Overload Measurement Specifications; Theory Of Operation; Voltage Mode; Edge Mode - Fluke 5520A Service Manual

5520A
Service Manual

6-17. Overload Measurement Specifications

Source
Voltage
5 V to 9 V

6-18. Theory of Operation

The following discussion provides a brief overview of the following SC600 operating
modes: voltage, edge, leveled sine wave, time marker, wave generator, video, pulse
generator, input impedance, and overload. This discussion will allow you to identify
which of the main plug-in boards of the Calibrator Mainframe are defective. Figure 6-1
shows a block diagram of the SC600 Option, also referred to as the A50 board. Functions
that are not depicted in the figure are generated from the DDS Assembly (A6 board). For
a diagram of all Calibrator Mainframe board assemblies, refer to Figure 2-1.

6-19. Voltage Mode

All signals for the voltage function are generated from the A51 Voltage/Video board, a
daughter card to the A50 board. A dc reference voltage is supplied to the A51 board from
the A6 DDS board; all dc and ac oscilloscope output voltages are derived from this signal
and generated on the A51 board. The output of the A51 board is passed to the A50 Signal
board (also attached to the A50 board) and attenuator module and is then cabled to the
output connectors on the front panel. The reference dc signal is used to generate both +
and - dc and ac signals that are amplified or attenuated to provide the complete range of
output signals.

6-20. Edge Mode

The edge clock originates on the DDS A6 board and is passed to the A50 board. The
signal is then shaped and split to generate the fast edge and external trigger signals. The
edge signal is passed from the A50 board first to the attenuator assembly (where range
attenuation occurs) and then to the SCOPE connector BNC on the front panel. If turned
on, the trigger is connected to the Trig Out BNC on the front panel.

6-21. Leveled Sine Wave Mode

All of the leveled sine wave signals (from 50 kHz to 600 MHz) are produced on the A50
board. The leveled sine wave signal is passed from the A50 board to the on-board
attenuator assembly. The attenuator assembly provides range attenuation and also
contains a power detector which maintains amplitude flatness across the frequency range.
The signal is then passed to the SCOPE connector BNC on the front panel.
6-12
Table 6-14. Overload Measurement Specifications
Typical 'On' current
indication
100 mA to 180 mA
Typical 'Off' current
indication
10 mA
Maximum Time Limit DC or
AC (1 kHz)
setable 1 s to 60 s