3–1
3. TROUBLESHOOTING
This chapter contains:
• A guide for troubleshooting problem situations.
• Board drawings, test points, and connector pin assignments.
3.1 Troubleshooting guide
The following chart lists situations that may occur while using the monitor. Follow the
recommended action in the order listed until the cause is isolated and corrected.
NOTE: Procedures for replacing monitor parts are in the Service Procedures chapter.
Situation Cause Action
Dashes are displayed
for measurement.
Poor signal quality caused by a
disconnected or improperly
applied sensor, low perfusion, or
interfering substances (such as
excessive ambient light, nail polish,
or an electrosurgical device).
Overlapping cables or a device
connected to the RS-232 port can
also cause interference.
Check the sensor connection and placement.
Change the site or use a different style of sensor in
the presence of continuous, severe motion.
Remove sources of interference.
Make sure cables do not overlap. Disconnect the
cable from RS-232 port.
Disconnect the power cable from the monitor and
use battery power.
Signal interference due to an
incorrect line power frequency
setting.
Set the line power frequency to match your local
AC power source (50 Hz or 60 Hz). See Functional
check in the Service Procedures chapter.
Signal interference due to poor
grounding at AC power source.
Use a grounded AC power source or use battery
power.
Signal interference due to
adjacent sensors (two or more
SpO
2
sensors on the same hand
or foot, for example).
Apply only one sensor to the hand, foot, or any
other site.
Flashes ON/OFF.
Low battery. Monitor can be
powered by battery only 10 to 60
minutes longer.
NOTE: Press the Alarm Silence
button once to cancel the alarm.
Connect the monitor to external power as soon as
possible to recharge the battery.
NOTE: When the battery is completely depleted, all
display and measurement functions are switched
OFF and a continuous tone sounds.
Start-up tones did not
sound.
Speaker is disconnected or faulty.
Connect the speaker cable to the System board.
Power ON. If the tones do not sound, replace the
speaker.
Alarm system failure. Replace the System board.
Power supply cable
disconnects easily
from the power jack.
If the pin inside the power jack is
slotted, the sides of the pin may
be pressed together.
To expand the slot, slowly insert a very small flat-
blade screwdriver into the slot and gently move it
from side to side.
Damaged or worn power jack. Replace the power jack assembly.
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