CPI CMP 200, Service Manual

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CPI Canada Inc. AEC Calibration
3D
Use and disclosure is subject to the restrictions on the title page of this CPI document.
CMP 200
®
Service Manual Ch # 901476-05 Rev. A Page 3D-24
3D.4.0 SHORT AEC TIME COMPENSATION
Use these steps to perform the short AEC exposure time compensation.
Step Action
THESE STEPS ONLY APPLY IF AEC EXPOSURES LESS THAN APPROXIMATELY 15 MS ARE REQUIRED AND THE AEC
BOARD HAS SHORT AEC TIME ADJUSTMENT POTENTIOMETERS.
1.
Select the image receptor to be short AEC-time compensated, i.e. table Bucky.
2.
Select the highest film speed used on the selected receptor, and then select 75 kV.
3.
Set the mA per table 3D-8 for the film speed being used. Reinstall the absorber as per table 3D-8 for the 75 kV breakpoint.
4.
Make an exposure and confirm the mAs readings as previously recorded in table 3D-9.
5.
Increase the mA such as to decrease the AEC exposure time to approximately 10 ms.
6.
Adjust the short AEC time compensation pot for the AEC channel being calibrated such that the mAs is approximately the same as
previously recorded (step 4).
7.
Increase the mA again such as to decrease the AEC exposure time to approximately 6 ms (but not less).
8.
Adjust the short AEC time compensation pot for the AEC channel being calibrated such that the mAs is approximately the same as
it was in step 6.
9.
The short AEC-time compensation adjustments affect the AEC calibration at longer exposure times. Therefore, it may now be
necessary to readjust the gain pot (at 75 kV) for the AEC channel being calibrated to restore the mAs values to the values
previously recorded in table 3D-9. Ensure that the absorber thickness and mA values are as per table 3D-8 when readjusting the
AEC gain pot.
10.
Using 75 kV exposures, films should be exposed and developed, and the O.D. checked at AEC exposure times of approximately 6
ms and approximately 100 ms. If the film density is not acceptable at both short and long AEC exposure times, it will be necessary
to iterate the adjustments of both the short AEC time compensation pot and the AEC gain pot by repeating steps 3 to 8.
11.
Repeat steps 1 to 10 for each image receptor (AEC channel) to be short AEC time compensated.