Hologic DISCOVERY A - 4.8 A;D Gain Control Adjustment

Discovery QDR Series Technical Manual
4-27
• On systems without a separate A/D Converter board, the adjustment is the only poten-
tiometer on the X-Ray Detector assembly.
Caution:Any adjustment of this potentiometer affects the QC highs and lows. You must
run detector flattening after adjusting the A/D gain. DO NOT ADJUST THE A/
D GAIN UNLESS ABSOLUTELY NECESSARY AS DEFINED BY “Check
and Verify the A/D Gain” on page 4-27.
4.8.1 Check and Verify the A/D Gain
1. Install all system covers that are normally in the X-ray beam.
2. Install the table pad onto the table.
3. Start the QDR/APEX software in Service mode.
4. On the QDR/APEX main screen, select Utilities|Service Utilities|X-Ray
Survey.
5. Set Pulse to 1, press <ALT><P>.
6. Set
a. Hi Gains to 2.
b. Lo Gains to 1.
c. X-ray Mode to 3.
d. Aperture to 7.
5. Press <Enter>.
6. Display the X-Ray Survey bar graph, press <Ctrl><Page Down>.
7. Observe Hi Air, press <Alt><S>.
8. Turn on X-rays, press <F1>.
9. Verify that the average X-ray signal level is 6.25V and that all detectors are
within the 4.5V to 8.5V range. If these conditions are met, the procedure is com
-
plete. Do not adjust the A/D gain.
If these conditions are not met, continue to “Adjust the A/D Gain” on page 4-27.
4.8.2 Adjust the A/D Gain
Caution:Do not adjust the A/D gain unless absolutely necessary as defined by “Check
and Verify the A/D Gain” on page 4-27.
1. Adjust the A/D gain potentiometer to achieve an average X-ray signal of 6.25V.
2. Check that all detectors are within a range of 4.5V to 8.5V.
3. Perform the Detector Flattening procedure described in “Detector Flattening ” on
page 4-29.