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Instruction Manual
IB-106-300NH Rev. 4.3
May 2005
6-4 Troubleshooting Rosemount Analytical Inc. A Division of Emerson Process Management
World Class 3000
Table 6-2. Heater Troubleshooting (continued)
Problem
Cause
Corrective Action
Status is HtrEr or OFF.
Cell TC > 28.4 mV.
Cold Junction 273 to 330 mV (normal).
O
2
Display = 0%
1. Triac failure.
Check the triac. Repair as needed.
2. Wrong TC set point.
Check electronics manual and verify the set point; typically 1356°F (736°C).
3. Wrong heater voltage selected. HPS voltage jumpers setup wrong.
For 44 V heater, make sure JM7 is installed and JM8 is removed. For 115 V heater, JM7 is
removed and JM8 is installed. The 115 V heater has an identifying stainless steel tag attached
in the junction box.
Status is HtrEr or OFF.
Cell TC < 28.4 mV.
Cold Junction < 273 mV.
O
2
Display = 0%
1. Wiring error, thermocouple wires reversed.
Verify TC wiring at junction box terminal and electronics. The yellow chromel line connects to
terminal 3. The red alumel line connects to terminal 4. Trace line through the HPS (if used)
and the electronics. Reverse wires if needed.
2. Faulty thermocouple. At a cold junction reference of 77°F (25°C), the probe TC should read about
29.3 mV.
Replace faulty thermocouple.
3. Faulty AD590. At normal ambient temperatures, cold junction sensor should be 273 to 330 mV.
Replace faulty sensor.
Status is HtrEr or OFF.
Cell TC = -40 mV.
Cold Junction 273 to 330 mV (normal).
O
2
Display = 0%
1. Faulty thermocouple connection or open.
Verify TC wiring at junction box terminal and electronics. The yellow chromel line connects to
terminal 3. The red alumel line connects to terminal 4. Trace line through the HPS (if used)
and the electronics. Repair connection or wiring as needed.
2. Thermocouple fault. At a cold junction reference of 77°F (25°C), the probe TC should read about
29.3 mV.
Replace faulty thermocouple.