Model 141A Section IV
Paragraphs 4- 1 to 4- 10
SECTION IV
PRINCIPLES OF OPERATION
4-1. OVERALL FUNCTIONAL 4- 5. HIGH-VOLTAGE SUPPLY. A transistorized
DESCRIPTION. oscillator and a step-uptransformerare used to gen-
erate negative andpositive high voltages for the CRT.
4-2. Refer to the block diagram, Figure 4-1, for
Both the +5000-volt and -2350-volt supplies are elec-
this explanation. The Model 141A Oscilloscope has
tronically regulated.
four main circuits: a low-voltage supply, a high-voltage
supply, a calibrator circuit, anda pulse circuit. The 4-6. PULSE CIRCUIT. This circuit generates a
horizontal and vertical amplifier circuits are in the pulse of variable level and width. The pulse and other
plug-in units and operate directly into the CRT. dc voltages from the circuit are applied to the storage
and persistence elements in the CRT. All voltages
4-3. LOW-VOLTAGE SUPPLY. The low-voltage from the low-voltage supply are used in the pulse
supply uses 115 or 230 voltsac (rear panel switch), circuit.
single phase, 50-60 Hz. Output voltages are -12.6,
- 100, +lo0 and +250 volts dc; all outputs are fused and 4-7. CIRCUIT DESCRIPTION.
are electronically regulated. Voltagesare distributed
4-8. LOW-VOLTAGE SUPPLY.
to the high-voltage supply, the calibrator, pulse cir-
cuits, and to the horizontal andverticalplug-ins. 6. 3 4-9. The low-voltage supply consists of an indepen-
vac is supplied from the low voltage transformer to dent -100-volt and three dependent supplies (-12.6,
the main filament of the CRT and as a signal to the +lo0 and +250). The -100-volt supply is a reference
calibrator. for the otherthree supplies. The +250 volts is ob-
tained by stacking a +150-volt supply on the +100-volt
4-4. CALIBRATOR. The 6. 3 vac applied to the cali-
supply.
brator circuit is shaped into a square wave (of line
frequency) and applied to two front panel connectors, 4-10. Figure 4-2 is a simplified block diagram of
10Vand 1V (peak-to-peak amplitude). The 1-volt out- regulator used in the low-voltage supply. The series
put is also supplied to the vertical and horizontal regulator acts as avariable resistance in the regulated
plug- ins for sensitivity calibration. Accuracy of the output A sensor (or differential amplifier) compares
calibrating signal is rt 1% the output voltage with a reference voltage (dc return
<a
m
r---- ----- 1
115/230
I
VOLT LOW VOLTAGE -6.3VAC t250 +IO0 -LOO -12.6 I HORIZONTAL I
' -
~~~~~- POWER SUPPLY UNBLANKING
/PERSISTENCE 1
P/O TRIGGER
BEAM t / CONNECTION BEAM
FINDER FINDER
- PULSE - I
CIRCUIT 7 VERTICAL I
J PLUG-IN
I
. I
A L --------- J
d
HIGH VOLTAGE -
POWER SUPPLY
~~ ~
Figure 4- 1. Model 141A Block Diagram
02567- 1 4- 1
ACEC
