Model 140A Section IV
Paragraphs 4-1 to 4-8
SECTION IV
PRINCIPLES OF OPERATION
4-1. GENERAL. are made available on the front panel as calibratin
signals accurate to *l%. The 1-volt square wav
4-2. Figure 4-1 is a simplified block diagram ofthe
is also applied to the plug-ins for internal use i
Model 140A Oscilloscope. Three major circuits are
horizontal and vertical sensitivity calibration.
included in the main unit of the oscilloscope: a low-
voltage power supply, an amplitude-and-time cali-
4-5. HIGH-VOLTAGE POWER SUPPLY. A tran
brator, and a high-voltage power supply for the
sistorized oscillator and step-up transformer ar
cathode-ray tube. The vertical and horizontal plug-
used to generate high voltages for the CRT. Bot
ins are not part of the main unit, and operate directly
positive (5 kv) and negative (2.5 kv) supplies ar
into the CRT.
used, and are electronically regulated.
4-3. LOW-VOLTAGE POWER SUPPLY. The low-
voltage power supply uses 115/230 volt single-phase 4-6. LOW-VOLTAGE POWER SUPPLY.
power from the line, and generates the following
4-7. The low-voltage power supply includes an
output voltages: +250, +loo, -100, and -12.6 volts
independent supply (-100 volts) and three dependent
DC, and 6.3 volts AC. All DC supplies are regulated.
supplies (+250, +lo0 and -12.6 volts). The -100
Voltages are distributed to the calibrator, the high-
volt supply is a reference for the +lo0 volt supply.
voltage power supply, and the vertical and horizontal
A breakdown diode serves as the reference for the
plug-in units.
-12.6 volt supply. The +250 volt supply is obtained
by stacking a 150-volt supply on top of the +lo0 volt
4-4. CALIBRATOR. The calibrator uses a 6.3-volt supply.
signal from the power transformer to drive a tunnel
diode which shapes the signal to a square-wave output. 4-8. Figure 4-2 is a simplified block diagram of a
Outputs of 10-volts and 1-volt (peak-to-peak amplitude) regulated power supply. The series regulatnv 3-t~
<m
llvl
r------ 1
115/230 I
LOW VOLTAGE 6.3VAC 4-250 +IO0 -100 -12.6
VOLT ,
POWER POWER SUPPLY
INPUT
UNBLANKING
w
HIGH VOLTAGE
Z-AXIS POWER SUPPLY
OD-Y-306
I/.
/
Vld // /
I/
ASTIGMATISM^^
Figure 4-1. Model 140A Block Diagram
01638-1 4- 1 |
ACEC
