6
3M™ Bair Hugger™ Warming Unit Model 775 – Service Manual
Warming Unit Power‑On‑Reset
The warming unit automatically performs the following power-on-reset
sequence after you connect the warming unit to a properly grounded power
source (See Figure 1):
•
Performs all self-test functions.
•
Illuminates indicator lights and all pixels in the alphanumeric
display momentarily.
•
Displays the text
“MD 700’s”
and the software revision level in the
alphanumeric display.
•
Sounds the alarm (three low-level clicks).
•
Enters the
Standby
mode with the
high fan
setting selected by default.
NOTE:
The
low fan
setting indicator light will not illuminate during
power up.
If the warming unit loses power for less than 1 second, the warming unit
software will return the warming unit to the operating mode you selected
prior to the power loss. However, if the warming unit loses power for longer
than 1 second, the warming unit software will reset when you restore power.
The warming unit will then enter the
Standby
mode with the
high fan
setting
selected by default.
Temperature Modes
The warming unit has 4 operating modes:
Ambient, 32°C, 38°C, 43°C
.
To select the
32°C, 38°C, 43°C,
or
Ambient
mode, press the corresponding
button. The warming unit will operate within the specified temperature
range, shown in the table below.
TEMPERATURE MODE TEMPERATURE OF DELIVERED AIR
32°C
32°C ± 1.5°C
38°C
38°C ± 1.5°C
43°C
43°C ± 1.5°C
Ambient
Warming unit will supply air at
room temperature
After you select a temperature mode, the following events occur:
•
Corresponding temperature indicator light illuminates.
•
Blower operates at selected fan speed.
•
Heater activates except in
Ambient
mode.
•
Temperature mode timer and hour meter activate.
•
Temperature at the blanket-end of the hose appears in the
alphanumeric display.
•
Temp in Range
indicator light illuminates when the temperature at the
blanket end of the hose is within ±1.5°C of the selected setting; this
indicator light does not illuminate in the Ambient mode
.
Airflow Modes
The warming unit has two preset fan speed settings: a default or
high fan
setting
(
)
and a reduced or
low fan
setting
( )
. The warming unit will
reset/default to the
high fan
setting each time the warming unit is powered
up or
Standby
is selected. The
low fan
setting
( )
may be preselected while
in
Standby
prior to selecting the desired temperature.
Standby Mode
To place the warming unit in
Standby
mode, press the
Standby
button.
When in Standby mode, the following events occur:
•
Standby
indicator light illuminates.
•
Blower and heater are turned OFF.
•
Alphanumeric display deactivates.
•
Alarm and fault detection functions remain active.
•
Operating timer pauses.
•
Airflow mode resets/defaults to the
high fan
setting.
Fault Conditions
The warming unit software recognizes several nonhazardous fault
conditions including:
•
Sensor failures
•
Heater failures
•
Computer failure
•
Software failure
•
Keypad failure
•
Power supply failure
•
Blower motor failure
•
Forced over-temperature test failure
When a fault condition exists, the following events occur:
•
Fault indicator light flashes.
•
Audible alarm sounds.
•
Blower and heater turn off.
•
Fault code appears in the alphanumeric display.
•
Up to 5 fault codes are stored in memory.
When the audible alarm sounds, press any button on the keypad to silence
it. The warming unit must be unplugged before it can be restarted. See
“Viewing the Fault Code Log” on page 8 and the “Fault Code Table” on
page 9 for more information about specific fault codes.
Over‑Temperature Condition
When an over temperature condition exists, the following events occur:
•
Over‑temp
indicator light flashes.
•
Audible alarm sounds.
•
Blower, heater, and operating mode indicator lights automatically
turn off.
•
Fault code appears in the alphanumeric display (see page 9).
When the audible alarm sounds, press any button on the keypad to silence
it. The warming unit must be unplugged before it can be restarted.
Alternative Modes
The warming unit has 5 alternative modes that allow access to the service
and calibration utilities of the warming unit (see Figure 2 on page 7).
ALTERNATIVE MODES
DESCRIPTION
AltMode0
Hour Meter
AltMode1
Calibration
AltMode2
Fault Code Log
AltMode3
System Information
AltMode4
Over-temperature Detection Test
The
Hour Meter
mode displays the cumulative amount of operating time (in
Ambient, 32°C, 38°C, and 43°C
modes) the warming unit has been in use.
The time is displayed in whole hours only.
The
Calibration
mode allows a technician to check and adjust the hose
end sensor calibration offset value. This should be done as part of routine
maintenance and after servicing the warming unit or replacing the hose.
The hose end sensor temperature can be altered a maximum of ±3.0°C by
adjusting the calibration offset value. In the
Calibration
mode, the warming
unit operates in the
Ambient
temperature mode, and the alphanumeric
display shows the current hose end sensor temperature and calibration
offset with 0.1°C precision.
The
Fault Code Log
mode sequentially displays the last 5 fault codes stored
in system memory. Please refer to the “Fault Code Table” on page 8 for
more information about a particular fault code.
7
GB / 34-8718-8817-7
The
System Information
mode allows the technician to view important
system information including the firmware, system identification, serial port
baud rate, 5V power supply status, and the control board serial number.
The
Over‑temperature Detection Test
mode allows the user to test the
operation of the independent over-temperature shutdown system.
Accessing the Alternative Modes
To access the alternative modes, you must press the
Alternative Mode
button that is located on the front panel of the warming unit but is
unlabeled. Press the center of the Bair Hugger logo when the instructions
direct you to press the
Alternative Mode
button.
TEMP IN RANGE
FAULT
OVER TEMP
STANDBY
AMBIENT
MODEL
775
43
C
MEDIUM
HIGH
TEMPERATURE
AIR FLOW
38
C
LOW
32
C
System
System
Information
AltMode3
Alternative
Mode button
AltMode0
Over‑temperature
Detection
Test AltMode4
Fault
Code Log
AltMode2
Calibration
AltMode1
Figure 2. Location of Alternative Mode button
To enter one of the
alternative
modes, press the
Alternative Mode
button in
combination with one of the operating mode buttons, also located on the
front panel. Figure 2 indicates which keys must be pressed to enter each of
the 5
alternative
modes. When the correct combination of keys is pressed,
the display reads
“Hold for AltModeX,”
where “X” represents the selected
alternative
mode.
Exiting an Alternative Mode
Exit the alternative modes by pressing the
Alternative Mode
button or by
waiting for 60 seconds. You will need to access the
alternative
modes for
several of the service procedures described in this manual.
Required Preventative Maintenance
Note:
Auto tester must not interrupt the voltage during warming unit on
power reset or an Error 053/054 may result.
Calibrating the Operating Temperature
!
Caution:
Perform all temperature testing of the warming unit with a
3M Model 22110 temperature test unit.
3M assumes no responsibility for the reliability, safety, or performance
of the Bair Hugger temperature management system if temperature
tests or adjustments are made in any manner other than those described
here. Improper measurement or adjustment of the warming unit’s normal
operating temperature could result in patient exposure to temperatures
outside of the indicated range and may lead to patient injury.
Service frequency
Every 6 months or 500 hours of use, or whenever service is performed.
Tools/equipment
Model 22110 temperature test unit
Calibrated thermocouple temperature monitor
NOTES:
•
The Model 22110 temperature test unit simulates the operating
characteristics of 3M warming blankets and gowns when used with
Bair Hugger warming units.
•
When using the Model 22110 temperature test unit, take temperature
readings using a calibrated thermometer that can accept a male,
subminiature connector and read a “K” style thermocouple (e.g., a
Fluke Model 52 K/J Thermometer). If the test unit connector does not
fit your thermometer, remove the connector from the test unit and
attach a connector that fits your meter. Be certain to observe polarity.
METHOD
Note:
If the warming unit has been stored at a temperature lower than
20°C, allow it to reach ambient temperature before beginning the
calibration procedure.
1.
Attach the Model 22110 temperature test unit to the end of the
warming unit hose.
2.
Connect the warming unit to a grounded power source. The
warming unit performs a self-test and automatically proceeds to
Standby
mode.
3.
Press the
Ambient
button to place the warming unit in
Ambient
mode. Allow the warming unit to run in
Ambient
mode for at least
ten minutes to equalize the temperature of the warming unit’s
internal components.
NOTE:
Verify warming unit is set to
high fan
setting by ensuring the
indicator light next to the upper fan is illuminated.
4.
Press the
Alternative Mode
button (see Figure 2. Location of
Alternative Mode button on page 7) and the
Ambient
button
simultaneously for 3 seconds. The warming unit is now in
Calibration
mode. In this mode, the warming unit performs the following tasks:
•
32°C
and
38°C
indicator lights flash indicating they can be used
to adjust the offset value.
• Blower remains on.
• Heater elements remain off.
• The text
TMP
and the end of hose temperature in °C (0.1°C
resolution) appear in the alphanumeric display.
• The text
OS
and the current calibration offset value (0.1°C
resolution) appear in the alphanumeric display.
5.
Compare the temperature shown on the alphanumeric display and the
temperature shown on the thermocouple monitor.
• If the temperatures match, no adjustment is necessary, press
the Alternative Mode button to return the warming unit to
Standby mode.
• If the temperatures do not match, adjust the warming unit
displayed temperature:
a.
Press the
32°C
button to decrease the temperature or the
38°C button to increase the temperature by 0.1°C. You can
adjust the temperature of the warming unit a maximum
of ±3°C.
b.
Continue to press the
32°C
or
38°C
button(s) until the
temperature in the alphanumeric display matches the
temperature on the thermocouple monitor as close
as possible.
c.
Press the
Alternative Mode
button to store the calibration
offset value and return the warming unit to
Standby
mode.
Note:
If it is necessary to enter an offset value greater than ±3°C, there may
be a defect in the warming unit hose end sensor. Remove warming unit from
service until a new hose assembly can be substituted.
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