Ohmeda 3000 - Page 12

1/Functional Description
Power Up Testing
On power up the following tests are performed.
1. Instruction Test (Error #01)
Selected instructions are tested and verified opera-
tional.
2. Checksum (Error #04)
The hex values of Eprom locations from 0000 to
1FFD are added together and a 2 byte sum is
stored. Eprom locations 1FFE and 1FFF contain a 2
byte number which when added to the calculated
checksum should total zero.
3. RAM Test (Error #05)
Rams 10 through 7F are tested with patterns of 00,
FF, AA, and 55.
4. Test Port 1 Lines (Error #06)
The port one I/O lines are tested to verify they can
be toggled.
On Line Testing
The following tests are run during the normal oper-
ation of the software. An error on any of these tests
results in a System Failure alarm.
1. ADC Calibration Test (Cal High Error #02, Cal
Low Error #03)
Verifies that readings of the precision calibration re-
sistors are within 0.3 degrees of the nominal values.
These readings can be checked by depressing the
hidden switch on the display panel (located directly
above the alarm silence switch) for 2 seconds.
After 2 seconds the displays should indicate as fol-
lows:
‘Patient Temperature is 25.0 + 0.3 degrees.
Control Temperature is 37.9 + 0.3 degrees.
2. Hardware Triac Test
A circuit independent of the microcontroller moni-
tors that the micro can switch the heat “Off”. Every
3 minutes 24 seconds in 60 Hz operation (4 minutes
and 5 seconds for 50 Hz operation) a request is
made to the micro to switch the heat “Off”. If the
heat does not go “Off", a hardware latch is latched
and a relay contact is opened so thera is no heat.
This verifies that the triac is not shorted and that
the micro is still able to control the heat. This failure
does not display an error number because it is not
controlled by the micro but will cause the software
triac test to fail when heat is called for by the pro-
gram.
3. ADC Converter not Converting (Error #07)
Verifies that the ADC conversion complete occurs
within 1.second.
4. Hardware Triac Timer Not Running (Error #08)
Verifies that the request from the hardware triac
test circuit occurs within 256 seconds.
5. Software Triac Test (Error #09)
The heater status line is checked to verify that the
heat is “On” when the micro is switching it “On”.
This verifies that the triac is not failed open.
1-6
6. Line Voltage Out of Range (Error #10)
Verifies that the line voltage is within the range of
82.6% to 117.4% of nominal input voltage. (95v to
135v, for 115v units)
Diagnostic Testing
Diagnostic testing can be accessed by one of the
following:
1. Depressing and holding the Apgar Tones switch
while powering up unit. This causes the unit to
cycle in the self test loop until power is removed.
See Self Test Loop in step 2e.
2. Selecting one of the test positions on the 4 posi-
tion “Dip” switch located on the control board.
Following is a description of the functions of the
“Dip” positions:
a. Switches All Open (“Off”) Normal Operating Posi-
tion (00).
b. Switches 2,3,4, Closed (“On”) and Switch 1 Open
(“Off”) Hardware Triac Test (0E) .
This mode can be used to test the hardware triac
test circuit. The heat is switched “On” all the time
to simulate a failed triac. The elapsed time display
will start at zero on power up and display the
elapsed time. At about 3 minutes 24 seconds for
60Hz operation (4 minutes and 5 seconds for 50 Hz
operation) a failed triac should be detected. The
high priority audio alarm should come “On” and the
heat should go “Off". The heat indicator LED lo-
cated on the control board should be checked to
verify that. the heat is “Off”.
c. Switches 1,2,3, Open (“Off”) and Switch 4 Closed
(“On") ADC Calibration (08)
The system displays the actual ADC counts on the
elapsed time display, the patient temperature on
the patient display even if outside of the normal dis-
played range, and the % of nominal line voltage on
the control display. This position is used for calibrat-
ing the analog to digital converter and the line vol-
tage compensation circuit.
d. Switches 1,2,4 Open (“Off”) and Switch 3 Closed
(“On”) Alarm Calibration (04)
All segments of all LEDS are lit. The heater, over-
head alarm lamps, and the observation lamp are on.
The audio alarm emits a steady low priority alarm
sound. The 2 kHz alarm frequency can be adjusted
using this mode.
e. Switches All Closed (“On”) Self Test Loop (0F)
In this mode the unit cycles through a display test,
checks ADC calibration, cycles the heater, alarm
lights, and observation lights, and steps through the
tests described in power up testing. It also monitors
the touch switches and sounds the critical alarm
while any switch is depressed. If any error occurs
the error number will be displayed on the elapsed
time display and the critical alarm will sound for
two seconds, The program will then continue to
loop through this test, even if the 4 DIP switches
are retumed to “Open” (“Off”).