Carbon Monoxide Alarm User Manual

Page 33
Chapter 7 Trouble-shooting and
repair
Repair procedures may only be performed by
authorized personnel!
7.1 Changing PhD
2
sensors
The PhD
2
must be turned off prior to removing or
replacing sensors. A Phillips screwdriver is used to
remove the three screws securing the sensor cover to the
PhD
2
case.
7.1.1 Replacing toxic sensors
(1) Identify which of the two toxic sensors you wish to
replace.
(2) Gently pry the sensor out of its socket.
(3) Press the replacement sensor into place.
(4) Allow at least one hour for the sensor to stabilize.
Nitric oxide (NO), hydrogen chloride (HCl), ammonia
(NH3), and TOX 1 broad range sensors require 24
hours to stabilize.
(5) Recalibrate the toxic channel.
7.1.2 Replacing combustible gas sensors
(1) Gently pry the square sensor out of its socket.
(2) Press the replacement sensor into place. Make sure
that the sensor seats all the way down.
(3) Recalibrate the LEL channel.
7.1.3 Replacing oxygen sensors.
(1) Remove the two screws and lock washers that hold
the O2 sensor tabs. A nylon spacer bushing
separating the red (positive) sensor tab from coming
into direct contact with the PhD
2
case. Be careful
not to lose this component.
(2) Remove the O2 sensor.
(3) Place the replacement sensor in the socket and line
up the sensor tabs with the screw mounting holes.
(4) Replace the nylon spacer, sensor mounting screws,
and lock washers.
(5) Allow one hour for the sensor to stabilize.
(6) Recalibrate the oxygen channel in fresh air.
7.1.4 Adding, removing, or re-configuring
sensors
See Section 5.3. for the procedure for configuring
PhD
2
sensors.
7.2 Troubleshooting
There are a few troubleshooting and repair procedures
besides sensor and battery replacement which can be
done in the field.
7.2.1 Re-booting the microprocessor
software
Occasionally it may be necessary to re-boot or "cold
start" the PhD
2
microprocessor software. Deep battery
discharge, disconnecting the battery, static discharge
through the dual purpose RS-232 / battery charger
connector, or use of keypad push-buttons in unauthorized
combinations may occasionally cause the microprocessor
to lockup or "crash." In this event it may be necessary re-
boot the microprocessor before the PhD
2
can be turned
back on and put back into normal operation.
The most significant symptom of a microprocessor which
has locked-up is inability to turn the instrument back on in
the normal manner. Inability to turn the instrument on
may also result from a dead battery. Make sure the
battery is charged before attempting to re-boot.
If the re-boot is unsuccessful, try the procedure again
while the instrument is connected to a 110 VAC power
source through the battery charger.
Note: The PhD
2
detector must not be located in a
hazardous location while the battery is being charged
or while the instrument is being operated while
connected to the battery charger.
The PhD
2
is Classified by Underwriters Laboratories,
Inc. as to Intrinsic Safety for use in Hazardous
Locations Class I, Groups A, B, C, and D. This
classification is voided while the PhD
2
is operated
while connected to the battery charger in hazardous
areas.
To re-boot the microprocessor:
(1) Press and hold down the large black on / off MODE
button for thirty seconds.
(2) Release the button.
(3) Press the on / off MODE button to turn the
instrument on in the normal manner. If the re-boot
procedure has been successful, the instrument
should resume normal operation.
7.2.2 Re-initializing the PhD
2
.
During production, PhD
2
detectors are initially set-up or
programmed with a default or standard configuration.
This standard configuration includes oxygen, combustible
gas, carbon monoxide, and hydrogen sulfide for the
sensors installed. The alarms are set to the default
values for these hazards, and a datalogging interval of
one minute is specified. The default configuration may be
restored at any time by using the following procedure.
CAUTION: Reinitialization destroys all logged data
currently in the instrument memory. Re-initialization
will cause the current instrument configuration to
revert to the default settings. Span calibration values
currently in memory will be lost. Custom alarm
settings and other configuration values must be re-