Oxymitter 4000

 

HEATER T/C

 

DIAGNOSTIC

HEATER

SW2

ALARMS

O2 CELL

ON

 

 

CALIBRATION

 

CALIBRATION RECOMMENDED

Instruction Manual

IB-106-340 Rev. 3.0

December 2003

c. 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,

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

below the membrane keypad or the LOI

module.

Membrane Keypad. When Fault 3 is de-

tected, the HEATER T/C LED flashes three

times, pauses for three seconds, and re-

peats.

1. Using a multimeter, measure TP3+ to

TP4-.

2. If the reading is negative, the thermo-

couple wiring is reversed.

KEYPAD

Alarms

O2 T/C Reversed

LOI

37260021

Figure 8-5. Fault 3, Reversed Thermocouple

3.

Check red and yellow wires in the J1

 

connector for the proper placement.

4.

If the wiring is correct, the fault is in the

 

PC board. See paragraph 9-4d,Elec-

 

tronic 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 as- sembly.

2.Reconnect power to the Oxymitter 4000.

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

Rosemount Analytical Inc. A Division of Emerson Process Management

Troubleshooting 8-7