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Instruction Manual
IB-106-340 Rev. 3.0
December 2003
Rosemount Analytical Inc. A Division of Emerson Process Management Troubleshooting 8-9
Oxymitter 4000
LOI
KEYPAD
DIAGNOSTIC
ALARMS
TEST
POINTS
HEATER T/C
HEATER
O2 CELL
CALIBRATION
CALIBRATION RECOMMENDED
O2 CELL mV +
O2 CELL mv -
HEATER T/C +
HEATER T/C -
INC INC
DEC DEC
HIGH
GAS
LOW
GAS
CAL
TEST GAS +
PROCESS -
% O2
SW2
TP1
J1
TP2
TP3
RED
YEL
GRN
ORG
TP4
TP5
TP6
ON
37260023
Alarms
O2 Heater Open
Figure 8-7. Fault 5, Open Heater
e. Fault 5, Open Heater
Figure 8-7 shows the electronic assembly
for an Oxymitter 4000 with a membrane
keypad (upper view) and an Oxymitter 4000
with an LOI (lower view).
Membrane Keypad. When Fault 5 is de-
tected, the HEATER LED flashes once,
pauses for three seconds, and repeats.
1. Remove power.
2. Remove the electronic assembly per
paragraph 9-4d, Electronic Assembly
Replacement.
3. Using a multimeter, measure across
the heater connector J8.
4. The measurement should be approxi-
mately 72 ohms. If the heater is open,
see paragraph 9-4h, Heater Strut
Replacement.
LOI. When Fault 5 is detected, the LOI dis-
plays the “O2 Heater Open” message.
1. Remove power. Unscrew and remove
the LOI module from the electronic as-
sembly.
2. Perform the diagnostic steps 2 through
4 shown for the membrane keypad.