Tektronix 7704A User Manual

HI level on one of
five
o
u tput lines to in d icate t he selected
vertical mode ; t
he remaining lines are L O (notice t h at
only fo
u
r of t
h e lines from t h e VER TICA
L M OD E switc h
are
use d on t h is sc h ematic)
.
O p eration of
t h is stage is as
follows :
Wh en t he
VER TICA L M OD E switc h is set to R IG H T, α
HI level is connecte
d
to
the base of Q2553 t h roug h R2501 .
T h
is forward-
b iases Q2553, and the p ositive-going level at
its emitter is connected to t he emitter of Q2556
. T he
collector of Q2556 goes HI to
indicate t h at t he rig h t
vertical unit is to b
e
displayed .
F
or t
h e CH O P position of
t he VER TICA L M OD
E
switc
h ,
α HI
level is ap plied to t he
ano d es of C R 2501-C
R
2502
t h roug h R 2502 . B ot h d iodes
are forwar d biase d so t
h
at
t he V ertical C ho pp i ng Signal
from pin 1 of U 2520 can
pass to t h e base of Q2553 . T h is
signal switc h es b etween
t he
HI
and L O levels at t h e Cloc k
Generator rate and p ro d uces α
corres ponding MF C h annel
Switch Signal (Display
R ig h
t)
output at t he collector of
Q2556 . Wh en t h is outp
u t is HI, t h e rig h t vertical
unit
is
d isplaye d and w
h en it switc h es to LO, t h e left vertical
unit
is displayed .
In t he
A LT p osition of t h e
VER TICA L M OD E switc h , α
HI level is a p
plied to t h e anodes of
C R 2552-C R 2553
t h ro
ug h R 2551 . T h ese dio d es are forwar d
biase d so t he
Dis p lay
R
ig
h
t
Command from p in 6 of t
h e V ertical B inary
stage can
pass to t he base of 02553 to
d etermine t he M
F
C
h annel Switch Signal (Dis p lay
R ig h
t)
level . T he Display
Rig h t Command switc h es
between its HI an d L O
levels
at
α
rate determined b y t h e
V ertical B inary stage .
T he con trol levels in t he
LEF T
an
d ADD positions of
t h e VER TICA L M OD
E
switc
h
are
not con n ected to t h is
stage . However, since only t h
e selecte
d
line from t h e
VER TICA L M OD E switc h can be
HI, t h e RIG H T, CH O P ,
an d A LT lines m u st remain at
t h eir L O level w h en eit h er
LEF T or ADD are selected .
T h erefore, t he base of Q2553
remains L O to produce α
L O MF C h annel Switch Sig n al
(Display R ig h
t)
ou tput
level
at
t he collector of Q2556 .
Α logic diagram of
t he V ertical M ode L ogic stage is
s h own in
F
ig . 2-19 .
VE R TIC X
L
C HO PP I N G
SIG
N A L
F
R
O M
PIN
Ι
_U2520
FR O M VE
R
TICA L
M
OD
E
SWITCH
DIS P
L
AY R IG HT
CO MM AN
D
FR
O M
PIN b
_U12535
Trigger M odes
1 .
LEF T VER TICA L M OD
E
Fig .
2-19 . L ogic diagram of Vertical M ode Logic stage .
Circuit Descri p tio n - 7704A Service
TR IGG ER S ELE CTO R
T he Trigger Selector circuit d etermines t he source of t h
e
t r
iggering signals connecte d to t h e Α ΗΟ
R ΙΖ
an d
Β ΗΟ R ΙΖ
p lug-in com p a r tments . In add ition, t
he Β Trigger Selector
stage provi d es t he d rive for t
he V ertical Signal Out
amplifier (see d iagram 7) .
F igure
2-20
s h ows α simplifie d
d iagram of t he Trigger Selector
circuit .
T h e switc h es s h own on t he left si d e of t he diagram
in
F
ig . 2-20
d etermine t he operation of t h e Trigger
Selector
stages .
Wh en t he Α or Β T R IGG ERSO UR CE switc h is set
to t h
e LEF T VER T
or
RIG H T VER T position, t h e trigger
signal is obtaine
d from t he in d icated vertical compartment ;
w h en in t
h e VER T M OD E positio n , the
VER TICA L M OD E
switc
h setting determines t h e trigger source .
T h ese switc h es
are self-ca n celing ; i .e ., only one bu tton on
t he switc h can b e
presse d at α time .
T
he
following discussion gives op erating d
etails for t h e Α
Trigger
Selector stage ; t h e o p eratio n of t
h e Β Trigger
Selector stage is exactly t
h
e same
exce p t for t he circuit
num b ers .
VER
T M OD E . In t he VER
T
M
OD E p osition of t h e Α or
Β TR IGG ER SO UR C
E
switc
h , t h e setting of t h e
VER TICA L M OD E switc h determines
t he trigger source, as
follows :
In
t
he LEF T vertical
mode, 02090 is not biase d on
so
pin
4 of U 2404 is
h el
d
L O b y voltage d ivi d er
R2093-
R 2094- R 2095 . P in 14 of
U 2404 is h el dL O t hroug
h
C
R
1064
and CR 1065 . Wh
en pi n s 4 an d 14 are bot
h LO, the
LEF T VER T unit su p
plies t he trigger signal (see
F ig . 2-21) .
MF
C
H A NNEL
S W ITC H SIG N A L
(DIS PL AY R
IG
H T)
2- 25

Tektronix 7704A Specifications

General

Brand	Tektronix
Model	7704A
Category	Test Equipment
Language	English