Fluke Biomedical 956A-201-M2 - Manual (Page 32)

3-6
Check Source Mode
The check source pushbutton and electronics are provided to verify detector operation. To operate the
check source, press the CHECK SOURCE pushbutton and hold it down. The check source relay will
energize, the check source indicator will illuminate (green), and the check source mechanism will expose
the check source (sealed capsule of
36 CI) to the G-M tube by positioning the source over an access on the
detector printed circuit board. The counters will be cleared and radiation values displayed on the front
panel will reflect the average of the new values received. Releasing the check source pushbutton will
return the source capsule to its shielded position, clear the radiation value stored in the UDR counter and
extinguish the check source indicator, allowing normal UDR operation to resume. After approximately 60
seconds, the displayed value will indicate the average of the previous 60 one-second values stored. An
internal configuration jumper (JP3-5) allows alarms to be activated or muted if alarm limits are exceeded
by the check source radiation value.
The bargraph operates normally during Check Source operation.
The bargraph and alarms are inhibited from changing state for five (5) seconds upon entry and exit of the
Check Source function.
The front panel Alarm and Warn status indicators are disabled during Check Source operation.
The analog outputs are set to zero (i.e. 4 mA or 0V) during Check Source operation.
Calibration (scaler) Mode Operation
Calibrate mode for the UDR is entered by turning the rotary setpoint switch to position 8 and pressing the
ENTER button.
The current calibration time setpoint is displayed in seconds, with the first digit flashing to indicate the edit
mode. The bargraph will turn off, the analog output will remain fixed at their value just prior to entering
Calibrate, the Fail LED will illuminate, the radiation unit backlights will turn off, the HIGH, WARN and
Range LED’s will turn off, and the Fail Safe High, WARN and Fail relays will de-energize. The calibration
setpoint may be edited, but will reset to 60 seconds whenever the unit is turned off or the functional switch
is moved from position 8.
Once the desired calibration time is set, momentarily pressing the ENTER button again will start the
calibration. The display will go to zero and the unit’s backlight will begin to flash. The UDR will count for
the entered calibration time, displaying the current summation of counts each second. When the
calibration is completed, the final summation of counts for the calibration time is displayed and the unit’s
backlights will be steady on.
Another calibration can then be executed by pressing the ENTER key, and the system will again display
the calibration time for editing. Pressing the Enter button again will start the Calibrate timer. A calibration
in process can be stopped by pressing the ENTER key or by moving the rotary switch to a position other
than position 8. The calibration mode is exited by moving the rotary function switch out of position 8. The
UDR will reset, the Fail Safe High, Warn, and Fail relays will energize, and the UDR will continue normal
operation.
When the calibrate mode is initiated (i.e. rotary setpoint switch at
position 8 and the Enter button is pressed), the Alarm, Warn, and
Fail relays change state to indicate the monitor is in a non-
operational state.
NOTE