Emerson Process Management OXYMITTER 4000 Alarms O2 T/C Open, Fault 1, Open Thermocouple, Keypad

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

a. Fault 1, Open Thermocouple

Figure 8-3shows 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,

located on the microprocessor board, below

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 TP2 TP3 TP4

TP5 TP6

J1 RED YEL GRN ORG

the membrane keypad or the LOI module.

Membrane Keypad. When Fault 1 is

detected, the HEATER T/C LED flashes

once, pauses for three seconds, and

repeats.

1. Check connector J1. Ensure the con-

nector is properly seated.

2. Using a multimeter, measure the volt-

age from TP3+ to TP4-. If the reading

is 1.2 VDC ±0.1 VDC, the thermocou-

KEYPAD

Alarms

O2 T/C Open

LOI 37260019

Figure 8-3. Fault 1, Open Thermocouple

	ple is open.
3.	Remove power. Disconnect J1. Meas-
	ure the resistance across the red and
	yellow thermocouple leads. The resis-
	tance should be approximately 1 ohm.
4.	If the thermocouple is open, see para-
	graph 9-4g,Heater Strut Replacement.

LOI. When Fault 1 is detected, the LOI displays the “O2 T/C Open” message.

1.Remove power. Unscrew and remove the LOI module from the electronic assembly.

2.Reconnect power to the Oxymitter 4000.

8

3.Perform the diagnostic steps 1 through 4 shown for the membrane keypad.

Rosemount Analytical Inc. A Division of Emerson Process Management Troubleshooting 8-5