Tektronix 2213 - Page 31

T
h eory of
Operation-2213
Service
circ
u it f un ctions to eit h er produce
no d elay, dis p lay an
intensifie d zone on t he Swee
p dis p lay, or to d elay t he
start of t he Swee p fo r α p
erio d of time after receivi n g α
triggering signal . T he d elay time
is esta b lis hed by two
front-panel
controls : t he D EL AY TIME
switc h w h ic h sets
t
h
e b asic
d elay, an d t h e MUL TI PL I ER p
otentiometer
w
h
ic
h increases t he basic d elay b y α
factor of
up
to twenty
times .
Out p ut signals from t he Delay
circuit are app lie d to
α
logic gate circuit to control bot
h
t
he timing of t h e start
of t
he swee p an d t he Ζ -Axis drive .
T he Ζ -Axis d rive from t h e
Sweep
L ogic
circuit is a pp lie d
to t he Ζ -Axis amplifier . T he output
signal from t he Ζ -Axis
Am p lifier circuit sets t he crt
intensity . Α
C
h op Blan k ing
sig n al from the C
h
o p
Oscillator circuit b lan k s t he crt
d is p lay d uri
ng
t
he transition between t he vertical ch annels
w hen
using
C
H
O
P VER TICA L M OD E .
T h e DC Restoration circuit raises
th e ou t pu t level of t he
Ζ -Axis Am p lifier to allow it to
be couple d to t h e crt
control gri d . Direct coup ling is
not em p loyed due to t he
am p litude of the voltage levels app lied
to t he crt elemen ts .
In p ut Cou p ling
3-4
VER TICA
L ATT ENU ATO R S
Bot h t he C h annel 1 and C
h annel 2 Atte n uator ci r cuits,
s h own in Diagram 1, are
identical in op eration . In t he
following d isc u ssio n , only t
h
e C
h annel 1 Attenu ator circ u it
is d esc r i bed . T h e matc
h
ing
com p onents in t he Ch a n nel 2
Attenuator ci r cu it perform t
h e same f un ction .
T
h
e
Atte nu ator circ u it (see
F
igu
r e
3-2) p
rovi d es control
of
inp u t coupli n g, vertical deflection
factor, and varia b le
volts- p
er- d ivision bala n ce . Input
signals for crt vertical
d eflectio n may b e connecte
d to eit h er or bot h t he C H 1 O R
Χ and t he CH 2 O R
Υ i nput connectors . In t h e Χ - Υ M ode
of op eration, t h
e
signal a pp
lied to t h e CH 1 O R Χ con-
nector provi d es
ho r izontal ( Χ -Axis) d
eflection fo r t h e
d is p lay, a nd t
he sig n al ap p lie d to t he C
H
2 O
R Υ co n nector
provides
t h e vertical (Y-Axis) deflection
for t he dis p lay .
T he signal ap p lied
to
t
he CH 1 O RΧ in pu t connector
can be ac-cou p le d , dc-cou
p le d , or internally disconnecte d
from t
h e input of t h e H ig h - Ζ In p ut Atte
n
uato
r circuit .
T he Swp Duty
signal from t h e Sweep L ogic circuit is
ap p lie d to t he A
u to Intensity circuit . T he Auto Inte n sity
circuit provides
partial cont r ol of t he intensity of t h e
d is p lay w hen switc
h ing b etween differe n t p ositio n s of t
h
e
SEC/DI V switc h .
T h e P ower Sup p
ly provides all t he necessary op erati ng
voltages for t h e instrument circuitry .
O
p
erating p otentials
are ob tai n ed fro m α circuit
com p osed of t he P rereg u lator,
Inverte r an d T r ansforme
r ,
an
d Rectifiers an d F ilters . T he
P rereg u lator p rodu ces app
roximately +45 V f r om t h e ac-
power-input source w
h
ic
h is used to drive t he 20- kH z
Inverter stage . T he T
r ansformer second ary win d ings p r ovi de
various ac levels t h at
are
rectifie
d
an
d filte r ed to p r oduce
t h e operating voltages . Α H ig
h -voltage M ultiplie r circuit
p ro d uces t h e
accelerating, foc u s, and cat hod e potentials
re qu ired by t
h e crt .
Α
front- p anel PR O BE AD JU ST out p ut
is provi de d for
use in a
d j usti ng probe com p ensation . T
he voltage at t h e
PR O BE AD
JU
ST
con nector is α negative-going sq
u are wave
t h at h as α p ea
k -to- peak amplitu d e of approximately 0 .5 V
an d α repetition
rate of a pp roximately 1 kH z .
D
E TAI LE D CI
R C U IT D E SC
R I P TIO N
Sig n als a pp lie d to t he CH 1
in p ut con nector are ro u te d
t h ro u g h r esistor R101 to In
p ut
Co
up ling switc h S101 .
Wh en S101 is set fo r do coupli
n g, t he
C
H 1 signal is ap p lie d
d i r ectly to t he in p ut of t h
e
H ig
h - Ζ Attenuator stage . Wh en
ac-couple d , the in p u t sig n al p asses
t h roug h R 100 and
d
c-
b loc k ing ca p acitor C102 . T
h e bloc k ing ca p acitor
p reve n ts t h e do com p o
n ent of t he inp u t sig n al fro m being
applie d to t h e Atte
n
uator
circuit . Wh e n S101 is set to
G N D, t h e direct sig n al pat
h
is
op e ned an d t he in p ut of t he
atte n uato r is connecte d to ground
.
T
h is
p
rovi d es α groun d
reference wit hout t h e need to d isco n
nect t h e a pp lie d signal
from t
h e in pu t connector . T h e cou p
ling
ca
p acitor is
allowe d to
prec h arge t h roug h R 102, α hig
h -resistance com-
ponent, w h ic h is connecte d across
Input Cou p li ng switc h
S101
in the G ND position .
H ig h - Ζ
Attenuator
T
he first section of attenuator
switc h
S105A
d i r ects
t h e in
p
ut
signal to on e of t
h
ree
p
at
h
s :
directly t h roug h
R 103
(no atten u ation) ; t
h
roug
h
α
10 Χ attenuato r con-
sisting
of C105, C107, R 105,
R 106, R 107, and R 108 ;
o r t h roug h α 100 Χ atte
n uator consisting of C111, C112,
R 110, R 111, R112,
R114, an d R 115 . M edium-fre que
n
cy
no r malization
of
t
he i npu t cap acitance is accomplis
hed by