natus XLTEK EMU128 Troubleshooting guide

XLTEK EMU128
User and
Service Manual

Xltek EMU128 Headbox User & Service Manual
1
Publisher’s Notice
Part Number: 103727 REV D
Change Order: ECO #7084
PUBLISHED BY:
Natus Medical Incorporated
Excel-Tech Ltd. (XLTEK)
2568 Bristol Circle
Oakville, Ontario, L6H 5S1 Canada
Toll Free: [phone] or Fax: [phone]
Local Tel: [phone] or Fax: [phone]
Natus Sales and Support: 800-303-0306
Email: [e-mail] or [email protected]om
Website: www.natus.com
NOTIFIED BODY:
British Standards Institution (Re: # 0086)
Product Services
Maylands Avenue
Hemel Hempstead, Hertfordshire
H2P 4SQ UNITED KINGDOM
Phone: [phone]
EUROPEAN AUTHORIZED REPRESENTATIVE:
Natus Europe GmbH
Bärmannstrasse 38
D-81245 München, Germany
CE 0086
Copyright © 2009 by Excel-Tech Ltd. (XLTEK)
The information in this publication is provided for reference only. All information contained in this
publication is believed to be correct and complete. Excel Tech Ltd. shall not be liable for errors
contained herein nor for incidental or consequential damages in connection with the furnishing,
performance, or use of this material. All product specifications, as well as the information
contained in this publication, are subject to change without notice.
This publication may contain or reference information and products protected by copyrights or
patents and does not convey any license under the patent rights of Excel Tech Ltd., nor the rights
of others. Excel Tech Ltd. does not assume any liability arising out of any infringements of
patents or other rights of third parties.
All rights reserved. This document contains confidential or proprietary information of Excel Tech
Ltd. No part of this document may be reproduced or transmitted in any form or by any means
without the written permission of Excel Tech Ltd.
Excel Tech Ltd. makes no warranty of any kind with regard to this material, including but not
limited to the implied warranties of merchantability and fitness of a particular purpose.

Xltek EMU128 Headbox User & Service Manual
3
Table of Contents
Publisher’s Notice .............................................................................................1
Part Number: 103727 REV D ............................................................................1
About the Xltek EMU128 Headbox.....................................................................5
EMU 128 Headbox Specifications......................................................................5
Classifications..............................................................................................................5
EMU128 Specifications (Continued).............................................................................7
Analog Specifications - EEG Channels .............................................................7
Digital Specifications .........................................................................................7
Modes of Operation...........................................................................................7
Safety................................................................................................................7
Warnings and Cautions......................................................................................8
General Warnings ........................................................................................................8
Electrical Warnings and Cautions.................................................................................8
Patient-Related Warnings and Cautions.......................................................................9
Assembly Instructions .....................................................................................10
Hardware Connections............................................................................................... 10
Testing the EMU128 Headbox..........................................................................12
EMU128 Headbox Calibration and Verification...........................................................12
Channel Test..............................................................................................................13
Channel Test Signal Control ......................................................................................13
Allowable Channel Test Signal Settings ........................................................14
Maintenance ......................................................................................................15
Maintenance ......................................................................................................15
Troubleshooting................................................................................................16
Troubleshooting Checklist..........................................................................................16
To Adjust the Gain, Timebase and Filter Settings.........................................16
Opening the Troubleshooting Section of the Online Help............................17
Theory of Operation..........................................................................................18
Introduction ................................................................................................................18
System Overview .......................................................................................................18
Power Sources to the Headbox:......................................................................18
Board-Level Theory....................................................................................................20
Analog Back Plane .......................................................................................... 20
Digital Motherboard......................................................................................... 21
Relay Matrix Board ..........................................................................................21
Analog Board ................................................................................................... 22

User & Service Manual Xltek EMU 128 Headbox
4
Digital Board ....................................................................................................23
How the Digital Board Works ..........................................................................23
Servicing ....................................................................................................................24
Problems Starting a Study ..............................................................................24
Problems with Signal Quality..........................................................................24
Run a Channel Test ........................................................................................24
Disassembly.....................................................................................................25
Adjustments.....................................................................................................25
Getting Help.......................................................................................................26
To open the EMU128 Headbox Tutorial: .........................................................26

Xltek EMU128 Headbox User & Service Manual
5
About the Xltek EMU128 Headbox
The XLTEK EMU128 package, designed specifically for
epilepsy monitoring, allows for flexibility in set up and
configuration. Four X 32 channel input boxes can be
connected to the EMU128. The EMU128 permits single or
multiple channel configurations including grid electrodes up to
128 channels.
There are two trigger inputs – one for the patient, and one for
family / staff. The patient-worn input boxes are small and lightweight, for maximum
patient comfort. Proven amplifier design for top-notch digital signal processing in a
compact lightweight form redefines flexibility in EEG systems. This 128-channel
epilepsy-monitoring unit acquires detailed readings, giving you the picture that you are
looking for.
Summary of XLTEK EMU128 Features
• Flexible setup
• Flexible configuration
• Four 32 channel breakout boxes
• 32 / 64 / 96 / 128 channel setups
• Two trigger inputs
• Connects to XLTEK’s desktop computer system
We strongly recommend that you read the Warnings and Cautions section
before operating any headbox.
EMU128 Headbox Part Numbers
• EMU128 FS Headbox: 10344
• EMU128 Breakout Box: 102710
EMU 128 Headbox Specifications
Classifications
Protection against electric shock: Class II
Degree of protection against electric shock: Type BF applied parts
Degree of protection against harmful ingress of water: Ordinary
Mode of operation: Continuous
Do not use this system in the presence of FLAMMABLE ANAESTHETIC
MIXTURE WITH AIR OR OXYGEN OR NITROUS OXIDE.
Operating temperature range: 10°C to 40°C
Humidity range: 30-75% RH
Transport and storage temperature range: -40°C to 70°C
Transport and storage humidity range: 10-100% RH including condensation

User & Service Manual Xltek EMU 128 Headbox
6
Transport and storage Atmospheric Pressure: 500 hPa – 1060 hPa
Altitude: up to 4600m above sea level
Atmospheric Pressure: 700 hPa – 1060 hPa
Thermal Gradient: 20°C/hour max
North America
Power Input: from Desktop Computer equipped with Excel Tech Headbox Interface Card
(ISA card) or XLTEK NeuroWorks.
Fuse Rating: None
Europe
Power Input: From Desktop Computer equipped with Excel Tech Headbox Interface
Card (ISA card) or NeuroWorks
Fuse Ratings: None

Xltek EMU128 Headbox User & Service Manual
7
EMU128 Specifications (Continued)
Analog Specifications - EEG Channels
EEG Channels Up to 128 acquisition channels plus 1
reference channel
Reference Channels User Selectable: External, Common
Differential Input Impedance N/A. Inputs are not differential.
Common Mode Input Impedance 50 MOhms
Common Mode Rejection ratio > 110 dB @ 60Hz
Input Noise < 2µV pk-to-pk @ full bandwidth
EEG Channel Hardware Gain 156
Maximum AC input before clipping 20mV pk-to-pk
Maximum Operational DC input voltage
electrode offset
+/-300mV
Anti-aliasing Filter Bandwidth 131 Hz (For 500 Hz sampling freq.)
Input Bias Current < 20pA
Channel Crosstalk < -60dB
Digital Specifications
Sampling Frequency (Standard EMU128) 250 or 500 Hz, user selectable
Sampling Frequency (Advanced
EMU128FS)
250, 500, 1000, 2000 Hz, user selectable
Sampling Resolution - EEG channels
(Standard EMU128)
22 bits
Sampling Resolution - EEG channels
(EMU128FS)
16 bits
Sampling Quantisation - EEG channels 4.8nV
Storage Resolution - EEG Channels 16 bits
Storage Quantisation - EEG channels 0.31µV
Modes of Operation
Impedance Check < 2.5, < 5, < 10, < 25 kOhms
Channel Test Signal 15.625Hz, 80µV pk-to-pk
Digital Post Processing same as XLTEK EEG 32
Safety
Dielectric Strength 4 KVAC
Patient Leakage Current < 30 microamps for 550VAC applied
between system side and patient side of
the headbox. < 8 microamps for 120 VAC
normal conditions.
Headbox Mechanical
Size ~ 150 (h) x 265 (w) x 192 (d) mm
Weight ~ 2.7 Kg
General Circuit diagrams and parts lists are
available on request.

User & Service Manual Xltek EMU 128 Headbox
8
Warnings and Cautions
General Warnings
Proper use of this device depends on careful reading of all instructions and
labels that come with or on the system. Inaccurate Measures may be caused by
incorrect application or use.
The NeuroWorks system is classified as an IP0 – ordinary degree of protection
against ingress of water according to IEC 529.
Inaccurate measurements may be caused by incorrect application or use.
Only qualified personnel should operate this equipment.
The computer used with the NeuroWorks system must either be approved by
Xltek and supplied as part of an IEC 601 approved system or it must be
approved to IEC 950 or similar and kept outside of the patient environment.
To ensure the validity of signals, do not operate the device near any sources of
electromagnetic interference.
Turn off the system power before cleaning. Prevent detergent solution or cold
sterilization agents from seeping into the electronics of the system. Be careful
around all connectors and edges. Do not use abrasive agents.
Explosion Hazard: This system is not AP or APG rated. DO NOT USE this
system in the presence of a flammable anesthetic mixture with air, oxygen or
nitrous oxide.
The accessories of this device may include several kinds of disposable, sterile
needle electrodes. These needles are labeled as STERILE and the method of
sterilization is documented on the packaging. These electrodes should not be
used if the sterile packaging has been tampered with.
The sale, distribution or use of this device is restricted to, by, or on order of a
physician.
Electrical Warnings and Cautions
The system is intended for connection to a properly grounded electrical outlet
only
Periodically check the system ground integrity, the system leakage current, and
the patient contact leakage current. This should be performed at least ONCE
PER YEAR.
Do NOT turn on the system power until all cables have been connected, verified
and visually inspected for any damage. Failure to inspect the cables may result in
electrocution.
Do NOT connect or disconnect the patient headbox with the system power on.
ELECTRICAL SHOCK HAZARD: Do NOT connect electrode inputs to earth
ground. The patient headbox contains warning symbols reminding you that the
connections are intended for isolated patient connections only. Connecting to an
earth ground might result in electrocution.
ELECTRICAL SHOCK HAZARD: Do NOT service the system. Refer servicing to
qualified personnel only.

Xltek EMU128 Headbox User & Service Manual
9
The system uses a three-wire power cord with a hospital grade plug. The system
is earth grounded. For grounding reliability, only connect the device to a hospital
grade or hospital-only receptacle. Inspect the power cord often for fraying or other
damage. Do NOT operate the system with a damaged power cord or plug.
Do NOT place the isolation transformer on the floor.
Plug only XLTEK-recommended components into the isolation transformer.
Patient-Related Warnings and Cautions
Disconnect the patient's recording electrodes from the system before your turn it
on and off. Disconnecting the electrodes prevents shock.
Connect all patient electrodes to fully electrically isolated physiological devices
only. Connecting patient electrodes to any other device or external outlet may
result in personal injury.
The patient headbox accepts only touch-proof style electrode inputs. Do NOT
attempt to use any other style of patient electrode input.
Patient connections are NOT intended for direct cardiac contact.
As with all medical equipment, carefully route patient cabling to reduce the
possibility of patient entanglement or strangulation.

User & Service Manual Xltek EMU 128 Headbox
10
Assembly Instructions
Hardware Connections
1. Unpack the headbox and headbox cable.
2. Connect the cable between the headbox data port (labeled Connect to
computer) and the acquisition system (a desktop computer or NeuroWorks
Acquisition System). Use only the supplied headbox cable.
3. If provided, insert the patient event switch into the Patient Event Switch jack
#2.
4. Connect the headbox to the breakout box with the required number of cables.
Ensure that the cables are plugged into the appropriate ports (for example,
the cable for channels 1-32 on the headbox should be plugged into the port
for channels 1-32 on the breakout box, and so on). A cable must always be
connected for channels 1 to 32 because this cable also connects the
Reference input from the breakout box to the headbox.

Xltek EMU128 Headbox User & Service Manual
11
5. A Reference electrode and Common electrode are required for a successful
recording. With this headbox system, there are two sets of ground (common)
and reference electrode ports: one set is found on the breakout box and one
set is found on the headbox. Connect the reference electrode from the patient
to the reference jack on either the headbox or breakout box. Likewise,
connect the common electrode from the patient to the common jack on either
the headbox or breakout box.
6. Connect the patient leads to the breakout box.
Overview of Hardware Connections
The Patient Event Switch jacks are not isolated from the patient. Only an XLTek
patient event switch may be plugged into these inputs.

User & Service Manual Xltek EMU 128 Headbox
12
Testing the EMU128 Headbox
The EMU128 Headbox hardware is:
• Fully assembled, tested and calibrated prior to being shipped to you.
• Designed to work with XLTEK NeuroWorks software.
The following sections describe how to use NeuroWorks with the EMU128 Headbox to
perform a channel test.
Note: A minute electric current is transferred during an impedance check. To protect grid
patients, impedance checks are disabled for the EMU128 Headbox.
EMU128 Headbox Calibration and Verification
There is no need to calibrate the NeuroWorks Software or the EMU128 Headbox. All
calibration is done at the factory before the system is shipped. To verify that the
EMU128 Headbox system is correctly calibrated, perform the following procedure:
1. Connect the EMU128 Headbox to the acquisition station, then connect the
acquisition station to an XLTEK DT computer. Turn on the system.
2. Start XLTEK Database (XLDB).
3. To start a new study, click New.
4. Choose Edit->Settings->Acquisition (tab).
5. In the Acquisition tab, set the Reference Electrode to Common.
6. Design four bipolar montages that take the difference of adjacent channels within
each 32-channel group, for example, C1-C2, C2-C3, C3-C4, C32-C1.
7. Apply a sine wave of 50 microvolts, peak-to-peak amplitude, 10 Hz to all channels of
the group using a signal generator.
8. Set the LFF filter to 0.1, the HFF filter to OFF and the Notch filter to OFF.
9. Apply each montage in turn.
10. Verify that no sine wave is greater than 50 microvolts peak-to-peak. 50 microvolts
represents gain match to 1%.
For more information on setting up a montage, see Creating a Montage in the
NeuroWorks Settings book of the online help. To open the online help, choose
Help->XLTEK NeuroWorks EEG Help.

Xltek EMU128 Headbox User & Service Manual
13
Channel Test
While in the NeuroWorks live recording screen, a channel test may be performed to
verify the integrity of the signal processing from the amplifier input through to the display.
A channel test applies a test signal to all channels. This allows you to examine the
waveforms on the screen to see if all of the channels are functioning.
NOTE A channel test does not validate the connection from the patient electrode to the
amplifier input.
To Run a Channel Test
1. In NeuroWorks EEG, choose Edit->Settings. The Edit Settings window appears.
2. To open the Acquisition dialog box, click the Acquisition tab.
3. Select Common in the Reference Electrode list box and click OK.
4. To start the channel test, open the Controls menu and select Channel Test Signal.
The Channel Test control bar appears above the waveform window.
5. Using the channel test signal control, select the desired channel test shape,
frequency and amplitude.
6. To stop the channel test, click Done.
Channel Test Signal Control
The Channel Test Signal control in NeuroWorks EEG turns on the channel test
signal according to the last settings saved and displays a Test Signal toolbar.
The toolbar has controls for shape, amplitude and frequency.
Channel Test Signal Toolbar is located above the Trace Display

User & Service Manual Xltek EMU 128 Headbox
14
Allowable Channel Test Signal Settings
(At a sampling frequency of 500Hz)
Shape Sine or Square
Amplitude Sine wave amplitude can be 79, 158, 316, 632, 1264, 2527.5,
5055 and 10110 µV peak to peak. Square wave amplitude can be
50, 100, 200, 400, 800, 1600, 3200, and 6400 µV peak to peak.
Frequency Sine wave frequency can be 16, 32 or 64 Hz. Square wave
frequency can be 0.25, 0.5 or 1 Hz

Xltek EMU128 Headbox User & Service Manual
15
Maintenance
To keep the EMU128 Headbox system in good working condition, follow a regular
schedule of preventive maintenance. Regular preventive maintenance does not involve
access to the interior of the EMU128 Headbox and components. For service problems
that require corrective maintenance and/or internal component service, call XLTEK’s
Service department at 1-800-387-7516, or contact your local XLTEK representative.
Periodically check cable connections and electrodes for damage and wear. Inspect
cables for bent pins. Replace frayed or worn cables. Also, regularly inspect and clean all
system components, including:
• Connectors and jack ports
• Headbox and headbox cable
• Breakout box and cable
• Electrodes and accessories
Taking basic care of the system and avoiding extreme physical abuse helps prolong the
lifespan of the headbox.
Disconnect the EMU128 Headbox and breakout box from the computer before
wiping. Disconnect all cables. Use a lint-free cloth. Do not use cleaners on any
system component.
Be careful not to allow any fluid to seep into the internal electronic components of
the headbox or breakout box.
Do NOT leave the headbox or breakout box attached to the computer when
transporting the unit.

User & Service Manual Xltek EMU 128 Headbox
16
Troubleshooting
If the acquired waveforms are flat, do not appear, or do not appear correctly (or as
expected), try shutting down the computer for at least 10 seconds, and then set up the
test again from the beginning. Shutting down and starting over resets the headbox and
sometimes solves the problem. If you are still experiencing problems, here are some
more solutions to try:
Troubleshooting Checklist
□
Ask the patient to relax.
□
Inspect your cables.
□
Make sure that there is a tight connection between the headbox, the breakout box
and the computer.
□
Make sure that the patient electrodes are connected to the correct channel in the
headbox.
□
Make sure that the patient electrodes fit properly into the headbox (not loosely).
□
Make sure that there are no apparent breaks in the patient electrode cables.
□
Are any of the electrodes touching? If so, they are causing a short circuit and will
develop an artifact.
□
Unplug any other devices on the same circuit such as printers, mechanical beds,
vacuum cleaners, or other potential sources of interference.
□
Install a medical grade ground to make sure that your clinic has a properly grounded
electrical system.
□
Change the acquisition cable. You should always have a backup acquisition cable.
□
Check the gain and timebase settings to ensure that they are appropriate for the
current test. You may also want to check the LFF, HFF, and Notch Filter settings.
To Adjust the Gain, Timebase and Filter Settings
Choose Edit->Settings->Montage tab. To change the three filter settings (LFF,
HFF and Notch filter), right-click a cell in the appropriate column and select a
value from the menu.
• LFF (Low Frequency Filter): Filters out low frequency interference below the
set value.
• HFF (High Frequency Filter): Filters out high frequency interference above the
set value.
• Notch filter: Minimizes interference from nearby electrical equipment.
• Gain:Increasing the gain (sensitivity) of a channel makes the traces appear
larger on the screen.

Xltek EMU128 Headbox User & Service Manual
17
Opening the Troubleshooting Section of the Online Help
1. In NeuroWorks, choose Help > XLTEK NeuroWorks EEG Help.
2. Click the Contents tab.
3. Double-click NeuroWorks.
4. Double-click the Troubleshooting book. The Troubleshooting book expands to
show the contents.
5. Click a topic to display the content in the topic pane on the right.
Troubleshooting Section of the NeuroWorks Online Help

Xltek EMU128 Headbox User & Service Manual
18
Theory of Operation
Introduction
This section describes the theory of operation of the 128-channel EEG, Model
EMU128-S. The initial discussion is primarily signal-flow oriented. Detailed board-level
theory is provided later in this section.
System Overview
Features of the EMU128-S system:
The EMU128-S performs the basic function of a digital EEG front end.
• Provides a Breakout Box to connecting patient electrodes.
• Amplifies and digitizes the electrode signals.
• Transmits the digitized waveforms to a NeuroWorks computer.
• Allows selection of reference signal.
• Provides internally-generated test signals (sine and square) for user assessment of
equipment performance.
• Allows a technologist to apply a stimulus from an external stimulator to any pair of
electrodes.
• Maintains continuous signal monitoring while relay closures connect the stimulus to
the selected electrode pair.
Components of the Communications Link:
• Digitized waveforms are transmitted to the computer as synchronous serial data,
using three differential pairs: Clock, Data and Frame Sync.
• Commands and replies are handled with a much slower asynchronous link (UART),
with one differential pair in each direction.
Power Sources to the Headbox:
• 12VDC from the computer power supply is used for the communications interface
only. Most of the Headbox is powered by 12VAC 40KHz, generated by the XLTEK
Headbox Interface Card in the computer ISA slot or one of the PCI slots.
• For this modular design, four 32-channel groups (identical to the boards used in the
XLTEK EEG32) are plugged into an Analog Back Plane PCB and a Digital
Motherboard PCB to function as a system.