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Maintenance— 2440 Service
Table 6-6 (cont)
Using the CH 2 probe:
Check for activity on the write enable line pin 27.
Check for activity on the output enable line pin 22.
Check the data I/O pins (pins 11, 12, 1 1 ,1 5 , 16, 17, 18, 18) for activity.
Check the data I/O pins (pins 11, 12, 13, 14, 15, 16, 17, 18,) of U660 for activity. If not active,
check its write enable and output enable lines (pins 1,1 9).
4000
Front Panel
nP
A 13U 700 (schematic diagram 3):
FPP
Testing Method:
The Front Panel Processor test first sets all test results to NULL. Any failure to complete all the tests
will result in a locked front panel. Depending on the nature of the failure, the Trigger LEDS may be
latched in the first number of the test level that failed, the failure code may be flashed out on the LEDs
(if it is the first failed test), or it may make it through the diagnostic, but with the FPP test marked
FAIL. That information will help to isolate which circuitry may be defective and gives the starting point
in troubleshooting a failure. It will be necessary to turn off the scope and turn it back on again to
repeat the diagnostic testing from the front panel; however, testing may be done using GPIB diagnos
tic test commands.
The Front Panel
nP
internal diagnostics require that the
ixP
be reset. Therefore, the structure of the
FPP tests is such that the processor is initialized when completed. This requires that ALL of the tests
be run in order. Therefore, all tests will be run even though it appears that only a sub-test is being
executed.
Test Steps:
4100
U861 pin 9 should be reset to its LO state via U862B and U862A.
4200
U861 pin 6 should be reset to its HI state via U862C and U 862D.
4300
U861 pin 9 (W R TO H O ST) should dock pin 9 HI.
4400
U700 (Front Panel
m
P) checks its internal RAM , R O M , Tim er, and A /D . Any failure will set the
test result to FAIL.
4500
U861 pin 6 (FPDNRD) should dock pin 6 LO.
4600
U 742 and U 751. Four bit patterns are w ritten to the FPP and echoed back. If these are not
returned properly, the test result = FAIL.
Troubleshooting Procedure:
Failure of one of the Front-Panel
nP
tests may be indicated only by flashing out the failed test number
on the Trigger LEDs, but if the diagnostic testing can continue past the failure, the Extended Diagnos
tic menu will be seen with the FPP test marked FAIL. The usual result of a Front Panel
nP
failure is a
locked up front panel (the button and pots will not be functional). To rerun the diagnostic testing from
the front panel to check the Trigger LEDs for the failed test number, it is necessary to turn off then
turn back on the scope.
6-78
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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