Battery indi-
cator
F. Trouble Shooting
Problem
Corrective Action
SENS ERR in display
Replace sensor
Tick rate inconsistent
Replace batteries / sensor
Weak LCD display
Replace Batteries
G. Maintenance
Battery Replacement:
Depress the latch on the back housing and slide the cover down.
Replace batteries (2 x “C” alkaline) and reattach the cover.
Sensor Replacement:
Turn the 721 off. Turn the sensor cage counter clockwise and remove
it. Unplug the old sensor and discard. Replace sensor and sensor cap.
Cleaning your 721:
Use a mild detergent and slightly damp cloth to clean the surfaces of
the 721. For factory service please return your 721 to:
TPI / Attn: Service
9615 SW Allen Blvd. Suite 104
Beaverton, OR 97005
H. Accessories
Replacement Sensor: A739
Soft Pouch: A780
Earphone: A710
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Additional Features (continued):
Mute Function
When the 721 encounters a gas concentration above the alarm set
point the alarm will begin to sound. Pressing the key will
silence the alarm.
Zero Function
If the 721 fails to auto zero the zero key can be used to zero the dis-
play. Turn the 721 on in a clean air environment, wait for the sensor
test to end, then press the key.
Battery Indicator
The battery indicator is located in the upper right corner of the display
and monitors the condition of the battery:
The battery indicator will show full capacity ( ), half capacity
( ), one quarter capacity ( ), and replace ( ).
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