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Adjustment Procedure— 2440 Service
4. Set CM /G N-DA C counts, CH 1 side 2 and 4,
at 500 ns: Push the left-most menu button to move
to CM 1E (Common-Mode count, CH 1, Even sides);
then rotate the INTENSITY knob to set this count to
4095. Now check, and set to within limits if neces
sary, the GN-DAC counts for sides 2 and 4 as was
just done for sides 1 and 3 in subpart 3.
5. Set CM /G N-DA C counts, CH 2 all sides, at
500 ns: Rotate the CH 1 POSITION knob to return
the CH 1 trace to center screen. Push VERTICAL
MODE and set CH 2 on and CH 1 off in the menu.
Set CH 2 VOLTS/DIV to 50 mV and rotate the CH 2
POSITION knob to move the CH 2 trace up off
screen. Now, return to the CM counts menu; push
MENU OFF/EXTENDED FUNCTIONS twice; then
push SPECIAL; then push FORCE DAC. The menu
for adjusting the CM counts should now be at the
bottom of the screen, with the CCD counts for CH 2
CCD sides and the message “TESTING CHANNEL
2 ” displayed above that menu. Push the left-most
menu button until C M 20 appears; then repeat sub
parts 3 and 4, adjusting the CH 2 common-mode
counts, C M 2 0 instead of C M IO , and CM 2E instead
of CM IE .
6. Turn off CCD counts display: Vertically posi
tion CH 2 back to center screen. Next, push MENU
OFF/EXTENDED FUNCTIONS twice; then push
SPECIAL; then push CCD ADJ. Now, push the
ADJ T 1 A2 menu button to turn off the A and T
clock adjustment numbers.
7. Match CH 1 CM counts at 200 ns and 100 ns
to 500 ns: Push VERTICAL MODE and set CH 1 on
and CH 2 off. Push MENU OFF/EXTENDED FUNC
TIONS twice; then push the SPECIAL menu button,
and, when the menu changes, push FORCE DAC.
Note the C M IO and CM IE counts obtained in sub
part 4. (Use the left- and right-most menu buttons to
display
C M IO
and
CM1E.)
Now change the
SEC/DIV setting to 200 ns, and use the INTENSITY
control to set C M IO and CM IE to the values just
noted. When finished, push W RITE TO CALSTORE,
followed by the A HORIZONTAL MODE button.
Change the SEC/DIV to 100 ns and match C M IO
and CM 2E to the 500 ns values also.
8. Match CH 2 CM counts at 200 ns and 100 ns
to 500 ns: Push VERTICAL MODE and set CH 2 on
and CH 1 off. Return the SEC/DIV to 500 ns. Repeat
subpart 7 for CH 2, adjusting C M 2 0 and CM2E,
rather than C M IO and CM1E. Remember to push
W RITE TO CALSTORE followed by A HORIZONTAL
MODE after each CM adjustment.
e.
Do a SELF CAL and verify initial CCD gain: Skip
to, and perform, the procedure found under SELF CALI
BRATION in this section. (At this stage of instrument
adjustment,
SELF CALIBRATION
may take several
minutes to run rather than the 10 seconds mentioned in
the SELF CAL procedure.) If instrument passes the SELF
CAL (see NOTE in SELF CAL procedure), skip to part f of
this procedure and continue. If, after redoing a SELF CAL
as directed in parts e and f of the SELF CAL procedure,
any test level except level 7000 has FAIL status, quit this
procedure and refer the instrument to service personnel.
If only test level 7000 failed, verify that CCD gain test
7210- 30 passed: repeatedly push the down-arrow menu
button to move down the underline pointer at test level
0000 until it is under test level 7000. Push RUN/SEL, and
when the menu changes, use the down-arrow button to
underline 7200. Push RUN/SEL. Test levels 7210, 7220,
and 7230 should all have PASS status (ignore 7240 and
7250); if so, push MENU OFF/EXTENDED FUNCTIONS to
remove diagnostic menu and continue with subpart f; if
not, quit this procedure and refer the instrument to
qualified service personnel for repair.
f. C heck CH 2 and CH 1 LF-linearity and position-
effect, and fine-adjust CM counts:
1. Set up instrument for check: Set A SEC/DIV
to 50
n s.
Next, push COUPLING/INVERT and set
50
Q
ON!OFF to ON for both CH 1 and CH 2. Push
ACQUIRE and set REPET O N IO FF to ON. Push
TRIGGER SOURCE and set to VERT in the menu.
Connect the + FAST RISE output of a Calibration
Generator to the CH 2 input connector via a 50-fi
cable. Set the generator output for a 1 ms period
and for exactly 2 vertical divisions (discount trace
width) of amplitude. Vertically center the display.
2. M ake linearity check: Rotate the CH 2
POSITION knob to align the bottom of the waveform
to the horizontal graticule mark 2.5 divisions above
the center horizontal graticule line (the top of the
waveform will be off screen). Now push SAVE, verti
cally reposition the waveform to center screen, and
check that the amplitude of the saved waveform is
between 1.9 and 2.1 divisions. Push ACQUIRE and
repeat the linearity check, this time aligning the
to p
of the waveform to the mark 2.5 divisions below the
center horizontal graticule line before pushing SAVE.
Push ACQUIRE when finished.
3. M ake position-effect check: Set SEC/DIV to
5 ns. Adjust the amplitude of the calibration genera
tor for 5 divisions, vertically center the pulse, and
REV SEP 1988
5 -9
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 ...
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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 ...
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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