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Instruction Manual
IB-106-340C Rev. 4.1
July 2004
DIAGNOSTIC
ALARMS
CALIBRATION RECOMMENDED
TEST
POINTS
INC
INC
HIGH
LOW
GAS
GAS
DEC
DEC
KEYPAD
Alarms
O2 Temp Low
Figure 8-10. Fault 8, Low Heater Temp
8-12
Troubleshooting
HEATER T/C
HEATER
SW2
O2 CELL
CALIBRATION
O2 CELL mV +
TP1
O2 CELL mv -
TP2
HEATER T/C +
TP3
HEATER T/C -
TP4
CAL
TEST GAS +
TP5
PROCESS -
TP6
% O2
LOI
37260026
Hazardous Area Oxymitter 4000
h. Fault 8, Low Heater Temp
Figure 8-10 shows the electronic assembly
for a Hazardous Area Oxymitter 4000 with
a membrane keypad (upper view) and a
Hazardous Area Oxymitter 4000 with an
LOI (lower view).
Membrane Keypad. When Fault 8 is
J1
detected, the HEATER LED flashes four
times, pauses for three seconds, and
repeats.
1. The low heater temperature alarm is
2. If the thermocouple reading continues
3. Power down the electronics. Remove
4. If the heater is good, the reading will be
LOI. When Fault 8 is detected, the LOI
displays the "O2 Temp Low" message.
Refer to the comments and procedures in
paragraphs 1 through 4 above.
Rosemount Analytical Inc. A Division of Emerson Process Management
active when the thermocouple reading
has dropped below 28.6 mV.
to ramp downward for one minute and
does not return to the temperature set
point of approximately 29.3 mV, then
an Open Heater fault will be displayed.
the electronic assembly per paragraph
9-4c, Electronic Assembly Replace-
ment. Using a multimeter, measure the
resistance across the terminals of
heater connector, J8.
approximately 70 ohms. If the heater is
open, see paragraph 9-4g, Heater Strut
Replacement.
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