Respiratory Pressure Meter Service Manual
Contents
1. converter A micro controller reads the A D converter and after applying a calibration factor displays the result on an LCD which is directly driven from the controller The measurement displayed is the maximum pressure recorded over a one second interval when the unit is switched to the MIP MEP position When the unit is switched to the SNIP position the peak pressure is displayed Power Supply and battery monitoring The Mouth pressure meter is powered by a PP3 9V Alkaline battery with reverse polarity protection D1 and is monitored by channel 2 of the A D converter through the resistive divider R13 and R14 Battery power is supplied to the circuit via TR2 A bi stable circuit consisting of U2 U9 R6 R7 C5 and R17 controls TR2 The bi stable circuit can be switched to the off state pin 4 of U2 high by either the front panel switch SW1A or by the micro controller via TR1 pulling pin 1 of U2 low The unit is switched on when SW1A is set to the middle position pulling on side of R7 low and applying a momentary pulse to pin 2 of U9 through the AC coupling action of R6 and C15 The nominal 9 volt supply from the battery is applied to the low drop out 5 volt regulator U4 which supplies the rest of the circuit Pressure Sensor Conditioning Circuit The mouth pressure meter consists of an internally temperature compensated solid state pressure transducer U5 The instrumentation amplifier U6 amplifies the differential signal from the press2. converter U11 The serial peripheral interface is used to clock data into U11 The buzzer is driven from port D pin 19 with a square wave at approximately 1 kHz The buzzer is driven in a push pull arrangement using the inverter U8 The controller is factory programmed using the on board connector CON1 The controller is set to program mode by activation of the reed switch SW2 Communication with PC software is achieved through a RS232 interface The converter U10 has on board circuitry to generate the required 10 Volts and is connected to the serial interface of the controller pins 9 and 10 Parts List Designation Description U1 Motorola OPT Microcontroller U2 Single surface mount NAND gate U3 Texas Instruments dual low power OP Amp U4 Low drop out surface mount 5 volt regulator U5 5 PSI pressure transducer U6 Analogue devices instrumentation amplifier U7 Maxim 12 bit 4 channel surface mount serial D A U8 Single surface mount NAND gate U9 Single surface mount NAND gate U10 Maxim RS232 transceiver U11 8 bit SIPO shift register TR1 Rhom NPN surface mount transistor TR2 Zetex PNP surface mount transistor TR3 Rhom NPN surface mount transistor D1 Schottky diode DISPLAY 3 1 2 digit custom display R1 22K Surface mount resistor 0 125 watt 196 size 0805 R2 1 5K Surface mount resistor 0 125 watt 196 size 0805 R3 5 6K Surface mount resistor 0 125 watt 196 size 0805 R4 22K Surface mount resistor 0 125 w
3. Contents page Introduction 3 Operation 3 Respiratory Pressure Meter Layout 4 Cleaning and Maintaining the Respiratory Pressure ES m Meter 5 OO MIP MEP UNO OO C gt OO gt o PP Rip e a Disassembling the OO OO Respiratory Pressure co e oo Meter 5 ool loo 201 Q pe Reassembling the Me poo Respiratory Pressure os ek p y 60000000000 Meter 5 FGO QOO OCH CH OO OOOO OQ Q Q 0 00 Circuit Description 6 00000000000 looo GASS A Parts List 8 V yt O Muf AE O O V MA O S Q O00 00 00000 x 0000000 i Technical Support 10 a 8606 ov Bic iil Circuit Diagram 11 O N A sed Respiratory Pressure Meter Service Manual 064 22 Iss 1 0 October 2004 Medical Respiratory Pressure Meter Service Manual Information in this document is subject to change without notice and does not represent a commitment on the part of Micro Medical Limited Only the parts supplied by Micro Medical Limited should be used to complete the service operation described in this manual If in any way you feel unsure about the successful completion of the service operation you should contact Micro Medical Limited or its appointed agent in your country or region and arrange the despatch of the product to a Micro Medical Limited Service Centre Copyright 2004 by Micro Medical Limited All rights reserved Drawing no 064 22 Version 1 0 October 2004 All othe
4. att 1 size 0805 R5 10K Surface mount resistor 0 125 watt 1 size 0805 R6 1M Surface mount resistor 0 125 watt 1 size 0805 R7 1M Surface mount resistor 0 125 watt 1 size 0805 R8 10K Surface mount resistor 0 125 watt 1 size 0805 R9 10K Surface mount resistor 0 125 watt 1 size 0805 R10 1K Surface mount resistor 0 125 watt 1 size 0805 R11 10 ohm Surface mount resistor 0 125 watt 1 size 0805 R12 10K Surface mount resistor 0 125 watt 1 size 0805 R13 100K Surface mount resistor 0 125 watt 1 size 0805 R14 39K Surface mount resistor 0 125 watt 1 size 0805 R15 10M Surface mount resistor 0 125 watt 1 size 0805 R16 10K Surface mount resistor 0 125 watt 1 size 0805 R17 1M Surface mount resistor 0 125 watt 1 size 0805 R18 10K Surface mount resistor 0 125 watt 1 size 0805 R19 Not used R20 Not used R21 Not used R22 Not used R23 10K Surface mount resistor 0 125 watt 1 size 0805 R24 10K Surface mount resistor 0 125 watt 1 size 0805 R25 33K Surface mount resistor 0 125 watt 1 size 0805 R26 Not used R27 100K Surface mount resistor 0 125 watt 1 size 0805 R28 330K Surface mount resistor 0 125 watt 1 size 0805 R29 1 2K Surface mount resistor 0 125 watt 1 size 0805 R30 10K Surface mount resistor 0 125 watt 1 size 0805 VR1 Bourns 1k 25 turn potentiometer C1 2 2nF ceramic surface mount capacitor size 0805 C2 22pF ceramic surface mount capacitor size 0805 C3 6 8nF ceramic surface mount capacitor size 0805 C4 1uF ceramic surface mo
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6. ice However the Respiratory Pressure Meter can be calibrated if in doubt by the Micro Medical Service Centre Disassembling the Respiratory Pressure Meter If the Respiratory Pressure Meter becomes faulty then the following procedure is needed to investigate the fault 1 Turn the unit face down and slide back the battery cover 2 Remove the battery and place to one side 3 Remove the 2 screws from the bottom moulding Item 8 and put to one side 4 Turn the unit face up and ease the top moulding from the bottom moulding and turn the top moulding to reveal the PCB as shown in Fig 1 page 4 5 Remove the PCB from the bottom moulding and put the bottom moulding to one side 6 The Respiratory Pressure Meter is now ready for fault finding Reassembling the Respiratory Pressure Meter 1 Place the PCB into the bottom moulding and route the battery lead as shown in Fig 1 2 Position the top moulding on top of the bottom moulding and push together ensure that the battery leads are not trapped Turn the unit face down and secure the unit with the retained screws Refit the PP3 battery ensuring correct polarity Slide on the battery cover DA aR w The Respiratory Pressure Meter is now ready for operation Circuit Description Overview A piezo resistive pressure transducer monitors pressure at the mouthpiece holder After conditioning the signal from the pressure transducer is applied to a 12 bit analogue to digital
7. internal reference and communicates with the micro controller using the serial peripheral interface The A D converter has an input range of COM VREF 2 to COM VREF 2 where VREF is the internal reference voltage of 2 5 Volts The voltage applied to COM pin 6 is approximately 1 5 volts This is derived from VREF pin 8 using a potential divider R1 and R25 and a buffer amplifier U3B The input range for the A D converter is therefore 0 25 to 2 75 volts Channel 0 pin 2 is used to measure the pressure signal Channel 1 pin3 is connected to the common pin 6 and to the reference pin of the instrumentation amplifier U6 and is only read during factory set up Channel 2 pin 4 is connected to the reference output and is only read during factory set up Channel 3 pin 5 is used to read the battery terminal voltage via the potential divider R13 and R14 Micro controller The micro controller U1 is an 8 bit device with integrated RAM FLASH program memory storage and power on reset circuitry The controller communicates with the A D converter to measure the pressure signal and monitor the battery voltage using its serial peripheral interface bus This synchronous bus consists of a clock line pin 15 a data transmit line pin14 and a data receive line pin 13 The controller directly controls 22 of the display segments and the back plane from ports PA PB and PC The remaining 4 segments are connected to the outputs of a serial to parallel
8. piezo ceramic sounder X1 32 768 KHz crystal WATCH package Technical Support Great Britain and World Headquarters Micro Medical Ltd PO Box 6 Rochester Kent ME1 2AZ Telephone 44 0 1634 893500 Fax 44 0 1634 893600 Web Site http www micromedical co uk Email servicesupport micromedical co uk roductsupport micromedical co uk Contact Micro Medical Ltd for the local agent in your region or country for local service 10 Il Joppes Av g umea HOS 10 r90AroryA D E Jo Dous T00c320 0c Tq vv ZI 10 790 UOISIADY Joaquin E UIEISeIp PNAD 1939 A ANSSI Aide LL any A E a 67 E er A HOPCIXVIN P Scu 201 An 15 eu ATZ TW YO ad Ce z hi 9 ciu Lo L 9 L S T AS AEN dOTILZITL S ST Y 9T XOT al oX c ral Ln any 0 0 1 AS Ku SA 3 xi Tni Si Glen E 3 vus pasoxds 19 sn JOTUL 7 dec 9 Sco 1 ACC 9s d Adr py el un t ven Joo 97 codv guo La 9n o AS any aud ad anro ad Ang ard TZ LI AS yoedep Surjdnosag ls uo BPTIIDIG 3 t TAS yovil 6 9 I OT S X001 any D D LTA IVIITZEXVIA vu ei zi CAL l 4 z m ral T 6 8 any AS un sn T Je la or L put TAI Wat AVIdSId ZVId 8 SS 1 9 kein A z EN NA a vi E 9 E
9. r products are trademarks or registered trademarks of their respective owners Introduction The Micro Medical respiratory pressure meter RPM is a hand held instrument designed for rapid assessment of inspiratory and expiratory muscle strength The unit can measure the maximum inspiratory and expiratory mouth pressures MIP and MEP and the Sniff Nasal Inspiratory Pressure SNIP The result of each measurement is presented in units of cmH20 gauge pressure on the liquid crystal display screen The MIP and MEP measurements represents the maximum pressure sustained for 1 second The SNIP measurement represents the peak pressure detected in the manoeuvre Respiratory Pressure Meter Layout 1 Respiratory Pressure Meter PCB 2 Top Moulding 3 Bottom Moulding 4 Mouthpiece Holder 5 Retaining ring 6 55mm of 1 16 I D 1 8 O D Tygon tubing 7 Nylon barb connector 8 Countersunk screws 9 Plastic bolt M5 x 6mm 10 Cable tie Cleaning and maintaining the Respiratory Pressure Meter The Micro Medical Respiratory Pressure Meter requires no routine maintenance or servicing Calibration is factory set and should remain constant throughout the lifetime of the dev
10. unt capacitor size 0805 C5 22pF ceramic surface mount capacitor size 0805 C6 1uF ceramic surface mount capacitor size 0805 C7 1uF ceramic surface mount capacitor size 0805 C8 1uF ceramic surface mount capacitor size 0805 C9 1uF ceramic surface mount capacitor size 0805 C10 0 1uF ceramic surface mount capacitor size 0805 C11 10nF ceramic surface mount capacitor size 0805 C12 33nF ceramic surface mount capacitor size 0805 C13 0 1uF ceramic surface mount capacitor size 0805 C14 0 1uF ceramic surface mount capacitor size 0805 C15 0 1uF ceramic surface mount capacitor size 0805 C16 0 1uF ceramic surface mount capacitor size 0805 C17 0 1uF ceramic surface mount capacitor size 0805 C18 0 1uF ceramic surface mount capacitor size 0805 C19 0 1uF ceramic surface mount capacitor size 0805 C20 0 1uF ceramic surface mount capacitor size 0805 C21 0 1uF ceramic surface mount capacitor size 0805 C22 1uF ceramic surface mount capacitor size 0805 C23 0 1uF ceramic surface mount capacitor size 0805 C24 0 1uF ceramic surface mount capacitor size 0805 C25 33pF ceramic surface mount capacitor size 0805 C26 33pF ceramic surface mount capacitor size 0805 C27 33pF ceramic surface mount capacitor size 0805 C28 10uF Tantalum capacitor size A C29 1uF ceramic surface mount capacitor size 0805 C30 1uF ceramic surface mount capacitor size 0805 C31 Not used SW1 double pole 3 position slide switch SW2 reed switch J1 3 5mm Stereo jack socket SPK1
11. ure transducer The gain of U6 is adjusted by the calibration potentiometer VR1 that is accessible externally The reference pin of U6 and the A D converter U7 are driven by the output of U3B at a voltage derived from the reference output of the A D converter The signal from U6 is passed through a filter consisting of U3A R3 R4 C3 and C1 This is further filtered by R30 and C30 before being applied to Channel 0 of the A D converter Display The display is a 3 1 2 digit custom LCD A square wave of approximately 30 HZ is continuously applied to each segment and the back plane BP To turn a segment off the square wave applied to it is in phase with the square wave applied to the back plane To turn a segment on the square wave applied to it is in anti phase with the back plane 22 of the segments and the back plane are driven directly from ports PA PB and PC of the micro controller U1 The remaining 4 segments are connected to the outputs of a serial to parallel converter U11 The serial peripheral interface of U1 is used to clock data into U11 The clock signal is inverted by TR3 to obtain the correct polarity The pull up resistor for TR3 is connected to the chip select line of the A D converter which is also on the serial peripheral interface disabling the clock signal when the A D converter is being accessed by the micro controller Analogue to Digital converter The A D converter U7 is a 4 channel 12 bit serial device with
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