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Maintenance— 2440 Service
Table 6-6 (cont)
Now using CH2 probe:
2.
Check that U754 pin 1 RESET is HI.
3.
Run test 2170 in CONTINUO US mode and check the clock line to A 12U754 at pin 11 for LO-to-HI
transitions. Since this is the register that provides the strobe to W ORD TRIG, there should be four
clock pulses, one at each end of the trigger strobe and two under it. If not, troubleshoot the clock
source to isolate the problem.
4.
Test that U 754 pin 19 has a LO-to-HI transition on the third strobe. If there is no LO-to-HI transi
tion, replace U 754. If there is, then test A 12U854 pin 15 for the same signal as at U759 pin 19.
If
present, replace U854; if not, find the open.
2180
Video Option Mode Register A 12U750 (schematic diagram 20):
FLD2
Testing Method:
TVREG U750 is set = 00000000 and PM ISC IN A 12U 750 pin 3 (schematic diagram 1) is tested for 0.
The test result is set accordingly.
TVREG U750 pin 2 (bit DO) is then set to 1 and PM ISC IN (bit D7) is tested. If the test fails, the test
result is set to FAIL.
Troubleshooting Procedure:
If test = FAIL then look for failure using the following steps:
1.
Set up the test scope as per Step 1 of the 2110 troubleshooting procedure.
Now using the CH 2 probe:
2.
Run test 2180 in CONTINUO US mode and check the clock line to A 12U750 TVREG, pin 11
(schematic diagram 20) for LO-to-HI transitions. There should be two clock pulses under the
trigger strobe. If not, troubleshoot the clock source back through Decoder A 12U884 (schematic
diagram 1) to isolate the problem.
3.
Test that U750 pin 2 (FLD2) has a LO-to-HI transition on the second strobe. If there is no LO-to-
HI transition, replace U 750. If there is, then test U854 pin 17 (schematic diagram 1) for the same
signal as at U750 pin 2. If present, replace U854; if not, find the open.
2190
Miscellaneous Register A 12U760 (schematic diagram 1):
MW PDN
Testing Method:
A BUSTAKE is executed (previously tested), Interrupt Latch bit D2 is set true (W PDN) and PM ISC O U T
Register U760 pin 2 (the mask for W PDN), is set to 0.
INTREG U654 pin 18 (bit DO) is tested for 0 and the test result is set accordingly.
P M ISC O U T U760 pin 2 (bit DO) is set to 1 which should unmask the W PDN that is already set true.
INTREG (bit 0) is tested for 1. If test fails, the test result is set to FAIL.
6-57
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 ...
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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