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Maintenance— 2440 Service
Table 6-6 (cont)
FOCUS
If all the focus voltages and adjustments are correct in the following checks and proper focusing can
not tie attained, suspect a defective crt. Check all the crt voltages and EXT CAL Display ADJUSTS for
the crt to verify their accuracy before changing a suspected crt.
No Focus at Any Intensity:
1.
Check the ASTIG adjustment.
2.
Check junction of R262 and R145 for a voltage swing of 0 to 15 V as the FOCUS pot is adjusted
from one extreme to the other. If not correct, troubleshoot pot, connectors between the pot and
the junction, and the 15 V supply to the FOCUS pot.
3.
Check at the collector of Q152 for a voltage swing of —175 V to - 1 1 5 V as the FOCUS pot is
adjusted from one extreme to the other.
4.
Check for - 3 0 0 V at the junction of R248 and R247. If not correct, check CR611, CR610, C618
and the 150 V peak ac supply.
A n H V p ro b e is re q u ire d fo r th e fo llo w in g s te p .
5.
Check the intensity grid, cathode, and anode voltages for correct levels. If not correct, trouble
shoot faulty circuit.
Poor Focus at High Intensity:
1.
Check the HIGH DRIVE FOCUS adjustment.
2.
Check the wiper of R400 for a varying voltage as the DISP INTENSITY is increased to high inten
sity levels. If not correct, check Q500, C R500 and VR316 for shorts or opens.
3.
If the output of R400 tracks the display intensity changes, check R395, R297, C295, and P I 74.
Poor Edge Focus:
1.
Check the EDGE FOCUS adjustment.
2.
Check the collector of Q269 for a voltage swing of —131.8 V to - 1 1 1 . 8 V as the EDGE FOCUS
pot is adjusted from one extreme to the other. Check the wiper of R300 for a voltage swing of 0
to 50 V as the pot is adjusted from one extreme to the other. If not correct, check the pot and the
+ 6 1 V supply.
DEFLECTION
Display Output (schematic diagram 18):
PROBLEM
Vertical Deflection Bad (Horizontal stripe only) or Horizontal Deflection Bad (Vertical stripe only).
1. Press PRGM and then press the fifth menu selection button to do a PANEL INIT.
2. Connect the CALIBRATOR output signal to the CH 1 BNC using one of the supplied 10X
coded probes. Set the 2440 VO LTS/DIV setting to 200 mV.
Press SAVE on the 2440,
then MENU OFF.
6-49
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 ...
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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 ...
Page 476: ...WAVEFORMS FOR DIAGRAM 20 ...
Page 490: ...YES ...
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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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