Ball Electronic Display Division TV-50 User manual

SERVICE MANUAL
TV -50/90/120
Data Display Monitor
5-017-1035
REV. A Nov., 1977
Electronic
Display
Division
BALL ELECTRONIC DISPLAY DIVISION P.o. BOX 43376 • ST. PAUL. MINNESOTA 55164 • TELEPHONE: [phone]·8900 • TWX: 910·563·3552

PART I
Section
1.
2.
3.
PART II
Section
4
5
CONTENTS
ILLUSTRATIONS AND TABLES
OPERATING DATA
GENERAL INFORMATION
1.1 General Description
1.2 Electrical Specifications
1.2.1 Input Data Specifications
1.2.2 Data Display Specifications
1.2.3 Display Specifications
1.2.4 Geometric Distortion Specifications
1.2.5 Power Requirements
1.3 Mechanical Specifications
1.4 Environmental Specifications
1.5 Human Factors Specifications
INSTALLATION
2.1 Mechanical
2.2 Electrical
2.2.1 DC Input
2.2.2 AC Input
2.3 Location
2.4 Grounding Techniques
2.5 Input Signal Lead Routing
OPERATION
3.1 General
3.2 Brightness Adjust
3.3 Contrast Adjust
SERVICE DATA
THEORY OF OPERATION
4.1 Video Amplifier
4.2 Vertical Deflection
4.3 Horizontal Deflection
4.3.1 Low Level Stages
4.3.2 High Level Stages
4.4 Low Voltage Supply
ADJUSTMENT AND MAINTENANCE
5.1 Horizontal Adjustments
5.2 Vertical Adjustments
5.3 Focus Adjust
IM1035
Page
iii
1
1-1
1-1
1-1
1-1
1-3
1-3
1-4
1-4
1-4
1-7
2-1
2-1
2-1
2-1
2-1
2-1
2-1
2-3
3-1
3-1
3-1
3-1
4
\ 4-1
4-1
4-1
4-2
4-2
4-2
4-5
5-1
5-1
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5-1
i

IMI035
Section
6
7
Figure
1-1
1-2
2-2
4-1
5-1
6-1
6-2
6-3
6-4
G-5
6-6
6-7
6-8
Table
1-1
ii
CONTENTS (Cont.)
ADJUSTMENT AND ~~INTENANCE
5.4 Centering
5.5 Troubleshooting Guide
5.6 Raster Shifting
SERVICE DATA
6.1
General
6.2
Ordering
Parts
6.3
Returning Parts
6.4
Waveforms
6.5
Board Assembly Part
Number
SUPPLEMENT
7.1 General
ILLUSTRATIONS
Synchronization and Blanking Generator Waveform
TV 50, 90, 120 a Tilt with Bonded Panel Dimensions
Interface Connections
Horizontal Drive Processing and Timing Chart
Schematic for Raster Shifting
TV 50 Schematic
TV 50 Parts List, Waveforms and Component Layout
TV 90/120 12V Schematic
TV 90/120 12V Parts List, Waveforms and Component
Layout
TV 90/120 15V Schematic
TV 90/120 15V Parts List, Waveforms and Component
Layout
TV 90/120 AC Schematic
TV 90/120 AC Parts List, Waveforms and Component
Layout
TABLES
Mechanical Specifications
Page
5-1
5-1
5-1
5-2
6-1
6-1
6-1
6-1
6-2
6-2
7-1
7-1
Page
1-2
1-6
2-2
4-3
5-3
6-3
6-4
6-5
6-6
6-7
6-8
6-9
6-10
Page
1-5

PART 1
OPERATING DATA
This section of the service manual provides data
concerning the specification, installation and
operation of the TV 50, 90, and 120 Data Display
Monitor.
IMI035
1

IM1035
Section 1
GENERAL INFORMATION
1.1 GENERAL DESCRIPTION
The TV 50, 90 and 120 series monitor is a raster scan display designed speci-
fically for data terminals. They are designed for high quality display of alpha-
numeric dot characters.
The data monitor accepts video, horizontal drive and vertical drive as separate
TTL level signals, eliminating stripping circuits in the data display unit as
well as mixing circuits in the external logic interface.
The 100% solid state silicon circuitry of the PWA provides cool operation and
high reliability. The electronic package.has been miniaturized for compati-
bility with small volume requirements.
1.2 ELECTRICAL SPECIFICATIONS
1.2.1 Input Data Specification
PWB Edge Input Connector: Viking -2VKlOS/1-2
Ampheno1 -225-21031-101
Cinch -
250-10-30-170
BBRC No. -1-039-0119
Video Input Amplitude Low
High
0.0 + 0.4 - 0.0 volts
4.0 ± 1.5 volts
Video Pulse Width
Vertical Drive Rate
Horizontal Drive Rate
Rise and Fall Times
Input Signal Format
50ns or greater
49 to 61 Hz
15,250 to 16,250 Hz
Video
Vertical
Horizontal
Less than 20ns
Less than lOOns
Less than SOns
Refer to figure 1-1
1.2.2 Data Display Specifications
Input Impedance:
Video
Input (Class A)
Vertical Drive Input
Horizontal Drive Input
Min Shunt
Resistance
4k
1.2k
5l0n
Max Shunt
Capacitance
40-60pF
40pF
40pF
1-1

IMl035
F
lO T040J.lS~
~----------------H ~I
HORIZONTAL F~TRA~CE , i-
1
---- ..... [HIGH:+4±1.5V
DRIVE]-- 7ps l _________ _
- LOW:
tl t2 t2+7 O+O.4V
-O.OV
VIDEO -r~-B-L-A-N-KI-N-G---- H
~HIGH
UNBLANK .... ...:--IOJ.ls--t~ .... -._t---VIDEO PULSE---~ ...
MINIMUM INFORMATION
LOW
~ """E--TR--ACE-'-- V----..t·1
VERT'CAL1600 ~ ~ I f,HIGH
DRIVE ~s 50JlsMIN.
1.4msMAX.
'-- ________ ~ LOW
t5
-HIGH
V IDEO -r ... ----e-L-A-N-K-I-N-G--- V
UNBLANK
... ~--- 850J,Js - __ ;..~ .. ~~-VIDEO PULSE--+
MINIMUM INFORMATION
LOW
NOTES:
I. HORIZONTAL RETRACE IS INITIATED AT t2 (I.S TO 7.0,,1 AFTER t" DEPENDING ON SETTING OF AI03).
2. VERTICAL RETRACE IS INITIATED AT ts WITHOUT DELAY.
3. H=PERIOD OF ONE LINE: 63.S}!1 ~3% •
4. V= PERIOD OF ONE FIELD: 16.4ml MIN. TO 20.4ms MAX.
5. VIDEO PULSE WIDTH SHOULD BE SOns MIN.
TABLE I. t3 Vstl TIMING FOR CENTERED HORIZONTAL TABLE
2. 'c. Vs ts TIMING FOR CENTERED VERTICAL
VIDEO AS FUNCTION OF V BLANKING WIDTH.
VERT ICAl VIO£O BLANKING
VIDEO AS FUNCTION OF H. BLANKING WIDTH.
HORIZONTAL VIDEO BLANKING
WIDTH . LEAD / LAG WIDTH
LEAD / LAG
ts- t6
~
10,,1 -5.S TO O~II
ISOp. IUpl
Ilpi -4.5 TO hll
tOOPI
ISOpl
14pI - 3.S T.O 2,,1
1000pi
100pi
16pI
-1.S TO 3pI
1l00pi
SOOPI
18pI
-I.S TO 4pI
1400pI 400pI
20pI
-O.S TO 5pI
Figure 1-1
Synchronization and Blanking Generator Waveform
1-2

Video Amplifier:
Bandwidth
Rise and Fall Time
(10 to 90% amplitude)
Storage Time
Retrace Time:
Vertical
Horizontal
1.2.3 Display Specifications
12 MHz -3db (Class A mode)
Less
than 3sns (linear mode)
lsns max (linear mode)
60Dl1s
71Js
CRT Display (without bonded panel) Horizontal Resolution @ 15,750 Hz
1.2.4
Nominal Diagonal
*Reso1ution
(TV
lines)
Measurement
Inches/mm Phosphor
Center Corner
5/127
P4
650 @ 60
fL** 550 @ 60 fL**
9/229
P4
800 @ 40
fL 650 @
40 fL
12/305 P4
900 @ 40 fL 750 @ 40 fL
12/305
P39
900 @ 20
fL 750 @
20 fL
*Resolution is measured in accordance with EIA RS-37sA ex-
cept burst modulation is adjusted for 100% and burst fre-
quency is then increased to the point where resolution of
the lines is just discernible.
**Set reference black to visual cutoff with brightness con-
trol and reference white to the indicated fL with contrast
control.
Geometric Distortion Specif~cations
IM103s
On-Axis Scan Non-Linearities - No picture elements displaced from true position
by more than 2% of active raster height. Measurement made using "EIA Linearity
Chart" in accordance with RS-37sA.
If measured on a field of characters, the character height and width are within
10% of that for any adjacent character and within 20% of that for any character
on screen
Perimeter Non-Rectangularity -The perimeter of a full field of characters
approaches an ideal rectangle of 4 by 3 aspect ratio to within ±l.s% of the
rectangle height.
1-3

IM1035
1.2.5 Power Requirements
AC Models
120V 220V/240V
Voltage:
105-130 VRMS ±10% 220 or
240 VRMS ±10%
Frequency:
49-6lHz 49-6lHz
Power:
24
Watts Nominal 24
Watts Nominal
Fuse: 2A 2A
DC Models l2VDC
15VDC
Voltage: l2±0.2 VDC
15± 0.2 VDC
Ripple:
100 mV p-p for refresh synchronous with power freq.
10 mV p-p for refresh
non-synchronous with power freq.
Current: 750 rnA DC nominal 900rnA DC nominal
1.0 A DC maximum
1.5
A DC maximum
Fu~e:
2A 2A
MATING CONNECTORS REQUIREMENTS
Power (AC models only): 4-contact male connector shell (Mo1ex 03-06-1041)
with female contact (Molex 4529T).
Signal (and power for DC models): 10-contact board edge connector
(Refer to paragraph 1.2.1 for details.)
WARNING
ANY POWER TRANSFORMER MUST BE WELL
REMOVED FROM CRT AND/OR BE OF LOW
EXTERNAL FLUX FIELD DESIGN
1.3 MECHANICAL SPECIFICATIONS
Table 1-1 and figure 1-2 lists the mechanical specifications for the TV 50/90/120
Data monitor. For further information, contact our General Sales Offices. They are:
Addison, Illinois [phone]
Ocean,
New Jersey [phone]
Santa Clara, California [phone]
Upland,
California [phone]
1.4 ENVIRONMENTAL SPECIFICATIONS
Temperature (Ambient)
Humidity (Non-Condensing)
Altitude
1-4
OPERATING
RANGE
5 to 80%
Up to 10,000 ft/
3048m
STORAGE
RANGE
-40°C to 65°C
5 to 90%
. Up to 30,000 ft/
9144m

* DIMENSIONS (Inches/Millimeters)
WEIGHT
MODEL
TILT A B c: D
Lbs/kg OUTLINE NO
TV50
DC
OU
4.56/116
5.12/130 8.62/219
4.56/116
3.0/1.4
2-030-0319
TV90
DC
0°
7.00/178
9.50/241 9.75/248
6.16/156 6.8/3.1 2-030-0401
TV90 AC 0°
7.00/178
9.50/241 9.75/248
6.16/156
10.1/4.6 2-030-0401
TV90
DC
10°
6.90.175
9.50/241 9.75/248
6.16/156
6.8/3.1
2-030-0401
TV90
AC
10°
6.90/175
9.50/241
9.75/248
6.16/156
10.1/4.6 2-030-0401
TV120 DC 0°
9.06/230
11.40/289 11.84/301
5.75/146 11.0/5.0
2-030-0400
TV120
AC
0°
9.06/230
11.40/289 11.84/301
5.75/146 13.4/6.1 2-030-0400
TV120
DC
5°
9.03/229
11.40/289 11.84/301
5.75/146 11.0/5.0 2-030-0398
TV120 AC 5°
9.03/229
11.40/289 11.84/301
5.75/146 13.4/6.1
2-030-0398
..
TV120
DC 71 °
9.00/229 11.40/289 11.84/301
5.75/146
11.01/5.0
2-030-0399
~
TV120
AC
71 °
9.00/229
11.40/289 11.84/301
5.75/146 13.4/6.1 2-030-0399
~
TV120
DC 10°
8.92/227 11.40/289
11.84/301
5.75/146
11.01.5.0
2-030-0397
TV120
AC
10°
8.92/227 11.40/289 11.84/301
5.75/146 13.4/6.1 2-030-0397
TV120
DC
15°
10.25/260
11.40/289 11.88/302 10.25/260 10.5/4.8 2-030-0396
TV120
AC 15° 10.25/260
11.40/289 11.88/302 10.25/260 12.9/5.9 2-030-0396
~
I L- ________________________________________________________________________________ ~
V1
Table 1-1 Mechanical Specifications

IM103S
DIMENSIONS
TV-50 5 INCH DIAGONAL
n
y
""
] ( A
I
~
j I
I
=--..
B
~
TV-90 9 INCH DIAGONAL
---- C ------41
TV-120 12 INCH DIAGONAL
IT
I
A
J
~~ ~:::'-=--B- _- _- _-= _= _::.L. ...... --':~
t------ C ----f(
;1: ,.. \
--..- 6·32 THO MTG HOLES (4) ~
.....
Zi4
.188 X .500 REND MTG SLOT (4)'
5 X 13
...
6·32 THO MTG HOLES THRU PLATE (4)
Figure 1-2 TVSO, 90, 120 00 tilt with bonded panel dimensions

IM1035
1.5 HUMAN FACTORS SPECIFICATION
X-Ray
Radiation
The TV 50, 90 and 120 Data monitor complies with the Federal Regulation for
Radiation Control as required by the Radiation Control for Health and Safety
Act of 1968, and as implemented by Title 21, Subchapter J of the Code of Federal
Regulation.
These regulations place certain requirements upon manufacturers of products
which can emit x-rays under some conditions of operation or failure. This in-
cludes CRT data display monitors.
Label Visibility
Certification of compliance 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 easily 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 pro-
duct is fully assembled for use ... " Each monitor is supplied with an extra
label attached to the face of the CRT. The user will remove this label and use
it as stated above.
Power Requirements
The Data monitor is designed to operate and meet radiation requirements when
operated within the respective AC or DC input power specifications. Radiation
testing is performed at the maximum specified input voltage for AC powered mon-
itors or at 130 VAC for those nominally powered at 110-120 VAC, 60 Hz.
DC powered monitors have an additional requirement because the DC source is
usually regulated and subject to failure of the series pass element. This can
result in an appreciable increase in the anode voltage and consequent emission
of x-rays. This is not a problem for monitors equipped with over voltage pro-
tection. For monitors not so equipped, it is necessary for the buyer to ensure
that the normal adjustment of his regulator does not exceed the maximum level
specified for the particular monitor. Furthermore, he shall ensure that the
maximum available voltage from the supply cannot exceed 1.33 times nominal mon-
itor input when the supply has a single failure such as to cause the highest
possible output voltage.
User Operating Controls
The only external control required for operation of the TV 50, 90, and 120 dis-
play unit is the contrast control. This control is a carbon composition var-
iable resistor, 500n±20%; ~ watt.
The brightness control is mounted on the printed wIrIng board and is an in-
ternal adjustment by the user. An option is available where this control is re-
moved from the board and a remote brightness control supplied by the user is
utilized. The remote brightness control is a carbon composition variable resistor,
100kn±20%; ~ watt.
1-7

IMl035
Section 2
INSTALLATION
-..J
2.1 MECHANICAL
The TV 50 data monitor has four 6-32 clinch nuts for mounting the unit. The
TV 120, 0°, 5°, 7~0 and 10° monitors have four 6-32 clinch nuts on the frame
for installation purposes. The TV 120, 15° monitor uses three 6-32 clinch nuts
for mounting. The TV 90 data monitor has four .188X.sOO radius end slots for
installation. Refer to figure 1-2
2.2 ELECTRICAL
2.2.1 DC Input
The TV 50/90/120 DC models can be operated from either a 12 VDC or IS VDC source.
Refer to section 1.2.5 for details. The DC input power is applied through the
10 pin edge connector.
2.2.2 AC Input
The TV 90/120 AC models have their own self contained AC power supply. This
supply can operate either on 120 VAC or 220/240 VAC depending on which plug of
the jumper plug assembly P2 is inserted into the power supply module.
The power
transformer is wired to operate on either 120 VAC or 220/240 VAC
SO/60Hz. To operate the power supply on 120 VAC, take the connector shell of
P2 marked with 120 and insert it in to J2. Conversely, to operate at 220/240 VAC
insert the connector shell of P2 marked with 240 into J2.
AC power is supplied to the unit via Jl. Jl is a 4 contact female connector
shell (Molex #03-06-2041) with male contacts (Molex #45295)
2.3 Location
The TV 50/90/120 models shall not be located in an area that restricts air flow
around
the unit nor shall it be placed near any heat generating sources, since
this may cause the unit to overheat.
2.4 GROUNDING TECHINIQUES
The method of interconnecting and grounding the equipment is a function· of the
signal frequency. Optimum grounding depends largely on the system in which the
equipment is used. The following grounding technique is recommended when instal-
ling the monitor. Refer to figure 2-1 for interface connections.
The horizontal, CRT arc and video/vertical board circuit grounds are terminated
at JlOl. The horizontal ground (JlOl-1) and CRT arc ground (JlOl-5) is connected
together by a jumper wire on the board and they are connected to the frame by a
wire from EllO.
2-1

T2A BRN
T2A WHT-~iZJ
~1+--T2B BLK
T2B YEL --t1~
(5)11H--T2B BLU
T2B ORN--t1~
(7)11H--T2B RED
QI08
JI03-----",
-{i+15VDC
FROM A2
P.S. GND 2
TO 12.6VAC OF T I
TO 12.6VAC OF TI
8 -- VIDEO INPUT
7--(OPTIONAL} 12VII5V DC INPUT
6--HORIZ DRIVE
Figure 2-1 Interface Connections
LIBfthL
VERT
CHOKE I YEL
VERT
L2A CHOKE
VERT 4 L2A
DEFL
COIL 102 VERT
PiN J DEFL
COIL
PIN 4
5--ARC
4--} OPTIONAL EXTERNAL
3-- BRIGHTNESS CONTROL
2---
I --HORIZONTAL GRD
N
I
N

IMl035
A
connection to system ground must be made at both JlOl-l and JlOl-lO. When the
frame is an integral part of system ground, one of three possible ground config-
urations can be used.
1. When a good electrical ground connection cannot be made between the
monitor frame and system ground, then JlOl-l and JlOl-lO is wired
separately to the system ground.
2. When a good ground connection can be made between the monitor frame and
system ground, then JlOl-lO is wired to the system ground and JlOl-l is
left open.
3. When the ground connection between the monitor frame and the system
ground is acceptable and it is desired to omit the wire from JlOl-lO,
then add a jumper wire to the board to connect JlOl-5 and JlOl-lO to-
gether. JlOl-5 is then wired to the system ground. The monitor is
normally supplied without the jumper wire from JlOl-5 to JIOl-lO to
prevent horizontal circuit ground currents from flowing in the video
ground circuit.
In cases of severe arc related problems, the jumper between JlOI-1 and JlOl-5
can be removed and JlOI-5 or EllO can be connected separately to the frame or
CRT aquadag ground. JIOl-l or El02 must then be connected either to the frame
or system ground.
To isolate the frame from system ground, JlOI-1 and JlOI-IO should be wired
separately to system ground. Add another wire to JlOI-l and connect it and JlOl-5
to the frame (aquadag ground) through a capacitor. The frame cannot be completely
isolated, since an AC connection between the signal ground and frame must be
maintained to assume a complete circuit for the CRT aquadag capacity.
When the video is routed in by a long cabling, shielded cable should be used.
To avoid a ground loop, only one end of the shield should be grounded.
2.5 INPUT SIGNAL LEAD ROUTING
The input signal leads probably will carry high frequency signals and should be
given the following considerations:
A. To minimize distributed capacity and capacitive pickup of nearby radiated
fields, route the video leads separately and away from all other wiring.
B. Make the lead length as short as possible, consistent with the packaging
requirements.
C. Ideally, the video line should meet the requirements of a terminated
coaxial system; i.e., the video line should exhibit a constant impedance
from
source load.
2-3

IMl03S
Section 3
OPERATION
3.1 GENERAL
After power, video and drive signals have been applied to the monitor, the con-
trast and brightness controls may be adjusted to provide the optimum display.
3.2 BRIGHTNESS ADJUST
The
monitor is used to display alphanumeric information. The video polarity is
usually white characters on a black background. The brightness control should
then be adjusted for visual cutoff of the raster. A maximum contrast ratio can
now be obtained when video is applied.
3.3 CONTRAST ADJUST
The
video amplifier is designed to operate linearly from +.65 to +2.5 V signal
input. The contrast control should be adjusted to the point where defocusing
sets in and then backed down slightly. This occurs at a lS-20V p-p video swing
at the CRT cathode for the TV90/l20, and at a l2-lSV p-p swing for the TVSO.
In no case should contrast be adjusted to cause saturation of QlOl, as this im-
pairs the pulse response of the video amplifier.
3-1

PART II
SERVICE DATA
Section 4 through 6 and the supplement are for
qualified service personnel.
The TV 50, 90, 120 has no end user serviceable
parts inside. Refer service to qualified service
personnel.
IM1035
4

IMI035
Section 4
THEORY OF OPERATION
4.1 VIDEO AMPLIFIER
The
video amplifier consists of QlOl and its associated circuitry. The incoming
video signal is applied to the monitor through JlOl-8 and RlOl to the base of
QlOl.
Transistor QlOl has a nominal gain of 15, and operates as a class B amplifier.
QlOl remains cutoff until a DC coupled, positive-going signal arrives at its
base and turns it on. Rl03 provides series feedback which makes the terminal
to terminal voltage gain relatively independent of transistor parameters and
temperature variations. RI02 and CIOI provide emitter peaking to extend the
bandwidth to 12~1Hz. .
The
negative going signal at the collector of QIOI is direct coupled to the
CRT cathode. The class B biasing of QIOI allows a large video output signal
to modulate the CRT's cathode and results in a maximum available contrast
ratio.
The overall brightness at the screen of the CRT is also determined by the neg-
ative potential at its grid which is varied by the brightness control:
4.2 VERTICAL DEFLECTION
QI02 is a thyristor used as programmable unijunction and together with its ex-
ternal circuitry forms a relaxation oscillator operating at a vertical rate.
The sawtooth forming network consists of AIOI, Cl03 and Cl04. These capacitors
charge exponentially until the voltage at the anode of Ql02 exceeds its gate
voltage at which time QI02 becomes essentially a closed switch, allowing a
rapid discharge through LIOI. The rate of charge or frequency is adjustable by
AIOI. The oscillator is synchronized by a negative pulse coupled to its gate
from the vertical drive pulse applied externally at JIOI-9.
A divider network internal to AIOI sets the free running frequency by establish-
ing a reference voltage at the gate. This programs the firing of QI02 and
amounts
to resistive selection of the intrinsic standoff ratio. The frequency
is controlled by passive components only. CRIOI provides temperature com-
pensation for Ql02 while controlling the gate impedance to allow easy turn on
and
off of QI02. LIOI forms a tuned circuit with Cl03 and Cl04 during conduction
of QI02 which provides a stable control on the drop-out time of QI02 to assist
in maintaining interlace. Ql03 collector to base forward diode clamping action
prevents the voltage from swinging too far negative during this flywheel action.
The sawtooth at the anode of Ql02 is direct coupled to the base of Ql03. This
stage functions as a darlington pair emitter follower driver for the output stage
QI04. It presents an extremely high impedance in shunt with AlOI and prevents
the Beta dependent input impedance of QI04 from affecting the frequency of the
4-1

IMl03S
sawtooth forming network.
Linearity control of the sawtooth is accomplished by coupling the output at
Ql03 emitter resistively back into the junction of Cl03 and Cl04. This pro-
vides integration of the sawtooth and inserts a parabolic component. The
slope change rate of the sawtooth at Ql03 output is controlled by the setting
of Al02. The output at Ql03 is coupled into a resistive divider ..
Height control RllO varies the amplitude of the sawtooth voltage applied to the
base of Ql04 and controls the vertical raster size on the CRT. CIOS is used
to limit the amplitude of the flyback pulse at Ql04 collector.
The vertical output stage Ql04 uses an NPN power transistor operating as a
class AB amplifier. The output is capacitively coupled to the yoke. Ll pro-
vides a DC connection to B+ for Ql04; it has a high impedance compared to the
yoke inductance which causes most of the sawtooth current of Ql04 to appear in
the yoke. Rl14 prevents oscillations by providing damping across the vertical
yoke coils.
4.3 HORIZONTAL DEFLECTION
4.3.1 Low Level Stages (Figure 4-1)
The purpose of QlOS and Ql06 is basically to process the incoming horizontal
drive signal into a form suitable to drive the output stage Q108. The duty cycle
of Q108 becomes essentially independent of the amplitude and pulse width of the
drive pulse. This is a necessary condition to assure stability and reliability
in the output stage. In adddition, these stages provide a horizontal video
centering adjustment by delaying retrace with respect to the horizontal drive
pulse.
The drive pulse is presented to Q10S via J10l-6. The base circuit of QlOS in-
cludes a clamp and a differentiator which makes Q10S output insensitive to drive
pulse amplitude and width changes. The only requirement is that pulse amplitude
be of 2.S volts minimum and pulse width should be lO-40~s. QlOS together with
Ql06 functions as a monostab1e multivibrator with Ql07 being a slave that pro-
vides a positive feedback. Specifically, when Q10S is turned on by the drive
pulse, it discharges Cl12 at a rate determined by the setting of Al03. When
Cl12 is discharged to 2.7S volts, Q106 turns off. This change of state turns
Ql07 on and the base drive to Ql06 from R128 is shunted thru Ql07. QI06/Q107
remains in this state for nominally 2S~s until Cl12 recharges through Al03 to
8.2S volts. At this time, Q106 is biased on again by the current through Al03.
The mu1tivibrator is now in a state that Q106 is on and Q10S/Q107 is off. It
will remain in this state until the next drive pulse occurs or power is turned
off. Cl12 is the only timing capacitor in the circuit and has two time constants
associated with it. Primarily, the charge path between pin 1 and pin 3 of Al03
determines the on time of Q107 while the discharge path through the video center-
ing control and QlOS determines the delay between application of the drive pulse
and start of retrace (turn on of Ql07).
4.3.2 High Level Stages
These stages consist of Ql07 driving the output stage, Ql08 and its associated
4-2

10 - 40
n
"sec
fl
HORIZ
DRIVE
DIFFERENTIATOR
CII3
RI25
d I : 0.5-6.0)1 lec
dZ : 17" sec
d.+ dZ • 17.5-23,. sec
8
n
t,
ONE-SHOT
TRIGGER
0105
I I I
8-dl~: I
18
Idl+I I I Id
,+'
I I I I
d, I I I
I Id
Z I , I d2 I
I I : I I: I
if
~
t I J :
, I
fl
t,+d
l
dl
VARIABLE
DELAY
AI03 PIN 2-3
CIIZ
dl+d
Z
VARIABLE
DELAY
AI03 PIN 1-3
CII2
d2+
8
A
25 ~,
f,+ dl
ONE-SHOT
OUTPUT
0106
POSITIVE
FEEDBACK
RIZ8
ONE-SHOT
SLAVE
0107
Figure 4-1 Horizontal Drive Processing and Timing Chart
d2+
8
25 ~.
t::J
fl+dl
TO
0108

IMl035
""~,:,,
.,
circuitry thru TlOl. Ql07 is an inverting slave of QI06 and is driven alter-
nately into saturation and cutoff as are all stages in the horizontal circuit.
Ql07 output is transformer coupled to the output stage with phasing of TlOl
chosen such that Ql08 turns off when Ql07 turns on. This allows Ql08 to turn off
quickly, thus minimizing dissipation. A careful review will show that Ql08
turns off at a variable delay time after receipt of the drive pulse. This
action causes retrace to begin.
During conduction of the driver transistor, energy is stored in the coupling
transformer. The polarity at the secondary is then phased to keep Ql08 cut off.
As soon as the primary current of TlOl is interrupted due to the base signal driving
Ql07 into cut off, the secondary voltage changes polarity. Ql08 now saturates
due to the forward base current flow. This gradually decreases at a rate deter-
mined by the transformer inductance and circuit resistance. However the base
current is sufficient to keep Ql08 in saturation until the next polarity change
of TlOl.
The horizontal output stage has two main functions: 1) to supply the deflection
coil with the correct horizontal scanning currents: 2) to develop high voltage
for the CRT anode and DC voltage for the CRT bias, focus and accelerating grids
as well as the DC voltage for the video output stage.
(
Ql08 acts as a switch which is turned on or off by the rectangular waveform on
the base. When it is turned on, the supply voltage plus the charge on C123
causes deflection 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 polarity change of TlOl which causes the output circuit to
oscillate. A high reactive voltage in the form of a half cycle negative voltage
pulse is developed by the deflection coil inductance and the primary of T2.
The peak
magnetic energy which was stored in the deflection coil during scan
time is not transferred to Cl22 and the deflection coil distributed capacity.
During this cycle, the beam is returned to the center of the screen.
The charged capacitances now discharge into the deflection coil 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 coil moves the ·scanning beam to the
left of the screen.
After slightly less than half a cycle, the decreasing voltage across Cl22 biases
the damper diode CRIll into conduction and prevents the flyback pulse from fur-
ther oscillation. The magnetic energy that was stored in the deflection coil
from the discharge of the distributed capacity is now released to provide sweep
for the left half of scan and to charge Cl23 through the rectifying action of
the damper diode. The beam is now at the center of the screen. The cycle will
repeat as soon as the base of QI08 becomes positive with respect to its emitter.
e123 serves to block DC current from the deflection coil and to provide "S"
shaping of the current waveform. "S" shaping compensates for stretching at the
left and right sides of the picture tube because the curvature of the CRT face
and the deflected beam do not follow the same arc.
LI03 is an adjustable width control placed in a series with the horizontal de-
4-4