Ohmeda 3000 - Calibration and Adjustments; Control Unit Access and Board Checks; Display Brightness and Alarm Volume Adjustment

4/Calibration and Adjustments
CAUTION: Use the Static Control Work Station
(Part No. 0175-2311-000) to help ensure that static
charges are safely conducted to ground. The Velos-
tat material is conductive. Do not place electrically
powered circuit boards on it.
Note: The audio alann will sound for about 2 sec-
onds whenever powering up the unit.
Note: Warm up the unit for 5 minutes before mak-
ing these adjustments.
A. Control Unit Access
1.. Disconnect the power cord for the Infant Warmer
System from the wall outlet.
2. Remove the mounting screws for the back panel.
B. Power Supply Board Voltage Checks
1. Set the test switch (S1) located on the control
board to the following test positions:
Switch #1,#2,#4 Open (“Off”)
Switch #3 Closed (“On")
2. Connect the controller assembly to the power
source (listed voltage + 10%), and switch the In-
fant Warmer “On”.
3. Check that all display segments are “On”, the
observation lamp is “On”, the alarm light is
“On”, the heater radiates heat, and-a continuous
alarm tone sounds.
4. Check that the following D.C. voltages are pre-
sent at the test connector (T1) located on the
control board. Voltages should be within the to-
lerances specified:
TP7 Ground (common)
TP3 (9.0 Vdc ST.) +9V + 0.2V (adjust R4 on P.S. Bd.)
TP4 (5.0 Vde LEDS) +5V + 0.2V (replace P.S. Bd.)
TP5 (5.0 Vdc ST.) +5V + 0.2V (replace P.S. Bd.)
C. Display Brightness Check
Note: The display brightness is precalibrated at the
factory and should only require adjustment if replac-
ing a component on the display board.
With the test switches set as follows:
Switch #1,#2,#4 Open (“Off”)
Switch #3 Closed (“On”)
Check that all the displays are lit and are of uniform
brightness. If the displays are acceptable proceed to
Section D. If the displays are not illuminated
adequately proceed with the adjustment procedure.
Adjustment Procedure
CAUTION: The back panel and display panel may
drop down when the bottom cover mounting
screws are removed, Be sure to secure the panels
with tape before disassembly.
1. Set the test switch ($1) located on the control
board to the following test positions:
Switch #1,#2,#4 Ореп ("ОН")
Switch #3 Closed (“On")
2. Tape the display panel and back panel to the top
cover.
3. Remove the four outside corner mounting screws
from the bottom of the display panel. Do not re-
move the two inside mounting screws.
4. Connect a digital voltmeter across R10 located on
the bottom edge of the display board.
5. Adjust R9 on the display board until the voltage
across R10 is 3.30V + 0.2V.
6. Verify that all segments of all displays are lit and
are of uniform brightness.
D. Alarm Volume Adjustment
Note: The alarm volume and frequency are precalib-
rated at the factory and should only require adjust-
ment if replacing a component on the control board.
1. With the test switches set as follows:
Switch #1,#2,#4 Open (“Off”)
Switch #3 Closed (“On”)
2. Ensure the alarm tone and volume are adequate.
Verify that the audio alarm level is adequate ina
lecation with a background noise level of 55 dBA
max. If the audio alarm level is acceptable go to
step E. If the audio alarm level is unacceptable
proceed with the adjustment procedure.
Adjustment Procedure
3. Verify the frequency output at U7 pin 9 is 2 kHz
+ 0.1 kHz. Adjust R38 on the control board as re-
quired.
Note: If test equipment is not available for check-
ing the 2 kHz frequency, adjust R38 for maximum
sound level.
4. Verify that R37 on the control board is set fully
CCW (maximum volume).
E. Analog to Digital Converter (ADC)
Note: The following resistance values are available
on the Temperature Simulator and the switch posi-
tions are listed in parentheses.
1. Switch the power switch “Off”.
2. Set the control board test DIP switch (located on
the upper edge) to the calibration positions as
follows:
Switch.#1, #2, #3 Open (“Off”)
Switch #4 Closed (“On”)
3. Connect a resistance of 5900 ohms + 0.1% (17) to
the patient jack connector.
4-1