Tektronix WFM 601A, Service Manual

Page: 61 / 368

Block Diagram Descriptions
3–6
WFM 601A, WFM 601E, & WFM 601M Service Manual
The microprocessor controls this serial in/parallel out register. It outputs control
signals that are not synchronized to the video signal.
The Serial Interface is a latch, driven by the microprocessor, that outputs the chip
select and enables for the serial devices, such as the DACs and the serial/parallel
registers used for the Remote and Front Panel.
There are a number of DACs used to decode microprocessor instructions and
output positioning, gain, and DC offsets to many instrument circuits. These
DACs are serially loaded and clocked devices, which are commonly referred to
as Daculators. The DACs have 15 outputs each that hold their programmed
output once it is set.
The RS-232 input consists of a 9-pin D connector and a line driver. It is used to
calibrate the instrument and for remote control using the remote command set.
The Remote input consists of a 25-pin D connector and parallel in/serial out
registers. The Remote interface provides an external interface for low-level
remote control of the waveform monitors.
Power Supplies
The low-voltage power supply is of the switching, high efficiency type. It is a
universal supply that operates over an AC source range of 90 to 250 V
AC
. The
high-voltage power supply provides an acceleration potential of approximately
13.75 kV. Figure 3–1 provides a block diagram of the power supply.
Low Voltage
Power Supply
High Voltage
Power Supply
4X Multiplier
40 V
DC
40 V
DC
100 V
DC
11 V
DC
5 V
DC
–11 V
DC
To all
circuits
+11 kV
–2.75 kV
CRT
–5.2 V
DC
Figure 3–1: Power supply block diagram
Serial Static Outputs
Serial Interface
Digital-to-Analog
Converter (DAC)
RS232
Remote