H Ig H-Voltage R Egulator; H Ig H-Voltage Outputs; Ca L Ibr Ato Rci R C Uit - Tektronix 5440 Instruction Manual

Ad
j
ustment-5440
Th
e out
p
ut voltage level of t
h
e Ζ -Axis Amplifier is
voltage for t
h
e crt cat
h
o
d
e is also obtained from t h
e Τ 410
d etermine d by t
h
e voltage drop ac r
oss R 349 an d R 350 i n
secon
d
ary wi
n
d ing . C
R
412
h
alf-wave rectifies
t
h
e
reference to t h
e voltage level at t
h
e summi
n
g p oi
n
t for t
h
e
transformer outp u
t an d su
pp
lies t h
e 3
kV
to t
h
e crt
am
p
lifier (base of Q345) . T h
e curre
n
t t
h
roug
h R
349-
R
350
cat
h o d
e . R 418 connects t
h
e crt cat h
o d e voltage to t
h
e crt
is determi
n
ed by t
h
e i
n
put c
u
rre
n
t from a n
y combinatio
n
s filament to p revent cat h
o d e-to-filament brea k
down .
of several sources, suc
h
as I
N
T
EN
SITY control, p lug-in
interface (unblan
k
i
n
g, readout un b
lan
k
i
n
g), a
n
d from
Q320 a
n
d 0335 . Q320 is an o p
erational amplifier t
h
at sets
Dio d es C
R
420 a
n
d C
R
422 p rovi d et
h
e rectifie d
n
egative
t
h
e ΕΧΤ I
N
T
EN
SITY I
NPU
T connector signal to α level
control voltage for t
h
e crt control gri d
. T
h
e out p ut level of
suitable for p ro p er Ζ-Axis Amplifier resp onse . Q335 acts
t
h
is s
u
p ply is set by t h
e Inte
n
s R a
n
ge ad
j
ustment, R 435 .
as an electro
n
ic switc
h
to cause t h
e crt display i
n
tensityto
Dio
d
es C
R
428 an d
C
R
430 cli p
th
e crt gri d bias voltage
increase w
h
en t
h
e BEAM F I
N
D
ER
switc
h
is pus
h
ed . 0340 from t
h
e Τ 410 seco nd
ary, to determine t h
e o
p
erati
n
g level
acts as an im p e
d
ance-matc
h
ing an d bias-setti n
g tran- at t
h
e control grid . C R
428limitst
h
e negative exc u
rsions of
sistor for t h
e Ζ -Axis Amplifier . C R
352 an d
cu
rrent limiting t h
e bias voltage, d e
p
ending upon t
h
e output voltage of t h e
resistor
R
352 act as α p rotection circuit for t
h
e Ζ -Axis Ζ-Axis Am p lifier ; t h
e positive clip p ing level at t h
e cat
h
o d e
Am
p
lifier i
n
case of α
h
ig
h
-voltage s
h
ort .
of C
R
430 is set by t h
e Inte
n
s
R
ange a
dj
ustment . R 420
con
n
ects t
h
e crt gri d voltage to t h
e crt cat
h
o d e voltage to
ensure t h
at t
h
e crt gri d is more
n
egative .
H
ig
h
-
V
oltage R egulator
H ig h
-
V
oltage
P
rimary . Α repetitive, sinusoidal signal is
CRT Cont
r
ol Circuits
produce
d
by α rege
n
erative fee
d
bac
k
oscillator in t
h
e
p
r
imary of T410 and induce d
i
n
to t
h
e secondary. Current
In ad d itio
n
to t
h
e I
N
T
EN
SITY co
n
trol d iscusse d p re-
drive for t
h
e primary winding is fur n
is
h
ed by Q410. T
h
e
viously, fro n
t-panel
F
OC
U
S an
d
internal astigmatis m
con d uction of Q410 is controlle d by t
h
e collector voltage co
n
trols
h
ave bee
n
i
n
corporate
d
for arrivi
n
g at an op-
of Q400 .
timum crt dis p lay .
F
OC
U
S co
n
trol R 440 provides t
h
e
correct voltage for t h
e secon d
an
o d e i
n
t
h
e crt .
P
roper
voltage for t
h
e t
h
i
r
d ano d
e is obtained by a
dj
usting Astig
Hig
h
-
V
oltage R egulation . R egulation is accom p lis
h
ed
control R 370 . In order to obtain optimum s p ot size and
by sampling t
h
e -3
kV
across voltage d ivider R 395A- s
h
ape, bot
h
t
h
e
F OC
U
S and Astig controls are ad
j
usted to
R 395 B
. If t
h
e out p ut level of t
h
e cat
h
ode su
p
ply goes provi
d
e t
h
e proper electrostatic lens co n
figuratio
n
in t
h
e
above t
h
e
n ominal -3
kV
(goes more negative), t h
e i
n
p ut crt .
base of Darlingto
n
transistor 0390 goes
n
egative from its
quiescent 0
V.
T
h
e out p ut of 0390 goes more p ositive,
reducing t
h
e con
d
uction of Q400 an d 0410. T
h
is re
d
uces T
h
e G
E
O
M
ad
j
ustment R 365variest h
e p ositive level on
t
h
e p ea
k
-to-pea
k
si
n
usoidal signal am
p
litude, resulting in
t
h
e
h
orizontal deflection plate s
h
iel d s to control t h
e
α re
d
uced voltage in t
h
e secon d
ary of Τ 410 . Co
n
versely, if overall geometry of t h
e dis p lay . T
h
etrace rotation control,
t
h
e out
p
ut dro p s below -3
kV
(goes more positive), 0410
R 375, p ermits ad j
ustme
n
t of t
h
e do currentt
h
roug
h
beam-
will conduct more, i .e .,
h
ave α larger sinusoi d al signal
rotation coil L 375 to align t
h
e dis p lay wit h
t
h
e
h
orizontal
amplitu d e . C
R
395 and C395form α delaytur n
- οη circuit to graticule lines .
prevent t
h
e crt beam from coming on imme d iately at
instrument turn-on . T h
e d elay time is co
n
trolle d by t
h
e
time itta
k
esC395tocharge to+30 .6
V
t
h
ro
u
g
hR
397from
LO
W
-
V
O
L
TAG
E P O
WER S UPPL
Y A
N
D
th
e +200 ν p ower su p ply . At t
h
e moment t
h
e to
p
of C395
CA
L
I
BR
ATO
R
CI
R
C
U IT
reac
h
es +30 .6
V,
d io
d
e C
R
395 will t
u
r
n
on a
n
d clamp t
h
e
C
R
395-C395-
R
397-
R
395A
j
unctio
n
at 30
V. R 402 a
n
d T h
e L ow-
V
oltage
P
ower Supply circuit provides t h
e
C402 limit t
h
e ban
d
widt
h
of t
h
e regulator to prevent
o perati
n
g pow er for t h
e oscilloscope system .
E lectronic
oscillations .
regulation is
u
sed, w
h
ere necesssary, to p rovide sta
b
le,
low-ripple output voltages. T
h
e circuit also inclu d es t h
e
Calibrator circuit to produce an accurate s q uare-wave
H
ig
h
-
V
oltage Outputs
output .
T
h
e secondary win d
ing of Τ410 p rovi d es t
h
e
n
egative
an d positive accelerating potentials for t h
e crt an
d
t
h
e bias
voltage for t
h
e control gri
d
.
P
ower is a pp lie d to t
h
e primary of tra
n
sformer
P
ositive accelerati n
g voltage for t
h
e crt ano
d
e is
Τ 800/
F
300/S300 t
h
ro
u
g
h
t
h
e dis p lay u
n
it (fuse
F
300,
supplied by voltage qua
d
rupler U 410 . T
h
e a
pp
lie
d
voltage
t
h
ermal c
u
tout S300,
P
ower switc
h
S302, an d
line-selector
to t
h
e i
np
ut of U 410 from t
h
e Τ410 seco
n
dary wi
n
ding is bloc
k
Ρ 800 or Ρ 801) . Th
e line-selector b loc
k
s allow
about +3
kV p
ea
k
-to-
p
ea
k
. T
h
e out p ut voltage of U 410 is
c
h
anging t
h
e primary-win
d
i
n
g ta p
s of T800 to fit differe
n
t
about +12 kV
at t
h
e crt ano
d
e . T
h
e negative accelerating
line re
qu
irements .
3-4
P
ower I
n
p ut
REV
Α A
U
G 1979