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M a in te n a n c e - 2 4 4 0 Service
Table 6-6
2440 Troubleshooting P ro cedu res (cont)
2.
Check for LO at U861 pin 6; replace U861 if pin 6 is HI.
3.
Check A12U654 pin 13 for LO. Replace A12U654 if pin 13 is LO and test is failing.
4600 A13U742/A13U751:
1.
Check for a pattern of 10100101 at U742 pin 1 9 ,1 6 ,1 5 ,1 2 ,9 , 6 ,5 , and 2 at the rising edge of
the trigger strobe (Word Recognizer Probe is useful for this check). If not, and U742 pin 11 is
LO, then replace U742. If U742 pin 11 is HI, replace U700.
2.
Check the enable pulse at U751 pins 1 and 19. Save and move to REF1.
3.
Display REF1 and check for a 10100101 pattern coincident with the enable pulse at U751 pins
1 7 ,1 5 ,1 3 ,1 1 ,8 ,6 ,4 , and 2. If not ok, replace U700.
4.
Display REF1 and check for a 10100101 pattern coincident with the enable pulse at U751 pins
3 ,6 ,7 ,9 ,1 2 ,1 4 ,1 6 , and 18. If not ok, replace U751.
4700 BATT STATUS
Battery A12BT800 (NVRAM keep-alive battery) (schematic diagram 1):
Testing Method:
There is no hardware exercised for this test. The operating system is informed by the front panel
processor if the battery voltage is either high or low. The “test” is to read a memory location where
the System (
jl
P has stored the status after checking with the FPP. If the status is unknown, the result
is NULL. If the test “passes,” it means that it is not defective in that direction.
Troubleshooting Procedure:
4710 HIGH:
1.
Measure the drop across A12R900, for a voltage in the range, 2.4 V to 3.7 V. If the battery
voltage is in range, proceed to step 2, otherwise proceed to step 3.
2.
Check the voltage at A13U700, pin 21, in the range of 2.4 V to 3.7V. If the voltage is correct,
replace A13U700. If the voltage is not correct, backtrack and check the voltage follower,
A12U940A. If A12U940A is ok, proceed to step 3, otherwise replace A12U940A and retest.
3.
If the above steps do not fix the overvoltage condition, then check the + 5 VD supply in the
range of 4.75 V to 5.25 V.
4720 LOW:
There is a sub-menu, defining three battery tests:
4720 /FPP/BATT-STATUS/LOW
4721 BT800
4722 U664BT
4723 U360BT
Only U664BT and U350BT are actually used. If either NVRAM modules, A12U664 or A12U350
internal battery voltage is too low, a data write is prevented and a FAIL is placed on the NVRAM
module, 4722 U664BT and/or 4723 U350BT. Should a FAIL occur for 4721 BT800, then the voltage
detection circuitry (A12U940A, A13U700, A12R900, A12R801) is defective.
4721 BT800:
Measure the voltage at the junction of A12R900 and A12R801. The voltage should be in the range,
2.4 V to 3.7 V. If the voltage is low, check the resistors, A12R900 and A12R801, and the + 5 VD
supply. If the voltage measured is correct, then check voltage for range at A12U940A, and at
A13U700, pin 21.
REV JUN 1991
6-81
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 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 517: ...10 16 R E V J U L 1993 Replaceable Mechanical Parts ...
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