Digital Equipment VR14 User manual

VR14/VR17 CRT display
monitor user's manual
EK-VR14-0P-005
digital equipment corporation:. maynard. massachusetts

1st Edition, April 1971
2nd Printing (Rev) June 1971
3rd Printing (Rev) June 1972
4th Printing (Rev) January 1973
5th Printing, July 1973
2nd Edition, December 1973
7th Printing, November 1974
Copyright © 1971,1972, 1973, 1974 by Digital Equipment Corporation
The material in this manual is for infonnational
purposes and
is subject to change without notice.
Digital Equipment Corporation assumes no respon-
sibility for any errors which may appear in this
manual.
Printed in U.S.A.
The following are trademarks of Digital Equipment
Corporation, Maynard, Massachusetts:
DEC
FLIP CHIP
DIGITAL
PDP
FOCAL
COMPUTER LAB

CHAPTER 1
1.1
1.2
1.3
CHAPTER 2
2.1
2.2
2.3
2.4
2.5
CHAPTER 3
3.1
3.2
3.3
3.4
3.5
3.6
3.6.1
CHAPTER 4
4.1
4.2
4.2.1
4.2.2
4.3
4.3.1
4.3.2
4.3.3
4.3.4
4.3.5
CHAPTER 5
APPENDIX A
APPENDIX B
APPENDIXC
CONTENTS
Page
GENERAL INFORMATION
INTRODUCTION
...................................... 1-1
SPECIFICATIONS ..... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1-1
BLOCK DIAGRAM DESCRIPTION ............................. 1-3
OPERATION
INSTALLATION ...................................... 2-1
FRONT PANEL CONTROLS ................................ 2-1
REAR PANEL CONNECTORS ............................... 2-2
INTERNAL CONTROLS
.................................. 2-2
INPUT SIGNAL REQUIREMENTS ............................. 2-2
THEORY OF OPERATION
X- AND Y- DEFLECTION CIRCUITS .......................... " 3-1
PLUS AND MINUS LOW VOLTAGE REGULATED SUPPLY ............... 3-5
CRT ELECTRODE VOLTAGES ............................. " 3-6
HIGH VOLTAGE POWER SUPPLY
............................. 3-6
W682 AND W684 INTENSITY CIRCUITS
......................... 3-10
LIGHT PEN AMPLIFICATION ............................... 3-13
375 Light Pen
.. 3-14
MAINTENANCE
PREVENTIVE MAINTENANCE
.............................. 4-1
TROUBLESHOOTING ................................... 4-1
No Picture ....................................... 4-1
Faulty Picture ..................................... 4-5
ASSEMBLY REPLACEMENT INSTRUCTIONS
...................... 4-5
Deflection
Heat Sink Removal ............................. 4-5
7007165 Power Regulator Assembly Removal ........ . . . . . . . . . . . .. 4-7
Regulator Heat Sink Removal
............................. 4-9
Yoke and CRT Removal ................................ 4-9
High Voltage Supply Removal
............................. 4-11
ENGINEERING DRAWINGS
POWER SUPPLY TROUBLESHOOTING
DEFLECTION AMPLIFIER TROUBLESHOOTING
A225 REPAIR
iii

Figure No.
1-1
1-2
2-1
2-2
3-1
3-2
3-3
3-4
3-5
3-6
3-7
3-8
4-1
4-2
4-3
4-4
4-5
Table No.
1-1
2-1
2-2
2-3
3-1
4-1
5-1
5-2
ILLUSTRA nONS
Title
Block Diagram
ofVR14 Without Light Pen Option
VRI4L/VRI7L Block Diagram
Input Power Jumper .....
Locations of Internal Controls
X and Y Deflection Circuit . .
G836 Circuit Board,
Part of the 7007165 Power Regulator Assembly
Intensity Amplifier W682, Circuit Schematic
W684 Intensity Control
........... .
G838 Circuit Diagram
............ .
VRI4L/VRI7L Brightness and Contrast Control
Light Pen Amplifier ........ .
Light Pen Pulse Timing,
G840 Module
VRI4/VRI7 Interior View .... .
Deflection Heat Sink Removal
.. .
7007165 Power Regulator Assembly
7007165 Removal .....
Regulator Heat Sink Removal
TABLES
VR14 and VR17 Configurations .
J17 Rear Connector Pin Assignments
J18 Rear Connector Pin Assignments
Control Settings ........ .
Brightness Control
....... .
VRI4/VRI7 Voltage Check Points
VR14 Engineering Drawings
VR17 Engineering Drawings ...
Title
iv
Page
1-4
1-5
2-1
2-6
3-3
3-7
3-9
3-10
3-11
3-12
3-13
3-14
4-3
4-6
4-7
4-8
. 4-10
Page
1-1
2-3
2-5
2-7
3-12
4-2
5-1
5-1

WARNING
Maintenance procedures should be performed
by qualified service personnel only.
High voltages are present within the unit and,
under certain conditions, are potentially
dangerous. All electrical safety precautions
must be observed.
Inherent implosion protection is employed in
the CRT design; however, the tube may be
damaged if it is subjected to rough treatment or
dropped while being removed from or installed
in the display. Exercise caution during these
operations.

1.1 INTRODUCTION
The VR14 and VR17 are completely self-contained CRT
display monitors that require only analog X- and Y-position
information and an intensity input, to generate sharp,
bright displays. The VR14 and VR17 are electrically
identical. The VR17, however, has a larger display screen
(17 inches diagonal) than the VR14
(12 inches diagonal).
This necessitates a correspondingly larger enclosure, and a
CRT support bracket for the VR17. Except for the CRT
itself, both VR14 and VR17 are composed of fully solid
state circuits, utilizing high-speed magnetic deflection to
enhance brightness and resolution. The inputs for the
X-
and Y- deflection may be balanced or single ended, bipolar
or offset, and positive- or negative-going without any
modification
to the VR14/VR17.
The VR14 and VR17 come in several configurations, listed
in Table 1-1.
Table
1-1
VR14 and VR17 Configurations
Designation Mounting Power Light Pen
Option
VR14-0 Rack
115V
No
VR14-A Rack 230 V No
VR14-B Rack
100V
No
VR14-C Table 115V No
VR14-D Table 230 V
No
VR14-E Table
100V No
VR14-LC Table 115 V Yes
VR14-LD Table 230 V
Yes
VR17-LC Table 115 V Yes
VR17-LD Table 230V Yes
The VR14 versions without the light pen option contain a
W682 Intensity Control Circuit Board and a G838 Fault
Protection Circuit Board,
as well as a front panel
CHANNEL switch which operates with the W682 board. In
CHAPTER 1
GENERAL INFORMATION
1-1
this variation, intensity pulses may be time multiplexed or
gated
by a separate input to allow the screen to be
timeshared
by two inputs.
The VR14/VR17 versions with the light pen option
(VR14-LC, VR14-LD, VR17-LC, VR17-LD) do not have
this timesharing capability nor channel selectivity. They
contain a W684 Intensity Control Circuit Board in place
of
the W682, and a G840 Light Pen Amplifier in place of the
G838. The G840 circuit board, however, contains the fault
protection circuitry
of the G838 board.
1.2 SPECIFICATIONS
VR14/VR17 specifications are as follows:
Physical:
Height
Width
Depth
Weight
Viewable
VR14
10-1/2 in. (267 mm)
19 in. (483 mm)
17 in. (432 mm)
75 lb (34 kg)
VR17
15 in. (381 mm)
21-1/2 in.
(546 mm)
27 in. (686 mm)
85 lb (39 kg)
Area 6-3/4 in. X 9 in. 8-1/4 in. X
11 in.
(171.45 X 228.6 mm) (210 X 280 mm)
VR14 and VR17
Spot Size:
<20 mils inside the usable screen area at a brightness of
30 fL
Jitter:
< ±1 /2 spot diameter
Repeatability:
<±1 spot diameter
(Repeatability
is the deviation from the nominal loca-
tion of any given spot)

Gain Change:
From a
flXed point on the screen, less than ±0.3% gain
change for each
±1 %line voltage variation
Temperature Range:
0° to 50° C(operating)
Relative Humidity:
10% to 90% (noncondensing)
Brightness:
~ 30 fL for VRI4, ~ 25 fL for VRI7; measured using a
shrinking raster technique
Linearity:
Maximum deviation
of any straight line is ~ 1% of the
line length, measured perpendicular to a best-fit straight
line.
Deflection Method:
Magnetic (70° diagonal deflection angle)
Focus Method:
Electrostatic
High Voltage:
10.5 kV dc nominal (voltage proportional to input line
voltage). Supply
is self-contained and equipped with a
bleeder resistor.
Shielding:
CRT
is fully enclosed in a magnetic shield.
Overload Protection:
Unit is protected against fan failure or air blockage by
thermal cutouts. Power supply and amplifiers
are current
limited. Phosphor protection
is provided against fault
conditions.
Deflection Amplifier
a. Deflection amplifiers are dc coupled and are capable
of sustaining a full screen ac or dc deflection at
environmental extremes.
b. Input Specifications:
1. Inputs are differential.
2. Differential input impedance,S
kQ minimum.
3. Input sensitivity, 500 mY/inch maximum (200
mVlinch with resistor change)
1-2
4. Common mode rejection ratio, 40 dB
5. Maximum operating input, ±6 V. (Maximum oper-
ating input is the sum of the common mode input
and the differential input.)
6. Input offset not to exceed ±1/2 peak-to-peak
input signal.
7. Maximum nonoperating input, ±50 V
c. Full screen deflection and settling time to within ±1
spot diameter, ~ 18 }J.S.
d. Small signal settling time to within 1/2 spot diameter,
~1 }J.s for a 0.1 inch deflection
e. Small signal linear slew rate, ~ 0.4 inch/l }J.S
f. Velocity error coefficient, 500 ns maximum (average
ramp delay between input and output)
Z-Axis (on VR14 without Light Pen Option)
a. Z-Input - A negative transition from ~ +2.4 V, but
not exceeding
+8 V, to ~ +0.8 V, but not more
negative than
-4 V, in ~ 20 ns, causes an unblanking
pulse at the CRT cathode from approximately +62 V
to ground with a duration of ~ 200 ns at the 50
percent points. Delay between the 50 percent point
of the negative input transition to the 50 percent
point
of the output pulse is less than 100 ns. Driver
must sink 4 rnA.
b. Z-Direct - A positive-going pulse not exceeding
65 V,
but at least 45 V in height and not exceeding 10 }J.S,
but at least 1 }J.S in duration, unblanks the CRT to a
viewable intensity. This signal
is ac coupled to the
CRT grid.
c." Channel Select -With the Channel Select Switch in
the
Channell position, a positive level of greater than
+2.4 V, but not exceeding
+8 V, enables the Z-input
circuit. A level
of less than +0.8 V, but not more
negative than
-4 V, disables the circuit. With the
switch in the Channel 2 position, a positive level
disables the Z-circuit; a negative level enables it.
Placing the switch in the Channel 1 & 2 position
disables this input.

Z-Axis [on VR14/VR17 with Light Pen Option (VR14L
and VR17L)]
a. Z-Input -This is a TTL logic signal. When a TTL
low, it unblanks the CRT by causing the cathode
voltage to change from approximately +62 V
to
ground. The CRT will remain unblanked as long as
the Z-input is at a logic low.
b. Intensity
0, 1, 2 - These three signals, together with"
the brightness control, generate a voltage of from
-80 V to 0 V on the CRT grid 1,
to determine image
brightness. The combination
of the three intensity
signals asserts one
of eight possible analog voltages,
which in turn
is ANDed with the output of the
brightness control to generate a grid voltage in the 0
to -80 V range. Thus, there are eight intensity levels
at each
of the infinite positions of the brightness
control.
Power
a. All power supplies necessary for operation of the unit
are self-contained.
b. Input Requirements
Voltage: (Selectable by tap changes)
100 V ± 10%
115 V ± 10%
230 V ± 10%
Frequency - 50-60 Hz
Power -
::;:;;;; 500 W
Current - ::;:;;;; 5 A
Type -Single Phase
1.3
BLOCK DIAGRAM DESCRIPTION
Figure I-I is the functional block diagram of the VR14
without the light pen option. The X- and Y- position signals
are connected to their respective A225 Deflection Ampli-
fier Circuit Boards. The A225s boost the input signal to a
level sufficient
to drive the power transistors, while also
providing gain and position controls. In turn, the power
transistors drive
the deflection yoke that positions the
electron beam on the screen. The yoke currents are then
passed through a 0.5 n resistor that converts the yoke
currents back into voltages that are used
as feedback for
each A225 deflection amplifier. This feedback allows the
A225 to produce an exact current replica in the yoke
of the
input signals.
The intensity input
is applied to the W682 circuit board
that converts this input to a 60 V pulse which drives the
cathode. The cathode pulse
is negative going; this pulse
turns on the electron beam, creating a spot on the screen.
1-3
The W682 accepts a gating input that allows the intensity
pulse
to be time-multiplexed between two input sources.
The G838 Fault Protection Board disables the intensity
circuit in the event
of a ±22 V failure. This prevents the
phosphor screen from burning,
as there would be no
deflection under these conditions.
Line power
is passed through a fuse, an on-off switch, and
then through one normally closed thermal cutout switch.
The switch
is located on the +22 V regulator heat sink, and
in the event
of a fan failure or excessive temperature on the
heat sink,
VRI4/VRI7 input power will be shut off until it
cools down. The line power is then connected to the power
transformer, the high voltage power supply, and the fans.
The high voltage supply converts the input line voltage to
10.5 kV that is connected to the CRT anode. The power
transformer has three basic secondaries: a 6.3 V for fila-
ment, a 70/150 for CRT electrodes, and a 72 V center
tapped for deflection. The 72 Vac
is rectified and filtered
to provide ±43 Vdc unregulated. This ±43 Vdc
is regulated
with circuits on the G836 board, along with four power
transistors on the regulator heat sink assembly. The
regulated output
is ±22 Vdc and is distributed to the
deflection amplifiers. The 70/150
ac is rectified and filtered
on the G836 to generate ±80 Vdc and +400 Vdc. The
-80 Vdc is used for the brightness potentiometer which is
tied to the grid. One side of the brightness control is
connected to another potentiometer on the G836 which
can adjust the maximum brightness range of the brightness
potentiometer. The +400 Vdc
is supplied directly to grid 2
and also
to one side of the focus potentiometer on the
G836 board. The wiper
of the focus potentiometer goes
directly to the focus electrode on the CRT.
Figure 1-2 is a block diagram of the VRI4L and VRI7L,
i.e., VRI4/VRI7 with the light pen option. Note that the
G840 Light Pen Amplifier replaces the G838 Fault Protec-
tion Circuit Board. The G840 contains the G838 circuitry
as well as an amplifier to detect and shape pdse outputs
from the light pen. The output
of the light pen amplifier is
brought out of the VRI4L/VRI7L through pin 19 of the
24-contact amphenol connector (117) at the rear
of the
display monitor.
Note that in the VRI4L and VRI7L, the W684 intensity
control replaces the W682. The W684 allows an intensity
pulse to the cathode whose duration
is equal to that of the
Z intensify signal. The W684 circuitry also modifies the grid
I bias voltage, thereby allowing eight intensity levels for a
particular setting
of the front panel brightness control.
All other circuits represented in Figure 1-2 are identical to
those represented in Figure I-I.

-
~
115~o---J CUTOUT
Y I FROM THERMAL
VAC
INPUT »------------------~l
115
115VAC VAC
POWER
TRANSFORMER
UNIT POWER
RECTIFIERS
+ FILTER CAP.
CHANNEL 1> o......a>----
CHANNEL 2> 0
Z INTENSITY > .. ,
+22V
115VAC~
POWER SUPPLY a
REGULATOR BOARD
G836
+80V
X FEEDBACK
THERMAL
CUTOUT
+22V
-22 V
~----- ... - FOCUS
_. I In !' un I DEFLECTION
YOKE
115VAC
HIGH
VOLTAGE
POWER
SUPPLY
~
10.500VDC
ANODE
0.5.n.
;. II I I I CURRENT
-22V
X INPUT
) -,
X
POWER
TRANSISTOR
y
y INPUT; ~DEFLECTION ~22V Y
AMPLIFIER POWER
A225 RANSISTOR
+20V
-20V
IG;'NI,hosYTIONI
r:::l---< 115
~VAC
Y FEEDBACK
Figure 1-1 Block Diagram ofVR14 Without Light Pen Option
SAMPLE
0.5.n.
CURRENT
SAMPLE
CP-0758

-
In
115~~ CUTOUT
Y IFROM THERMAL
VAC
INPUT )>-------------.1
115
115VAC VAC
POWER
TRANSFORMER
UNIT POWER
RECTIFIERS
+ FILTER CAP.
INTENSITY O~ *
l~tt~~IH 1 >------------ ... = .... I...L.----
INTENSITY OUT :
LIGHT PEN
INPUT
+22V
-22V
115VAC~
POWER SUPPLY a
REGULATOR BOARD
GS36
LIGHT PEN
PULSE
-x INPUT::> -I
+Y INPUT; ~
-Y INPUT
Y FEEDBACK
THERMAL
CUTOUT
+22V
§
-22V
FOCUS
+400V
+SOV
-SOY
,-- __ n I DEFLECTION
YOKE
115VAC
HIGH
VOLTAGE
POWER
SUPPLY
10,500VDC
ANODE
0.5.n.
.? II I I CURRENT
X
POWER
TRANSISTOR
Y
POWER
RANSISTOR
+22V
-22V
r:::t----< 115
~VAC
SAMPLE
0.5 J),
CURRENT
SAMPLE
cp- 0760
Figure 1-2 VR14L/VR17L Block Diagram

2.1 INSTALLATION
The VR14 is shipped either as a standard RETMA 19 inch
by 10-1/2 inch (l0-7/16 inch) rack-mounted unit or as a
table-top model (without chassis slides) with its own
decorator cover. 'The VR17 comes only in a table-top
model. The
VR14/VR17 can operate from a power line
frequency between
47 and 63 Hz. The input line voltage,
however,
is specified by a letter designation after the
VR14/VR17 (O,C is 115 V; A,D is 230 V; and B,E is
100 V). The VR14/VRI7 can operate with any of the three
input line voltages simply by changing the jumpers and
interconnections
on TB1 and TB2 (Figure 2-1 and drawing
D-CS-7007084-0-1).
Equipment cooling
is the most important VR14/VR17
installation requirement. Fans draw air from
the bottom of
the unit; therefore, at least 1 inch of free air space must be
provided below
the bottom chassis. The table-top model
keeps the
bottom 1 inch above the table surface. In the
rack-mounted unit,
if equipment is mounted immediately
below the
VR14, as long as there is open area under the
VR14 fans (a screen
is acceptable; a solid plate closer than
1 inch
is not), proper cooling can occur. The same
requirements apply,
on the rack-mounted unit, to the area
immediately above the unit. The table-top model has a solid
top cover. The cooling air exits from the rear of the unit.
Therefore, at least 2 inches
of free space must be provided
immediately behind
the unit. (Do not push the
VRI4/VRI7 flush against a wall or solid vertical surface
that would cut off air circulation.)
NOTE
Before applying power to the VR14/VR17,
ensure
that the position potentiometers are set
for the particular input signals being used.
Because
of the universal nature of allowable
input signals, the deflection amplifiers may be
driven
into saturation far off screen by position
settings. Leaving the deflection amplifiers satu-
rated way off screen continuously may cause
damage. See Paragraph 2.S and Table 2-2 for
propersettings.
2-1
Interchange
Orange
with
Red (from
Transformer)
CHAPTER 2
OPERATION
115 Vac
TBl
TB2
1 1
@ ~ __ ~ju_m~p_er ____ ~@
3 3
4 4
5 5
@ jumper @
230 Vac
TBl TB2
1 1
(2)
CV
3
jum
3
4 per 4
5 5
@ ®
100 Vac
TBl
TB2
1
CV
jumper Interchange
3 White
with
4 Gray
(from
5 Transformer)
@ jumper
Figure 2-1 Input Power Jumper
2.2 FRONT PANEL CONTROLS
The on/off, brightness control, and the channel select
control
(not applicable to VRI4L/VRI7L) are located on
the front panel. The on/off switch turns on input power to
the VRI4/VRI7 when the knob is rotated clockwise from
the maximum counterclockwise
off position. Turning the
knob clockwise also increases the brightness
of the dis-

played information. A delay of about 30 seconds occurs
before information appears
on the screen while the CRT
filament warms up. In an operating system, it is recom-
mended that power be left on the display even when it is
not in continuous use so that the filament warmup delays
do
not occur.
The channel select switch
on VR14s without the light pen
option works in conjunction with the channel select signal
applied at the rear connector. When
not using the dual-
channel feature, the select switch should be in the 1 & 2
position. When using the dual-channel system, points
on the
screen will be intensified from Z-intensity inputs only when
the channel select signal at the rear connector
is high and
the channel select switch
is in the Channell position. If the
channel select
input signal goes low while the select switch
is at 1, intensification ceases. On the other hand, the
Channel 2 position works in the opposite manner. If the
channel select
input signal is low and the select switch is at
2, Z-intensification signals will intensify on the screen.
Thus,
if a group of information points is to be separated
from another group, separation can be achieved
by having
group 1 intensification pulses occur only when the Z-select
line
is high, and group 2 intensification pulses occur only
when
the Z-select line is low. Channel select position 1 & 2
overrides
the select input signal and displays every intensifi-
cation pulse of both channels at once. To observe only
Channel 1 information, select Channel 1 and all Channel 2
signals are locked out. By selecting Channel 2, only Channel
2 signals are displayed.
2.3 REAR PANEL CONNECTORS
The rear panel has an Amphenol 14·contact connector
(JI8) and an Amphenol 24-contact connector (JI 7). Tables
2-1 and 2-2 list rear connector pin assignments.
2.4 INTERNAL CONTROLS
The VR14/VRI7 internal adjustments include six potenti-
ometers: X position, X gain, Y position, Y gain, focus, and
brightness preset. Access to the adjustments
is gained by
removing
the case cover (Figure 2-2).
The gain and position adjustments are located
on the top,
left central portion
of the VR14/VR17 (as viewed from the
front). The two forward potentiometers on the deflection
circuits are the horizontal gain
on the left, and vertical gain
on the right. The two rear potentiometers are the hori-
zontal position on the left, and the vertical position on the
right.
The gain adjustments allow
the VR14/VR17 to accom-
modate a range of input signal amplitudes and expand or
contract the horizontal and vertical deflection to suit full
screen requirements. The position controls accommodate a
2-2
variety
of input signals and allow offset inputs to be
centered on the CRT screen. Once initially adjusted for the
particular
input Signals used, the gain and position controls
rarely have to be adjusted. Gross positioning
off screen or
excessive gain deflecting
off the extremities of the screen
should be avoided, since the deflection amplifiers will go
into current limiting and may overheat
if allowed to stay in
this condition any length
of time. Turning the X and Y gain
controls clockwise, increases
the gain or displayed image
size. Turning
the X and Y positions clockeise moves the
displayed information right and up, respectively.
The focus and brightness preset adjustments are located at
the
top, right central portion of the unit. They are on the
power supply regulator circuit (G836)
that is somewhat
recessed from
the top of the unit. The brightness preset is
the rear-most of the two. This potentiometer allows the
range
of the front panel brightness control to be limited to
any maximum brightness desired. Turning the brightness
preset counterclockwise increases the maximum brightness
range
of the front panel control. Generally, this control is
set so that at maximum brightness setting on the front
panel knob,
the displayed information does not "bloom"
causing a degradation in resolution. The focus potenti-
ometer is in front of the brightness preset. The adjustment
is quite insensitive and requires several turns to go through
focus.
The VR14L and
VR17L also contain a contrast adjusting
potentiometer (R29), located
on the W684 module. It is
accessible from the top of the VR14/VR17. This control is
used to extend or contract the brightness range of the CRT
display. It does not normally have to be changed after an
initial adjustment
is made to compensate for component
variations.
2.5 INPUT SIGNAL REQUIREMENTS
NOTE
The deflection amplifiers must not be driven so
that
the CRT beam is off screen for any length
of time or permanent damage may occur.
Ensure
that input deflection signals fail to a
safe, on-screen value.
The VR14/VR17 requires analog voltage inputs for
X- and
V-deflection, and a logic level change or pulse for intensify.
The
X- and V-inputs are identical. However, because the
CRT is a 3 X 4 rectangle, only 3/4 of the horizontal
deflection
is required for full vertical deflection. The
deflection inputs are differential
but may be driven from
single-ended sources. When using single-ended sources, the
differential input
is helpful in eliminating annoying ground
loops and hum. By carrying
the "local" common or ground

Table 2-1
117 Rear Connector Pin Assignments
VR14 VR14
L/VRI7 L
11724-Pin Destination Signal Name Function Signal Name Function
Connector
Pin 1
A4L Z-Select High input enables Z-intensify to
Intensity 2 Determines intensity level
occur
if channel select switch on 1. A
low input enables Z-intensify
to occur
if channel select switch on 2.
Pin 2
A4B
Not Used Intensity 0 Determines intensity level
Pin 3
A4K
Not Used Intensity 1 Determines intensity level
Pin 4
A4J Z-Input When this input
goes from high to low, Z-Input
When this input is low, an intensify
an intensify pulse
is generated. signal is applied to the CRT.
Pin 5 GND
~
w Pin 6 GND
Pin 7
A2B
-X Input One side of X~input signal line -xInput One side of X-input signal line
Pin 8
A2E
+X Input Other side
of X input signal line +X Input Other side of X-input signal line
(ground for single ended input) (ground for single ended input)
Pin 9
A2H X-Signal GND
X signal reference ground X-Signal GND X signal reference ground
Pin 10
A3B
-Y Input One side
of V-input signal line
-Y Input One side
of Y-input signal line
Pin 11
A3E +Y Input Other side
of Y input signal line +Y Input Other side of Y input signal line
(ground for single ended input) (ground for single ended input)
Pin 12
A3H
V-Signal GND
Y signal reference ground V-Signal GND Y signal reference ground
Pin
13 A4D
Z-Direct Input signal that directly modulates Not Used
CRT grid (ac coupled)
Pin 14
N/C

Table 2-1 (Cont)
J1 7 Rear Connector Pin Assignments
VR14 VRI4L/VRI7L
J1724-Pin Destination Signal Name Function Signal Name Function
Connector
Pin
15
JI8-Pin4
Not Used Bell (Speaker) Used in LK40 option
Pin 16
N/C
Pin
17
JI8-Pin 5 Not Used
+K.B Signal Used in LK40 option
Pin 18
JI8-Pin 6 Not Used -
K.B Signal Used in LK40 option
Pin 19
AIH
Not Used Light Pen Out Amplified light pen pulses
Pin 20
JI8-Pin 12 Not Used
+5 VIN Used in LK40 option
N
~
Pin 21
N/C
Pin 22
JI8-Pin 8 +22 V +22 V
is available if JI8-Pin 8 is +22V +22 V is available if JI8-Pin 8 is
jumpered to JI8 pin 1.
jumpered to J18 pin 1.
Pin 23
JI8-Pin 10
-22 V
-22 V is available if JI8 pin 10 is
-22 V is available if JI8 pin lOis
jumpered to JI8 pin 3. jumpered
to JI8 pin 3.
Pin 24
JI8-Pin9
GND
JI8 pin 9 must be jumpered to JI8 pin GND
JI8 pin 9 must be jumpered to JI8
2. pin 2.
-

Table 2-2
Jl8 Rear Connector Pin Assignments
Jl8 14-Pin Connector Destination
Pin 1 +22 V Regulated
Pin 2
GND
Pin 3 - 22 V Regulated
Pin 4 117 Pin
15
Pin 5 117 Pin 17
Pin 6 117 Pin 18
Pin 7 N/C
Pin 8 117 Pin 22
Pin 9 117 Pin 23
Pin 10 117 Pin 24
Pin 11
N/C
Pin 12 117 Pin 20
Pin 13
GND
Pin 14
-22 V
along with the deflection signal from where it is generated,
a quasi-differential signal is generated. Instead of termi-
nating this ground at the VRI4/VRI7 chassis, use the
ground
as if it were one side of a differential signal (the
other side being the deflection signal itself).
The,
VRI4/VRI7 uses the deflection signal with respect to its
own ground and not the
VRI4/VRI7 ground, which, most
likely, is different and could cause picture ripple and hum.
If a separate ground is not available, the single deflection
Signal is applied to one side of the differential input. The
remaining differential input is terminated with the source
impedance
of the driving signal or, if this is low, the input is
simply grounded (signal ground not chassis ground). (Signal
ground is pin 9 and pin 12" X- and Y -signal ground,
Signal Name Function
+22 V For
VRI4/VRI7 options
GND For VRI4/VRI7 options
-22 V For VR14/VR17 options
Bell (Speaker) Used with LK40 option
+KB Signal Used with LK40 option
-KB Signal Used with LK40 option
Not Used
+22 V Jumpered from J18 pin 1 to 118 pin
8 by P18
GND
Jumpered from 118 pin 2 to 118 pin
9 by P18
-22V
Jumpered from 118 pin 3 to 118 pin
10 by P18
+5V Provides +5 V to LK40 option
GND Provides
GND to LK40 option
-22 V Provides -22 V to LK40 option
respectively.) Never
use chassis ground for X- and V-input
reference -always use Signal ground. When using balanced
or differential inputs, tie each side
of the twisted-pair
shielded cable to the two inputs and the shield to the signal
ground. The importance
of using signal ground cannot be
overstated; most noise and washing displays are a result of
indiscriminate grounding.
.2-5
The minimum voltage Signal for full X-deflection is 2 V
peak-to-peak and 1.7 V for Y when Rl and R2 on the
A225 are 3.3
kn (Figure 3-1). For larger input signals, Rl
and R2 are normally 10 kn. With 10 kn, the maximum
input sensitivity
is 0.5 Vlinch. The input impedance is 5 kn
minimum for maximum sensitivity (RI and R2: 3.3 kn)

POSITION ---r .........
HORIZONTAL
VERTICAL
5481-1
Figure 2-2 Locations of Internal Controls
and 20 kQ minimum for Rl and R2 = 10 kQ. When driving
long cables (more than 30 feet), high-speed deflection may
not be possible unless the cables
are terminated in a low
impedance
(less. than 100 Q) since the VR14/VR17 input
impedance
is too high for this application.
Input signals larger than 2 V may be used by attenuating
with the gain controls and Rl and R2 on the X- and
Y-deflection circuit boards. However, the potentiometers
become much too sensitive for input signals greater than
10 V peak-to-peak and Rl and R2 should be increased to
provide pre-attenuation for these larger input signals. The
input signals may be bipolar such
as ±5 V or unipolar such
2-6
as 0 V to +5 V or 0 V to - 5 V. The position potentiometer
allows the deflection to be offset plus or minus half a
screen; thus, a unipolar signal may be completely centered
on the screen. Offsets more than half
of the full-scale inputs
cannot be handled. In other words, if the full-scale
deflection
is offset from 0 V by more than half its'full scale
value, centering on the screen cannot be accomplished. A
3 V peak-to-peak deflection signal, for example, may not
be
offset from 0 by more than ±1.5 V. So ±1.5 V, 0 V to -3 V
or 0 V to +3 V are all acceptable, but a deflection input
that goes from +1 V to +4 V cannot be used until it is
shifted down a minimum of 1 V. Table 2-3 summarizes the
control settings for various inputs.

Input Deflection
±2 Vto 5 V
0,0 = center
+2 V to +5 V is up
and to right
oV to +2 V to +5 V
0,0 = upper right
screen
oV to - 2 V to - 5 V
0,0 = lower left
Table
2-3
Control Settings
Position Setting
With no inputs, set X- and Y-
position potentiometers to get
o Vat A02-A (for X) and A03-A
(for Y).
With no inputs, set -2.2 V @
A02-A, A03-A with X- and
V-position potentiometers.
With no inputs, set +2.2 V @
A02-A, A03-A with X- and
Y-position potentiometers.
The Z-intensify input requirement
is simply a TTL transi-
tion from high to low. In VR14s using a W682 Intensity
Control, this triggers the intensity circuit to generate a
300 ns intensify pulse. In VR14Ls and VR17Ls, which use
the W684 Intensity Control, the intensify circuit is trig-
gered, and remains active, until Z-intensify goes high.
NOTE
The intensify signal must be delayed from the
X- and V-position signal for an appropriate
length
of time to allow the deflection coil to
settle the electron beam to its required posi-
tion. Failure to do so displays smeared dots
that are located incorrectly on the screen. Also,
at least a 500 ns waiting period must be allowed
to intensify a dot before commanding the
electron beam to move to its next location. Not
giving enough time to intensify a dot after the
deflection
is settled will also smear the dot,
since the deflection amplifier
will start "drag-
ging" the dot to the new position. The amount
of delay required from the time new X- and
V-position information
is presented to the
VRI4/VRI7 and the intensify pulse is
requested depends upon how large a position
change
is requested and how perfectly settled
the dot has to be to its final ideal position.
Full-scale deflection changes, such
as far left to
far right or corner to corner, require a 20 J.ls
waiting period for the dot to settle to within
0.01 inch of its final value. If larger errors can
be tolerated, 18 J.ls may be used. Small deflec-
tion changes require much
less time. A 0.1 inch
change can be settled in
less than 1 J.lS. If there
2-7
is no way for the circuits driving the
VRI4/VRI7 to distinguish small position
changes from large ones, each change must be
assumed to be large and thus requires the
worst-case delay. Also,
if the D/ A converters
driving the display have "gliches" (error spikes
generated while changing values), proportion-
ately longer delays are required since the
deflection amplifiers have to recover from the
"gliches."
The Z-direct input (applicable only to VR14s without light
pen option) allows direct modulation
of the brightness.
Positive-going signals increase brightness. This input is not
direct coupled; therefore, dc brightness information cannot
be used. The RC time constant is approximately 30 ms. The
Z-direct may be used with or without the Z-intensify input.
If Z-direct is used with Z-intensify, it can alter the
brightness of the normal intensify pulse by adding or
subtracting at the CRT grid. This is accomplished by
pulsing the Z-direct with a pulse of equal duration with the
Z-intensify. By varying the amplitude and polarity of the
Z-direct pulse, the dot will be of a different brightness.
When using Z-direct without the Z-intensify (such as for
vector intensity control or any other non-point plotting
application) the signal must be large enough to overcome
the CRT cutoff. A typical direct signal will have 5 V to
10 V of actual brightness information riding on top of a
40 V pedestal; the 40 V pedestal ensures that the CRT will
reside below cutoff.
The Z-select input (applicable only to VR14s without light
pen option) works in conjunction with the front panel
channel select switch. The Z-select allows the Z-intensify
pulse to be gated or time multiplexed.
When the channel
select switch
is on the 1 & 2 position, Z-select inputs have
no effect on the VR14. When the channel select switch is in
the 1 position, Z-intensification occurs only when Z-select
input
is a TTL high. When the channel select switch is at 2,
Z-intensification occurs only when Z-select
is held at a TTL
low. Thus,
if two separate pieces of information are to be
displayed, by placing Z-select at a high only during Channel
1 intensification times, and low only during Channel 2
intensification times, both curves
will be displayed when
the channel select switch
is at 1 & 2, and only Channel 1
when Channel 1
is selected, and Channel 2 when Channel 2
is selected.
In the VR14L and VR17L, brightness level
is a function of
three input signals [Intensity (2:0)], as well as the front
panel brightness control. These input signals combine in the
W684 module to generate a voltage which is applied to grid
1 of the CRT, establishing a particular brightness level.