Metex 2200D/P91 Dissolved Oxygen Controller/Analyzer - Manual (Page 25)

Model 2200D/P91 Page 23
• Output High and Low - See Section 5.4. (For Model 2200D-X-2)
• Control Relay - See Sections 5.8 and 5.9.
• Alarm Relay - See Sections 5.12 and 5.13.
d) After all the above operations are performed the FAIL LED will turn off (For
Model 2200D-X-1) and STATUS LED will turn green (For Model 2200D-X-2)
and Status “0” should be obtained.
e) The unit may be tested now, using the TEST menu item (See Section
5.5), or the built-in self-testing feature, (See Section 9.1.4)
f) Bring the unit on line for measurement and control.
9.3 Printed Circuit Board Replacement
9.3.1 a) To replace printed circuit boards or relays shut off all power to the 2200D,
including any independent power to the relay contacts. Make a record of the
external wiring, then disconnect the wires. Unplug the ribbon cable connector.
b) The power supply circuit board is fastened to the back of the enclosure by four
screws, remove the screws and the board is free. Reverse the procedure to
mount a replacement board.
c) The microprocessor circuit board is located on the swing-out assembly behind
the door. Swing the assembly out, lift it up to unseat the lower hinge pin (the
upper hinge pin is spring loaded.) The assembly is now free. The circuit board
is fastened to the front panel by three screws. Remove the screws to release
the circuit board.
9.4 Sensor Fault
9.4.1 If the membrane of the sensor cartridge is pierced, the alarm relay contacts will
close and the FAIL LED (For Model 2200D-X-1) and STATUS LED (For Model
2200D-X-2) will be illuminated. However, it may be difficult to see the leakage with
the naked eye. A slight pressure on the membrane with a finger will produce a drop
of liquid. The cartridge must be replaced. See Section 9.4.3.
9.4.2 With operating time silver oxide will build up on the anode (silver wire). When the
anode becomes brown as a result of the deposit, it is time to replace the sensor
cartridge.
9.4.3 To replace the sensor cartridge, unscrew the retaining nut, remove and discard the
spent cartridge and replace with a new cartridge. AquaMetrix Part No. P91-D.
9.5 Relay Replacement
9.5.1 The relays are plugged into the power supply board just above the terminals. Be
sure all the power including independent power to the relay is off. Unplug the relay
in question and replace with a new relay. AquaMetrix Part No. 17-38.