Emerson Process Management IM-106-340 instruction manual Alarms O2 T/C Reversed

Instruction Manual

IM-106-340, Rev. 4.0

May 2006

Figure 8-5. Fault 3, Reversed Thermocouple

	HEATER T/C
DIAGNOSTIC	HEATER	SW2
ALARMS	O2 CELL	ON
	CALIBRATION

CALIBRATION RECOMMENDED

Oxymitter 4000

Fault 3, Reversed Thermocouple Wiring or Faulty PC Board

Figure 8-5shows 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.

TEST

POINTS

INC INC

HIGH LOW GAS GAS

DEC DEC

O2 CELL mV +

O2 CELL mv - HEATER T/C + HEATER T/C -

CAL

TEST GAS + PROCESS - % O2

TP1	J1
TP2
TP3
TP4	RED YEL GRN ORG

TP5

TP6

Membrane Keypad

When Fault 3 is detected, the HEATER T/C LED flashes three times, pauses for three seconds, and repeats.

1.	Using a multimeter, measure the voltage
	from TP3+ to TP4-. If the reading is
	negative, the thermocouple wiring is
	reversed.
2.	Check red and yellow wires in the J1
	connector for the proper placement.
3.	If the wiring is correct, the fault is in the PC
	board. See "Electronic Assembly

KEYPAD

Alarms

O2 T/C Reversed

LOI 37260021

Replacement" in Section 9: Maintenance

and Service.

LOI

When Fault 3 is detected, the LOI displays the "O2 T/C Reversed" 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 3 shown for the membrane keypad.

8-9