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Adjustment Procedure— 2440 Service
a. First, power the scope off. Then, perform subparts
b-f of part 3 of the Removal and Replacement procedure
in Section 6 to access the processor board of the instru
ment. Connect a X I 0 probe to the CH 2 input; then con
nect the ground lead of that probe to pin 5 of J 125 of the
processor board and the probe tip to the cathode of
CR502. (CR502 is immediately above Q504 on the proces
sor board; see the Processor Board drawing in the
Diagrams section to locate CR502.) Power the scope back
on.
b. Set up the scope: if a menu is displayed, press the
MENU OFF/EXTENDED FUNCTIONS button to remove it
from the screen. Select SETUP PRGM, and press the
menu button labeled INIT PAN EL Make the following
changes to the front-panel setup:
Set:
A SEC/DIV
CH 1 VOLTS/DIV
CH 2 VOLTS/DIV
TRIGGER SLOPE
2
ms
500 mV
2 V
- (minus)
Select BANDWIDTH
Set:
20 MHz
On
Select TRIGGER MODE
Set:
AUTO
On
c. Connect the Full-Field Signal output of the video sig
nal generator to the CH 1 input of the scope via a 75 S2
cable and a 75 fi terminator.
d. Set the generator output for a field square wave
producing a 100 IRE pedestal output for all lines. One line
of video, with sync tip and color burst, should be displayed
on screen in CH 1. (See top waveform in Figure 5-12.)
e. ADJUST— R419 while watching the output signal on
the bench scope. First turn R419 all the way clockwise.
Now, slowly rotate the adjustment counter-clockwise until
the IRE pedestal appears on both the rising and falling
edge of the waveform and the bottom of the waveform
moves up slightly. Adjustment is correct when the output
is not overdriven, with the IRE pedestal missing on the ris
ing and edges, or underdriven, with excessive aberrations
on the bottom of the waveform. (See bottom waveform in
Figure 5-12.)
f. Disconnect the test setup. Perform, in reverse order,
subparts b-f in part 3 of the Removal and Replacement
procedure to return the processor board to its normal
position.
Figure 5.12 Input and output (after adjustment) waveforms.
REV SEP 1988
5-2 1
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 ...
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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 ...
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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 ...
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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 ...
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