Datex-Ohmeda S/5 M-EEG Use and care manual

Datex-Ohmeda
S/5TM EEG Module, M-EEG (rev. 01)
S/5TM EEG Headbox, N-EEG (rev. 01)
Technical Reference Manual Slot
All specifications are subject to change without notice.
Document No. 800 1011-1
June 2001
Datex-Ohmeda Inc.
3030 Ohmeda Drive
53707-7550 MADISON, WIS
USA
Tel. [phone],Fax [phone]
www.us.datex-ohmeda.com
Datex-Ohmeda Division,
Instrumentarium Corp.
P.O. Box 900, FIN-00031
DATEX-OHMEDA, FINLAND
Tel. [phone] Fax [phone]
www.datex-ohmeda.com
Instrumentarium Corp. All rights reserved.

Table of contents
Document No. 800 1011-1
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TABLE OF CONTENTS
EEG Module, M-EEG and EEG Headbox, N-EEG
TABLE OF CONTENTS I
TABLE OF FIGURES II
INTRODUCTION 1
1 SPECIFICATIONS 2
1.1 General specifications ..............................................................................................................................2
1.1.1 Headbox ..........................................................................................................................................2
1.1.2 Module ............................................................................................................................................2
1.2 Technical specifications............................................................................................................................2
1.2.1 EEG .................................................................................................................................................2
1.2.2 AEP..................................................................................................................................................3
1.2.3 EMG ................................................................................................................................................3
1.2.4 Impedance measurement.................................................................................................................3
2 FUNCTIONAL DESCRIPTION 4
2.1 Measurement principle .............................................................................................................................4
2.1.1 EEG .................................................................................................................................................4
2.1.2 FEMG...............................................................................................................................................4
2.1.3 AEP..................................................................................................................................................4
2.1.4 Impedance measurement.................................................................................................................5
2.2 Main components.....................................................................................................................................5
2.2.1 Neuro board.....................................................................................................................................5
2.2.2 Headbox board.................................................................................................................................6
2.3 Connectors and signals.............................................................................................................................7
2.3.1 Module bus connector......................................................................................................................7
2.3.2 Module front panel connectors..........................................................................................................8
2.3.3 Headbox input connector..................................................................................................................8
3 SERVICE PROCEDURES 9
3.1 General service information.......................................................................................................................9
3.2 Service check .........................................................................................................................................10
3.2.1 Recommended tools ......................................................................................................................10
3.3 Disassembly and reassembly..................................................................................................................14
3.3.1 M-EEG ...........................................................................................................................................14
3.3.2 N-EEG............................................................................................................................................14
4 TROUBLESHOOTING 15
4.1 Troubleshooting chart .............................................................................................................................15
4.2 Troubleshooting flowcharts......................................................................................................................16
5SERVICEMENU 18
5.1 EEG & EP service menu...........................................................................................................................19
6 SPARE PARTS 23
6.1 Spare part list.........................................................................................................................................23
6.1.1 M-EEG rev. 00................................................................................................................................23

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6.1.2 S/5 M-EEG rev. 01.........................................................................................................................23
6.1.3 N-EEG rev. 00 ................................................................................................................................24
6.1.4 S/5 N-EEG rev. 01 .........................................................................................................................24
6.1.5 Front panel stickers........................................................................................................................25
7 EARLIER REVISIONS 26
APPENDIX A 27
SERVICE CHECK FORM A-1
TABLE OF FIGURES
Figure 1 Measurement setup ............................................................................................................................. 1
Figure 2 Neuro board block diagram .................................................................................................................. 5
Figure 3 Audio stimulator circuitry ...................................................................................................................... 6
Figure 4 EEG headbox board block diagram........................................................................................................ 6
Figure 5 EEG module troubleshooting flowchart ................................................................................................16
Figure 6 Headbox troubleshooting flowchart .....................................................................................................17
Figure 7 Exploded view of module box and EEG module ....................................................................................23
Figure 8 Exploded view of headbox...................................................................................................................24

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INTRODUCTION
This Technical Reference Manual Slot provides information for the maintenance and service of the
Datex-Ohmeda S/5 EEG Module, M-EEG and Datex-Ohmeda S/5 EEG Headbox, N-EEG. The EEG
module is a single width plug-in module designed for use with the S/5 monitors. Later in this
manual modules can be called w/o system name S/5.
Please see also related Technical Reference Manual for information related to system e.g. related
documentation, conventions used, symbols on equipment, safety precautions, system description,
system installation, interfacing, functional check and planned maintenance.
The EEG module and the EEG headbox together measure:
•electroencephalography (EEG)
•spontaneous facial muscular activity with frontal electromyography (FEMG)
•auditory evoked potentials (AEP)
The EEG Headbox, N-EEG, is responsible for EEG and FEMG signal amplification, filtering and
digitalization and electrode impedance measurement. It is situated close to the patient’s head. The
Headbox has connectors for the EEG leads, either for a referential or a bipolar montage, and for the
AEP stimulation earphones.
The EEG module M-EEG creates auditory stimulus pulses and takes care of AEP signal processing.
It has one connector for the EEG headbox.
13
2
4
5
Figure 1 Measurement setup
(1) EEG module measuring EEG and EP
(2) Module-headbox cable
(3) EEG Headbox
(4) Organizer
(5) Earphones (for AEP measurement only)

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1SPECIFICATIONS
1.1 General specifications
1.1.1 Headbox
Box size, W ×D ×H 96 ×170 ×34 mm/3.8 ×6.7 ×1.3 in
Box weight 0.5 kg/1.1 lbs
Power consumption 1.9 W
1.1.2 Module
Module size, W ×D ×H 37 ×180 ×112 mm/1.5 ×7.1 ×4.4 in
Module weight 0.37 kg/0.8 lbs
Power consumption 3.1 W
1.2 Technical specifications
1.2.1 EEG
Amplification 10 000
Resolution 60 nV
Max amplitude 800 µVpp
Sampling frequency 100 Hz per channel
Range ±400 µV
Frequency range 0.5...30 Hz
Input impedance 8 MΩ@ 10 Hz
Noise level <0.5 µV rms from 0.5 Hz to 30 Hz
CMRR >100 dB @ 50 Hz
Parameters from power spectrum SEF, MF, relative power in frequency bands
Burst suppression calculated burst-suppression ratio (BSR)
Defibrillation protection 5000V, 360 J
Allowable Input Offset ±300 mV

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1.2.2 AEP
Amplification 10 000
Resolution 60 nV
Max amplitude 1000 µVpp
Stimulation
Click (condensating) duration 100 µs
Frequency 1.1...9.1 Hz (1 Hz steps) @ 10 ms measurement
1.1...8.1 Hz (1 Hz steps) @ 100 ms measurement
Intensity 10...90 dB nHL, 10 dB steps
Measurement
Sampling frequency 2400 Hz for MLAEP/ 4800 for BAEP
Frequency range 0.5...1000 Hz
Highpass filter off/10/30/50/75/100/150 Hz
Single average:
Averaged responses 100...2000 stimuli
Moving average:
Gross average 100...2000 stimuli
Update interval after every 100 stimuli (200, when gross average is 2000)
1.2.3 EMG
Amplification 50 000
Resolution 100 nV
Max amplitude 100 µVpp
Frequency range 60...300 Hz
Amplitude Root Mean Square (RMS)
1.2.4 Impedance measurement
Measurement frequency 75 Hz
Current 10 µA
Range 0...30 kΩ
Resolution 100 Ω
Accuracy ±1k or ±10 % whichever is greater
Measurement time, all leads 3 s
Start of measurement manual/automatic
Leads off detection >3 MΩ, continuous

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2FUNCTIONAL DESCRIPTION
2.1 Measurement principle
2.1.1 EEG
EEG is differential voltage signal measured from electrodes attached to the patient’s skin. EEG
measures the spontaneous electrical activity of the brain. This electrical activity reflects the state of
the brain.
Electrode connections can be made with two different principles: bipolar or referential montage. In
bipolar montage every channel has two electrodes and the signal is the potential difference
between these two electrodes. In referential montage the referential electrode delivers its potential
to every channel’s minus-input. The signal is the potential difference between this common
reference electrode and the electrode connected to plus input. Purpose of the ground electrode is
to reduce common mode noise. It cannot be used as referential electrode.
Bipolar connection Referential connection
The EEG signal is amplified, antialias filtered, digitised and software filtered. After that the EEG
signal is shown on the screen and various characteristics are calculated out of it. These include
spectrum, rms amplitude, spectral edge frequency, median frequency, burst-suppression ratio and
percentage of total power in four different bands: theta (1...4 Hz), delta (5...9 Hz), alpha (9...13 Hz)
and beta (>13 Hz).
2.1.2 FEMG
FEMG is electrical signal originating from facial muscles. In the headbox the signal of channel 1 is
divided to two different amplification and filtering paths. One is the EEG path and the other is the
FEMG path. FEMG signal has much broader spectrum than EEG and it overlaps with EEG at low
frequencies. Because of this the rms amplitude of FEMG signal is calculated from band
60...300 Hz. Mains power frequency and its harmonics are digitally filtered away to reject
interference noise from power lines.
2.1.3 AEP
AEP is an electrical response of the nervous system to external auditory stimulus. It is measured
using same electrodes as in EEG measurement, but the sampling frequency and bandwidth are
different. The electrical signal resulting from one stimulus is weaker than the spontaneous activity

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of the brain. To overcome this the stimulus is repeated several times (100...2000), and average of
all responses is calculated. Responses containing big artefacts are removed from the average to
improve the signal to noise ratio.
2.1.4 Impedance measurement
The impedance measurement is done from one channel at a time and the EEG or EP measurement
is stopped during the impedance measurement.
Differences in electrode impedance of the electrodes causes common mode noise coupling to
measured signal. To minimise this the electrode impedance is measured and a warning of
unsatisfactory impedance level is generated when necessary. The impedance of an electrode is
measured by applying a known current through the electrode and measuring the voltage drop over
the electrode. This way the impedance of a single electrode can be resolved instead of a sum
impedance of an electrode pair.
2.2 Main components
2.2.1 Neuro board
The Neuro board consists of the following functional sections:
•audio stimulator
•microprocessor for stimulation and measurement control, and for counting the
measurement results
•two serial communication drivers
The serial bus speed to monitor is 500 kbps and the bus itself is half duplex, i.e. data can be
transferred to both directions but only one way at a time.
The serial bus speed to the headbox is 500 kbps and the bus is full duplex i.e. data can be
transferred to both directions at the same time.
Module
Keys
RS485
Driver
Reset
Data
Power
+15 V
±5 V
±12V
CPU
3048
Module Bus
Patient Isolation 5 kV
Power
supply
Opto
Isolation
EEPROM
AEP
Stimulator
RS-422
driver
+15 V
Data
AEP stimulus
To
To
EEG
EEG
Head-
Head-
box
box
RAM
Figure 2 Neuro board block diagram

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Audio
generator
Audio level
adjustment
Timing
control
PWM
H83048
CTRL
Earphones
Headbox
Figure 3 Audio stimulator circuitry
2.2.2 Headbox board
The Headbox board consists of the following functional sections:
•input protection
•EEG amplifiers and filters
•FEMG amplifier and filter
•current feeding circuitry and amplifiers for impedance measurement
•microprocessor
•serial communication
RS
422
driver
Data
AEP stimulus
Impedance
check
EEG
signal
1-4
1-4
A
/
D
AEP
stimulus
1p
a
t
i
e
n
t
+15 V
CPU
3048
Isolation kV
Opto
Isolation
Power
supply
Headbox
Keys
±5 V
±12V
Figure 4 EEG headbox board block diagram

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2.3 Connectors and signals
2.3.1 Module bus connector
13
1
14
25
Table 1 Module bus connector (X1) pin description
Pin No. I/O Signal
1 I RESET_RS485
2 I -15 VDC
3 I +15 VDIRTY
4 I +15 VDC
5 I/O -DATA_RS485
6 I/O DATA_RS485
7 - Ground & Shield
8 I -RESET_RS485
9 I CTSB
10 O RTSB
11 I RXDB
12 O TXDB
13 - Ground & Shield
14 I +32 VDIRTY
15 I GroundDIRTY
16 I CTSC
17 O RTSC
18 I RXDC
19 O TXDC
20 - ON/STANDBY
21 - PWM_ECG
22 - RXDD_RS232
23 - TXDD_RS232
24 I +5 VDC
25 I +5 VDC

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2.3.2 Module front panel connectors
Table 2 Headbox connector
Pin No. Signal
6
8
9
0
1
2
4
5
7
3
1
2
3
4
5
6
7
8
9
0
Ground
Ground
+15 V
TXD+
EP Audio
Power sync 43 kHz
RXD+
EP Sync
RXD-
TXD-
2.3.3 Headbox input connector
Table 3 Headbox input connector
Pin No. Signal
1
2
3
4
5
6
7
8
9
10
Lead set id
1+
2+
3+
4+
Ground
1- / Ref
2-
3-
4-
15
610

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3SERVICE PROCEDURES
3.1 General service information
Field service of the M-EEG and N-EEG is limited to replacing faulty circuit boards or mechanical
parts. Faulty circuit boards should be returned to Datex-Ohmeda for repair.
Datex-Ohmeda is always available for service advice. Please provide the unit serial number, full
type designation, and a detailed description of the fault.
The Datex-Ohmeda EEG Simulator (order No. 90502) is recommended for functional checks.
CAUTION Only trained personnel with appropriate equipment should perform the tests and
repairs outlined in this section. Unauthorized service may void warranty of the unit.

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3.2 Service check
These instructions include complete procedures for a service check. The service check is
recommended to be performed after any service repair. However, the service check procedures can
also be used for determining possible failures.
The procedures should be performed in ascending order.
The instructions include a check form, Appendix A,which should be filled in when performing the
procedures.
The mark ?in the instructions means that the check form should be signed after performing
the procedure.
The procedures are designed for monitors with S/5 monitor software of revision 01. However, most
of the procedures also apply to monitors, which contain some other monitor software
type/revision.
3.2.1 Recommended tools
Tool Order No. Notes
EEG simulator 90502
Screwdriver
Earphones
•Detach the module box by removing the two screws from the back of the module. Be careful
with the loose latch and spring pin for locking.
•Detach also the cover of the EEG headbox by removing the four screws from the bottom of the
box. Be careful with the two wired connectors in the circuit board attached to the cover.
1. Check internal parts of the module and the headbox:
−screws are tightened properly
−cables are connected properly
−the EMC cover is attached properly in the module
−there are no loose objects inside the module or the headbox
?
2. Check external parts of the module:
−the front cover and the front panel sticker are intact
−connectors are intact and are attached properly
−the module box, latch and spring pin for locking are intact
?

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3. Check external parts of the headbox
−cover and the base of the headbox are intact
−the headbox sticker is intact
−connectors are intact and attached properly
?
•Reattach the module box and the cover of the EEG headbox.
•Turn the monitor on and wait until the normal monitoring screen appears.
•Configure the monitor screen so that information regarding the EEG measurement is shown:
Monitor Setup - Screen 1 Setup - Waveform Fields - Field 1 - EEG1
Monitor Setup - Screen 1 Setup - Waveform Fields - Field 2 - EEG2
Monitor Setup - Screen 1 Setup - Waveform Fields - Field 3 - EEG3
Monitor Setup - Screen 1 Setup - Waveform Fields - Field 4 - EEG4
Others - EEG - Montage - EEG Channels - 4
Others - EEG - Montage - Montage type - Bip
Others - EEG - EEG Setup - Numeric 1 - MF
Others - EEG - EEG Setup - Numeric 2 - Ampl.
4. Plug in the module. Check that it goes in smoothly and locks up properly
?
5. Check that the module is recognized, i.e. the EEG header with related information appears in
the chosen waveform fields and ‘Headbox off’ message is shown on the four fields.
?
6. Connect the headbox to the module. Check that the headbox is recognized i.e. message ‘EEG
measurement off’ is shown on the four waveform fields. If the EEG leads are connected ‘EEG
measurement off’ message disappears after 15 seconds.
?
7. Enter the service menu:
Monitor Setup - Install/Service (password 16-4-34) -Service (password 26-23-8)
Record the information regarding the software of M-EEG and N-EEG by selecting SCROLL
VERS and turning the ComWheel.
?

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8. Enter the EEG module service menu:
Parameters - More… - EEG & EP
Check that the ‘Timeouts’, ‘Bad checksums’ and ‘Bad c-s by mod’ values in the module view
are not increasing faster than by 50 per second. Check that the memories of the module have
passed the internal memory test, i.e. ‘RAM’, ‘ROM’ and ‘EEPROM’ all state OK.
?
9. Check that the ‘HB Mod Timeouts’, ‘HB Mod Bad Checksum’ and ‘Mod HB Bad Checksum’
values are not increasing faster than by 50 per second. Check that the memory of the
headbox has passed the internal memory test, i.e. ‘HB Rom Error’ in the headbox view
states 0.
?
10. Check the EP Start/Stop and Imp. Check membrane keys both of the module and the
headbox. Go to module view and press each key for at least one second and check that the
key being pressed is identified, i.e. the corresponding text is highlighted in the service menu.
Repeat in headbox view with headbox keys.
?
11. Select 10 kΩas imped. pos. and imped. neg. value on the simulator. Go to EEG & EP service
menu and select Check Electr.From the headbox view check that the impedances in all four
channels are 10 kΩ±1 kΩ.
?
12. Connect the EEG simulator to the headbox. Select 2 kΩas imped. pos. and imped. neg.
value on the simulator. Select 10 Hz 200 µV sinewave on the simulator and check that all the
four waveforms have same form. Check that the size of the waveforms is 200 µVpp ±5 µV.
Check that the MF value is 10 ±0.5 Hz. Check that the amp value is 71 µV ±3 µV.
?
13. Select 75 Hz 50 µV signal on the simulator. Check that the FEMG value is 16 ±3 µV.
?
•Preset the AEP measurement settings:
Others
EP - Cycle - Cont.
EP - AEP Setup - AEP Channels - 2
EP - AEP Setup - Responses -100
EP - AEP Setup - Stim. Frequency - 1.1Hz
EP - AEP Setup - Stim. Intensity - 60 dB
EP - AEP Setup - Sweep length - 100 ms

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14. Plug in the earphones to the headbox. Be careful with load stimulation from the earphones
when starting AEP stimulation. Start AEP stimulation by pressing the EP Start/Stop button
on the module. Check that the clicking sound comes from the earphones in 1.1 Hz frequency.
Stop the stimulation by pressing again the EP Start/Stop button on the module. Check that
the clicking stopped.
?
•Modify the AEP measurement settings:
Others
EP - AEP Setup - Stim. Frequency - 8.1Hz
EP - AEP Setup - Stim. Intensity - 90 dB
EP - EP Size - 1
15. Connect the AEP testing cable between the simulator and the headbox. Select 2 kΩas
imped. pos. and imped. neg. value on the simulator. Select 40 µV amplitude in the EP waves
menu on the simulator and start AEP measurement in the Others - EP menu. Wait until you
get the response on the display. Check that the shape of the response is one period of a sine
wave. Save EP and adjust the markers to minimum and maximum level of the response curve
in both channels. Check that the amplitude is 40 µV ±5 µV.
?
16. Perform an electrical safety check and a leakage current test.
?
17. Check that the module functions normally after performing the electrical safety check.
?
18. Clean the module with suitable detergent.
?
•Fill in all necessary documents.

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3.3 Disassembly and reassembly
3.3.1 M-EEG
Disassemble the M-EEG in the following way. See Figure 7 Exploded view of module box and
EEG module
1. Remove the two screws from the back of the module.
2. Pull the module box slowly rearward and detach it from main body. Be careful with the loose
latch and spring locking pin.
3. Detach the Neuro board by removing the two screws located near the front panel frame,
disconnect the cable and pull out the front panel frame.
To reassemble the module, reverse the order of the disassembly steps.
CAUTION When reassembling the module, make sure that the cables are reconnected
properly.
3.3.2 N-EEG
Disassemble the N-EEG in the following way. See Figure 8 Exploded view of headbox.
1. Remove the four screws from the bottom of the headbox.
2. Lift off the cover and disconnect the two cables connected to the EEG headbox board.
3. Disconnect the module-headbox cable and the headbox input unit connectors from the EEG
headbox board.
4. Remove the four screws on the corners of the EEG headbox board and detach the EEG
headbox board.
To reassemble the N-EEG, reverse the order of the disassembly steps.
CAUTION When reassembling the headbox, make sure that the cables are reconnected
properly.

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4TROUBLESHOOTING
4.1 Troubleshooting chart
Trouble Cause Treatment
No EEG waveforms on screen. EEG waveforms not selected on screen. Press Monitor Setup key and select EEG
waveforms on the screen.
No EEG waveforms on screen and ‘EEG
measurement off’ message shown in the
number field.
Electrodes not attached properly to skin or
electrode cables not connected to headbox.
Check electrodes and electrode cables.
All EEG Waveforms not drawn on screen
even if electrodes and cables are OK.
The number of channels chosen on montage
setup is smaller than the number of
channels connected to patient.
Check that the number of channels in menu
Others -EEG - Montage is same as the
number of channels connected to patient.
Number fields show ‘---‘ and message ‘High
EMG’ is displayed.
Patient has high muscle activity in the head
region or noise from some equipment is
coupling to electrode cables.
Relax the patient or remove the noise
source.
EEG signal looks noisy and artefact message
is displayed in the number fields.
Electrodes are poorly connected or electrical
interference is coupling to electrode cables.
Check the electrodes and electrode
impedances. Remove noise sources if
necessary.
Leads off message is shown on other
channels than channel 1 in referential
connection.
The montage chosen in monitor is not
referential.
Change the montage to referential from
monitor menu Others -EEG - Montage.
Electrode impedance measurement is not
available on menus.
EEG measurement is off. EEG measurement starts 15 seconds after
first electrode pair is connected.
Electrode impedance measurement is not
available on menus.
EP measurement is on. Wait until EP measurement ends or stop EP
measurement.
Electrode impedances show ‘---‘ and check
ground electrode message is displayed on
number fields after impedance
measurement.
Ground electrode is poorly connected to
patient or ground electrode cable is not
connected to headbox.
Check the electrode and cable. If the
electrode has too high impedance (>50k)
the measurement fails even if the electrode
is properly attached. Cure for this is to use
better electrodes or prepare the skin better.
Electrode impedances show ‘---‘ The electrode impedances are too high and
out of measurement range.
Prepare the skin better or use better
electrodes.
Start EP measurement not available on EP
menu.
The EEG measurement is off. Connect electrodes and wait 15 seconds
and the measurement starts.
EP measurement parameters cannot be
changed.
The EP measurement is on. Stop EP measurement.
All or most of the EP epochs are rejected
(Rej. counter on EP screen increases more
rapidly than Ave. counter).
The signal has too much noise/artefacts in
EP measurement band. Especially coupled
50/60 Hz is not shown on EEG waveform
because of filtering, but may be present in
EP signal.
Check that electrode impedances are below
5k and the impedances of the same
channel are close to one another. If this
does not help then try to remove noise
sources.
EP wave is shown only on one channel even
if two channels EP measurement is selected.
Leads are off in the channel where the EP
wave is not shown.
Check the electrodes and electrode cables.
No clicks can be heard from earphones. The earphones connector is not in place. Check that the earphones plug is firmly
pushed into the headbox’s earphone
connector.

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4.2 Troubleshooting flowcharts
Possibl y faul ty EEG
module.
Take al l modules out of
the frame.
Insert M-EEG and turn
power on
Does fault
sti ll appear? Fault not in EEG module
Enter the EEG Service
menu
OK?
Does another
mod ul e wo rk i n
the same slot?
No
No
No
Yes
Check are the Timeouts,
Bad checksums or Bad
c-s by mod running?
Check RAM, ROM and
EEPROM
OK? Replace Neuro board
Yes
No
Connect headbox into
module connector
Yes
Yes
Check from headbox
view are the Timeouts,
HB Mod Bad
Checksums or Mod Hb
Bad Checksums running
OK?
Check front panel key
functions
Yes
Does another
modul e work wi t h
headbox?
No
Yes
Faul t not in EEG module
No
OK? Is t he keypad
connected?
No Connect the keypadNo
Does the test
pass with
another
keypad?
Yes
Replace the keypadYes
Replace Neuro board
No
Connect earphones into
the headbox and start
AEP measurement
Yes
Can clicks
be heard?
No
Can clicks be heard
with another
headbox?
Yes Fault not in EEG modul e
No
WHI TE
Figure 5 EEG module troubleshooting flowchart