Emerson Process Management OXYMITTER 4000 Alarms O2 T/C Reversed, Or Faulty PC Board

Hazardous Area Oxymitter 4000

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

CALIBRATION RECOMMENDED

Instruction Manual

IB-106-340C Rev. 4.1

July 2004

c. Fault 3, Reversed Thermocouple Wiring

or Faulty PC Board

Figure 8-5shows 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). The upper view also

shows J1 and test points TP1 through TP6,

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

located on the microprocessor board, below

the membrane keypad or the LOI module.

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 volt-

age from TP3+ to TP4-. If the reading

is negative, the thermocouple wiring is

reversed.

KEYPAD

Alarms

O2 T/C Reversed

LOI 37260021

Figure 8-5. Fault 3, Reversed Thermocouple

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 paragraph 9-4c,
	Electronic Assembly Replacement.

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

Rosemount Analytical Inc. A Division of Emerson Process Management Troubleshooting 8-7