Emerson Process Management OXYMITTER 4000 IM-106-340 - Manual (Page 108)

8-16
Instruction Manual
IM-106-340, Rev. 4.0
May 2006
Oxymitter 4000
Figure 8-12. Fault 10, High Cell mV
Fault 10, High Cell mV
Figure 8-12 shows the electronic assembly for
an Oxymitter 4000 with a membrane keypad
(upper view) and an Oxymitter 4000 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
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 4000.
3. Perform the diagnostic steps 1 through 4
shown for the membrane keypad.
37260028 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
Alarms
O2 Cell Open