EEG32 HEADBOX User and Service Manual

PART #103748 PUBLISHED BY Excel Tech Ltd. 2568 Bristol Circle Oakville, Ontario, CANADA L6H 5S1 Toll Free: 1-800-387-7516, Fax: (905) 829-5304 Email: [email protected] NOTIFIED BODY British Standards Institution (Re: # 0086) Product Services Maylands Avenue Hemel Hempstead, Hertfordshire H2P 4SQ UNITED KINGDOM Phone: 44 (0)1442-230442 NOTIFIED BODY TÜV Rheinland (Re: # 0197) Product Safety GmbH Am Grauen Stein/Konstantin-Wille-Str. 1 51105 Köln Postal address: 51101 Köln GERMANY AUTHORIZED REPRESENTATIVE mdi Europa GMBH Michael Bain Wittekamp 30 D-30163 Hannover, GERMANY Phone: 49-511-3908-9539, Fax: 49-511-3908-9539 Copyright © 2003 by Excel Tech Ltd. 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.

EEG32 Headbox

Service Manual

Table of Contents About the XLTEK EEG32 Headbox ... 7 Using This Manual ... 8 EEG32 Headbox Specifications ... 9 Warnings and Cautions... 10 General Warnings... 10 Electrical Warnings and Cautions ... 11 Patient-Related Warnings and Cautions... 11

Description of Symbols ... 12 Illustration of EEG32 Headbox... 13 EEG32 Headbox Functionality ... 14 Assembly Instructions ... 15 Hardware Connections ... 15 Testing the EEG32 Headbox ... 16 Calibration and Verification... 16 Impedance Check... 17 Channel Test ... 18 Channel Test Signal Control ... 18 Allowable Channel Test Signal Settings... 19

Maintenance ... 19 Troubleshooting ... 20 Troubleshooting Checklist ... 20 Troubleshooting Section of the Online Help ... 21

Theory of Operation ... 22 Introduction ... 22 System Overview ... 22 Features of the EEG32 System ... 22 Power Sources to the Headbox ... 22 Servicing ... 23 Problems with Signal Quality... 23 Disassembly ... 24 Adjustments... 24

Getting Help ... 25 Warranty ... 26 Extent of Limited Warranty ... 26

5

EEG32 Headbox

Service Manual

Limitations of Warranty ... 26 Limitations of Liability... 27 Extended Warranty ... 27

Appendix 1: Board Level Theory... 28 Connector/LED Board... 28 Analog Board ... 28 Digital Board ... 29 How the Digital Board Works ... 30 Problems Starting a Study ... 31

Appendix 2: Schematics ... 33

6

EEG32 Headbox

Service Manual

About the XLTEK EEG32 Headbox Thank you for purchasing the EEG32 headbox from XLTEK, one of the world's top manufacturers of neurodiagnostic equipment and software. XLTEK is an ISO 9001 certified company committed to providing you with technologically advanced products that are practical and easy to use. XLTEK uses a vertically integrated process to design, build, test, distribute and support its equipment. By retaining all of these processes within one organization, XLTEK maintains absolute control over the quality of its equipment. At the same time, XLTEK has the flexibility to improve products continually to meet your needs. We encourage your feedback and suggestions regarding any aspect of the NeuroWorks EEG system, documentation, accessories, and support services. The XLTEK EEG32 headbox offers advanced signal acquisition capabilities for accurate data acquisition with 500 Hz sampling rates and 22 bit conversion. The highest signal-to-noise ratios available and fast recovery from saturation for stable baselines are available with the EEG 32. The XLTEK EEG32 headbox connects to: • The XLTEK Desktop for low-cost applications. • The XLTEK Laptop for portable applications. WARNING: We strongly recommend that you read the Warnings and Cautions section before operating any headbox.

EEG32 Headbox Part Number: 10163

7

EEG32 Headbox

Service Manual

Using This Manual This manual describes the theory, features, set up, operation, and maintenance of the EEG 32 headbox. It also provides information on troubleshooting, specifications, getting help, and rights and warranty. When going through the procedures, we recommend you read the entire section first, before beginning a sequence. Also, please follow instructions carefully. Various symbols and typographical conventions are used throughout the manual. The following table illustrates them and describes their meanings and functions.

Symbol/ Convention

Description/Function A warning or caution that provides important information that should not be missed. Read all warnings and cautions carefully before starting the system for the first time. In some cases, a personal safety hazard may be indicated. A note that provides extra information.

Bold

Bold text denotes key words and phrases.

BOLD CAPS

Bold capital letters indicate extra emphasis.

8

EEG32 Headbox

Service Manual

EEG32 Headbox Specifications Digitization Sampling Rate Analog/Digital Converter Voltage Resolution Amplifiers Channels Maximum Input range Crosstalk between channels

500 Hz or 250 Hz per channel, simultaneous sampling 22 bits Accurate to 0.3 µV 32 ± 10 mV ≤ 0.1% (≥ 60 dB)

Noise Level (0.1-100 Hz)

≤ 2 μV p-p

Input Impedance

≥47 MΩ

CMRR at Patient Inputs

≥ 100 dB from 0.1-100 Hz (> 100,000:1)

Bandwidth Channel Test Signal Power Supply Power consumption 32 Channel Headbox Mechanical Size Weight Main Voltage Operating Parameters Operating temperature range: Humidity range: Transport and storage temperature range: Transport and storage humidity range: Altitude: Thermal Gradient: Safety Tested and certified to IEC601

0.1 to 100 Hz 15.6 Hz, 80 µV p-p 3W 8.5” x 5.5” x 2.0” 2 lbs. Powered from XLTEK DT or LT system 10 ° C to 50 ° C 5-85% RH non-condensing -40° C to 60° C 5-95% RH non-condensing 760 hPa – 1200 hPa 20° C/hour max

9

EEG32 Headbox

Service Manual

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. The EEG32 headbox 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 EEG32 headbox and the NeuroWorks EEG 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. This device does not contain any hazardous components; therefore, no special precautions are required for their disposal.

10

EEG32 Headbox

Service Manual

Electrical Warnings and Cautions The system is intended for connection to a properly grounded electrical outlet only Periodically check the system ground integrity and the system 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. 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 an earth ground might result in electrocution. ELECTRICAL SHOCK HAZARD: Do NOT service the system. Refer servicing to qualified personnel only. 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 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. To prevent cabling entanglement/strangulation, ensure no loose cables are accessible to the patient. Patient connections are NOT intended for direct cardiac contact. The patient event switch attached to or on the EEG32, EMU128, and Mobee headboxes is not intended for critical patient-safety-related incidents. Do NOT use the XLDetect montage with custom channel labels.

11

EEG32 Headbox

Service Manual

Description of Symbols Symbol

0086

IEC Publication 384

Description ATTENTION: Consult Accompanying Documents

417-5019

Protective Earth (Ground)

878-02-02

Type B Equipment

878-03-01

Dangerous Voltage

417-5032

Alternating Current

417-5007

Power On

417-5008

Power Off

Medical Device Directive 93/42/EEC

CE Mark

60950

Class II Equipment (nongrounded enclosure)

12

EEG32 Headbox

Service Manual

Illustration of EEG32 Headbox

Standard Channel Inputs

Consult Accompanying Documents Symbol

Protective Earth (Ground)

Class II Equipment (non-grounded enclosure) Type B Device – Not Waterproof Symbol

Auxiliary Channel Inputs

13

EEG32 Headbox

Service Manual

EEG32 Headbox Functionality The following is a block diagram of the EEG32 headbox showing its functionality. NOTE: For proper viewing, rotate page 90° right.

14

EEG32 Headbox

Service Manual

Assembly Instructions Breakout Box Connector (for optional patient lead connection)

XLTEK DT Computer

Headbox cable attaches to PCI or ISA card

Patient Event Switch (Optional)

Patient Leads

EEG32 Headbox Hardware Connections

Hardware Connections 1. Unpack the headbox and headbox cable. 2. Connect the cable between the headbox data port 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. 4. A Common electrode is required for a successful recording. Connect the Common electrode from the patient to the Common jack on the headbox.

5. Connect the patient leads to the headbox or breakout box. WARNING: The Patient Event Switch jacks are not isolated from the patient. Only an XLTEK Patient Event Switch may be plugged into these inputs.

15

EEG32 Headbox

Service Manual

Testing the EEG32 Headbox EEG32 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 EEG32 Headbox to perform a channel test.

Calibration and Verification There is no need to calibrate the NeuroWorks Software or the EEG32 headbox. All calibration is done at the factory before the system is shipped. To verify that the EEG32 headbox system is correctly calibrated, perform the following procedure: 1. Connect the EEG32 headbox to the acquisition station to an XLTEK DT computer and turn on the system. 2. Start NeuroWorks Database (NwDb). 3. To start a new study, click New. 4. Choose Edit > Settings > Acquisition. 5. In the Acquisition tab, set the Reference Electrode to Common. 6. Design a bipolar montage using pairs of the channels to be verified. For example, to verify C3, C4, O1 and O2, use a montage with C3-C4 and O1-O2. 7. Apply a sine wave of 5 millivolts ±2% peak-to-peak amplitude, 10 Hz to all channels of the group using a signal generator. Ensure that there is a 50 Ohm load on the generator output if the generator is designed to deliver the specified level into this load. 8. Set the LFF filter to 0.1, the HFF filter to OFF, and the Notch filter to OFF. 9. 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 the topic Creating and Editing a Montage in the NeuroWorks EEG Settings book of the online Help.

16

EEG32 Headbox

Service Manual

Impedance Check An Impedance Check is performed to ensure that the electrode contact with the patient is satisfactory. You can perform an impedance check at any time during a study. The impedance check will exhibit high accuracy only if at least six patient leads plus Common electrode are connected.

To Activate an Impedance Check Do one of the following: • • •

On the keyboard, press the minus (-) key on the number pad. Choose Controls > Impedance Check. At the headbox, press the white Impedance button at the base of the headbox (for the EEG 32 channel headbox only).

Running an Impedance Check When an impedance check is initiated, the software scans all channels (in auto scan mode). You can monitor the contact of a single channel by locking onto it and then adjusting the electrode contact to acceptable impedance levels.

To...

Do This...

Lock onto a channel

Click the Lock Channel button to the left of the Channel # that you wish to lock. This confines the scanning to that channel. You can then make adjustments to the electrode connection until satisfactory levels are achieved.

Allow the system to scan all channels and run a full impedance check

Click Release Lock.

Save the impedance check as part of the EEG record

Click End and Start Recording.

End the impedance check

Click End.

Interpreting an Impedance Check An impedance check displays bar graphs that show the impedance of each electrode connection. A green bar indicates the reading is below the threshold. A red bar indicates the reading is above the threshold. To set the impedance threshold, click one of the Threshold buttons in the Threshold Group box on the right side of the Check Impedance screen. To read a numerical value for the impedance in kOhms, double-click on the headbox picture on the screen after closing Impedance Check. This brings up a table that lists the impedances for all channels that were checked. NOTE: If the impedance check is run with a Protocol, the threshold is determined in the Action settings in the Protocol tab of the Edit > Settings box. Otherwise, the threshold is determined by manually clicking the option buttons in the Threshold section of Impedance Check dialog box.

17

EEG32 Headbox

Service Manual

Channel Test While you are working 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. 2. 3. 4.

In NeuroWorks EEG, choose Edit > Settings. The Edit Settings box appears. To open the Acquisition dialog box, click the Acquisition tab. Select Common in the Reference Electrode list box and click OK. 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 signal 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 the Channel Test Signal toolbar. The toolbar has controls for shape, amplitude and frequency.

Channel Test Signal Toolbar (above Trace Display)

18

EEG32 Headbox

Service Manual

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

Maintenance To keep the EEG32 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 EEG32 headbox and components. For service problems that require corrective maintenance and/or internal component service, call the XLTEK 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.

Maintenance Warnings Disconnect the EEG32 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.

19

EEG32 Headbox

Service Manual

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. 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, consult the checklist below.

Troubleshooting Checklist Ask the patient to relax. Inspect your cables. Make sure there is a tight connection between the headbox, the breakout box and the computer. Make sure the patient electrodes are connected to the correct channel in the headbox. Make sure the patient electrodes fit properly into the headbox (not loosely).

Make sure 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 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. (Choose Edit >Settings > Montage.) • LFF – Filters out low-frequency interference. • HFF – Filters out high-frequency interference. • Notch filter – Minimizes electrical interference. • Gain – Increasing gain makes traces appear larger.

20

EEG32 Headbox

Service Manual

Troubleshooting Section of the Online Help 1. In NeuroWorks, choose Help > NeuroWorks Help. 2. Click the Contents tab. 3. Double-click the Troubleshooting book. The Troubleshooting book expands to show the contents. 4. Click a topic to display its content in the pane on the right.

Online Help Window

21

EEG32 Headbox

Service Manual

Theory of Operation Introduction This section describes the theory of operation of the 32-channel EEG headbox. The initial discussion is primarily signal-flow oriented. Detailed board-level theory is provided later in this section.

System Overview Features of the EEG32 System The EEG32 headbox performs these 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.

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.

Circuit Board Assemblies Inside the Headbox A. Connector/LED Board • Patient connections are made through these boards through touch-proof pins recessed behind the front panel. These signals pass through four connectors to the Analog Board for amplification and DC removal. • Patient connections can be made optionally to a breakout box that plugs into the 37-pin D connector on this board. • Dual light-emitting diodes for each channel display the impedance check status: green for impedances below the selected threshold (“Pass”) and red for impedances above the selected threshold (“Fail”). B. Analog Board • Handles amplification and DC removal for 32 channels. • Amplifiers are designed to handle signals far in excess of even abnormally high EEG, while also providing exceptional sensitivity and resolution. • Two time constants are available in the DC removal. A normal time constant and a short time constant for accelerated recovery during Trace Restore. 22