Emerson Oxymitter 5000 Instruction Manual page 110

Oxymitter 5000
Figure 8-12. Fault 10, High Cell mV
DIAGNOSTIC
ALARMS
CALIBRATION RECOMMENDED
TEST
POINTS
INC
HIGH
GAS
DEC
Alarms
O2 Cell Open
8-16
HEATER T/C
HEATER
SW2
O2 CELL
CALIBRATION
O2 CELL mV +
TP1
O2 CELL mv -
TP2
HEATER T/C +
TP3
HEATER T/C -
TP4
INC
CAL
LOW
GAS
TEST GAS + TP5
DEC
PROCESS -
TP6
% O2
KEYPAD
LOI
Fault 10, High Cell mV
Figure 8-12 shows the electronic assembly for
an Oxymitter 5000 with a membrane keypad
(upper view) and an Oxymitter 5000 with an LOI
(lower view). The upper view also shows J1 and
test points TP1 through TP6, located on the
microprocessor board, below the membrane
keypad or the LOI module.
Membrane Keypad
J1
When Fault 10 is detected, the O2 CELL flashes
once, pauses for three seconds, and repeats.
1. Using a multimeter, measure across TP1+
to TP2-. If you measure 204 mV to 1 volt
DC, the cell reading is due to high
combustibles. This is a self-clearing alarm,
once the combustible conditions go away.
If you measure 1.2 VDC, the cell wires,
either orange or green, have become
detached from the input.
2. One possible cause is connector J1. The
orange or green wire has come loose from
the crimped connection.
3. The platinum pad could also be at fault.
The pad could have broken free from the
back of the cell.
4. Replace heater strut per "Heater Strut
Replacement" in Section 9: Maintenance
and Service. If necessary, replace the cell
and flange assembly per "Cell Replace-
ment" in Section 9: Maintenance and Ser-
vice.
LOI
When Fault 10 is detected, the LOI displays the
"O2 Cell Open" message.
1. Remove power. Unscrew and remove the
LOI module from the electronic assembly.
2. Reconnect power to the Oxymitter 5000.
3. Perform the diagnostic steps 1 through 4
shown for the membrane keypad.
Instruction Manual
IM-106-350, Rev 2.2
July 2008