on pins A B and C forcing output Y3 EXOUTEN L low This enables the output port for writing Note that in this condition A15 A14 A12 A11 and A10 are high and A13 is low The output port uses the address space of DEOO DFFF When data is written to that address the output port enable signal EXOUTEN L is activated Because the CPU is configured to use a 16 bit bus except for RAM any even address in the DEOO DFFF range could be used for external port access In other words reading or writing address DF 00 DEO2 DE04 etc will all produce the same results U7A generates the EPROMs active low enable signal ROMEN L The active low signals RAMEN L and EXOUTEN L are basically used as EPROM disable signals When RAMEN L or EXOUTEN L or the Y3 output of UB are low the output of U7A ROMEN L is forced high disabling the ROM Therefore the EPROM is disabled for the range DEOO FFFF and enabled for the address range of O DFFF The memory system external to the CPU consists of an 8 K x 8 static RAM U 12 and a 64 K x 16 EPROM U5 The EPROM is 16 bits wide to enhance CPU performance Because RAM is infrequently accessed it is only 8 bits wide U12 is a standard 8K x8 static RAM Technical Supplement The program that the CPU runs is stored in U5 U5 is a 16 bit wide output one time programmable OTP EPROM During 16 bit wide bus accesses the CP
35. an be provided to the A D for measurement Central Processing Unit CPU An Intel 80C196KC 16 bit microprocessor The CPU sends and receives control signals to the SpO2 analog section display and printer infrared LED High Speed Outputs HSO The 6 HSO lines control most of the timing of the LED signal pulse and the demodulation of the received signal Input and Output Digital lines that are used by the CPU to read in data and output data Light Emitting Diodes LEDs Two LEDs are used in Ndlcor Puritan Bennet oximetry sensors Light is transmitted through body tissue and received by a photodetector circuit that converts it to photocurrent The two wavelengths which are used for calculation of pulse rate and oxygen saturation in blood aretransmitted at the following frequencies infrared IR light at 915 microns red light at 660 microns Pulse Width Modulation PWM The three 8 bit PWM outputs can be software controlled their duty cycle can be changed from 0 TO 99 6 percent of the total pulse duration PWM frequency is the crystal frequency of the CPU 10 MHz divided by 1024 The PWMs control the gains within the analog circuit RCal Sensor RCal value 15 a resistance value specific to an individual sensor This value is used by the software during oxygen saturation computations to maximize accuracy S3 1 Overall Unit Block Diagram Analysis Exdusive of batteries covers keys and external connectors the N
36. andheld pulse oximeter is illustrated in Figure 1 1 Figure 1 1 NPB 40 Handheld Pulse Oximeter The NPB 40 is operated using a four key keypad and LCD display on the front panel as shown in Figure 1 2 Refer tothe NPB 40 operator s manual for complete operating instructions l1 Section 1 Introduction Pulse Amplitude indicator Pulse Rate display Pulse Search display Low Battery indicator Sensor disconnect indicator Power On Off key Display Light Beep On Off key Store Data Print key Shift key 10 Store Data icon 6 11 Shift icon 12 Print icon 7 18 SpO2 display 13 ri Figure 1 2 NPB 40 Front Panel 1 2 SECTION 2 ROUTINE MAINTENANCE 2 1 Maintenance Overview 2 2 Battery Maintenance 2 3 Cleaning 2 1 MAINTENANCE OVERVIEW The NPB 40 requires no routine service or calibration The performance verification tests in Section 3 Performance Verification may be used following repairs or during routine maintenance if required by your local institution 22 BATTERY MAINTENANCE Warning The NPB 40 uses four AA cell alkaline batteries for operation If batteries are not replaced when recommended or are not disposed of properly serious personal injury or damage to the NPB 40 could result Caution When inserting the positive end of each battery exercise caution to not damage the small coiled spring contact Nellcor Puritan Bennett recommends that you comply with
37. at the PULSE SEARCH indicator illuminates momentarily and verify that the NPB 40 is displaying a pulse rate of 201 3 bpm that the pulse amplitude indicator is displaying properly that the SpO 296 indicator is displaying 79 to 83 that a pulse beep can be heard and that the PULSE SEARCH indicator is off Note If an HP82240B printer is not available skip steps 19 through 27 and proceed to step 28 Refer tothe printer operator s manual as needed Verify that paper is properly installed in the printer and turn the printer on Align the NPB 40 with the printer as shown in Figure 3 2 1 2 2 5 5 1 Figure 3 2 Printer Interface Setup 33 Section 3 Performance Verification 34 21 22 23 24 25 26 27 On the NPB 40 press the Shift key followed by the Store Data Print key on the front panel keypad Nate Inthefollowing steps printed 5 02 values will be 79 to 83 and pulse rate values will be 201 3 bpm Figures 3 3 and 3 4 are examples of typical print outs The NPB 40 will not display pulse or SpO2 values while printing Verify that the PRINT icon is illuminated on the NPB 40 display that the printer begins printing and that the printer prints out a summary report similar to that shown in Figure 3 3 elapsed time 00 00 46 Sp02 81 5 02 minimum 81 5 02 maximum 82 Sp02 average 81 BPM 201 BPM minimum 201 BPM maximum 202 BPM average 201 Figure 3 3 Typi
38. ated value may differ from the 40 SpO2 measurement This is because the calculated saturation may not have been corrected for the effects of variables that can shift the relationship between PaO2 and saturation Figure S2 1 illustrates the effect that variations in pH temperature partial pressure of carbon dioxide PCO2 and concentrations of 2 3 DPG and fetal hemoglobin may have on the oxyhemoglobin dissociation curve t pH Temperature 4 2 2 2 3 DPG 7 Fetal Hb DET 100 50 1 2 pH 1 Temperature t 2 3 DPG Saturation 96 50 100 PO mmHg Figure S2 1 Oxyhemoglobin Dissociation Curve CIRCUIT ANALYSIS This section provides an explanation of NPB 40 theory of operation using block diagrams and schematic diagrams The NPB 40 consists of three main functional components described in the following paragraphs The CPU block diagram Figure S3 2 and schematic diagram Figure S4 3 TheLCD PCB block diagram Figure S3 3 and schematic diagram Figure S4 4 The Front Panel PCB schematic diagram Figure S4 5 The relationship between these components and their interconnection is illustrated in the NPB 40 block diagram Figure S3 1 Technical Supplement Thefollowing is a list of terms and definitions used in the following paragraphs Analog to Digital A D converter The CPU has a 10 bit A D converter on board Up to eight different analog inputs c
39. c diagram of the front panel keypad Power Power 1 1 1 1 1 i control Raw power condition Batteries and PCB power power 1 Sensor 1 Power down 9 NT control Analog Patient sensor Sensor circuits input Function keys 1 1 i 1 i 1 analog signal i 1 1 1 1 1 i 1 1 1 1 1 Printer signal Printer IR LED drive External serial interface LCD enable External output control output Beeper port 1 1 1 1 i Backlight control 1 1 1 1 1 backlight 1 1 1 1 1 1 External 1 1 1 1 1 1 Figure S3 1 40 Block Diagram Technical Supplement Power from the batteries is controlled and filtered by the power control and PCB power circuits on the CPU PCB When the On Off key is pressed on the front panel keypad and the unit is turned off the power control circuits will turn on the unit If the unit is on when the On Off key is pressed the unit will be turned off The PCB power circuits provide filtered power for the circuits on the CPU and raw power is passed tothe LCD PCB where it is conditioned for the circuits there A patient sensor connected to the NPB 40 contains a resistance that is a calibration refere
40. cal Average Data Print Out With the SRC 2 connected to the NPB 40 and still set up as in step 18 press only the Store Data Print key on the front panel keypad and verify that the LCD display indicates 1 14 and the STORE DATA icon illuminates Press only the Store Data Print key on the front panel keypad and verify that the LCD display indicates 2 14 and the STORE DATA icon illuminates Press only the Store Data Print key on the front panel keypad and verify that the LCD display indicates 3 1 d and the STORE DATA icon illuminates Align the NPB 40 with the printer as shown in Figure 3 2 and press the Shift key on the NPB 40 front panel keypad followed by the Store Data Print key Verify that the PRINT icon is illuminated on the NPB 40 display that the printer begins printing and that the printer prints out data similar to that shown in Figure 3 4 As data stored in steps 24 25 and 26 is printed out the NPB 40 display will indicate 1 14 2 14 and 3 Id respectively Section 3 Performance Verification 40 1 5 02 82 201 40 2 Sp02 81 BPM 201 NPB 40 ID 3 Sp02 81 BPM 201 Figure 3 4 Typical Data Print Out 28 Press the On Off key on the front panel keypad 29 Verify that the NPB 40 shuts off 35 This page intentionally left blank SECTION 4 TROUBLESHOOTING 4 1 4 2 4 3 4 4 4 5 4 1 Introduction 4 2 Who Shoul
41. controls both the current to the LEDs and the amplification in the signal channel 5 13 Technical Supplement At initialization of transmission the LEDs intensity level is based on previous running conditions and the transmission intensity is adjusted until the received signals match the range of the A D converter If the LEDs reach maximum output without the necessary signal strength the PWMs will increase the channel gain The PWM lines will select either a changein the LED current or signal gain but will not do both simultaneously TheLED drive circuit switches between red and IR transmission and disables both for a time between transmissions in order to provide a no transmission reference To prevent excessive heat build up and prolong battery life each LED is on for only a small portion of the duty cycle Also the frequency of switching is well above that of motion artifact and not a harmonic of known AC transmissions The LED switching frequency is 1 485 kHz The IR transmission alone and the red transmission alone will each be on for about one fifth of the duty cycle this cycle is controlled by the H SOs of the CPU ThelIR and red LEDs are separately controlled with their drive currents multiplexed over two shared wires Current to the IR LED is in the range of 4 3 50 0 mA and current tothe red LED is in the range of 4 3 to 50 mA Currents are limited to less than 100 mA for two reasons 1 slight excess current can potent
42. d Perform Repairs 4 3 Repair Level Supported 4 4 How to Use This Section 4 5 Obtaining Replacement Parts 4 6 Troubleshooting Guide INTRODUCTION This section provides information for troubleshooting the NPB 40 and helping you to isolate a failure to the front panel keypad the CPU PCB or the LCD PCB A troubleshooting guide is provided in Paragraph 4 6 Troubleshooting Guide that lists possible difficulties along with probable causes and recommended actions to correct each difficulty The Technical Supplement at the end of this manual provides information on how the components of the NPB 40 function WHO SHOULD PERFORM REPAIRS Only qualified service personnel should remove and replace components of the NPB 40 Repairs to the NPB 40 are limited to the repair level identified in Paragraph 4 3 Repair Level Supported If your facility does not have qualified service personnel contact the Nellcor Puritan Bennett Technical Services Department or your local Nellcor Puritan Bennett representative REPAIR LEVEL SUPPORTED Besides the batteries the NPB 40 has five replaceable components the case top with the front panel keypad the case bottom the CPU PCB theLCD PCB and the battery compartment door HOW TO USE THIS SECTION Failures of the case bottom the battery compartment door and the case top not including the front panel keypad are determined by visually inspecting these components for cracks or deformations and for mecha
43. dure to disassemble the N P B 40 Reassemble the monitor in reverse order and if the unit is to be returned to service install batteries when reassembly is complete and replace the battery compartment door Nellcor Puritan Bennett recommends that you follow this disassembly procedure in the order presented Note Before you begin to disassemble the NPB 40 remove the battery compartment door and remove the batteries 1 Place the NPB 40 on a nonabrasive surface so that the back of the unit is up and the bottom of theunit is closest to you 2 Remove the four screws holding the case together as indicated in Figure 5 1 Nate Thetwo screws at the top of the NPB 40 are longer than those at the bottom When reassembling the unit be sure to install the longer screws at the top and the shorter screws at the bottom Caution When reassembling the NPB 40 hand tighten the screws that hold the NPB 40 case together to a maximum of 4 inch pounds Over tightening could cause the screws to strip out the screw holes in the top case rendering it unusable 51 Section 5 Disassembly Guide Remove screws Remove screws Figure 5 1 Opening the NPB 40 Case 3 While holding the case together turn the NPB 40 over with the front panel up and the bottom of the unit closest to you 4 Separate the case top from the bottom case on the right side of the unit and rotate the case top tothe
44. e inserted incorrectly and provide reverse current limiting and over voltage or spike protection addition a self resetting fuse protects the power supply from excessive current draw The power supply is also protected against electrostatic discharge and electromagnetic interference Power switch circuitry This circuit controls power applied to the power supply circuits Power control circuitry is connected to the batteries It senses any press of the front panel keypad On Off key and switches the power supply circuit on or off A control signal tothis circuit from the CPU will also shut off the NPB 40 when battery voltage drops to an unusable level Power supply circuits consist of a power generation circuit that provides 10 45Vdc and 5Vdc S 9 Technical Supplement S 10 S3 2 4 1 Power Entry Circuitry Self resetting fuse R22 protects the NPB 40 and will open when current in excess of 0 75 Amps is drawn the unit R22 will close when the condition causing excessive current has been eliminated CR7 provides reverse current protection and limits negative voltages batteries reversed to safe levels In either of these conditions CR7 will conduct and cause fuse R22 to open CR5 protects against large voltage transients caused by ESD EMI etc and will pass these undesirable transients to ground S3 2 4 2 Power Supply Feedback Circuitry The power supply feedback circuit consists of Q1 and its associat
45. ed components When batteries are installed and the NPB 40 is turned off the battery voltage VBAT is applied through resistor R2 at the collector of Q1 providing a logic 1 level voltage to the D input of flip flop U 1B in the power switch circuit When the NPB 40 is turned off VCC is at 0 volts and 01 15 turned off When the NPB 40 is turned on See Power Switch Circuitry the VCC potential is applied to the base of Q1 which turns it on The voltage at the D input of U1B then drops to a low voltage to provide a logic O S3 2 4 3 Power Switch Circuitry The power control circuit consists of U 1B and its associated components U 1B is a D flip flop with asynchronous preset and clear only the clear is used Battery voltage is applied to U 1B whenever batteries are installed The NPB 40 is turned on and off by pressing the On Off key on the front panel keypad The BTN PWR line is normally pulled up to the battery voltage by R3 When battery voltage is at an acceptable level and the On Off key on the front panel keypad is pressed the BTN PWR lineis grounded and the resultant high going pulse from U 2A toggles the CLK input of U1B and the high D input logic level is transferred to the Q output Thelogic state of the D input is controlled by the power supply feedback circuitry See Power Supply Feedback Circuitry When the NPB 40 is off the D input of U1B is high Pressing the front panel On Off key sets the Q output and the PWR ON signal
46. effect of fetal hemoglobin in neonatal blood on oximetry measurements Pulse Rate 20 250bpm 3 bpm Note Accuracy is expressed as plus or minus 3 bpm across the display range This variation equals plus or minus one standard deviation 1SD which encompasses 68 of the population amp 1 Section 8 Specifications 8 2 ELECTRICAL Instrument Power Requirements 6V supplied by battery power only Patient Isolation No electrical connection to patient inherently insulated Battery Type Four 1 5V alkaline AA size batteries Battery Capacity Typically 19 hours with four new disposable alkaline batteries Note all brands of off the shelf alkaline batteries provide the same battery life 8 3 ENVIRONMENTAL Operating Temperature Instrument 0 to 55 C Sensor Within physiologic range for specified accuracy Transport Storage Temperature boxed 40 to 70 C 15 95 RH Humidity Operating 15 95 noncondensing Storage unboxed 15 95 noncondensing over a temperature range of 20 C to 60 C Altitude Operating 1280 ft to 12 000 ft 390 m to 3 658 m 650 to 1060 hPa Storage 2330 ft to 15 000 ft 457 m to 4 573 m 572 to 1100 hPa 8 2 8 4 PHYSICAL Section 8 Specifications Weight with batteries installed 0 3 kg 11 oz Size 15 75 cm high x 7 5 cm wide x 3 8 cm deep 6 2 in high x 2 95 in wide x 1 5 in deep Equipment Classification IEC 601 1 CSA 601 1 UL 2601 1
47. er of one thousand times the AC modulation 16 bits of A D conversion would otherwise be required to accurately compare the IR and red modulations between the combined AC and DC signals The DC offsets are subtracted by using an analog switch to set the mean signal valuetothe mean of the range of the A D converter whenever necessary The AC modulation is then superimposed upon that DC level This is also known as AC ranging Each AC signal is subsequently amplified such that its peak to peak values span one fifth of the range of the A D converter The amplified AC signals are then filtered to remove the residual effects of the PWM modulations and finally areinput tothe CPU The combined AC and DC signals for both IR and red signals are separately input to the A D converter 3 3 4 1 Offset Subtraction Circuits Voltage dividers R53 and R49 red and R61 and R63 IR which are located between VREF and ground establish a baseline voltage of 2 75 V at theinput of the unity gain amplifiers U 12C red and U 12D IR Whenever SPST analog switches U 11A and U 11D are closed by HSOO active low the DC portions of the IR and red signals create a charge which is stored on C54 and C46 respectively These capacitors hold this charge even after the switches are opened and the resulting voltage is subtracted from the combined signal leaving only the AC modulation output This AC signal is superimposed the baseline voltage output by U 12C
48. he two PCBs together 5 3 This page intentionally left blank SECTION 6 SPARE PAHTS 6 1 6 1 Introduction INTRODUCTION Spare parts along with corresponding Nellcor Puritan Bennett part numbers are shown below Figure 6 1 shows the replaceable 40 monitor components with numbered callouts that correspond to item numbers in parentheses in the spare parts list below In December 1997 the external plastic parts of the NPB 40 were modifi ed Plastic parts made after that date are incompatible with parts made before that time To determine which part number to order look at the back of the instrument Tothe right of center just above the battery compartment door there will be either 3 holes or three slots for the speaker If your instrument has three slots use part numbers from the After 12 97 column If the instrument has three holes use part numbers from the Before 12 97 column Item Part Numbers Before 12 97 1 Case Top K eypad 045691 2 CPU PCB 034311 3 LCD PCB 034835 4 Case Bottom 035097 5 Battery Compartment Door 033880 048863 034311 034835 035397 034975 Part Numbers After 12 97 6 1 Figure 6 1 NPB 40 Expanded View SECTION 7 PACKING FOR SHIPMENT 7 1 General Instructions 7 2 Packing NPB 40 in Original Carton 7 3 Packing in a Different Carton 7 1 GENERAL INSTRUCTIONS To ship an NPB 40 handheld pulse oxi meter or one of it
49. hrough DS6 Resistors R3 and R4 provide current limiting for the LEDs Transistor Q2 is turned on when the LCD LIGHT signal from external output port U9 on the CPU PCB goes high which in turn illuminates the backlight LEDs 3 3 10 Printer Drive Circuit The printer drive circuit consists of R1 R2 Q1 and 057 The IR OUT signal from microprocessor U4 on the CPU PCB controls transistor Q1 which in turn controls infrared LED DS7 DS7 is used to provide a data signal that is transmitted to an external printer with an infrared receiver Technical Supplement S4 5 18 SCHEMATIC DIAGRAMS The following part locator diagrams and schematic diagrams are included in this section Figure Description Figure S4 1 CPU PCB Parts Locator Diagram Figure S4 2 LCD PCB Parts Locator Diagram Figure S4 3 CPU PCB Schematic Diagram Figure S4 4 LCD PCB Schematic Diagram Figure S4 5 Front Panel Keypad Schematic Diagram 5 eo ME Wes S ge eec va m 116 aes a gz M Ni 8 we E ct am oe Eei EDZ LE NPB 40 CPU FAB 034309A TOP SIDE T C36 8 IE E UU 5 e 9 5 e 09 TPT ATT
50. ially change the emission characteristics of the LEDs and 2 large excess current could create excessive heat at the sensor site ThelR red LED transmission signal HSO1 of the CPU is fed into the select inputs of the triple single pole double throw SPDT analog multiplexing switch U7 causing either the IR or the red LED transmission to be enabled PWM 1 which is filtered by the network of R45 R35 C41 and C42 is input tothe LED drive circuit switch U7 and controls the magnitude of the IR LED current supply PWMJ2 which is filtered by the network of R29 R39 C35 and C23 is also input to U7 and controls the red LED current magnitude Two NPN transistors Q8 and 010 act as current sources for the IR and red LED outputs Two PNP transistors Q9 and Q11 act as switches between the IR and red LED output lines Transistor Q12 acts as an LED drive current limiter it clamps the output of the current regulator circuit to the required level If any resistor in the LED drive circuit fails current tothe LED will still belimited to a safe level The RSENS line senses the RCal value and enables the CPU to make the proper calculations based on the type of sensor being used 3 3 2 Input Conditioning S 14 Input to the SpO2 analog circuit is the current output of the sensor photodiode order to condition the signal current it is necessary to convert the current to voltage A differential synchronous demodulation circuit is used
51. ll persists refer to Table 4 2 for the indicated failure and corrective action IIE Figure 4 1 Typical Error Code Display Once you have performed the recommended action reassemble the N PB 40 refer to Section 3 Performance Verification and conduct a performance verification before returning the NP B 40 to service If the symptom persists continue troubleshooting Table 4 1 Troubleshooting Guide Symptom ProbableCause Corrective Action ___ Theunit does not The batteries are Open the battery compartment turn on when the missing and if batteries are missing On Off key is install new batteries pressed The batteries are Open the battery compartment installed incorrectly andif batteries are not installed or are backwards correctly remove and reinstall the batteries The batteries areat Install new batteries or near a voltage too Continued on next low for the NPB 40 to operate 42 Section 4 Troubleshooting Table 4 1 Troubleshooting Guide Continued Symptom ProbableCause Corrective Action Theunit does not The sensor is Replace the sensor turn on when the defective On Off key is pressed continued The front panel Open the NPB 40 disconnect keypad is defective case from J the CPU PCB and connect an ohmmeter between the flex circuit conductor for J 3 pin 5 and the conductor for J 3 pin 3 Observe a short when the On Off key is pressed and an open when
52. lood and tissue The measurements that are obtained between arterial pulses reflect absorption by nonpulsatile blood and tissue By correcting during pulse absorption for between pulse absorption the NPB 40 determines red and infrared absorption by pulsatile arterial blood Because oxyhemoglobin and deoxyhemoglobin differ in red and infrared absorption this corrected measurement can be used to determine the percent of oxyhemoglobin in arterial blood SpO2 is the ratio of corrected absor ption at each wavelength 2 2 Functional Versus Fractional Saturation The NPB 40 measures functional saturation that is oxygenated hemoglobin expressed as a percentage of the hemoglobin that is capable of transporting oxygen It does not detect significant levels of dyshemoglobins In contrast some instruments such as thelL 282 Co oxi meter measure fractional saturation that is oxygenated hemoglobin expressed as a percentage of all measured hemoglobin induding dyshemoglobins Consequently before comparing NPB 40 measurements with those obtained by an instrument that measures fractional saturation measurements must be converted as follows functional fractional 100 saturation saturation X 100 96 carboxyhemoglobin 49emethemoglobin S 1 Technical Supplement 2 3 3 5 2 Measured versus Calculated Saturation When saturation is calculated from a blood gas measurement of the partial pressure of arterial oxygen PaO2 the calcul
53. nce for the sensor The analog sensor circuits on the LCD PCB then measure the signal from a photodiode in the sensor that is different based on the light absorption characteristics of each patient That signal is processed by the analog sensor circuits and measured by the CPU The LED drive signals are then adjusted by the CPU to obtain an optimum signal from the photodiode The CPU provides a drive signal for an IR LED on the LCD PCB When this IR LED is aligned with a receiving photodiode on an external printer patient data stored in the NPB 40 can be printed An external output port on the CPU PCB is controlled by the CPU and sends drive signals to the beeper and LCD backlight and display data tothe LCD An external serial data interface used during testing in manufacturing only is also controlled by the CPU This interface is only accessible with a special test fixture S3 2 PCB Theory of Operation Refer to Figure S3 2 for the CPU PCB block diagram and to Figure S4 3 for the CPU PCB schematic diagram in the following description The CPU PCB hardware and related circuitry which is illustrated in the following block diagram includes the following subsystems CPU 16 bit microprocessor that includes a serial port watchdog timer A D converter with an 8 input analog multiplexer 3 pulse width modulators and a high speed I O subsystem System memory External tothe CPU and consists of 8K x 8 static RA
54. nical failures such as the screw holes stripping out in the case top The case top and the front panel keypad are replaced together Use the troubleshooting guide provided in Paragraph 4 6 Troubleshooting Guide to isolate failure to the front panel keypad the CPU PCB or the LCD PCB Oncea failure has been isolated refer to Section 5 Disassembly Guide for instructions for removing and replacing a component of the NPB 40 OBTAINING REPLACEMENT PARTS Nellcor Puritan Bennett Technical Services Department provides technical assistance information and replacement parts To obtain replacement parts contact the Nellcor Puritan Bennett Technical Services Department or your local Nellcor Puritan Bennett representative Refer to parts by the part names and part numbers listed in Section 6 SpareParts 41 Section 4 Troubleshooting 4 6 TROUBLESHOOTING GUIDE If you encounter a problem that cannot be resolved through a visual inspection refer to Table 4 1 which provides a list of symptoms probable causes and recommended actions to take to correct the problem It is recommended that corrective actions be performed in the order presented For a symptom that is not listed in Table 4 1 contact the Nellcor Puritan Bennett Technical Services Department or your local Nellcor Puritan Bennett representative If an error code is shown on the front panel LCD display as shown in Figure 4 turn the NPB 40 off and back on again If the error code sti
55. o perform this procedure 31 Section 3 Performance Verification 32 10 11 Set the SRC 2 controls as follows RATE 112 LIGHT HIGH 1 MODULATION HIGH LOCAL RCAL LOCAL Press the On Off key on the NPB 40 front panel keypad When the self test is complete verify that the PULSE SEARCH indicator illuminates momentarily and verify that the NPB 40 is displaying a pulse rate of 112 3 bpm that the pulse amplitude indicator is displaying properly that the 5 2 indicator is displaying 81 2 96 that a pulse can be heard and that the PULSE SEARCH indicator is off Set the following SRC 2 controls as indicated RATE 38 LIGHT HIGH 2 MODULATION LOW Wait 30 seconds and verify that the NPB 40 is displaying a pulse rate of 38 3 bpm that the pulse amplitude indicator is displaying properly that the SpO 2 indicator is displaying 81 2 that a pulse beep can be heard and that the PULSE SEARCH indicator is off Set the following SRC 2 controls as indicated RATE 201 LIGHT LOW Wait 30 seconds and verify that the NPB 40 is displaying a pulse rate of 201 3 bpm that the pulse amplitude indicator is displaying properly that the SpO 2 indicator is displaying 81 2 96 that a pulse beep can be heard and that the PULSE SEARCH indicator is off Set the following SRC 2 control as indicated MODULATION HIGH Wait 30 seconds and verify that the NPB 40 is displaying a pulse rate of 201
56. quare inch psi bursting strength 3 Fill the bottom of the carton with at least 2 inches of packing material 4 Place the bagged NPB 40 or component on the layer of packing material and fill the box completely with packing material such that there is at least 2 inches of packing material around all sides of the item 5 Seal the carton with packing tape 6 Label carton with shipping address return address and RGA number 7 1 Section 7 Packing for Shipment Figure 7 1 Repacking the NPB 40 7 2 SECTION 8 SPECIFICATIONS 8 1 8 2 8 3 8 4 8 1 PERFORMANCE Performance Electrical Environmental Physical Measurement Range SpO2 0 10096 Pulse Rate 20 250 beats per minute bpm Accuracy SpO2 Adults 70 10096 t 2 digits 0 69 unspecified Neonates 70 100 t 2 digits 0 69 unspecified Note Accuracies are expressed as plus or minus X digits oxygen saturation percentage points between saturations of 70 100 This variation equals plus or minus one standard deviation 1SD which encompasses 68 of the population All accuracy specifications are based on testing the subject monitor on healthy adult volunteers in induced hypoxia studies across the specified range Adult accuracy is determi ned with 11 D 25 sensors Neonatal accuracy is determined with Oxisensor N 25 sensors In addition the neonatal accuracy specification is adjusted to take into account the theoretical
57. re the N P B 40 must have fresh batteries installed If any of the required observations cannot be obtained do not return the NPB 40 to service before referring to Section 4 Troubleshooting Y ou will need an SRC 2 pulse oximeter tester to perform this procedure If the performance of the printing function will be verified you will need an HP82240B printer The NPB 40 is to be turned off and any sensors disconnected before performing this procedure 1 2 Press the On Off key on the front panel keypad TheNPB 40 will perform a self test Verify that all display segments arelit during the self test as shown in Figure 3 1 Also verify that a low pitched audio tone is heard at the end of the self test Also verify that you then hear a high a low and a high pitch error tone indicating that a sensor is not connected Verify that dashes are shown on the display and the SENSOR DISCONNECT indicator is flashing g Figure 3 1 NPB 40 Self Test Front Panel Display Wait for 20 to 40 seconds Verify that two triple beeps are heard Verify that the NPB 40 then shuts itself off Connect an SRC 2 pulse oximeter tester to the NP B 40 sensor connector Note Ifthe SRC 2is connected directly to the NPB 40 sensor connector its controls will be facing the opposite direction of theNPB 40 controls Connecting the SRC 2 through a sensor extension cable such as the Nellcor Puritan Bennett model EC 4 or EC 8 will make it easier t
58. s components for any reason follow the instructions in this section Pack the NPB 40 or component carefully Failure to follow the instructions in this section may result in loss or damage not covered by any applicable Nellcor Puritan Bennett warranty If available usethe original carton and packing materials and follow the instructions in Packing in Original Carton If the original shipping carton and material are not available use other suitable shipping materials and container and follow the instructions in Packing in a Different Carton Prior to shipping the NPB 40 or component contact Nellcor Puritan Bennett Technical Services Department or your local Nellcor Puritan Bennett representative for a Returned Goods authorization RGA number Mark the shipping carton and any shipping forms with the RGA number Caution Observe SD electrostatic discharge precautions when packing any NPB 40 components 72 PACKING NPB 40 IN ORIGINAL CARTON If the original carton and packing materials are available repack the NPB 40 as shown in Figure 7 1 Add packing material in the bottom of the carton as needed so the NPB 40 will not be able to move during shipment 7 3 PACKING IN A DIFFERENT CARTON If the original carton and packing material are not available when shipping an NPB 40 or one of its components 1 Place the 40 or component in a plastic bag 2 Locate a corrugated cardboard shipping carton with at least 200 pounds per s
59. scription This subsection describes the SpO2 analog hardware The analog circuitry has high signal sensitivity and reduced susceptibility to noise Its design allows for a wide range of input signal levels and a broad range of pulsatile modulation The SpO2 analog circuitry consists of four subsections Sensor output LED control The CPU controls the gain of both LEDs sothat signals received at the input amplifier are within an acceptable dynamic range Signal channel gain may also need to be increased The CPU uses Pulse Width Modulation PWM lines to control LED current level or to amplify the signal channel Input conditioning Sensor output current is converted to voltage demodulation circuit minimizes the effects of other light sources and stray frequency inputs Because the IR and RED signals are at different current levels the two LED signals are demultiplexed and separately amplified so they can be compared with each other Two circuits handle the demultiplexing by alternately selecting LED signals using switches Technical Supplement Filters then remove noise and smooth the signals before sending them tothe amplifiers Signal gain The separated LED signals are amplified so that their current levels are within the A D converter s acceptable range The signals are filtered to improve the signal to noise ratio and clamped to a reference voltage AC ranging DC offset is eliminated from each LED signal
60. th a CPU PCB has failed known good PCB LCD backlight does The Display Light See One or more keys on the not come on when key on the front front panel keypad does not the Display Light panel keypad is work above key is pressed defecti ve The backlight LEDs Replacethe LCD PCB with on the LCD PCB known good PCB have failed The unit shuts off The batteries are at Install new batteries when the LCD or near a voltage too backlight is turned low for the NPB 40 to en operate 4 4 Section 4 Troubleshooting Table 4 1 Troubleshooting Guide Continued Symptom Probable Cause Corrective Action Printer will not The printer is turned Turn on the printer print off The Store Data key See Oneor more keys on the on the front panel front pand keypad does not keypad 15 defective work above The printer batteries Install new batteries in the are at or near a printer voltage too low for it to operate The NPB 40 and Refer tothe operator s manual printer are not for instructions for aligning the properly aligned NPB 40 with the printer Replacethe LCD PCB with a LCD PCB has failed known good PCB Replace the CPU PCB with a CPU PCB has failed known good PCB The printer is Attempt to print using another defective known good NPB 40 If the printer still does not print troubleshoot the printer Table 4 2 NPB 40 Error Codes Failure Indicated Corrective Action 100
61. to reduce the effects of other light sources and stray frequency inputs to the system Becausethe IR and red signals are absorbed differently by body tissue their recei ved signal intensities are at different levels Therefore the IR and red signals must be demodulated and then amplified separately in order to compare them to each other Demultiplexing is accomplished by means of two circuits that alternately select the IR and red signal Selection of the circuits is controlled by two switches that are coordinated with the IR and red transmissions A filter with a large time constant follows to smooth the signal and remove noise before amplification 3 3 3 Signal Gain Technical Supplement Before the current from the photodetector is converted to voltage any high frequency noise is filtered by C9 and R21 The op amp is used in parallel with the current to voltage converter U 5B to cancel any DC voltage effectively AC coupling the output of U5B The average value of the SpO2 analog reference voltage VREF of 058 5 V is measured at test point 6 U3B a single pole single throw SPST analog switch is controlled by the same linethat controls the on off pulsing of the LEDs When either of the LEDs areon the lineis low and the switch is closed U4B is used as a noninverting amplifier When the LEDs are both off U4B is used an inverting amplifier The signal at the output of amplifier U4B is then demultiplexed The CPU HSO lines SA

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