Fluke 9640A Series, Инструкция по эксплуатации

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Theory of Operation
Overall Functional Description
6
6-7
Power Supplies
Line power is fed via a Power Block module A7H1 mounted on the rear panel to the
A7T1 Power Transformer. The A7T1 Power Transformer has two primary windings
which can be connected either in series or parallel by means of a voltage-selector insert
within the power entry module (power block). Properly positioning the voltage-selector
insert allows the Instrument to accommodate its full range of line voltages.
The stepped-down voltage at the A7T1 Power Transformer secondary is rectified and
smoothed on the A4 Power Supply PCA to produce an unregulated DC output of +64 V
(nominal). From this output, switch mode and linear techniques are used to derive earth-
referenced regulated DC outputs which i5 V dc, -8.2 V dc, +12 V dc, +20 V dc,
and +38 V dc.
The +5 V dc supply is used to power the A3 Digital PCA where a +3.3 V dc supply is
also derived, both for internal use and to power the A6A2 Keypad PCA and color display
(when fitted). The +12 V dc supply provides power to the backlight inverter for the
display and is also routed via the A3 Digital PCA where it can be switched under
firmware control.
The +38 V dc supply feeds a trapezoidal waveform generator, located on the A4 Power
Supply PCA, which produces a differential pair of line locked, 76 V peak-to-peak,
200/240Hz, flat-topped waveforms with controlled rise and fall times.
The differential trapezoidal waveform is applied to the primary of the low voltage (LV)
transformer, T2. This transformer has three secondary windings whose outputs are
rectified, smoothed and regulated on the A1 Synthesizer PCA to produce floating supply
outputs of -5.2 V dc, +3.3 V dc, +5 V dc, -15 V dc, +2.5 V dc, +9 V dc, +12 V dc,
+15 V dc, and +25 V dc from which all functions on the A1 Synthesizer PCA, A2 RF
Output PCA and A9 Leveling Head are powered. These supplies can be shut down under
the command of a signal from the A3 Digital PCA which disables the +38 V dc regulator
on the A4 Power Supply PCA.