Test Step: Wloopfilt (Wideband Sensor Filter) - Fluke 5790A Service Manual

Troubleshooting 5
Introduction
This error indicates that the fault is probably on A6 Wideband assembly. There is a slight
chance the fault is on A15 A/D Amplifier assembly. Check that the chopper (AC signal)
is being transmitted to the A6 Wideband assembly. Trace through amplifiers to input of
sensor. From there it is routed through prescalers and filters to the COUNT motherboard
line back to the A15 A/D Amplifier assembly to U24.

5-25. Test Step: WLOOPFILT (Wideband Sensor Filter)

Tests slow mode sensor loop filter settling time.
Fault 3020: A10 Wideband: Sensor Loop Settling
Transfer board configured in 7 V wideband range, no inputs. Special chopper setup, 0 dB
attenuation. Connect sensor output to RCL. Positive instrumentation amplifier input to
RCL, negative to RCOM. Sensor loop filter in slow mode. Set DAC to 70 mV. Let the
sensor output settle. Measure sensor output with x1 A/D range. Switch in 40 dB
attenuation in chopper. Let it settle. Again switch out the 40 dB attenuation and then
immediately take 8 sample A/D readings. Compare this reading with first settled reading.
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