Service manual

LUMISCAN ACR-2000 SERVICE MANUAL – SECTION 7.0 DIAGNOSTICS
Enter > 20 (Display Noise Value)-
M =
B =
Enter > 21 (System Infor)- Detailed system information
Enter > 22 (Set CR/Scan5 Mode) -
Other commands you may enter (not specified by the DDT menu);
Enter> o (oscope)- plots the scanline to the screen.
Enter > s (screen) - dump contents of screen to a file
Enter > pl (plotcal) - Plots a data file to the screen, ie: results.dat.
The following sections are guidelines for troubleshooting sections of the scanner using DDT.
Autozero Check
The room lights should be dim and the unit covered to minimize stray light. Run DDT option 13/5.
Observe the reported results and verify that the voltage reported for Autozero is within the limits +1
volts(the closer to 0 the better). If not check the offset adjustment of the PMT Preamp, which should be
0 mv with P14 disconnected from the DACQ.
Verify AGC Function
Run DDT option 13/5 and verify that the reported AGC voltage is within + 1.0 volts, indicating little or
no AGC compensation required. Unplug the blue LED cable from J1 of the Ref LED/Scrn Pres board
and rerun option 13/5. Verify that the AGC voltage is more positive, indicating that it is adding high
voltage to compensate for signal loss. Reconnect the blue LED to J1 and repeat 13/5. Verify that the
voltage decreases.
Test DACQ Calibration and Lookup Table Access
Run DDT. From the menu choose 9. Test CAL and LUT Memory. From the submenu choose 1. Up
Ramp Test. The test was successful if the screen prints "PASSED" and returns to the main menu,
otherwise it will print the first 64 errors. Repeat test 9 for the following submenu choices:
2. Down Ramp Test
3. Walking 1 Test
4. Walking 0 Test
Test Cal Table Clear Function
From the DDT menu choose 6. Clear Calibration Table. There will be no output - the screen just
redisplays the menu. Choose 7. Plot Cal Table. A graph should appear on the screen displaying 1024
values of 4096 (Max Value = 4096, Min value = 4094). Press any key to return to menu.