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Maintenance— 2440 Service
Table 6-6 (cont)
CCD Output Troubleshooting Procedure (Schematic Diagram 14):
NOTE
Steps 1-6 troubleshoot only that section of the CCD OUTPUT (schematic diagram 14) that processes the
plus/minus signal pair (/CCDOD11 —) that is output by side 1 of the CH 1 CCD.
The references to
components and signals in these steps only apply to that channel and side.
See schematic diagram 14 to deter
mine the corresponding components for troubleshooting the sections processing the remaining signal pairs for
CH 1 CCD side 1 (/CCDOD12-, /CCDOD13-, and /CCDOD14-), and
those
for
the
CH
2
CCD
side
2
(/CCDOD21-,
/CCDOD22
- ,
/CCDOD23-, and /CCDOD24-).
1.
Input the 2440 calibrator signal to the channel that is not operating properly. If neither is work
ing, start with CH 1. (CH 1, side 1 components are referenced: see NOTE above.) Set the bad
channel to 100 mV/div, DC coupled, with 50 fl termination off. Adjust the screen waveform so
the ground dot on the scope under test is 2 divisions below center screen if possible. Set the
input coupling of the other channel to ground. Turn the A SEC/DIV to 5
fis.
2.
Verify that pin 3 (C C D O D 1 1 + ) of A30 (Gain Cell Board) looks similar to waveform 104 (on
schematic diagram 14), with center screen being at + 5 V. If this waveform does not appear,
troubleshoot the CCD/Clock Drivers. Verify that pin 2 (C CD O D 11—) of A30 resembles waveform
105. Again, if this waveform does not appear, go to the CCD/Clock Driver troubleshooting.
3.
Examine pin 18 of A30. The waveform here should have an offset of + 7 .5 V, which is shown at
center screen on waveform 106 for diagram 14. If this waveform does not look right, check the
components on A30 for failures.
4.
Compare pin 1 of A30 to waveform 107. If this waveform does not appear, check to see that pin
3 of U560 is switching between 0 and + 1 5 V; if it is, then the switch (U560) is bad. If it is not
switching, check to see if the base of Q 660 (Q670) is switching between 0.5 V and 0 V; if it is,
the transistor is bad. If it is not switching, trace OSAM1 back to the Time Base board.
5.
Observe the waveform at pin 1 of U770. It should be similar to waveform 110, except that an
offset of up to ± 1 .3 V may appear. If this is not the case, check the + 1 0 V RA supply and the
centering voltage (7.5 V ± 1 .3 V). If the voltages are correct, check U770 and its associated
transistors and other components for failure.
6.
Check the collector of Q773. It should look like waveform 109, where center screen corresponds
to ground; if not, check that the base of Q 773 is switching on and off. If base is switching but
the collector is not, check the transistor for a collector-to-emitter short. If it is not switching on
the base, trace the M S 1 1 signal back to the Time Base board. The timing relationships of the
OSAM and the M § signals are shown in waveform 45 through 51 of the System Clocks
schematic (diagram 7).
6-86
Summary of Contents for 2440
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Page 91: ...Theory of Operation 2440 Service 3 49 Figure 3 5 Simplified CCD architecture ...
Page 120: ...Theory of Operation 2440 Service Figure 3 10 DC Restorer 3 78 ...
Page 130: ...Theory of Operation 2440 Service 3 88 ...
Page 136: ...Theory of Operation 2440 Service Figure 3 15 PWM Regulator and Inverter 3 94 ...
Page 138: ...Theory of Operation 2440 Service Figure 3 16 PWM switching waveforms 3 96 ...
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Page 423: ...2440 Service Figure 9 4b 2440 Block diagram part 2 6330 27 BLOCK DIAGRAM PART 2 ...
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Page 428: ...2440 Service WAVEFORMS FOR DIAGRAM 1 6 2 8 5 3 2 ...
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Page 432: ...2440 Service WAVEFORMS FOR DIAGRAM 2 BUS ISOLATED 6 6 0 3 4 9 ...
Page 433: ...WAVEFORMS FOR DIAGRAM 2 ...
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Page 450: ...2440 Service WAVEFORMS FOR DIAGRAM 8 6603 27 ...
Page 455: ...W A V EFO R M S FOR D IAG RAM 11 WAVEFORMS FOR DIAGRAM 11 6603 29 ...
Page 458: ...WAVEFORMS FOR DIAGRAM 12 ...
Page 463: ...WAVEFORMS FOR DIAGRAM 14 ...
Page 471: ... C N i u i t e x r 4 j u J l i 1 i 6 28 5 44 WAVEFORMS FOR DIAGRAM 18 ...
Page 476: ...WAVEFORMS FOR DIAGRAM 20 ...
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Page 502: ...2440 Service FIG 1 C A B IN E T ...
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Page 510: ...2440 Service SISSVHO Z Old ...
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Page 512: ...A12 2440 Service F IG 3 C IR C U IT BOARDS ...
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Page 517: ...10 16 R E V J U L 1993 Replaceable Mechanical Parts ...
Page 518: ...2440 Service ...
Page 519: ...FIG 4 L V H V PWR SUPPLY ...
Page 520: ...FIG 5 ACCESSORIES 2440 Service ...
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