Figure 8-7. Fault 5, Open Heater - Emerson Rosemount Analytical Oxymitter 4000 Instruction Manual

Hazardous Area Oxymitter 4000
DIAGNOSTIC
ALARMS
CALIBRATION RECOMMENDED
TEST
POINTS
INC INC
HIGH LOW
GAS GAS
DEC DEC
KEYPAD
Alarms
O2 Heater Open
LOI

Figure 8-7. Fault 5, Open Heater

Rosemount Analytical Inc. A Division of Emerson Process Management
HEATER T/C
HEATER SW2
O2 CELL
CALIBRATION
J1
O2 CELL mV +
TP1
O2 CELL mv -
TP2
HEATER T/C +
TP3
HEATER T/C -
TP4
CAL
TEST GAS +
TP5
PROCESS -
TP6
% O2
37260023
Instruction Manual
e. Fault 5, Open Heater
Figure 8-7 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 5 is
detected, the HEATER LED flashes once,
pauses for three seconds, and repeats.
1. Remove power.
2. Remove the electronic assembly per
paragraph 9-4c, Electronic Assembly
Replacement.
3. Using a multimeter, measure the re-
sistance across the terminals of heater
connector, J8.
4. The measurement should be approxi-
mately 72 ohms. If the heater is open,
see paragraph 9-4g, 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.
IB-106-340C Rev. 4.1
July 2004
Troubleshooting 8-9
8