Fluke 900 User Manual
Page 93
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FLUKE 900 SERVICE MANUAL
Maintenance
probe B to the output of a related ’86 gate and measure t3 and t4.
- Press any key to abort the looping activity. Press lS)(l_fault) and measure t5, t6, t7,
t8 as indicated on figure 3b. Pressing any key aborts the looping activity.
A:
■A
B(HF)
B(LF)
CCLF)
fig. 3
q
fig. 3b
Calculate the following values:
A= abs(tl-t5)
B = abs(t2-t6)
If A>B then 74AS244 generates too big an offset and should be replaced.
If A<B then 74AHCT86 is faulty and should be replaced.
If A=B then calculate new values:
A = abs(t3-t7)
B = abs(t4-t8)
Now, if A>B then 74AS244 generates too big an offset and should be replaced.
If A<B then 74AHCT86 is faulty and should be replaced.
If A=B any of them may be replaced.
The calibration procedure should then be restarted.
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