Ball Electronic Display Division TD Series User manual

SERVICE
MANUAL
(
Video
Monitor
TD
Series
Electronic
Display
Division
5-017-1015
Aug.
31,
1979
Rev.
C
BALL ELECTRONIC DISPLAY
DIVISION
P.O.
BOX
43376
• ST.
PAUL,
MINNESOTA
55164
•
TELEPHONE:
{6121
786-8900
•
TWX:
910-563-3552

TABLE
OF
CONTENTS
SECTION
I
QENERAL
INFORMATION
1.1
General
Description
II
1.2
Electrical
Specifications
1.3
Mechanical
Specification
1.4
Human
Factors
Specification
1.4.1
X
Radiation
1.4.2
Power Requirements
1.4.3
UL
Requirements
INSTALLATION INSTRUCTIONS
2.1
General
2.2
Space
2.3
Power
2.4
Location
2.5
Cable
Termination
2.6
Initial
Turn-on
Procedure
III
CIRCUIT
THEORY
3.1
General
Information
3.2
Video
Amplifier
3.3
Sync
Processing
3.4
Vertical
Deflection
3.5
Horizontal
Deflection
3.6
Automatic
Frequency
Control
3.7
Low
Voltage
Power Supply
IV
ADJUSTMENT
AND
MAINTENANCE
4.1
General
4.2
HV
Shutdown
Resistor
Replacement
4.3
Vertical
Circuit
Adjustment
4.4
Horizontal
Circuit
Adjustment
4.5
Chassis
Removal
4~5.1
TD23
Model
4.5.2
TD12
and
TD15
Models
4.6
CRT
Replacement
4.6.1
TD23
Model
4.6.2
TD12
and
TD15
Models
V
WAVEFORMS
5.1
General
VI
TD
PARTS
LIST
6.1
General
6.2
Ordering
Parts
6.3
Returning
Parts
6.4
Component Replacement
Parts
Affecting
Product
Safety.
6.5
PWA
Identification
6.6
Monitor
Parts
List
IM1015
PAGE
1-1
1-1
1-1
1-2
1-2
1-2
1-3
1-3
2-1
2-1
2-1
2-1
2-1
2-1
2-2
'Z 1
"}-.L
3-1
3-1
3-2
3-2
3-3
3-5
3-5
4-1
4-1
4-1
4-3
4-3
4-3
4-3
4-3
4-3
4-3
4-4
5-1
5-1
6-1
6-1
6-1
6-1
6-2
6-2
6-2
i

IM1015
ILLUSTRATIONS
FIGURE
PAGE
2-1
Loop
Through Videq
Connection
between
Monitors
2-1
2-2
Front
and
rear
view
of
TD23
Monitor 2-3
2-3
Front
and
rear
view
of
TD12
and
TD15
2-4
4-1
Test
Equipment
lead
placement
for
selecting
R212
4-2
5-1
Circuit
board
component
location
and
intercabling
diagram
5-4
6-1 Schematic.
TD
series
6-11
ii

IMl015
Section
1
GENERAL
INFORMATION
1.1
GENERAL
DESCRIPTION
The
TD
monitor
is
a
solid
state
unit
for
use
in
industrial,
commer-
cial
and
data
display
fields,
where
reliability
and
high
quality
video
reproduction
are
desired.
Applications
such
as
remote
moni-
tor
for
computer
terminals
and
airline
flight
arrival/departure
displays
are
ideally
suited
to
this
unit.
1he
TD
monitor
has
a
single
plug-in
circuit
board
with
silicon
transistors.
The
unit
is
equipped
with
differential
input
for
composite
video
signal
to
minimize
hum
and
other
extraneous
pick-
up
on
long
video
feed
cables.
The 23
inch
cabinet
is
available
with
or
without
studs
for
versatile
mounting
configuration.
1.2
ELECTRICAL
SPECIFICATIONS
VIDEO
AMPLIFIER
Input
impedance
Input
connector:
Input
level:
Low
Frequency
tilt:
DC
restorer:
Gray
scale:
Bandwidth:
Rise
and
Fall
time:
SYNCHRONIZATION
Internal:
Vertical
retrace
Blanking:
Line
rate/Field
rate:
RETRACE
TIME
Horizontal:
Vertical:
DISPLAY
Picture
tube:
Center
resolution:
Geometric
Distortion:
10
K~
Hi-Z;
75~
Low
Z,
Rear
panel
switch
for
Hi-Z
or
75~
termination.
UHF-looping
.30
to
2.0
V
p-p
composite
5%
or
less
with
window
input
signal
Keyed
backporch
clamp
Linear
response
to
stairstep
signal
17 . 5
MHZ
@ - 3db
Less
than
20
nanoseconds
Composite
video
only
yes
525/60
Hz
or
625/50
Hz
(with
50
Hz
AC)
8
llseconds
600
llseconds
23
or
12
inch
rectangular
800
TV
lines
minimum (P4
at
30
FT-L no
panel)
Less
than
2%
of
active
raster
height.
1-1

IMI015
POWER
SUPPLY
Input
voltage:
Input
Power:
Output
voltage
ENVIRONMENTAL
Temperature:
Humidity:
Altitude:
100
to
240
AC,
50/60
Hz
46W
Nominal
+57
VDC
short
circuit
protected
+18
KV
nominal
Operating
range:
50C
to
55 0C
ambient
Storage
range:
-40oC
to
65 0C
ambient
5
to
80%
(non-condensing)
Operating:
up
to
10,000
ft.
S
tor
age
:
up
to
14,
00C
ft.
1.3
MECHANICAL
SPECIFICATION
Front
panel
controls:
Remaining
controls:
MODEL
TD23M
TD12C
TD12M
HEIGHT
18"
9-1/16"
10-5/16"
Off/On,
brightness
and
contrast
controls
Internal
DIMENSIONS
(NOMINAL)
WIDTH
23-1/16"
11-7/16"
12"
DEPTH
WEIGHT
(lbs)
18-1/2"
65
12-1/2"
15
12-13/16"
25
1.4
HUMAN
FACTORS
SPECIFICATION
1.4.1
X
Radiation
This
monitor
complies
with
the
Federal
Regulation
for
Radiation
as
required
by
the
Radiation
for
Health
and
Safety
Act
of
1968 and as implemented
by
title
21,
subchapter
J
of
The
Code
of
Federal
Regulations.
These
regulations
place
certain
requirements
on
manufacturers,
dealers,
and
distributors
of
products
which can emit X-rays under
some
conditions
of
operation
or
failure.
Critical
components (shaded
on
the
schematic) must be
replaced
with
EDD
approved components.
Title
21
of
the
code
of
Federal
Requlations,
part
1002
specifies
that
dealers
and
distributors
must keep
sales
records
for
all
electronic
products
which
are
subject
to
the
Federal
Radiation
Safety
Performance
Standards
to
permit
tracing
of
specific
television
recievers
to
;;pecific
purchasers.
(RefJ.
HEW
publication
(FDA)
78-8044,
Federal
Record Keeping Requirements).
1-2

IM1015
Certification
of
compiiance
with
radiation
regulations
is
shown
by a
label
attached
to
each
monitor.
The
user
is
responsible
for
labeling
his
product
in
a
similar
fashion
or
in
making
the
DHEW
label
easisly
visible
from
the
outside
of
the
enclosure.
The
regulations
state
that
"This
(certification)
information
shall
be
provided
in
the
form
of
a
tag
or
label
permanently
affixed
or
inscribed
on
such
product
so
as
to
be
legible
and
readily
accessible
to
view
when
the
product
is
fully
assembled
for
use
..
-:"
Each
monitor
is
supplied
with
an
extra
label
attached
to
the
CRT.
The
user
will
remove
this
label
and
use
it
as
stated
above.
1.4.2
Power
Requirements
The
TD
monitor
is
designed
to
operate
and meet
radiation
requirements
when
operated
within
the
respective
AC
input
power
specifications.
Radiation
testing
is
performed
at
the
maximum
specified
input
voltage
for
AC
powered moni-
tors.
1.4.3
UL
Requirements
The
TD
monitor
is
designed
to
meet:
UL
standard
796,
Printed
Wiring Board
UL
standard
478,
Standard
for
Electronic
Data
Processing
Units.
UL
standard
114,
Standard
for
Office
Appliances.
1-3

2.1
GENERAL
Section
2
INSTALLATION
INSTRUCTIONS
IMl015
This
section
describes
the
installation
procedures
of
the
TD
series
monitor.
It
also
contains
information
on
the
space,
power
and
cable
termination
requirements
of
the
monitor.
2.2
SPACE
The TD-23
monitor
occupies
an
area
of
18
inches
high,
23-1/16
inches
wide
and
18-1/2
inches
deep.
2.3
POWER
The
external
power
requirements
of
the
unit
is
105-130
VAC,
50-60Hz,
46
watts
nominal.
The
power
cable
supplied
with
the
unit
is
the
standard
3-wire
grounding
type.
2.4
LOCATION
The
monitor
shall
not
be
located
in
an
area
that
restricts
air
flow
around
the
unit.
Nor
shall
it
be
placed
near
any
heat
generating
sources;
such
as
heating
vents
and
heat
radiating
equipm~nt
since
this
may
cause
the
monitor
to
overheat.
2.5
CABLE
TERMINATION
The two
video
input
connectors
J1
and
J2
on
the
rear
panel
are
wired
in
parallel.
The
video
cable
is
connected
to
the
video
input
connector
and
is
terminated
by
positioning
the
video
termination
switch
Sl
to
the
75Q
position.
If
the
video
signal
is
looped
through
the
monitor
to
other
monitors,
the
video
termination
switch
is
set
to
the
Hi-Z
position,
except
on
the
last
monitor,
where
it
is
set
to
the
7SQ
posiiion,
see
figure
2-1.
II
MONiTOR
NO. I
INPUT
VIDEO
SIGNAL
MONiTOR MONiTOR
II
NO.2 NO.3
VIDEO TERMINATION SWrTCH
ON
MONITORS
NO.
I
AND
NO.2
SET
AT
HI-Z
POSITION;
ON
MONITOR
NO.3,
SWITCH
IS
SET TO
75.(1
POSITION.
Figure
2-1
Loop
through
video
connection
between
monitors.
2-1

IM1015
If
a
ground
loop
hum
is
apparent
in
the
picture,
placing
the
differential
input
switch
S2
in
the
ON
position
will
remove
any
hum
induced
in
the
cable
between
the
monitor
and
the
equip-
ment
which
is
causing
it.
If
a
ground
loop
hum
is
not
apparent
in
the
picture,
leave
the
differential
input
switch
in
the
OFF
position.
2.6
INITIAL
TURN-ON
PROCEDURE
The
TD
monitor
was
tested
and
aligned
before
shipment,
and
should
not
require
further
adjustment
after
installation.
The
following
procedure
is
recommended
for
turning
on
the
monitor
for
the
first
time:
2-2
(1)
(2)
Connect
the
monitor
to
a 120
VAC,
60Hz
power
source.
Connect
a
video
cable
to
video
input
connector
at
rear
of
chassis.
(3)
Set
the
video
termination
and
differential
input
switches
to
the
desired
position.
(4)
Place
power
switch
in
ON
position.
Adjust
Brightness
and
Contrast
controls
for
desired
effect.

On-Off
Brightness
Control
1/
..
·1111
11-::
111111
""
II
I""I
T(J.~EL£C.TM:$'iJOCK,OOl!lOf~etW£1t.
11)
Usu-s£lMC£AlU
II'AA'T!
1MsmE
I!IEHrtSlltY~T6~jit)iElMC[P£ItSUIf(L.
Figure
2-2
Front
and
Rear
view
of
TD-23
monitor.
IMlOlS
Contrast
Control
2-3

I~1015
Figure
2-3
Front
and
rear
view
of
TD12
and
TD15
2-4

IMlOls
SECTION 3
CIRCUIT
THEORY
3.1
GENERAL
INFORMATION
This
section
describes
the
circuit
theory
of
the
TD
series
monitor.
This
section
is
to
be
used
with
the
waveforms and
schematics
found
in
section
5
and 6
of
this
manual.
3.2
VIDEO AMPLIFIER
The
video
amplifier
consist
of
transistors
QlOl
through
Ql03,
integrated
cir-
cuit
UlOl and
transistor
Q10S
through
Qlll.
A
composite
video
signal
is
applied
to
the
PWA
through
Jl02-3
and
is
ac
coupled
to
the
differential
amplifier.
The
differential
amplifier
consists
of
QlOl and Ql03
with
Ql02
as
the
constant
current
source
for
the
pair.
The
video
gain
of
this
stage
is
essentially
unity.
Hum
is
rejected
when
S2
is
in
the
ON
position
because
of
the
inherent
common
mode
rejection
of
the
dif-
ferential
pair.
This
stage
presents
an
input
impedance
of
10K
to
the
incoming
video
signal.
The
composite
video
is
ac
coupled
to
the
electronic
attenuator
UlOl and
direct
coupled
to
sync
amplifier
Ql12.
Ul0l
is
an
integrated
circuit
and
its
gain
is
controlled
by
the
contrast
control
R3.
Its
advantage
over
the
conventional
method
is
that
the
video
signal
is
not
routed
through
the
contrast
control
and
the
stray
capacity
associated
with
these
long
leads
does
not
cause
a
roll-
off
in
high
frequency
response.
The
video
signal
is
ac
coupled
to
the
base
of
QlOs. QlOs
with
Ql06 forms a
compound
series
feedback
stage.
This
configuration
provides
a
high
input
impedance and a low
output
impedance
to
drive
emitter
follower
Ql08.
It
also
has
a
voltage
gain
of
9.
The
output
signal
from
Q106
is
coupled
to
the
base
of
Ql08, and
its
base
is
biased
by
the
keyed clamp
transistor
Ql07.
The
function
of
the
keyed clamp
stage
is
to
clamp
the
blanking
level
of
the
composite
video
signal
to
a
fixed
reference
voltage
which
is
constant
regard-
less
of
scene
content.
It
functions
as
a
DC
restorer
and
forces
the
input
voltage
during
blanking
at
Ql08
to
be
1.5
volts.
The
base
of
Ql07
is
driven
by
composite
negative
sync
and
caused
Ql07
to
saturate
at
the
trailing
edge;
thus
clamping
occurs
during
the
back
porch
of
the
composite
video.
Ql08
is
another
emitter
follower
which
isolates
the
keyed
clamp from
the
out-
put
stages
Ql09,
QllO and
Qlll.
Transistor
QllO and
its
components
compris
p
the
video
output
driver
with
a
gain
of
IS
to
18. The
bias
voltage
for
QllO
is
supplied
by
DC
coupling
from Ql08 which
in
turn
is
biased
by
the
keyed clamp.
QllO
operates
essentially
as
a
class
B
amplifier
and
is
referenced
to
blank-
ing
level
and
allows
a
greater
video
swing
in
the
output
stage.
R13s
adds
series
feedback
which
stabilizes
the
voltage
gain
and
operating
point
against
transistor
and
temperature
variation.
Clls
and C13s
increase
the
gain
of
the
3-1

IMl015
driver
at
the
high
frequencies
to
compensate
for
the
capacitance
in
QllO and
at
the
cathode
of
the
CRT.
The
signal
at
the
collector
of
QllO
is
direct
coupled
to
the
base
of
the
emitter
follower
Qlll,
which
provides
a low
source
impedance
for
driving
the
cathode
of
the
CRT.
Vertical
retrace
blanking
is
applied
to
the
base
of
Ql09,
which
conducts
harder
during
this
time
to
increase
the
voltage
at
Qlll
emitter
and
drives
the
cathode
of
the
CRT
to
cutoff.
R227
and
C159
forms a
protection
circuit
for
the
output
stages
in
the
event
of
a
CRT
arc.
If
a
transient
voltage
of
230
volts
or
greater
appears
at
the
CRT
cathode,
ionization
will
take
place
within
the
arc
gap,
providing
a low
impedance
path
to
ground.
3.3
SYNC
PROCESSING
The
sync
processing
circuit
consist
of
Ql12, Ql14,
Ql15 and
QllS.
The
func-
tion
of
this
circuit
is
to
provide
negative
vertical
sync
pulses
to
drive
the
vertical
oscillator
and
positive
horizontal
pulses
for
the
AFC
circuitry.
A
positive
going
composite
video
signal
at
the
collector
of
Ql03
is
applied
directly
to
the
base
of
the
sync
amplifier
Ql12.
This
amplifier
has
a
vol-
tage
gain
of
S and
it
applies
an
amplified
composite
video
signal
to
the
base
of
Ql14,
the
sync
stripper.
CllS
is
used
to
remove
the
3.5SmHz
color
burst
signal
from
the
back
porch
of
the
horizontal
pulse.
Ql14
is
turned
on when
triggered
by
the
leading
edge
of
the
sync
pulse
and
is
turned
off
by
the
trailing
edge
of
the
sync
pulse.
This
on/off
action
of
Ql14
results
in
a
negative
going
composite
sync
signal
of
approximately
l3.5V
p-p
at
its
col-
lector.
The
composite
sync
signal
is
sent
through
a
vertical
integrator
(R14S
and C122)
to
the
base
of
Ql15,
the
vertical
sync
separator.
The
vertical
sync
signal
at
the
collector
of
Ql15
is
used
to
trigger
the
vertical
oscillator
Ql16. The
zener
diode
in
the
collector
circuit
of
Ql15
is
used
to
limit
the
peak
to
peak
amplitude
of
the
vertical
sync
pulse
to
6.2V.
The
vertical
portion
of
the
composite
sync
signal
is
removed by
the
differen-
tiator
circuit
C129
and R167. The
horizontal
pulse
is
applied
to
QllS,
in-
verted
and
used
to
drive
the
AFC
stage
Ql19.
3.4
VERTICAL DEFLECTION
The
vertical
deflection
circuit
consist
of
a
vertical
oscillator,
an
emitter
follower,
a
vertical
output
amplifier
and
the
vertical
deflection
coil
of
the
yoke.
The
vertical
oscillator
Ql16
is
synchronized
by
the
vertical
sync
pulse
from
Ql15 and
it
produces
a
sawtooth
waveform
signal.
This
signal
is
fed
through
an
emitter
follower
to
the
input
of
the
vertical
output
amplifier
Ql.
This
amplifier
provides
a
sawtooth
current
waveform
for
the
vertical
deflection
coil
of
the
yoke.
3-2

IMIOIS
The
vertical
oscillator
Ql16
is
a
thyristor
functioning
as
a programmaole
unijunction
and
operates
as
a
relaxation
oscillator.
The
free
running
fre-
quency
is
set
by
the
DC
voltage
at
it's
gate
and
anode.
This
voltage
is
determined
by
the
resistive
voltage
divider
network
of
RIS3, RlS4 and RISS.
This
voltage
can
be
varied
by
the
vertical
hold
control
RIS4. The
oscillator
is
synchronized
by a
negative
vertical
sync
pulse
applied
to
the
gate
of
Ql16
from
QllS
through
C123.
The
sawtooth
forming
network
consists
of
C126, Cl27 and RlS7.
These
capacitors
charge
exponentially
at
the
vertical
rate
during
the
vertical
scan
time.
The
vertical
height
control
adjusts
the
amplitude
of
the
sawtooth
waveform by
controlling
the
charging
rate
of
C126 and C127.
To
maintain
a
linear
charging
rate,
the
output
of
Ql17
is
fed
back
through
R160
and
R161
to
the
junction
of
C126
and C12Z. The
charging
path
is
from
ground
through
C126
and C127,
past
the
anode
of
Ql16' and
through
the
vertical
height
control
CRlS8)
to
B+.
The
ver-
tical
oscillator
is
at
cutoff
during
the
time
that
these
capacitors
are
charging.
When
the
anode
voltage
exceeds
Ql16
gate
voltage,
it
turns
on and
rapidly
dis-
charges
C126
and
C127
through
LI02. The
tuned
circuit
consisting
of
LI02,
C126
and
C127
provide
a
stable
control
of
the
dropout
time
to
maintain
interlace.
The
sawtooth
signal
at
Ql16 anode
is
direct
coupled
to.
the
base
of
Qll7.
This
transistor
is
a
darlington
pair
emitter
follower
driver
for
the
vertical
output
amplifier.
It
presents
a
high
imput impedance
in
shunt
with
RIS7
to
prevent
loading
of
the
wave
shaping
network
across
which
the
sawtooth
waveform
is
shaped.
It
also
provides
a low
output
impedance and
high
current
gain
to
drive
the
base
of
the
vertical
amplifier
Ql.
The
positive
going
sawtooth
waveform
at
Ql17
emitter
is
fed
back
through
the
resistive
voltage
divider
of
R160
and R161.
This
divider
along
with
C127
inte-
grates
the
sawtooth
waveform and
introduces
a
parabolic
component
to
control
linearity.
The amount
of
feed
back
is
controlled
by
the
vertical
linearity
control
R160.
Height
control
RlS8
varies
the
amplitude
of
the
sawtooth
voltage
developed
by
controlling
the
effective
B+
applied
to
RIS7 and
therefore
controls
the
vertical
raster
size
on
the
CRT.
The
vertical
output
stage
Ql
uses
a
NPN
power
type
transistor
operating
as
a
class
AB
amplifier.
The
output
is
transformer
coupled
to
provide
a
proper
impedance match
with
the
yoke.
CRI08,
R164
and
C128
form a clamp
circuit
which
limits
the
collector
voltage
at
Ql
to
safe
levels
during
retrace.
R139
prevents
oscillations
by
providing
damping
across
the
vertical
yoke
coils.
3.S
HORIZONTAL DEFLECTION
Transistors
Q120
and
Q121
and
their
components form an
astable
multivibrator
operating
at
the
horizontal
rate.
Zener
diode
VRI03
and
R177
provide
a
stable
6.2
volts
source
to
this
circuit
from
the
18
volt
supply.
The
network
consist-
ing
of
R189,
R190
and
thermistor
RTIOI
is
used
to
stabilize
the
frequency
of
the
multivibrator
with
temperature
variation.
The
frequency
of
the
multi-
vibrator
normally
would
increase
with
temperature
due
to
base-emitter
voltage
3-3

IMl015
of
Q120
and Q12l
varying
inversely
with
temperature.
As
the
temperature
in-
creases,
the
thermistor
resistance
decreases;
thereby
lowering
the
effective
source
voltage
applied
to
the
main
timing
network
consisting
of
R187,
R185
and C140.
This
action
slows
down
the
charging
current
into
C140
and
holds
the
off
time
of
Q12l
constant.
The
other
timing
network
for
Q120
and Q12l
consists
of
R18l and C138. The
time
constants
chosen
are
such
that
the
output
square
wave
at
Q12l
is
positive
for
38
~seconds
and
grounded
for
25
~seconds.
This
establishes
the
proper
duty
cycle
for
the
output
stages.
The
output
at
Q12l
is
DC
coupled
to
pre-driver
inverter
Q122
which
produces
sharp
rise
and
fall
times
for
coupling
to
the
driver
transistor
Q129.
Q129
is
driven
alternately
into
saturation
and
cutoff
by
the
square
wave
ac
coupled
from Q122.
Its
output
is
transformer
coupled
to
the
horizontal
out-
put
stage
Q3.
Phasing
of
TlOl
is
chosen
such
that
Q3
turns
off
when
Q129
turns
on.
This
allows
Q3
to
turn
off
quickly,
thus
minimizing
power
dissipation.
During
conduction
of
the
driver
transistor,
energy
is
stored
in
the
coupling
transformer.
The
voltage
at
the
secondary
is
then
negative
and
keeps
Q3
cut
off.
As
soon
as
the
primary
current
of
TlOl
is
interrupted
due
to
the
base
signal
driving
Q129
into
cut
off,
the
secondary
voltage
changes
polarity.
Q3
~tarts
conducting,
and
base
current
flows.
This
gradually
decreases
at
a
rate
determined
by
the
transformer
inductance
and
circuit
resistance.
The
horizontal
output
stage
has
three
main
functions:
to
supply
the
yoke
with
the
correct
horizontal
scanning
currents;
develop
18
kV
for
the
CRT
anode and
DC
voltage
for
the
CRT
bias,
focus
and
accelerating
grids.
Q3
acts
as
a
switch
which
is
turned
on
or
off
by
the
rectangular
waveform on
the
base.
When
Q3
is
turned
on,
the
supply
voltage
plus
the
charge
on
C158
causes
yoke
current
to
increase
in
a
linear
manner and moves
the
beam from
near
the
center
of
the
screen
to
the
right
side.
At
this
time,
the
transistor
is
turned
off
by a
negative
voltage
in
its
base
which
causes
the
output
circuit
to
oscillate.
A
high
reactive
voltage
in
the
form
of
a
half
cycle
positive
voltage
pulse
is
developed
by
the
yoke's
inductance
and
the
primary
of
T3. The
peak
magnetic
energy
which was
stored
in
the
yoke
during
scan
time
is
then
transferred
to
C156
and
the
yoke'S
distributed
capacity.
During
this
cycle,
the
beam
is
returned
to
the
center
of
the
screen.
The
charged
capacitances
now
discharge
into
the
yoke and
induce
a
current
in
a
direction
opposite
to
the
current
of
the
previous
part
of
the
cycle.
The
magnetic
field
thus
created
around
the
yoke moves
the
scanning
beam
to
the
left
of
the
screen.
After
slightly
more
than
half
a
cycle,
the
voltage
across
C156
biases
the
damper
diode
CR12l
into
conduction
and
prevents
the
flyback
pulse
from
further
oscillating.
The
magnetic
energy
that
was
stored
in
the
yoke from
the
discharge
of
the
distributed
capacity
is
released
to
provide
sweep
for
the
left
half
of
scan
and
to
charge
C158
through
the
rectifying
action
of
the
damper
diode.
The
beam
js
the:l
at
the
center
of
the
screen.
The
cycle
will
repeat
as
soon
as
the
bias
voltag~
of
Q3
becomes
positive.
3-4

IM1015
C158
serves
to
block
DC
currents
through
the
yoke and
to
provide
usn
shaping
of
the
current
waveform. "S"
shaping
compensates
for
stretcnlng
at
the
left
and
right
sides
of
the
picture
tube
because
the
curvature
of
the
CRT
face
and
the
deflected
beam
do
not
describe
the
same
arc.
L103
is
an
adjustable
width
control
placed
in
series
with
the
horizontal
deflec-
tion
coils.
The
variable
inductive
reactance
allows
a
greater
or
lesser
amount
of
the
deflection
current
to
flow
through
the
horizontal
yoke and
varies
the
width
of
the
horizontal
scan.
The
positive
flyback
pulse
developed
during
horizontal
retrace
time
is
recti-
fied
by CRl16 and
filtered
by C148.
This
produces
approximately
600
VDC
which
is
coupled
through
the
focus
control
R219
to
G4
of
the
CRT.
The
resistive
divider
R221
and
R225
provides
approximately
400
VDC
for
the
G2
of
the
CRT.
This
same
pulse
is
transformer
coupled
to
the
secondary
windings
of
T3.
It
is
rectified
by
CRl
and
R5
to
provide
18kV
for
the
CRT
anode.
It
is
also
rectified
by
CR120
to
provide
a -80 V
source
for
the
brightness
control
R4.
In
the
event
the
-55 V
supply
voltage
rises
excessively
due
to
a
failure
in
the
regulator
circuit,
Q128
will
conduct
and
shunt
the
+18Vsupply
for
Ql18
through
Q122
to
ground.
This
will
shut
dO~T!
the
high
voltage
supply
of
the
monitor
and
prevent
X
radiation.
R212
is
a
selected
resistor
(for
replacement
of
R212,
see
section
4.2)
that
enables
Q128
to
conduct
when
the
+55
volt
supply
exceeds
59 V ±lV.
3.6
AUTOMATIC
FREQUENCY
CONTROL
The
function
of
this
circuit
is
to
compare
the
phase
(frequency)
of
the
hori-
zontal
oscillator
with
the
incoming sync
signal
and
generate
a
DC
control
vol-
tage
which
holds
the
oscillator
in
phase
lock
with
the
input
sync
signal.
The
automatic
frequency
control
circuit
consists
of
stages
Ql18, Ql19 and Q123.
The
composite
sync
coupled
from Ql14
is
differentiated
at
Ql18 and
fed
to
phase
splitter
Ql19. The
positive
and
negative
balanced
sync
outputs
of
Ql19
and
applied
to
the
diode
phase
detector
CRill
and CRl12. Also
applied
to
the
diodes
is
a
sawtooth
voltage
derived
from
the
horizontal
flyback
pulse
by
the
way
of
Q123
and
integrator
R173
and C134. The
phase
compared
output
appears
as
a
DC
correction
voltage
after
filtering
by R179,
C135
and C136.
This
correction
voltage
is
then
applied
to
the
base
of
Q121
to
effect
frequency
control.
3.7
LOW
VOLTAGE
POWER
SUPPLY
The low
voltage
supply
module
is
capable
of
operating
from
AC
line
voltage
of
100V, 120V,
220V
or
140V, SOi60Hz.
The power
supply
input
voltage
is
determined
by
the
setting
of
the
two
slide
switches
located
at
the
rear
of
the
supply.
These
switches
are
stamped
to
indicate
the
appropriate
line
voltage
setting.
3-5

IMIOl5
To
set
the
supply
for
a
particular
line
voltage,
the
numbers
on
the
two
switches
are
added
together.
This
allows
the
supply
to
be
set
for
four
different
input
line
voltages.
The
position
of
the
switches
and
the
resultant
input
voltages
is
shown
in
the
schematic.
NOTE
When
changing
the
AC
input
voltage
from
100/120
to
220/240~
the
fuse
(F1) must
also
be changed
INPUT
VOLTAGE
100/120
220/240
FUSE
SIZE
3/4A 125V
SE
3/BA 250V
SE
The low
voltage
supply
uses
a
series-pass
regulator
designed
to
maintain
a
constant
DC
output
for
changes
in
input
voltage,
load
impedance and
temperature.
Also
included
is
a
current
limiting
circuit
designed
to
protect
transistors
connected
to
the
55V
output
of
the
regulated
supply
from
accidental
output
short
circuits
and
load
malfunctions.
The low
voltage
regulator
consists
of
Q2, Q124, Q125, Q126, Ql27 and
their
components.
R206
and
its
circuitry
control
the
current
limiting
feature.
The
primary
voltage
is
stepped
down
at
the
secondary
of
TI where
it
is
rec-
tified
by a
full
wave
bridge
rectifier
AI.
Capacitor
C2
is
used
as
a
filter
capacitor
to
smooth
the
rectified
output
of
AI.
Transistor
Q2
is
used
as
a
series
pass
stage
to
drop
the
rectified
voltage
to
+57
VDC
and
to
provide
a
low
output
impedance.
Approximately
7
volts
is
applied
to
the
base
of
Q127
through
a
divider
network
of
R209
and
211.
A
reference
voltage
from
zener
diode
VRl04
is
applied
to
the
emitter
of
Q127.
If
the
output
voltage
changes,
an
error
current
is
generated
through
Q127.
This
error
current
modulates
the
base
current
of
Q125.
Since
Q2
is
driven
by Ql26
(in
a
darlington
configuration),
output
drive
is
regulated
in
this
manner
to
bring
the
output
voltage
back
to
its
proper
level.
The
short
circuit
protection
or
current
limiting
action
can
be
explained
as
follows.
Assume
the
55
volt
bus becomes
shorted
to
ground.
This
reduced
out-
put
voltage
is
sensed
by
the
base
of
Q127,
turning
that
transistor
off
because
of
the
reverse
bias
across
its
emitter
base
junction.
Simultaneously,
the
in-
creased
current
through
R206
increases
the
forward
voltage
drop
across
the
base
emitter
junction
of
Q126
and
turns
it
on. The
increased
collector
current
through
Ql26
shunts
away
the
base
current
of
Q125.
Since
Q2
is
driven
directly
from Q125,
its
output
current
becomes
limited.
This
closed
loop
oPeration
continues
until
a
stable
point
is
reached
at
which
the
current
available
during
a
short
circuit
condition
is
maintained
at
approximately
100
rnA.
This
"foldback"
action
limits
dissipation
in
the
monitor
to
safe
levels
during
fault
conditions
and
prevents
needless
device
failures
due
to
accidental
short
circuits.
3-6

IM1015
SECTION IV
ADJUSTMENT
AND
MAINTENANCE
4.1
GENERAL
This
section
is
for
the
adjustment
procedures
and
maintenance
procedures
for
the
TD
series
monitor.
CAUTION
NO
WORK
SHOULD
BE
ATTEMPTED
ON
ANY
EXPOSED
MONITOR
CHASSIS
BY
ANYONE
NOT
FAMILIAR
WITH
SERVICE
PROCEDURES
AND
PRECAUTIONS
4.2
HV
SHUTDOWN
RESISTOR
REPLACEMENT
(R212)
Refer
to
figure
4-1
for
component
location
on
PWA
and
test
equipment
termination.
1.
Connect a
DC
voltmeter
+
lead
to
R216
and
the
-
lead
to
chassis
ground.
This
meter
is
for
monitoring
the
B+
voltage.
2. Connect one end
of
a
clip
lead
to
R211
and
the
other
end
to
chassis
ground.
This
will
disable
the
voltage
regulator
circuit.
3. Connect a
lOOK
range
resistor
decade box
across
the
male molex
pins
for
R212
and
set
the
decade box
for
300n
resistance.
4. Plug
the
monitor
AC
plug
(P1)
in
to
a 0-140 V
variac
and
set
the
variac
voltage
control
for
0
volts.
5.
You
are
going
to
determine
what
value
of
R212
that
causes
HV
shutdown
(loss
of
raster)
when
the
B+
voltage
is
59V
±lV.
a.
Turn on
the
monitor
and
place
the
brightness
and
contrast
controls
in
the
center
of
their
rotation.
b.
Turn on
the
variac
and
slowly
increase
the
AC
input
voltage
to
the
monitor
while
watching
the
B+
voltage.
Note
the
B+
voltage
reading
prior
to
HV
shutdown
(loss
of
raster).
6.
If
HV
shutdown
occurs
prior
to
59V
±lV,
increase
the
value
of
R212
and
repeat
step
5b.
7.
When
the
HV
shutdown occur-s
at
59V
±1
V,
note
the
decade box
resistance
value
and
use
this
resistance
for
R212.
8.
Install
R212
and
repeat
step
5b
to
varify
that
the
,shutdown
voltage
will
occur
at
59V
±lV.
4-1

.J::>.
I
N
clse
DC
VOLTAGE
METER
100K
RESISTOR
DECADE BOX VARIAC
0-140V
REVISION LEVEL IDENTIFIER
(0
01
....
rQ"i2'9> R21
~
'\::!:..!.!J C
160
II::-:-<!IID-
RI
QI21
RIIS
=U
CI17
0
CI34
'-;--~
-1~,,---i.1'3
I~'
~6
~~:
-::~:;->-
+
~A133
RI3S
~
0
--fBIi&-
=
II:
......fC'i'4Ol-
I
Rla7
I--
Qlle
RISO
r"'\
I I
~.II,\I
II:
'i;:;:ia
\
~
N
,--,
Figure
4-1
Test
Equipment Lead
Placement
for
Selecting
R212
AC LINE CORD FROM
TO
MONITOR

IM1015
4.3
VERTICAL
CIRCUIT
ADJUSTMENT
1.
Apply a
crosshatch
video
signal
to
the
unit
via
J1
or
J2.
2.
Adjust
vertical
hold
control
R154
to
the
center
of
its
range.
3.
Adjust
vertical
height
control
R158
for
a
full
raster
from
top
to
bottom.
4.
Adjust
vertical
linearity
control
R160
and
vertical
height
control
R158
for
equal
spacing
between
the
horizontal
lines
of
the
crosshatch
signal.
4.4
HORIZONTAL
CIRCUIT
ADJUSTMENT
1.
Apply a
crosshatch
video
signal
to
the
monitor
through
J1
or,J2.
2.
Adjust
the
horizontal
hold
control
R187
to
lock
in
the
picture
horizontally.
3.
Adjust
width
coil
L103
for
a
full
raster
from
left
to
right.
4.
Adjust
linearity
sleeve
on
the
CRT
neck
for
equal
spacing
between
the
vertical
lines
of
the
crosshatch
signal.
4.5
CHASSIS
REMOVAL
4.5.1
TD23
Model
Remove
input
signal
cable
from
J1
or
J2.
Remove
screws
holding
cabinet
back
and remove back from
set.
Discharge
CRT
HV
anode
to
chassis
ground and
dis-
connect
it
from
CRT.
Disconnect
CRT
socket
deflection
coil
plugs,
brightness
and
contrast
control
plugs.
Remove
screws
holding
chassis
to
cabinet
bottom.
Remove
chassis
from
cabinet.
4.5.2
TD12
and
TD15
Models
Remove
input
signal
cable
from
input
panel.
Remove
screws
holding
cabinet
back
and remove
it
from
set.
Remove
screws
holding
chassis
to
cabinet
bottom and
lift
out
chassis
from
cabinet.
4.6
CRT
REPLACEMENT
4.6.1
TD23
Model
HARNING
Extreme care
shall
be
taken
when
hnndlina
the
CRT.
Safetu
alasses
~~d--gZ;~e~
-mu~t
be
w;~
~h~nhandling
the
CRT.
Care
must be
taken
to
prevent
scratching
or
nicking
the
Crt
or
subject
it
to
undue
pressure
when
removing
or
inserting
the
CRT
into
the
monitor.
DO
NOT
LIFT
CRT
BY
THE
ll/Eel{
Remove
signal
input
cables
from
input
panel.
Remove
screws
holding
cabinet
back and remove back from
cabinet.
Discharge
CRT
HV
anode
to
ground.
Disconnect
HV
anode,
deflection
coil
plugs,
brightness
and
contrast
controls
plugs.
4-3

IMI015
To
protect
CRT,
insert
a
thin
piece
of
cardboard
between
mask
and
CRT
in
the
upper
right
corner.
Insert
a
thin
wide
blade
screwdriver
between
the
mask
and
cardboard
insert
and
pry
the
mask
outward by
twisting
the
screwdriver
against
the
CRT
face.
Remove
screws
holding
the
CRT
and remove
CRT
from
cabinet.
Do
Not
lift
CRT
by
the
neck.
Reverse removal
procedure
to
install
CRT.
4.6.2
TD12
and
TD15
models
Follow
chassis
removal
procedures
in
section
4.5.2.
Discharge
CRT
HV
anode
directly
to
ground and remove anode
lead
from
CRT.
Dis-
connect
CRT
socket
and
deflection
coil
plugs.
On
TD12
models -remove screws
holding
mask
to
frame and
tilt
mask upward.
Remove
CRT
mounting screws and
lift
CRT
out
of
frame.
Do
Not
lift
CRT
by
the
neck.
On
TD15
models -
pull
mask outward from frame and
tilt
upward
to
provide
access
to
CRT
mounting
screws.
Remove
CRT
mounting screws and
lift
out
CRT
from frame.
Do
Not
lift
CRT
by
the
neck.
4-4
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