Teledyne gfc 7000ta operation manual Maintenance Schedule & Procedures, Theory of Operation

Table of Contents Model GFC7000TA Carbon Dioxide Analyzer

8. MAINTENANCE SCHEDULE & PROCEDURES	179
8.1. Maintenance Schedule	179
8.2. Predicting Failures Using the Test Functions	183
8.3. Maintenance Procedures	184
8.3.1. Replacing the Sample Particulate Filter	184
8.3.2. Rebuilding the Sample Pump	185
8.3.3. Performing Leak Checks	185
8.3.4. Performing a Sample Flow Check	186
8.3.5. Cleaning the Optical Bench	186
8.3.6. Cleaning Exterior Surfaces of the GFC 7000TA	186
9. THEORY OF OPERATION	187
9.1. Measurement Method	187
9.1.1. Beer’s Law	187
9.1.2. Measurement Fundamentals	187
9.1.3. Gas Filter Correlation	188
9.1.4. Interference and Signal to Noise Rejection	190
9.2. Pneumatic Operation	193
9.2.1. Sample Gas Flow	194
9.2.2. Flow Rate Control	194
9.2.3. Purge Gas Pressure Control	196
9.2.4. Particulate Filter	196
9.2.5. Pneumatic Sensors	196
9.3. Electronic Operation	197
9.3.1. Overview	197
9.3.2. CPU	199
9.3.3. Optical Bench & GFC Wheel	200
9.3.4. Synchronous Demodulator (Sync/Demod) Assembly	202
9.3.5. Relay Board	205
9.3.6. Mother Board	207
9.3.7. I2C Data Bus	210
9.3.8. Power Supply/ Circuit Breaker	211
9.4. Front Panel Touchscreen/Display Interface	212
9.4.1. LVDS Transmitter Board	212
9.4.2. Front Panel Touchscreen/Display Interface PCA	212
9.5. Software Operation	213
9.5.1. Adaptive Filter	213
9.5.2. Calibration - Slope and Offset	214
9.5.3. Measurement Algorithm	214
9.5.4. Temperature and Pressure Compensation	215
9.5.5. Internal Data Acquisition System (DAS)	215
10. TROUBLESHOOTING & REPAIR PROCEDURES	217
10.1. General Troubleshooting Hints	217
10.1.1. Interpreting WARNING Messages	218
10.1.2. Fault Diagnosis with TEST Functions	221
10.1.3. Using the Diagnostic Signal I/O Function	223
10.1.4. Internal Electronic Status LEDs	224
10.2. Gas Flow Problems	228
10.2.1. GFC 7000TA Internal Gas Flow Diagrams	229
10.2.2. Typical Sample Gas Flow Problems	232
10.2.3. Poor or Stopped Flow of Purge Gas	234
10.3. Calibration Problems	235
10.3.1. Miscalibrated	235
10.3.2. Non-Repeatable Zero and Span	236
10.3.3. Inability to Span – Touchscreen SPAN Button Not Visible	236
10.3.4. Inability to Zero – Touchscreen ZERO Button Not Visible	237
10.4. Other Performance Problems	238
10.4.1. Temperature Problems	238
10.4.2. Excessive Noise	240
10.5. Subsystem Checkout	241
10.5.1. AC Mains Configuration	241
10.5.2. DC Power Supply	241
10.5.3. I2C Bus	242

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