Teledyne 4700 Serivce Manual page 92

4700 Refrigerated Sampler Service Guide
Section 4 CPU and Power Supply
Table 4-2 CPU Board Functional Tests (Continued)
Function Command
Test refrigeration T30
control input and
This test outputs two 100ms pulses on each of
outputs
the four refrigeration control outputs.
The sample temperature input is not used and
not tested.
Display refrigerator T33
temperature
This test reads the resistance on the
refrigeration air temperature input (P6-1 and
P6-2) and returns it as a temperature in
degrees C. It then reads the refrigeration
evaporator temperature input (P5-1 and P5-3),
and returns it as a temperature in degrees C on
a new line.
Display PCB T34
temperature
This test reads the temperature from the
on-board temperature sensor and returns this
value in degrees C.
Display compressor T50
duty cycle
The duty cycle is computed from the state of the
compressor; this data is stored at one-minute
intervals.
Display input voltage T35
This test measures and returns the nominal 12V
input voltage to the board.
Additional input power testing:
Power Fail alert measured at TP12. Reduce power input at R34.
Goes low when 12V power to board falls to about 8 volts.
Measure the current draw of the board from the 12V supply (Power In at U11).
Measure the 5V power at U12 pin 1.
Measure the 3.3V power at TP9.
Measure the -3.3V power at TP5.
Display battery T36
voltage
This test measures and returns the voltage of
the lithium battery.
Display loaded battery T37
voltage
This test measures and returns the voltage of
the lithium battery with the 20K resistor loading
the battery.
Additional battery testing:
Measure the standby current draw from the battery.
Remove the 12V power from the board to perform this test. Using a meter that can read down to 0.01 millivolt,
measure this current by measuring the voltage between TP 11+ and TP 10-. The voltage should be less than 4mV.
4-10
Refrigeration/Temperatures
Power
Results
A pulse is output first on the compressor
output (5V on P14-1), then the refrigerator
fan (5V on P14-3), then the cabinet heater
(5V on P14-2) and finally the compressor
heater (3.3V on P14-4). There is a 100ms
pause between each pulse.
Returns OK to indicate completion
Returns OK to indicate completion
Returns OK to indicate completion
Returns duty cycle as a percent of ON time
for the compressor over the last 4 hours.
Returns OK to indicate completion
Returns OK to indicate completion
Returns OK to indicate completion
Returns the battery voltage at one second
intervals for 15 seconds.
Returns OK to indicate completion