Ac Signal Tracing; Option -09 Service Position - Fluke 8842A Instruction Manual

8842A
Instruction Manual
If the signal at the input to U801A (pin 5) is incorrect, U804 may be defective, or the
switch codes may be wrong. If the latter problem is suspected, refer to Table 6-28 and
test the control lines to U804 (U804-1, 8, 9, 16). If a logic error is found, it may be due to
excessive loading or a faulty data latch (U803), or other cabling or main-board digital
problems. High-frequency oscillation problems are usually caused by switches being on
when they should be off, resulting in positive feedback loops being closed around
portions of the scaling circuitry.
RANGE
200 mV
2V
20V
200V
700V
If the signal at TP802 is incorrect, but U801-5 is OK, the digitally controlled filter section
(U801A and U808) is probably defective.
6-68
Figure 6-20. Option -09 Service Position
Table 6-27. AC Signal Tracing
INPUT VOLTAGE (1
kHz)
100 mV
1V
10V
10V
100V
VOLTAGE AT TP801
20 mV
200 mV
2V
20 mV
200 mV
f6-20.wmf
VOLTAGE AT TP802
1 V
1 V
1V
100 mV
100 mV