Fluke 96000 Series Service Manual page 37

The differential trapezoidal waveform is applied to the primary of the low voltage
(LV) transformer. This transformer has three secondary windings whose outputs
are rectified, smoothed and regulated on the Synthesizer PCA to produce floating
supply outputs of +20 V dc unregulated, -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 Synthesizer PCA, RF Output PCA, Leveling Head and 27 GHz Control PCA
(96270A) are powered. These supplies can be shut down under the command of
a signal from the Digital PCA which disables the +30 V dc regulator on the Power
Supply PCA.
Line supply voltage input that is too low for the Instrument to operate is detected
by the SMPS, processed on the Power Supply PCA to drive a signal that shuts
down the Digital PCA until a suitable supply voltage is detected.
The potentiometer at the back right of the Synthesizer PCA should be adjusted to
minimize common mode on the floating RF common.
On the Digital PCA the floating RF Common circuitry powering the Power Sensor
Interfaces(96270A) has a local +5 V switching regulator supplied by the floating
+20 V unregulated supply. In the 96270A the status LEDs adjacent to the
Microwave Output & Leveling Head Output Connectors are driven by the Digital
PCA. The front USB Interface is controlled by the Digital PCA with signals routed
via the ribbon cable and keypad PCA in the Front Panel Assembly.
Theory of Operation
Overall Functional Description
2
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