Agilent Technologies 7820A User manual

A g i l e n t 7 8 2 0 A G a s
C h r o m a t o g r a p h
Service Manual

2
Agilent 7820 GC Service
Notices
© Agilent Technologies, Inc. 2012
No part of this manual may be reproduced in any form or by any
means (including electronic storage and retrieval or
translation into a foreign language) without prior agreement
and written consent from Agilent Technologies, Inc. as
governed by United States and international copyright laws.
Manual Part Number
G4350-90018
Edition
Third edition, August 2012
Printed in China
Agilent Technologies (Shanghai) Co., Ltd.
412 Ying Lun Road
Waigaoqiao Free Trade Zone
Shanghai 200131 P.R.China
Warranty
The material contained in this document is provided “as is, ”
and is subject to being changed, without notice, in future
editions. Further, to the maximum extent permitted by
applicable law, Agilent disclaims all warranties, either
express or implied, with regard to this manual and any
information contained herein, including but not limited to the
implied warranties of merchantability and fitness for a
particular purpose. Agilent shall not be liable for errors or
for incidental or consequential damages in connection with the
furnishing, use, or performance of this document or of any
information contained herein. Should Agilent and the user have
a separate written agreement with warranty terms covering the
material in this document that conflict with these terms, the
warranty terms in the separate agreement shall control.
Safety Notices
A warning calls attention to a condition or
possible situation that could cause injury to
the user.

Agilent 7820 GC Service
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A caution calls attention to a condition or
possible situation that could damage or destroy the
product or the user's work.
Contents
Notices 2
1Before Servicing the Instrument 13
Safety ....................................... 14
Hand tools ................................... 14
Specialized tools ............................ 15
Electronic tools ............................. 17
Pneumatic tools .............................. 18
For Checking Inlet Pressure.................. 19
2Inlets 23
Inlet overview ............................... 24
Split/Splitless Inlet........................ 24
Replacing the split/splitless inlet ....... 24
Replacing the split/splitless inlet top weldment
assembly .................................. 26
Replacing the split/splitless inlet split vent
line....................................... 27
Replacing the split/splitless inlet split vent
filter canister and valve assembly ........ 28
Reinstalling the split/splitless inlet .... 29
Purged Packed Inlet.......................... 31
Replacing the Purged Packed inlet ......... 31
Replacing the Purged Packed inlet heater .. 35
3Detectors 39
Detector overview ............................ 40

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Agilent 7820 GC Service
About the detector signal boards............. 40
Accessing detector signal boards............. 41
Replacing detector signal boards............. 41
Flame Ionization Detector (FID).............. 44
Selecting an FID jet ...................... 44
Replacing the FID interconnect assembly or
spring .................................... 46
Replacing the heater ...................... 48
Replacing the FID signal board ............ 53
Replacing the electrometer ................ 54
Replacing the glow plug (ignitor) ......... 55
Replacing the entire FID .................. 57
Ultrasonic cleaning the FID ............... 62
Nitrogen Phosphorus Detector (NPD)........... 65
Selecting an NPD jet ...................... 65
Removing the NPD electrometer ............. 66
Replacing the entire NPD .................. 67
Replacing an NPD signal board ............ 70
Replacing the NPD heater .................. 72
Replacing the NPD electrometer ............ 74
Cleaning the NPD jet and collector ........ 76
Cleaning the NPD .......................... 78
Thermal Conductivity Detector (TCD).......... 81
Replacing the TCD detector cell ........... 81
Replacing the TCD switching valve ......... 83
Micro-cell Electron Capture Detector (uECD) . 85
Replacing the uECD heater/sensor assembly . 85
Replacing the uECD makeup gas adapter ..... 86
Frequency test ............................ 87
Leak test ................................. 89
Performing a radioactivity leak test (wipe test)
........................................... 89
Flame Photometric Detector (FPD)............. 91
Preparing for maintenance ................. 91
Disassembling the FPD ..................... 91
Rebuilding the FPD optics assembly ....... 101

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Reassembling the FPD ..................... 108
Replacing the FPD ........................ 117
Bake out and run checkout test ........... 119
Replacing the heater/sensor assemblies ... 119
Replacing the FPD signal board ........... 123
4EPC modules 125
EPC overview ................................ 126
Repairing EPC modules....................... 126
Accessing EPC modules....................... 127
Replacing the EPC modules................... 128
Replacing EPC module proportional valves.... 129
5Performance Verification 131
About Chromatographic Checkout.............. 131
To Prepare for Chromatographic Checkout..... 132
To Check FID Performance.................... 132
Typical values ........................... 136
To Check NPD Performance.................... 136
Typical values ........................... 140
To check TCD Performance.................... 140
To Check uECD Performance................... 145
Typical values ........................... 149
To Check FPD Performance (Sample 5188-5953) 150
6Configuration 157
Configuration overview ...................... 158
Inlet example ............................ 159
Detector example ......................... 159
PCM example .............................. 160
Heater assignments ....................... 161

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Agilent 7820 GC Service
GC modules and the communications buss...... 163
To configure an MSD transfer line........... 165
To configure a valve box.................... 166
Replacing a GC module....................... 166
Removing a GC module........................ 167
Changing the GC configuration............... 167
Configuration locks......................... 168
Installing new devices...................... 169
Configuring time ............................ 170
7External Cabling 171
Connectors on the back of the GC............ 172
Remote Start/Stop ........................... 172
APG Remote Control ....................... 172
Cable pinouts, remote start/stop, general use
.......................................... 176
Cable pinouts, GC to 3395B/3396C Integrator
.......................................... 177
Automatic sampler for GC.................... 177
Analog signal outputs....................... 178
Analog cable: GC to 3395A/B or 3396B/C
Integrators and 35900 C/D/E Analog to Digital
Interface instrument ..................... 178
Analog cable: general use ................ 179
8Internal Cabling 181
Internal cabling overview................... 182
Ignitor cable, FID .......................... 182
NPD power cable ............................. 183
AC power inlet assemblies ................... 184

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Motor Harness & AC Control Assembly......... 184
Inlet/Detector heater harness............... 187
Aux Heater/Valve Box Harness................ 188
Communications Harness...................... 188
7820 GC/MS Second Inlet Upgrade Harness..... 191
Keyboard display cable...................... 192
Display Cable Assembly...................... 192
9Mainframe 193
Mainframe overview.......................... 194
Covers and Fans ............................. 194
Removing and replacing the covers ........ 194
Replacing the oven bezel ................. 196
Replacing the inlet cooling fan .......... 196
Replacing the EPC cooling fan ............ 197
Replacing the oven door..................... 199
Oven temperature control.................... 200
Oven temperature troubleshooting............ 200
Measuring inlet and detector heater and PRT
resistance .................................. 201
Testing resistance of the oven heater coil . 204
Replacing the oven shroud, oven fan, and oven fan
motor ....................................... 205
Replacing the oven flapper assembly......... 208
Replacing Components Inside the Electronics Panel
............................................ 209
Accessing the analog and power board ..... 209
Replacing the ALS board .................. 209
Replacing the fuse on the ALS controller board
.......................................... 212
Removing the valve bracket ............... 214

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Agilent 7820 GC Service
Replacing the logic board ................ 216
Replacing the analog and power board ..... 220
Replacing Components Inside the Lower Rear Metal
Cover ....................................... 223
Replacing the AC board ................... 223
Replacing the oven triac ................. 224
Replacing the power transformer .......... 226
10 Valves 229
Valves ...................................... 230
Introduction ............................. 230
Valco W-series minivalves ................ 231
Gas sample valves ........................ 233
Valve Box ................................... 234
Installing the valve box ................. 234
Removing the valve box assembly .......... 238
Actuators ................................... 240
Installing the actuators ................. 240
Valve actuator drivers ................... 242
Replacing a solenoid valve (new style) ......242
Valve actuator alignment ................. 246
Typical Valve Configurations................ 247
Custom Plumbing (diagram required), Option 700
.......................................... 247
Gas Sampling Option, Option 701 or 751 ... 248
Column Isolation, Option 702 or 752 ...... 248
Two Stream Selection (Requires Gas Sampling),
Option 703 or 753 ........................ 249
Custom Plumbing (Diagram Required), Option 800
.......................................... 249
Gas Sampling with Backflush of Precolumn to Vent,
Option 801 ............................... 250
Gas Sampling with Backflush to Detector, Option
802....................................... 250
Gas Sampling with Sequence Reverse and Backflush
of Column 1, Option 805 .................. 251
Troubleshooting ............................. 252

Agilent 7820 GC Service
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Chromatographic symptoms ................. 252
Loss of sensitivity or excessive drift ... 253
Loss of peaks in specific areas of the
chromatogram ............................. 253
Extraneous peaks ......................... 253
Peak broadening and tailing .............. 254
Baseline shifts .......................... 254
Baseline upsets .......................... 254
Variation in peak area and retention time 255
Pressure check ........................... 255
11 Electrical 257
Power options ............................... 258
Converting the power option................. 259
Remote start/stop connection................ 261
Remote control.............................. 262
Temperature sensor resistance............... 263
Ceramic and glass fuses..................... 263
AC power board schematic.................... 264
Oven shroud ................................. 265
12 Firmware 267
Firmware overview ........................... 268
Confirm firmware update..................... 268
To Update GC Firmware....................... 269
To Update Frit Constants.................... 271
13 Service Mode Diagnostics 275
Service mode overview....................... 276
Detector diagnostics........................ 276
Signal board diagnostics.................... 277

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Agilent 7820 GC Service
Multiplexed ADC............................. 279
Pneumatics .................................. 280
Power diagnostics ........................... 281
14 Printed circuit boards 283
AC power board .............................. 285
Analog and power board ...................... 287
Logic and communications board.............. 288
Keyboard interconnect board................. 288
FID signal board ............................ 290
TCD signal board ............................ 291
uECD signal board ........................... 292
NPD signal board ............................ 292
FID electrometer board...................... 293
uECD electrometer board..................... 294
NPD electrometer board...................... 294
FPD signal board ............................ 296
15 Illustrated Parts Breakdown297
Overview of the IPB......................... 297
Inlets ...................................... 298
Split/Splitless Inlet (SSL) .............. 299
Split/Splitless Inlet .......................300
SSL Split vent trap (7820) ..................301
Split Splitless Inlet Body ..................302
Split Splitless Inlet Warmer ................304
Consumables and Parts for the Split/Splitless
Inlet .......................................305
Purged Packed Inlet (PP) ................. 307
Purged Packed Inlet Upper Body ..............308
Purged Packed Inlet .........................310
Consumables and Parts for the Purged Packed Inlet