Fluke 863, Руководство по обслуживанию

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867B,863
Service Manual
2-18
mA/µA 2-32.
Milliamp and microamp measurements are connected at the and
â
inputs.
For the 300 mA and 30 mA ranges, input current flows through L9, F2, K1-4, K1-5, K1-
6, R42, and R109 to
â
. The voltage developed across R42 and R109 is sensed
through R151 by U16.
For 3000
µ
A and 300
µ
A ranges, input current flows through L9, F2, R49, R42, and
R109 to
â
. The voltage developed across R49, R42, and R109 is sensed through
R151 and R148 by U16.
For DC current (mA and
µ
A), voltage is sensed through R82 to U30-9. U30 routes this
voltage to the active filter and the Slow A/D Converter.
For AC current (mA and
µ
A), the voltage is sensed though another switch of U16 and
routed to the AC path.
Amps 2-33.
Amps measurements are connected at the
á
and
â
inputs. The current flows through
F1 and R109 to
â
. The voltage is sensed first though R42, then as described above
for mA/
µ
A measurements.
Table 2-9. Amps Measurement Paths
Range Shunt Slow A/D Converter Range
300
µ
A R49, R42, R109 30 mV
3000
µ
A R49, R42, R109 300 mV
30 mA R42, R109 30 mV
300 mA R42, R109 300 mV
3A R109 30 mV
10A R109 300 mV