Tektronix 2235 User Manual

Theory of
Operation-2235 Service
NOTE

tions the Β trace with respect to the Α trace when Alt Hori-
zontal M
ode
is selected .
Wh en readi n g t h is genera/ ci rc u it d escri p tio n of t he
2235 Oscilloscope, refe r to t he basic bloc k diag r am
( F ί gure 9-4) and to t he d etailed b loc k d ί ag r am ( F ί gure
The Α Trigger circuitry uses either an Internal
Trigger sig-
9-5) located in t he "Diag r ams" section of t h is manual .

ηαΙ , an External
Trigger signal,
or α
L ine Trigger signal ob-
/ η Figures 9-4 and 9-5, t he numbere dd iamon d sym b ol

tained from the ac p ower
line
to develo p
t
he gate
signal for
in eac h ma j or b loc k refers to t h e appropriate schema t-

t he Α Sweep Generator
.
The Β Trigger circuitry uses only
is diagram n umber .

t he Internal Trigger signal to gate the
Β
Sweep Generator
. Α
Ρ - Ρ Auto Trigger circuit ensures that the
range
of
the
Α TRIGGER LEVEL control tracks
the
p eak-to- p eak
ampli
Signals to b e displayed on the crt are applied to either

tude of
the trigger signal when either the Ρ - Ρ Auto or TV
t he CH 1 OR Χ input connector or t he CH 2 OR Υ input

Field trigger mo de is selected . This allows triggering on
connector . These signals may be directly (DC) coupled to

most signals without
n
eeding to adjust
the Α TRIGGER
t he Attenuator circuit or ac (AC) cou p led through an in p ut-

LEVEL control
.
In
Norm
mode,
the Α T RIGGER LEVEL con-
coupling capacitor . The in p ut signals may also b e d iscon-

trol must b e adjusted
for
the correct
trigger signal level
b
e-
nected from the oscilloscope circuitry and the in p ut

fore α sweep can b e generated .
When
t he
TRIG V IEW
attenuator grounded by setting the cou p ling switch to the

switch is activated, the
signal
app
earing
at
the input of the
GND p osition .

Α Trigger circuit is applied to the Delay
L ine Driver
and
d is-
p layed on the crt .
The output signal from the Attenuator circuit is ap plied to
the V ertical Preamplifier for further am p lification . Additional-

Α TV Field sync circuit p rovides stable triggering on tele-
Ιγ , the Channel 2 Attenuator can invert the Channel 2 d is-

vision vertical-sync pulses .
Triggering
at
the television line
play on the crt . Trigger Pickoff Amplifiers in each channel

rate is accomplished
when either Ρ - Ρ Auto or N orm mode is
supp ly an internal trigger signal from either or both channels

selected .
t o the Internal Trigger Am p lifier .
The Α Sweep Logic circuit controls sweep generation
Input signals are selecte d for d isplay by the Channel

and Ζ -Axis
unblanking
for
the Α Sweep d isplay . When t he
Switching circuit under control of the front-panel VERTICAL

Α TRIGGER Mode switches
are set to either Ρ - Ρ AUTO or
MODE switches . The output signal from the Channel

TV FIELD and no trigger signal is p resent, the Auto
B
aseline
Switching circuit is applied to α Diode Gate circuit to enable

circuit causes the Sweep L ogic circuit to produce α
sweep
either the vertical or trigger view signal to d rive the Delay

for reference p ur poses . In the
NORM setting, the Auto
L ine Driver stage . This stage converts α current input to α

B aseline circuit is d isabled and sweeps are
inhibited u ntil α
voltage out p ut and provides an impedance match for the

trigger
event occurs .
This
is
u seful for triggering on low-
Delay L ine . The Delay L ine produces app roximately 90 ns of

repetition-rate
signals
.
The SGL SWP setting enables only
delay in the vertical signal . This allows the Horizontal circuit-

one swee p to be generated after b
eing
reset .
Following the
ry time to start the sweep so that the operator can see the

single sweep, the
Α Trigger circuit is d isabled until the SGL
signal that triggered the sweep .

SWP button is p ressed again
.
Final am p lification of the vertical signal is p erformed by

The Α Sweep L ogic
circuit
controls
the
operation
of the
the V ertical Output Amplifier . This Am p lifier su p plies the sig-

Α Miller Sweep Generator circuit
.
The Swee p circuit pro-
ηαΙ levels necessary for vertical deflection of the electron

duces α linear sweep output with α ramp time that is con-
beam in the crt . The upper frequency response of the Ampli-

trolled by the Α SEC/DIV switch
. The
sweep
signal
is
fier can be reduced by enabling the Bandwidth Limit circuit-

a pp lied to the Horizontal
Preamplifier for initial amplification
ry . For locating the p osition of off-screen dis p lays, the

and then to
the H orizontal Output Amplifier to drive the crt
dynamic range of the
Amplifier
can be
limited with
t he
B
eam

h orizontal
deflection
plates .
Find circuitry . This circuitry also intensifies the trace and
limits h orizontal deflection .
The
Horizontal Preamplifier gain is increased by α factor
of 10
when the

X10
M agnifier is used . Horizontal positioning
The Α / Β Swee p Separation circuitry supplies α dc-offset

of the display is accomplished in the Horizontal Preamplifier
current to the
V
ertical Out
p
ut
Am p lifier which vertically posi-

circuit .
G ENER A L D E SC R I P TIO N

Tektronix 2235 Specifications

General

Brand	Tektronix
Model	2235
Category	Test Equipment
Language	English