YSI 55 - Manual (Page 8)

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Turn the instrument on by pressing and releasing the ON/OFF button on the front of the instrument.
The instrument will activate all segments of the display for a few seconds, which will be followed by
a self test procedure which will last for several more seconds. During this power on self test
sequence, the instrument’s microprocessor is verifying that the instrument is working. If the
instrument were to detect a problem, a continuous error message would be displayed. If the
instrument does not operate, consult chapter 7 Troubleshooting.
NOTE: The information on the display will be meaningless since the probe has not yet been
prepared.
You may also want to take the instrument into a dark room and, with the instrument ON, hold down
the LIGHT key. The instrument back-light should illuminate the LCD so that the display can be
easily read.
CALIBRATION CHAMBER
3.4. Calibration/Storage Chamber
The Model 55 has a convenient calibration/storage
chamber built into the instrument’s side. This
chamber provides an ideal storage area for the probe
during transport and extended non-use. If you look
into the chamber, you should notice a small round
sponge in the bottom. Carefully put 3 to 6 drops of
clean water into the sponge. Turn the instrument
over and allow any excess water to drain out of the
chamber. The wet sponge creates a 100% water
saturated air environment for the probe which is
ideal for dissolved oxygen calibration.
3.5. Hand Strap
The hand strap is designed to allow comfortable operation of the Model 55 with minimum effort. If
the hand strap is adjusted correctly, it is unlikely that the instrument will be easily dropped or
bumped from your hand.
To adjust the hand strap on the back of the meter, unsnap the leather cover and pull the two Velcro
strips apart. Place your hand between the meter and the strap and adjust the strap length so that your
hand is snugly held in place. Press the two Velcro strips back together and snap the leather cover
back into place.
3.6. The Meter Case
The meter case is sealed at the factory and is not intended to be opened, except by authorized service
technicians. Do not attempt to separate the two halves of the meter case as this may damage the
instrument, break the water-proof seal, and may void the manufacturer's warranty.