Thermo Scientific Dionex ED50A User manual

Dionex ED50A Electrochemical Detector
Operator's Manual
Document No. 065551
Revision 01
June 2013

© 2013 Thermo Fisher Scientific Inc. All rights reserved.
Chromeleon is a registered trademark of Thermo Fisher Scientific Inc. in the United
States.
Kel-F is a registered trademark of 3M Corporation in the United States and possibly other
countries. Tefzel is a registered trademark of E.I. duPont de Nemours & Co. in the United
States and possibly other countries. Ultem is a registered trademark of the General Electric
Company in the United States and possibly other countries.
PEEK is a trademark of Victrex PLC.
All other trademarks are the property of Thermo Fisher Scientific and its subsidiaries.
Thermo Fisher Scientific Inc. provides this document to its customers with a product
purchase to use in the product operation. This document is copyright protected and any
reproduction of the whole or any part of this document is strictly prohibited, except with
the written authorization of Thermo Fisher Scientific Inc.
The contents of this document are subject to change without notice. All technical
information in this document is for reference purposes only. System configurations and
specifications in this document supersede all previous information received by the
purchaser.
Thermo Fisher Scientific Inc. makes no representations that this document is complete,
accurate, or error-free and assumes no responsibility and will not be liable for any errors,
omissions, damage, or loss that might result from any use of this document, even if the
information in the document is followed properly.
Revision history: Revision 01 released June 2013
For Research Use Only. Not for use in diagnostic procedures.

Doc. 065551-01 6/13 i
Contents
1 • Introduction
1.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-1
1.2 Detection Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-2
1.3 Control Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-2
1.4 About This Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-3
1.4.1 Safety Messages and Notes . . . . . . . . . . . . . . . . . . . . . . . . . . .1-4
1.4.2 Declaration of Conformity . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-6
1.4.3 Safety Labels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-7
2•Description
2.1 Front Control Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-1
2.1.1 Control Panel Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-1
2.1.2 Control Panel Keypad . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-2
2.2 Rear Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-5
2.3 Electronics Chassis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-7
2.3.1 Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-8
2.3.2 Cards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-9
2.4 Amperometry Cell . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-10
2.4.1 Combination pH–Ag/AgCl Reference Electrode . . . . . . . . . .2-12
2.4.2 Monitoring the Amperometry Cell pH Readout . . . . . . . . . . .2-13

Dionex ED50A Electrochemical Detector
ii Doc. 065551-01 6/13
2.5 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-14
2.5.1 Operating and Control Modes . . . . . . . . . . . . . . . . . . . . . . . . 2-14
2.5.2 Local and Remote Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-15
2.5.3 Method Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-15
2.5.4 TTL Input Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-16
3 • Operation and Maintenance
3.1 Getting Ready to Run . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
3.2 Initial Screens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2
3.3 Selecting the Control Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4
3.4 Running Under Direct Control (Local Mode) . . . . . . . . . . . . . . . . . . . 3-4
3.5 Running Under Method Control (Local Mode) . . . . . . . . . . . . . . . . . . 3-5
3.5.1 Running a Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5
3.5.2 Changing the Running Method . . . . . . . . . . . . . . . . . . . . . . . . 3-6
3.5.3 Changing a Method-Controlled Parameter . . . . . . . . . . . . . . . 3-6
3.5.4 Creating a New Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6
3.5.5 Editing an Existing Method . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-8
3.6 Waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-9
3.7 Cyclic Voltammetry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-11
3.7.1 Cyclic Voltammetry with the Dionex ED50A . . . . . . . . . . . 3-11
3.7.2 Programming the Voltammetry Waveform . . . . . . . . . . . . . . 3-13
3.7.3 Running the Waveform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-14
3.8 Routine Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-15
3.9 Shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-16

Contents
Doc. 065551-01 6/13 iii
4 • Troubleshooting
4.1 No Detector Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-1
4.2 Low Detector Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-2
4.3 High Detector Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-2
4.4 Noisy or Drifting Baseline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-3
4.5 Tailing Peaks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-4
4.6 Amperometry Cell pH Readout Always 7.0 . . . . . . . . . . . . . . . . . . . . .4-4
4.7 Cannot Set Amperometry Cell pH Readout to 7.0 . . . . . . . . . . . . . . . .4-5
4.8 Shift in Amperometry Cell pH Readout . . . . . . . . . . . . . . . . . . . . . . . .4-5
4.9 No Amperometry Cell pH Readout or Intermittent Readout . . . . . . . .4-5
4.10 Discolored pH Reference Electrode . . . . . . . . . . . . . . . . . . . . . . . . . . .4-6
4.11 Leaking pH Reference Electrode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-6
4.12 Shift in Ag/AgCl Reference Potential . . . . . . . . . . . . . . . . . . . . . . . . . .4-7
4.13 Faulty DX-LAN Communication . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-8
4.14 Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-9
5•Service
5.1 Eliminating Liquid Leaks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-1
5.2 Polishing the Amperometry Cell Working Electrode . . . . . . . . . . . . . .5-2
5.3 Replacing the pH Reference Electrode O-Ring . . . . . . . . . . . . . . . . . . .5-4
5.3.1 Replacing the O-Ring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-4
5.4 Calibrating the Reference Electrode . . . . . . . . . . . . . . . . . . . . . . . . . . .5-8
5.5 Replacing the Main Power Fuses . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-10

Dionex ED50A Electrochemical Detector
iv Doc. 065551-01 6/13
A • Specifications
A.1 Physical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .A-1
A.2 Environmental . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .A-1
A.3 Electrical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .A-1
A.4 Display and Keypad . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .A-1
A.5 Detector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .A-2
A.6 Amperometry Cell . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .A-2
B • Installation
B.1 Facility Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .B-1
B.2 Power Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .B-1
B.3 Overview of DX-LAN Interface Connections (Optional) . . . . . . . . . .B-2
B.4 DX-LAN Interface Connections (Optional) . . . . . . . . . . . . . . . . . . . . .B-3
B.4.1 Installing the DX-LAN Cable . . . . . . . . . . . . . . . . . . . . . . . . .B-4
B.4.2 Cascading Hubs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .B-4
B.5 Amperometry Cell Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .B-5
B.5.1 Preparing the Cell Gasket and Working Electrode. . . . . . . . . .B-5
B.5.2 Preparing the Reference Electrode . . . . . . . . . . . . . . . . . . . . . .B-6
B.5.3 Calibrating the Reference Electrode. . . . . . . . . . . . . . . . . . . . .B-7
B.5.4 Installing the Reference Electrode . . . . . . . . . . . . . . . . . . . . . .B-8
B.5.5 Connecting the Amperometry Cell Cable . . . . . . . . . . . . . . .B-12
B.5.6 Plumbing the Amperometry Cell . . . . . . . . . . . . . . . . . . . . . .B-13
B.6 Recorder/Diagnostic Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . .B-14

Contents
Doc. 065551-01 6/13 v
C • User Interface
C.1 Operational Screens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-2
C.1.1 Menu of Screens—Integrated Amperometry . . . . . . . . . . . . . C-2
C.1.2 Main Screen—Integrated Amperometry . . . . . . . . . . . . . . . . . C-3
C.1.3 Detail Screen—Integrated Amperometry . . . . . . . . . . . . . . . . C-5
C.1.4 Method—Integrated Amperometry. . . . . . . . . . . . . . . . . . . . . C-6
C.1.5 Waveform—Integrated Amperometry . . . . . . . . . . . . . . . . . . C-8
C.1.6 Menu of Screens—DC Amperometry. . . . . . . . . . . . . . . . . . . C-9
C.1.7 Main Screen—DC Amperometry . . . . . . . . . . . . . . . . . . . . . C-10
C.1.8 Detail Screen—DC Amperometry . . . . . . . . . . . . . . . . . . . . C-11
C.1.9 Method—DC Amperometry . . . . . . . . . . . . . . . . . . . . . . . . . C-12
C.1.10 Menu of Screens—Voltammetry. . . . . . . . . . . . . . . . . . . . . . C-14
C.1.11 Main Screen—Voltammetry . . . . . . . . . . . . . . . . . . . . . . . . . C-15
C.1.12 Detail Screen—Voltammetry . . . . . . . . . . . . . . . . . . . . . . . . C-16
C.1.13 Waveform—Voltammetry. . . . . . . . . . . . . . . . . . . . . . . . . . . C-17
C.1.14 Module Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-18
C.1.15 Analog Out Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-19
C.1.16 Time Function In. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-20
C.2 Diagnostic Screens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-21
C.2.1 Diagnostic Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-21
C.2.2 Power-Up Screen. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-22
C.2.3 Elapsed Time. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-23
C.2.4 Analog Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-24
C.2.5 DX-LAN Status. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-25

Dionex ED50A Electrochemical Detector
vi Doc. 065551-01 6/13
C.2.6 Keyboard Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .C-26
C.2.7 Diagnostic Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .C-27
C.2.8 Leak Sensor Calibration and Status . . . . . . . . . . . . . . . . . . . .C-29
C.2.9 Signal Statistics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .C-30
C.2.10 Calibrate Conductivity Cell . . . . . . . . . . . . . . . . . . . . . . . . . .C-31
C.2.11 pH Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .C-31
D • TTL and Relay Control
D.1 TTL and Relay Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .D-2
D.2 TTL and Relay Output Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . .D-3
D.3 TTL Input Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .D-4
D.3.1 TTL Input Signal Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . .D-4
D.3.2 TTL Input Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .D-6
E • Signal Processor Functions
F • Connector Pinouts
F.1 Recorder/Diagnostic Signal Pinouts . . . . . . . . . . . . . . . . . . . . . . . . . . . F-1
F.1.1 Signal Electrical Parameters. . . . . . . . . . . . . . . . . . . . . . . . . . . F-2
F.2 TTL/Relay Pinouts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F-4
F.3 Amperometry Cell Connector Pinouts—SP . . . . . . . . . . . . . . . . . . . . . F-5
G • Reordering Information

Doc. 065551-01 6/13 1-1
1 • Introduction
1.1 Overview
The Thermo Scientific Dionex™ED50A Electrochemical Detector measures
current resulting from the application of potential (voltage) across electrodes in
flow-through cells. Depending on the method by which the potential is applied
and the current measured, several different properties of the flowing solution can
be determined. These measurements help answer the major questions analytical
chemists ask: What's in it, and how much is there?
Of course, other detectors are used in high performance liquid chromatography
(HPLC). The UV-visible absorbance detector dominates all other forms of
detection. Sensitivity is excellent for many analytes, especially aromatic species,
and transparent mobile phases are readily available. However, there are numerous
analytes that have very poor absorbance and are not detected with sufficient
sensitivity by UV absorbance. Most of these nonchromophoric molecules are
aliphatic organic molecules and inorganic ions. Low wavelength UV detection
can be used, but at a loss in selectivity. Refractive index detection can also be
used. However, maintaining a stable baseline can be difficult, and RI detection is
less sensitive and substantially less selective than UV detection.
Fortunately, a wide variety of nonchromophoric molecules can be detected with
good or excellent sensitivity by one of several forms of electrochemical detection.
These molecules include carboxylic, sulfonic, and phosphonic acids; alcohols,
glycols, aldehydes, and carbohydrates; primary, secondary, tertiary, and
quaternary amines; sulfates, sulfoxides, thiols, sulfides, and mercaptans; and
inorganic anions and cations. In addition, when compared to UV absorbance
detection, electrochemical detection provides substantial improvements in
sensitivity and selectivity for amine and hydroxy-substituted aromatics such as
catecholamines.
Several forms of electrochemical detection have become popular for certain
HPLC applications. Conductivity is the workhorse detection method in ion
chromatography, just as UV detection is for HPLC. DC amperometry is the
preferred method for neurochemical analyses. Pulsed amperometry is now
established as the superior detection method for carbohydrates. For most of the
numerous analytes listed in the previous paragraph, detection by UV-visible
absorbance is poor, while one of the three main techniques of electrochemical

Dionex ED50A Electrochemical Detector
1-2 Doc. 065551-01 6/13
detection provided by the Dionex ED50A provides superior sensitivity and
selectivity.
Electrochemical detection is not a substitute for UV-visible absorbance detection,
but is an important complement. A liquid chromatograph equipped with both a
Thermo Scientific Dionex absorbance detector and an electrochemical detector is
a versatile and powerful analytical instrument.
1.2 Detection Modes
The Dionex ED50A provides two major forms of electrochemical detection: DC
amperometry and integrated amperometry. Pulsed amperometry is a form of
integrated amperometry.
•DC Amperometric detection is based on the measurement of current resulting
from oxidation or reduction (electrolysis) of analyte molecules at the surface
of an electrode.
•Integrated and pulsed amperometric detection are similar to DC
Amperometry in that molecules are oxidized or reduced at the surface of an
electrode. However, current is measured by integration during a portion of a
repeating potential vs. time waveform.
In addition, the Voltammetry mode is used to determine potentials used in DC and
integrated amperometry.
NOTE Dionex ED50A detectors shipped in June 2013 or later
are not recommended for conductivity detection. If your
detector was shipped before June 2013, refer to ED50A
Electrochemical Detector Operator’s Manual (Document
No. 031772) for information about the Conductivity
mode. The manual is provided on the Thermo Scientific
Reference Library DVD (P/N 053891).
1.3 Control Modes
The Dionex ED50A can be controlled locally from the front panel or remotely
(via the Thermo Scientific Dionex DX-LAN™interface) from a host computer
running Thermo Scientific Dionex Chromeleon® 6.8 Chromatography Data
System and the Microsoft®Windows® XP Service Pack 3 operating system.

1 • Introduction
Doc. 065551-01 6/13 1-3
1.4 About This Manual
Chapter 1
Introduction
Provides a brief overview of the Dionex ED50A. Explains
the meaning of safety messages and icons in the manual
and safety labels on the detector.
Chapter 2
Description
Describes physical aspects of the Dionex ED50A,
including the front panel controls, electronics, and flow
cell. Explains the detector operating modes.
Chapter 3
Operation and
Maintenance
Describes operating features and how to create, edit, and
run methods from the Dionex ED50A front panel. Lists
routine preventive maintenance requirements.
Chapter 4
Troubleshooting
Lists possible causes of problems and step-by-step
procedures to isolate and eliminate them.
Chapter 5
Service
Contains step-by-step instructions for routine service and
parts replacement procedures.
Appendix A
Specifications
Lists the Dionex ED50A specifications and installation
site requirements.
Appendix B
Installation
Describes how to install the Dionex ED50A.
Appendix C
Display Screens
Illustrates and describes all operating and diagnostic
screens that can be displayed on the front panel.
Appendix D
TTL and Relay
Control
Describes the Dionex ED50A TTL and Relay control
functions. Provides installation instructions.
Appendix E
Signal Processor
Functions
Lists the functions of the Signal Processor (SP) card.
Appendix F
Connector Pinouts
Describes the pinouts for all Dionex ED50A connectors.
Appendix G
Reordering
Information
Lists spare parts for the detector.

Dionex ED50A Electrochemical Detector
1-4 Doc. 065551-01 6/13
1.4.1 Safety Messages and Notes
This manual contains warnings and precautionary statements that can
prevent personal injury and/or damage to the Dionex ED50A when
properly followed. Safety messages appear in bold type and are
accompanied by icons, as shown below.
Messages d'avertissement en français
Indicates an imminently hazardous situation which, if not avoided, will
result in death or serious injury.
Indicates a potentially hazardous situation which, if not avoided, may
result in death or serious injury.
Indicates a potentially hazardous situation which, if not avoided, may
result in minor or moderate injury. Also used to identify a situation or
practice that may seriously damage the instrument, but will not cause
injury.
Indicates that the function or process of the instrument may be
impaired. Operation does not constitute a hazard.
Signale une situation de danger immédiat qui, si elle n'est pas évitée,
entraînera des blessures graves à mortelles.
Signale une situation de danger potentiel qui, si elle n'est pas évitée,
pourrait entraîner des blessures graves à mortelles.
Signale une situation de danger potentiel qui, si elle n'est pas évitée,
pourrait entraîner des blessures mineures à modérées. Également
utilisé pour signaler une situation ou une pratique qui pourrait
gravement endommager l'instrument mais qui n'entraînera pas de
blessures.

1 • Introduction
Doc. 065551-01 6/13 1-5
Warnhinweise in Deutsch
Notes
Informational messages also appear throughout this manual. These are
labeled NOTE and are in bold type:
NOTE NOTES call attention to certain information. They alert
you to an unexpected result of an action, suggest how to
optimize instrument performance, etc.
Bedeutet unmittelbare Gefahr. Mißachtung kann zum Tod oder
schwerwiegenden Verletzungen führen.
Bedeutet eine mögliche Gefährdung. Mißachtung kann zum Tod oder
schwerwiegenden Verletzungen führen.
Bedeutet eine mögliche Gefährdung. Mißachtung kann zu kleineren
oder mittelschweren Verletzungen führen. Wird auch verwendet, wenn
eine Situation zu schweren Schäden am Gerät führen kann, jedoch
keine Verletzungsgefahr besteht.

Dionex ED50A Electrochemical Detector
1-6 Doc. 065551-01 6/13
1.4.2 Declaration of Conformity
The cETLus and CE marks on the Dionex ED50A model data label (on
the right-side panel) indicate that the Dionex ED50A is in compliance
with the standards below.

1 • Introduction
Doc. 065551-01 6/13 1-7
1.4.3 Safety Labels
The Dionex ED50A meets EN 61010-1:1993 (safety), CAN/CSA-C22.2
No. 1010.1-92 (safety), UL 3101-1/10.93 (safety), EN 50082-1:1992
(susceptibility), EN 55011:1991 (emissions). The TUV GS, C, US Mark
safety labels and the CE Mark label on the Dionex ED50A attest to
compliance with these standards.
The symbols below appear on the Dionex ED50A or on Dionex ED50A
labels.
Alternating current
Protective conductor terminal (earth ground)
Power supply is on
Power supply is off

Dionex ED50A Electrochemical Detector
1-8 Doc. 065551-01 6/13

Doc. 065551-01 6/13 2-1
2 • Description
2.1 Front Control Panel
The control panel on the front door of the Dionex ED50A contains the liquid
crystal display (LCD), the membrane keypad, and the actuator for the main power
switch. The electronics chassis, described in Section 2.3, is located behind the
front door.
Power Switches
The main power switch is on a bulkhead inside the electronics chassis (in the
front, left-hand corner). The actuator for the power switch is on the front door,
below the control panel (see Figure 2-1). The actuator functions only when the
front door is fully closed. When the door is open, press the main power switch to
turn the Dionex ED50A on and off.
2.1.1 Control Panel Display
The LCD, also called the screen, displays Dionex ED50A status and
operating information. Fields on the screen that are in reverse video (blue
letters on a white background) can be edited, while normal video fields
are simply informational displays.
•To adjust the screen contrast, rotate the knurled knob in the recess
below the Help and Menu buttons (see Figure 2-1).
•To adjust the brightness of the screen backlight, select a different
DISPLAY PANEL BACKLIGHT option on the MODULE SETUP screen
(see Section C.1.14).

Dionex ED50A Electrochemical Detector
2-2 Doc. 065551-01 6/13
2.1.2 Control Panel Keypad
Use the keypad to directly control Dionex ED50A operation, as well as to
create and modify programmed series of timed events, called methods. In
summary:
•Press Menu to display a list of available screens.
•In the screens, only fields shown in reverse video can be edited. Other
fields only display information.
•To edit a field, use the four directional arrow buttons to position the
cursor in the reverse video fields. Use the numeric buttons to enter
variable values.
•Use the Select and Select buttons to choose predetermined
options. Pressing a Select button increases (or decreases) a numeric
value by one; holding down a Select button increases (or decreases) a
numeric value continuously.
•Press Enter or a cursor arrow button to execute the selected value.
Figure 2-1. Dionex ED50A Front Panel
Main Power
Switch Actuator Tab
(for opening
the door)
Knob
(for adjusting
the contrast)

2 • Description
Doc. 065551-01 6/13 2-3
A high-pitched beep sounds when a button is pressed. When an error
occurs, this beep is lower in frequency. The beeps can be disabled from
the MODULE SETUP screen (see Section C.1.14).
Button Function
Offset Returns the analog (recorder) output to a predetermined baseline and
zeros the display. The resultant value of the offset required is displayed
on the DETAIL screen. This function can be programmed in a method.
Mark Sends a 10% positive event mark to the analog (recorder) output. A
mark is typically used to indicate a sample injection. This function can
be programmed in a method.
Insert Inserts a new step into a method.
To add a new step, move the cursor to the TIME field and press Insert.
A new blank step appears below the cursor position. After entering a
time value, press Enter or a cursor arrow button. Insert steps in any
order and they will be automatically reorganized in the correct
chronological order.
Delete Removes the value from the current entry field. To restore the previous
value, move the cursor from the field before entering a new value.
Pressing Delete when the cursor is in a step entry field on the
METHOD screen “blanks” the step parameter value. Moving the cursor
to another field does not restore the previous value; instead, the step
remains blank, indicating no change from the previous step.
To delete an entire method step:
1. Position the cursor in the method’s TIME field and press Delete.
The time is removed and the help line prompts you to press
Delete again to delete the step.
2. Press Delete again. Or, to restore the original time and step
parameters, press any button except Delete.
Table 2-1. Dionex ED50A Control Panel Button Functions

Dionex ED50A Electrochemical Detector
2-4 Doc. 065551-01 6/13
Hold/Run Turns the method clock off (Hold) and on (Run).
When the method clock is in Hold, pressing Hold/Run starts the clock
at either the initial step of a new method or, if resuming an interrupted
method, at the time at which the clock was put in Hold.
When the method clock is in Run, pressing Hold/Run stops the
method clock, thereby “holding” the method and freezing the current
conditions.
If the Dionex ED50A is in Voltammetry mode, pressing Hold/Run
runs or holds the waveform program.
Reset Changes the method clock time to INIT, causing the initial conditions
specified by the method to occur. This button functions only when the
detector is under Method control (see Section 2.5.3).
If the method is running, it continues running. If the method is in Hold,
the method clock executes the initial conditions and holds.
Select 
and
Select 
When the cursor is positioned at a field with predetermined
parameters, these buttons cycle through the options. In fields with
predetermined numerical values, pressing Select increases the
value by one unit; pressing Select decreases the value by one unit.
Holding down a Select button increases (or decreases) the value
continuously. Press Enter or a cursor arrow button to confirm the
selected value.
The four cursor buttons move the cursor, in the direction of the arrow,
to the next entry field. If there is no changeable field in that direction,
the cursor moves diagonally or remains in its current location.
In most cases, after entering a new value in an entry field, pressing an
arrow button saves and/or executes the change. The exceptions are the
METHOD SAVE TO field, the METHOD RUN field, any calibration
command, the DIAGNOSTIC TESTS screen, and all menu screens.
Help Displays a Help screen with information pertaining to the current entry
field.
Button Function
Table 2-1. Dionex ED50A Control Panel Button Functions (Continued)