DMX SRX-SR2-SR3 Service Manual

Contents

6.14 Fitting the Bluetooth Module (DMX) ...22 6.15 Fitting the Battery ...22 6.16 Fitting the Main PCB ...22 6.17 Fitting the Battery Terminals ...23 6.18 Connecting the Side Switch ...23 6.19 Case Reassembly ...24 7. Probe Head Replacement Procedure ... 25 7.1 Equipment Required ...25 7.2 Dismantling Procedure - (All probes except SR2, SR3) ...25 7.3 Dismantling Procedure - (SR2, SR3 Probes) ...26 7.4 New Head Fitting and Alignment ...27 7.5 Reassembly Procedure - (All probes except SR2, SR3) ...30 7.6 Reassembly Procedure - (SR2, SR3 Probes) ...30 7.7 Waterproof Inspection & Test Procedure - (SR2, SR3 Probes) ...32 7.7.1 7.7.2 7.7.3

Equipment Required... 32 Waterproof Testing ... 32 Probe Test - To test the completed probe... 32

8. Probe Function Test Specification ... 33 8.1 Equipment Required ...33 8.2 Functional Tests - Vascular Probes (VP4XS-VP10XS & EZ8) ...33 8.3 Functional Tests - Obstetric Probes (OP2XS, OP3XS, SR2, SR3) ...33 9. Fault Finding ... 34 9.1 No Sound...34 9.2 Unit dead ...34 9.3 No USB Communication ...34 9.4 No Display ...34 9.5 No Button 2 or 3...34 9.6 Time & Date Not Retained...34 9.7 Unit Does Not Charge ...35 9.8 Poor Heart Rate Tracking ...35 9.9 Poor Sensitivity, Crackling ...35 9.10 No PPG Waveform (DMX only) ...35 10. Spare Parts List ... 36 10.1 Control Unit Parts List ...36 10.2 Obstetric and Vascular Probes Parts List ...38 10.3 SR2, SR3 Probes Parts List ...39 11. End of Life Disposal ... 40 12. Ordering Information ... 40 12.1 Service Returns ...40 Appendix A ... 41 Special Handling Procedures ...41 Recommended Soldering Equipment for Rework...41 Appendix B ... 42 Electromagnetic Compatibility...42

3

General Information

1.

General Information Although every care has been taken to ensure that the information in this manual is accurate, continuous development may result in equipment changes. The Company reserves the right to make such changes without prior notification, and resulting manual inaccuracies may occur. This manual and any changes are protected by copyright.

1.1

Introduction This service manual provides the technical information required for repair and maintenance of the Huntleigh Healthcare Ltd DMX, SRX, SR2 and SR3 range of hand held Dopplers, including the range of OPXS (Obstetric), and VPXS (Vascular) interchangeable probes.

1.2

Servicing Policy Units within the warranty period must not be dismantled and should be returned to Huntleigh Healthcare Ltd for repair. Any units returned showing signs of tampering or accidental damage will not be covered under the warranty (refer to user manual for further details).

1.3

Description The range of Doppler products are as follows: (Model Number is shown on front and rear labels)

MODEL DMX

FUNCTIONALITY Vascular - Full Visual and audio functionality if a suitable vascular probe is attached. Obstetric - Full Visual and audio functionality if a suitable obstetric probe is attached. (Not suitable for underwater monitoring). PPG - PPG functionality if a PPG probe is attached.

SRX

Obstetric - Full Visual and audio functionality if a suitable obstetric probe is attached. (Not suitable for under water monitoring). Vascular - Audio functionality only if a suitable vascular probe is attached. Screen will display date/time, probe frequency and battery status only. PPG - No functionality.

SR2

Obstetric - Full Visual and audio functionality. 2MHz hard wired waterproof probe suitable for underwater monitoring.

No Vascular or PPG functionality as probe is hard wired and cannot be changed. SR3

1.4

Same as for SR2 model but with 3MHz hard wired probe.

Antistatic Handling Due to the nature of the components used within these products, special precautions must be taken to avoid damage to the CMOS and microcontroller based circuitry. Static damage may not be immediately evident but could cause premature failure. This series of units must only be dismantled and serviced within a specialised handling area (SHA) as defined by CECC00015 (published by CENELEC) to avoid damage to the assemblies.

4

Construction The control unit comprises a single PCB on which all circuitry and electro-mechanical components are mounted directly except for the loudspeaker which is attached by flying leads. A hard wired cable provides the connection to the probe. The PCB has surface mounted components on both sides. All leaded and electro-mechanical components are on one side. The case of the control unit is moulded in ABS polycarbonate alloy, and comprises two halves. The loudspeaker, on/off switch and display are on the front of the unit.

1.6

General Information

1.5

Product Controls

1

1

Headphone Socket

2

2

USB Port

3

LCD Panel

4

Function Button 1 / On/Off Button

5

Function Button 2

6

Function Button 3 / Setup

7

Loud-speaker

8

Probe Holder

9

Trolley mount

10

Volume Up

11

Volume Down

12

Pocket Clip

13

Battery Compartment + SD Card Slot

14

Rear Panel Label

3 6 5 4 7 8

12 13 14 9 10 11

5

Safety

2.

Safety The Doppler units and their probes are designed to high standards of performance, reliability and safety. Checks should always be made after carrying out any repairs or dismantling of the equipment. General Warning Attention, consult this manual. Refer to safety section. Attention, consult accompanying documents / Instructions for Use

Rx Only

2.1

Caution: Federal law restricts this device to sale by, or on the order of a licensed healthcare practitioner.

Maintenance / Inspection Inspection is recommended each time the product is used, paying particular attention to the probe tip, checking for cracks etc., and to the cable and connector. Any crackling or intermittent behaviour should be investigated. This product does not require periodic maintenance. For functional testing of specific product features, refer to the user manual. If you require any assistance with safety testing your Dopplex equipment, contact Huntleigh Healthcare Ltd or your supplier directly. For the U.K. refer to the Health Equipment Information Document No 95 - Code Of Practice For Acceptance Testing Of Medical Equipment. The following safety summary should be read before operating or carrying out any of the procedures described in this manual.

2.2

Warnings Do not use in the presence of flammable gases. Do not sterilise. Do not use in the sterile field unless additional barrier precautions are taken. Do not immerse in any liquid. (Except waterproof probes - fitted on models SR2, SR3. For underwater use where contamination or cross-infection may occur, additional barrier precautions must be taken). Do not dispose of batteries in fire as this can cause them to explode. Do not attempt to recharge normal dry-cell batteries. They may leak, cause a fire or even explode. If this product is connected to another item of electrical equipment, it is important that the system is fully compliant with EN60601-1. This product contains sensitive electronics, therefore, strong radio frequency fields could possibly interfere with it, e.g. mobile phones. This will be indicated by unusual sounds from the loudspeaker. We recommend that the source of interference is identified and eliminated. Do not expose the Doppler to excess heat, including prolonged exposure to sunlight.

6

Specifications

3.1

Equipment Classification

3.2

Type of protection against electric shock. Degree of protection against electric shock

Internally powered equipment

Mode of operation. Degree of protection against harmful ingress of particles and/or water. Degree of safety of application in the presence of a flammable anaesthetic

Continuous

Type B - equipment with an applied part

Main Unit: IP20 Probes (Tip only): IPX1 SR2/SR3 probes : IPX7 Equipment not suitable for use in the presence of a FLAMMABLE ANAESTHETIC MIXTURE WITH AIR, OXYGEN OR NITROUS OXIDE

Standards Compliance IEC 60601-1: Edition 3.1 ANSI/AAMI ES 60601-1:2005. CAN/CSAC22.2 No 60601-1:08. IEC 60601-1:1998+A2:1995 (2nd Edition)

3.3

Specifications

3.

JIS T 060606-1:2012 EN 60601-2-37:2008+A11:2011 IEC 60601-1-2:2007

FHR Performance* Standard Mode

Range - 60-210bpm Averaging - 4 beats

Resolution - 1bpm Accuracy - ±3bpm

Smoothed Mode

Range - 60-210bpm Averaging - 8 beats

Resolution - 1bpm Accuracy - ±3bpm

Manual Mode

Range - 60-210bpm Averaging - 10 beats

Resolution - 1bpm Accuracy - ±3bpm *(excluding user error)

7

Specifications

3.4

General Bluetooth®

Charger- ‘R’ models only

3.5

Bluetooth® : V4.0 – Dual-Mode Frequency : 2.402 - 2.480 GHz Transmit Power : + 8 dBm (maximum) Protection : Class II Input Voltage : 100-240 V AC ±10% Output Voltage : 5VDC ± 5% Input Frequency : 50 - 60Hz Standby power consumption: 230V AC ≤ 0.1W

Max. Audio Output (Loudspeaker) Auto shut-off

500mW rms typical

Headphone output

Max. output Power: Connector:

USB Port

Micro USB

SD Card Slot

Micro SD

Battery Type

LR6 (Alkaline cells 1.5V) NR06 (NIMH rechargeable 1.2V)

Battery Life

Typically, 500 x 1 minute examinations

Size

Length: 140mm

Weight

280g

3 minutes - Standby 10 minutes unconditional 32 mW rms (32Ω) 3.5mm stereo jack socket

Height: 33mm

Environmental Operating

Storage

+10°C to +30°C

Temperature range

-10°C to +40°C

10% to 90% (non condensing)

Relative Humidity

93% maximum

860mb to 1060mb

8

Width: 75mm

Pressure

860mb to 1060mb

Technical Description

4.1

Power Source The device can be powered from either 2 x AA primary alkaline cells or 2 x AA rechargeable NiMh cells. The cells are connected in series to provide a nominal 3V supply (alkaline cells) or 2.4V supply (rechargeable cells). If the external charger is connected, the device derives its power from the charger.

4.2

Power Supply The power supply regulates the battery (or charger) voltage and provides a 3Vdc rail to the digital circuits and audio amplifier inside the device. A secondary power supply steps up the 3v rail to provide a quiet stable 5Vdc supply for the Doppler probes and analogue circuitry.

4.3

Technical Description

4.

Signal Conditioning The Doppler probe signals may be of the order of a few mV. The signal conditioning hardware is effectively an analogue amplifier stage that boosts the Doppler signals to a sufficient amplitude for the microcontroller to process. This section outputs the following analogue signals which are fed to the ADC inputs of the microcontroller. •

I & Q - The in-phase and quadrature components of the Doppler signal from the probe

•

PPG – The signal derived from the optical Photoplethysmography sensor to detect volumetric blood flow

•

Pressure – The signal derived from the pressure transducer built into the PPG probe housing (for cuff pressure)

•

Probe detect – A voltage super-imposed on the Q channel to indicate what type of probe is connected to the doppler.

4.4

Microcontroller The Doppler design is based on the MK22FX512VLQ12 Freescale ARM Cortex M4 microcontroller. The microcontroller is powered from the 3V digital power supply and sits at the heart of the device, it is the main processing unit for all Doppler functionality. It runs an internal operating system and performs the following tasks…

4.5

•

Drives an external colour backlit display with a menu driven GUI

•

Reads the status of 5 external buttons for user input (e.g. menu selection, On/Off, Volume)

•

Samples external analogue probe signals (I & Q doppler data, pressure, PPG, probe detection, battery current & voltage)

•

Outputs analogue audio for reproduction on a loudspeaker or headphones

•

Streams sampled data to an external USB connection

•

Communicates with external on-board flash memory or micro SD memory for data storage and retrieval

•

Communicates with external Bluetooth equipped devices via the optional on-board Bluetooth module

•

Provides time and date through an internal Real Time Clock

•

Controls the charging of the NiMh cells

•

Processes the sampled I & Q data through an internal DSP engine to perform FFT, filtering, squelch and noise reduction

Audio Amplifier The audio amplifier is a class D device that amplifies the DAC outputs of the microcontroller. It is powered from the 3V digital power supply and drives a loudspeaker or headphones for Doppler signal reproduction. The microcontroller controls the amplifier gain, mute and headphone operation via an I2C bus. Sound from the amplifier is muted when not actively monitoring a patient in order to conserve battery life. 9

Technical Description

4.6

Display The display is mounted on a separate PCB with a backlight brightness controller and 3 user-input buttons. It is powered from the 3V digital power supply and connects to the microcontroller through a parallel bus. The display is a 2.4 inch colour LCD with LED backlight. The display resolution of 320 x 240 pixels (QVGA) displays numeric and graphical information to represent the Doppler & PPG signals. It also provides useful information to the user such as the probe frequency, time & date, battery status and also allows the user to navigate a menu structure for effective monitoring, storing and recalling of patient waveforms. The backlight is provided by a number of integral white LEDs the brightness of which are driven by the backlight controller user the control of the microcontroller.

4.7

User Input Buttons The device features 5 tactile buttons. Three are mounted on the display PCB assembly and are used for On/Off operation and menu navigation. Two are mounted on a separate PCB assembly on the side of the device and are used for volume and/or brightness up and down. The switches are connected directly to the port pins of the microcontroller.

4.8

USB Connector The device features a micro USB connector for connection of an external charger or connection to an external device such as a PC running Dopplex reporter software or FetalCare software. When connected to an external device this allows the streaming of live sampled data or saved data.

4.9

Bluetooth An optional Bluetooth module may be fitted to the Doppler. This communicates directly to the microcontroller via a serial link. The module supports the transfer of saved data between the Doppler and an external compatible device.

4.10 SD Card (microSD) The device may be fitted with an option microSD card for saving patient waveform files. The card is inserted into a connector accessible through the battery compartment of the device. The microcontroller communicates with the card via a serial SPI bus.

4.11 Flash & SRAM The device features on-board non-volatile flash memory that offers limited storage of patient waveform data. This is connected directly to the microcontroller via a serial SPI bus. Pseudo SRAM is also provided, this is volatile memoru connected to the microcontrollers FlexBus interface. This memory is used as a temporary store to buffer live data and for temporary storage of microcontroller data.

4.12 Battery Status The battery status is determined by monitoring the voltage across the two cells. The voltage is monitored via an analogue A/D input on the microcontroller. The microcontroller displays a symbol to indicate available battery capacity. It will also display a low battery warning when the combined battery voltage falls below 2.2V for a predetermined time. When the combined battery voltage falls below 2V (1V per cell) the microcontroller will display an empty battery symbol on the device display and switch the devive off in a controlled manner.

4.13 Charging The microcontroller controls the charging of the NiMh cells. It provides a PWM signal to limit the charge current and monitors the cell voltage throughout the process. Charging only occurs when the external charger is connected and the device is switched off. Charging is terminated when the cells reach their terminal voltage, or after a 5 hour timeout period has expired. 10

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4.14 Main Unit Block Diagram

11

Technical Description

4.15 Obstetric Probe Block Diagram Probe Head Tx Xtal

Transmitter

Oscillator

Rx Xtal

Demodulator

Amplifier / Filter

Probe Coding

Oscillator A ceramic resonator based oscillator circuit provides a reference for the probe receiver and, via the transmitter, the output signal.

Transmitter The output from the oscillator is amplified by a single transistor; the gain of this stage is controlled by a variable resistor. This allows the output voltage to be set according to the impedance of the probe head, thus setting the output power level

Demodulator The demodulator effectively removes the carrier (transmitter frequency), which leaves us with a Doppler shifted signal. The demodulator stage requires a reference signal from the transmitter stage.

Amplifier/Filter The amplifier/filter amplifies the signal from the demodulator stage and removes unwanted noise. The probe has a filter response tailored to maximise the output signal and minimise noise and overload.

Probe Coding This superimposes a DC level (depending on probe frequency) onto the output signal.

12

Block Diagram

Tx Xtal

Rx Xtal

Transmit Amplifier

Johnson Counter

Oscillator

Demodulator

Amplifier / Filter

Receive Amplifier Demodulator

Amplifier / Filter

To Control Unit

Technical Description

4.16 Vascular Probe

Probe Coding Oscillator A crystal oscillator provides references for the probe demodulator and output signal. The oscillator frequency is four times that of the probe ultrasonic output.

Johnson Counter The Johnson Counter provides two outputs, which are 90° phase shifted with respect to each other. It also divides the oscillator signal frequency by four.

Transmitter The output from the oscillator is amplified by a single transistor; the gain of this stage is controlled by a variable resistor. This allows the output voltage to be set according to the impedance.

Receive Amplifier The received signal is amplified by two FETs (cascode amplifier) providing the demodulators with a suitable signal.

Demodulators The demodulators effectively remove the carrier (transmitter frequency), which leaves the Doppler shifted signals. They have two quadrature reference signals from the Johnson Counter stage.

Amplifier/Filters The amplifier/filters amplify the signal from the demodulator stages and remove unwanted noise. Each probe frequency has filters whose response is tailored to maximise the output signal and minimise noise and overload.

Probe Coding This superimposes a DC level (depending on probe frequency) onto the output signal.

13

Technical Description

4.17 PPG Probe Block Diagram Sensor Opto Receiver

Amplifier 27dB

Opto Transmitter

Transmit Driver

Inverting Buffer 0dB

Voltage Regulator 4V

Pressure Sensor 300 mmHg

Synchronous Demodulator

Low Pass Filter 15 Hz

High Pass Filter 0.26 Hz

Logic Divider X 32

Oscillator 32 kHz

Voltage Reference 100 mV

Low Pass Filter 13 Hz

Amplifier 27dB

Power-up Timer 2.7 s nom.

Instrumentation Amplifier 27dB

Pressure / Probe code

APPG CHANNEL Sensor Contains an infra-red LED and phototransistor

Oscillator Generates a 32 kHz system clock

Logic Divider Divides the system clock by factor 32 to give 1 kHz modulation frequency

Transmit Driver Modulates the drive current in the opto transmitter LED at a frequency of 1 kHz

Amplifier 27dB Boosts the opto receiver output voltage

Inverting Buffer Generates an anti-phase replica of the 27 dB amplifier output signal

Synchronous Demodulator Removes the 1 kHz modulation from the received signal

Low Pass Filter 15 Hz A single pole filter to remove 1 kHz components from the synchronous demodulator output signal.

14

APPG

A two pole active filter which removes unwanted low frequency and DC signal components.

Low Pass Filter 13 Hz A two pole low pass filter which rejects unwanted high frequency signal components and noise

Amplifier 28 dB Boosts the APPG signal to match the DMX A/D convertor input voltage range

PRESSURE CHANNEL

Technical Description

High Pass Filter 0.26 Hz

Pressure Sensor A gauge type silicon pressure sensor with a maximum input pressure of 300 mmHg.

Voltage Regulator 4V A band-gap voltage regulator with an output voltage of 4V which supplies the ‘energise’ voltage to the pressure sensor

Instrumentation Amplifier A differential amplifier which boosts the pressure sensor output signal to give a sensitivity of 1.0V per 100 mmHg. The voltage gain is trimmed at manufacture.

Voltage Reference 100 mV This reference adds a positive 100 mV offset to the instrumentation amplifier output to enable small negative pressures to be measured. This offset is trimmed at manufacture.

Power-Up Timer At power-up, the timer controls the switch so that the probe code resistor is connected to the Pressure / Probe Code output. After approximately 2.7 seconds, the output is connected to the instrumentation amplifier output. This allows the APPG module to be correctly identified by the DMX hand unit.

15

Electrostatic Discharge (ESD) Precautions

5.

Electrostatic Discharge (ESD) Precautions

5.1

What is Static Electricity? Static electricity is generated when two materials move against one another. The voltage generated depends on the materials generating the electricity, the speed of movement, humidity and rate of discharge. All man made materials generate static, such as plastic coffee cups, plastic bags, binders and folders, all of which are likely to be within the working area. Activity

10-20% Relative Humidity

Walking across carpet

35,000 Volts

Walking across vinyl floor

12,000 Volts

Working at bench

6,000 Volts

Plastic folder

7,000 Volts

Poly bag lifted from bench

20,000 Volts

Foam padded work chair

18,000 Volts

Static electricity is generated very easily, and is only felt by us when we discharge the built up charge rapidly by touching a grounded object such as a door handle. The voltages felt by us are as low as 3kV, but only 20V is necessary to damage some components. Voltages as high as 35kV and current spikes of 40A have been known. The damage to the component, or assembly can be immediate or latent. Latent damage is not immediately obvious but can lead to the circuitry subsequently failing or becoming erratic.

5.2

Protective Measures Measures must be taken to ensure that all charges generated are safely discharged before they build up to a dangerous level. The use of dissipative mats for the work surface and wearing anti-static wrist straps are recommended ways of preventing this problem. The dissipative mats must be connected to ground via a resistance and the wrist strap to the same ground point. Anti-static bags must be used when storing or transporting static sensitive components. Conductive mats are no longer regarded as being suitable, as a PCB or component could be electrostatically charged and it would be rapidly discharged by placing it on the conductive mat. This sudden discharge would be as damaging as placing a charged object in contact with the PCB or device. All static sensitive devices or assemblies must be placed within an anti-static bag or container whenever being moved away from the specialised handling area.

16

Servicing Procedure - Control Unit

6.1

Removing the Micro SD Card Warning: The Micro SD card MUST be removed BEFORE any servicing procedure is carried out. Remove the Micro SD card as shown:

2

Remove the battery cover : Insert a suitable tool into recess to release the clip and gently lever off the battery cover.

!

!

AA

!

AA

Remove the batteries.

AA

!

3 AA

1

Remove the Micro SD card!

Servicing Procedure - Control Unit

6.

This equipment contains static sensitive devices. Refer to Appendix A for recommended antistatic handling precautions. It is essential that these procedures, or equivalent, are adopted to avoid static damage to the circuitry. Repairs should only be undertaken by suitably skilled service personnel.

6.2

Control Unit Case Opening Remove the foot support if rear case replacement is required

1

2

Remove the three grey screw caps.

3 Using a TORX Bit 8, unscrew the 3 Torx screws.

17

Servicing Procedure - Control Unit

4

6.3

Turn the Doppler over and carefuly seperate the front case from the rear case.

Side Switch Removal Lift (unplug) the side button assembly from the main PCB.

1

6.4

Battery Terminal Removal Using a TORX bit 6 remove the two TORX screws securing the battery support. Remove the support to access the battery terminals.

1

2

3

Lift out the two battery terminals situated next to the speaker assembly

Use tweezers to lift the negative battery terminal situated near the top of the control unit clear of the battery compartment. Lift the terminal away from the control unit’s base moulding.

18

Main PCB Removal Gently lift the PCB from the bottom of the case (1). Twist the PCB towards the left hand side (2) to free the USB connector from the case. (3) Pull the PCB towards the bottom of the Doppler case to remove the PCB from the bottom case.

1

6.6

Battery Removal

1

6.7

Servicing Procedure - Control Unit

6.5

Push the battery out of the battery holder in the direction shown.

Speaker Removal To remove the speaker, using solder wick, de-solder the two leads circled in red.

1

Ensure the holes are clean to enable the fitting of a replacement speaker. Ensure LEAD FREE solder is used when reconnecting a speaker.

6.8

Bluetooth PCB Removal (DMX only)

1

If fitted, unplug the Bluetooth module from the underside of the main PCB.

19

Servicing Procedure - Control Unit

6.9

Cable Removal

1

To de solder the cable or probe; turn over the PCB and de solder using solder wick. Ensure the holes are clean to enable cable replacement. Ensure LEAD FREE solder is used when reconnecting the cable or probe.

6.10 Display Removal

1

2

20

Use a TORX 6 Bit. Remove the two screws securing the display assembly to the front case.

Lift the display assembly at its base and move in a downwardly direction as shown, to release it from the top moulding.

Place the completed display assembly into front case making sure it goes under the lip and the lugs locate into slots in PCB.

1

2

Use a TORX bit 6 and screw in the 2 thread forming screws to a torque of 12 cNm.

Servicing Procedure - Control Unit

6.11 Fitting the Display Assembly

6.12 Fitting the Speaker Assembly

1

Attach the speaker assembly, solder the wires using LEAD FREE solder and crop the excess from the back of the PCB.

6.13 Retractile Cable Fitting

1

Attach retractile cable (DMX or SRX) or Probe assembly (SR2 or SR3) to PCBA as shown. Ensure LEAD FREE solder is used when reconnecting the cable or probe.

21