Fluke Biomedical 945A - Manual (Page 75)

19. Remove the TEST 977 V10 firmware and reinstall the 977 operating firmware in the Z10 location on
the 977-200-15 board. Make sure that the operating firmware is inserted correctly or damage to
the 977 or PROM could result.
20. Remove the 977 to terminal communications cable from J4 on the detector. Apply power to the
946 UDR. The 946 display should show a radiation value which will slowly decrease toward the
actual background level present in the detector’s location. If error code E0007 is displayed,
recheck jumper block JMP1 on the 977-210-10 board, and verify that it is in the A - B position and
the DIP switched are set correctly.
21.
If the detector is being returned to service, check the desiccant and replace if required.
22.
Place the lid clamps over the preamplifier box lid and tighten down the four screws. This completes
the adjustment.
Analog Output Adjustments (946A UDR)
1.
The following steps may be performed without the use of test firmware installed, but does require
that the detector is in a 1 mR/h field or greater. If the normal channel background is below 1 mR/h,
a bias source or the closed position of the Victoreen Model 848-8 Field Calibrator may be used to
provide the necessary constant dose rate. Zero and span adjustments are accomplished by
“forcing” the output low and high respectively through setpoint entry for analog low scale (position
4) and analog full scale (position 7) that adhere to the following criteria.
Zero Adjust low scale setpoint set above dose rate displayed on 946A
Span Adjust full scale setpoint set below dose rate displayed on 946A.
A one decade separation must be maintained between the analog low scale and analog full scale
setpoint. Both entries must exact powers of ten to be accepted as valid entries. The following
adjustment steps pertain only to the standard 0 - 10 Volt and 4 - 20 mA outputs. Refer to the appropriate
analog option instruction manual for adjustment details of option boards that may be supplied.
0 to 10 Volt, zero, and span adjust
1.
Note the dose rate value on the display and set the low scale setpoint value (position 7 of the 946A
function switch) to the next even decade value above the display value.
2.
Connect the DVM to the 946A connector P6-5 (+) and P6-6 (-).
3.
Adjust VR1 for a DVM reading of 0 ± 0.005 Volts. Return the low scale setpoint to the original
value.
4.
Set the analog full scale value (position 4 of the 946A function switch) to the next even decade
value below the display value.
7-5