Tektronix LA 501 User manual

Tektronix , Inc.
P.O. Box 500
Beaverton , Oregon
97077
070-2047-00
TEKTRONIX
LA 501
LOGIC
ANALYZER
WITH
OPTIONS
OPERATORS
INSTRUCTION
MANUAL
Serial Number
First
Printing SEP 1975

WU
WARRANTY
All TEKTRONIX instruments are warranted against
defective
materials and
workmanship
for
one
year
.
Any
questions
with
respect to the
warranty should
be taken up with your TEKTRONIX Field Engineer or
representative
.
All requests for repairs and replacement parts
should be directed to the TEKTRONIX Field Office
or representative in your area . This will assure you
the
fastest possible
service .
Please
include
the
instrument Type Number or Part Number and Serial
Number with all requests for parts or service .
Specifications and price change privileges reserved .
Copyright 1975 by Tektronix , Inc. , Beaverton ,
Oregon . Printed in the United States of America . All
rights reserved . Contents of this publication may not
be reproduced in any form without permission of
Tektronix
,
Inc.
U.S.A. and foreign TEKTRONIX products covered
by U.S. and foreign patents and / or patents pending .
TEKTRONIX is a registered trademark of Tektronix ,
Inc.
$

LIST
OF
ILLUSTRATIONS
LIST OF
TABLES
SECTION
1
OPERATING
INSTRUCTIONS
TM 500 -
SERIES
INSTRUMENTS
SAFETY
INFORMATION
Component Replacement
Soldering
TABLE OF CONTENTS
PAGE
¡ ¡
Semiconductor
Replacement
FRONT -
PANEL
CONTROLS
,
CONNECTORS , AND INDICATORS
INTERNAL CONNECTORS AND SWITCHES
1-1
Data Input Connector
1-1
Data Output Connector
1-1
1-4
1-5
1-5
1-5
1-6
1-6
1-6
1-7
1-8
1-9
1-10
1-10
1-10
External Clock Threshold Switch ( S848 )
Blanking Polarity Switch ( S720 )
Display Clock Switch ( S835 )
INSTALLATION
FUNCTIONAL CHECK
1-1
1-1
1-1
1-1
1-1
1-1
Test
Equipment
Required
Preliminary Set Up
Raster
Display
Display
Functions
Trigger
Functions
DETAILED
OPERATING
INFORMATION
Signal
Connection
Display
Monitor
SECTION 1 ( CONT . )
Sample
Interval
External
Clock
Input
Input
Threshold
Controls
Trigger
Controls
Format
Switches
Record
Controls
Monitor Output Signals and Controls
Data
Input
Signals
Data Output Connector
P300 Signal Selector
Internal
Switches
LA 501 GLOSSARY
APPLICATIONS
MICROPROCESSORS
STORAGE BUFFERS
SECTION 2 SPECIFICATION
STANDARD ACCESSORIES
RECOMMENDED ACCESSORIES
SECTION 3 INSTRUMENT OPTIONS
SECTION 4 BLOCK DIAGRAM
ACCESSORIES
LA
501
Operators
CHANGE
INFORMATION
PAGE
1-10
1-10
1-12
1-13
1-13
1-13
1-13
1-14
1-14
1-16
1-18
1-18
1-20
1-20
1-21
2-7
2-8

LA
501
Operators
FIGURE
NO .
Frontis
piece
1-1
=
:
1-2
1-3
1-4
1-5
1-6
1-7
1-8
LIST OF ILLUSTRATIONS
LA
501
Logic
Analyzer .
Front - panel controls , connectors , and
indicators .
Location of internal connectors and
switches .
LA 501
installation
and
removal
.
Equipment set up
for Functional
Check .
LA 501 and
monitor
X , Y ,
and Z signal
connections for Functional Check .
10X probe compensation set up and
procedure .
Location
of
EXT
CLOCK
polarity
selector
.
Pin assignments for the DATA INPUT
connector
,
J100 .
PAGE
iv
1-2
1-4
1-5
1-7
1-8
1-11
1-12
1-15
FIGURE
NO
.
1-9
1-10
1-11
1-12
1-13
1-14
2-1
Pin
assignments
for
the
DATA OUTPUT
connector ,
J120 .
Location of Signal Selector P300 , and
P300
pin
assignments .
P300 jumper placement procedure .
Internal Switch locations , and switch
selection
positions .
Typical set up for troubleshooting a
microprocessor
system with
the LA 501
Logic
Analyzer
.
Typical set up
and
display for trouble
shooting
a
storage
buffer
with
the
LA 501
Logic
Analyzer
.
LA 501
dimensional
drawing .
PAGE
1-16
1-17
1-18
1-19
1-20
1-21
2-6
Ⓡ
●

O
TABLE
NO .
1-1
2-1
6
Format
Output Levels at P300
Electrical
LIST OF TABLES
PAGE
1-17
2-1
TABLE
NO .
2-2
2-3
Environmental
Physical
LA
501
Operators
PAGE
2-6
2-6
iii

LA
501
Operators
iv
SAMPLE
INTERVAL
-IMS
20pF .
(
10X PROBE
ONLY
EXT
CLOCK
MONITOR
CH
TEKTRONIX
OZ
05 t
100K
230p
EXT
TRIG
2018
THRESHOLD
THRESHOLD
+
1.4V
EXT
INPUT
VAR
M
20pF
10X
PROBE
ONLY
CH 1
CH 2
ECL
MONITOR
FORMAT
CH
0-3
*
1024
CH
0.7
*
512
20ns
MAX
CH
0-15
*
256
50ms
MAX
TRIGGER
DATA
OUTPUT
TRIG D
CH
3
POST
CENTER
PRE
SLOPE
+
SOURCE
CH
O
EXT
INPUTS
PROBE
BNC
RECORD
DISPLAY
TIME C -
MANUAL
'
BLANK
OUT
LA
501
LOGIC
ANALYZER
CHANNEL /
POSITION
SELECT
POSITION
OFF
16
15
MAG
- C -
POS
MAG
- C
POS
X1
(
NORM
)
VERT
OUT
X1
(
NORM
)
HORIZ
OUT
DATA
INPUT
LA
501 Features
The
LA
501
Logic
Analyzer is
designed
for
rapid
troubleshooting of
digital
equipment
. The
simultaneous
multi -
channel .
raster can
be
displayed on
almost
any low
- frequency
X -
Y monitor
or
oscilloscope .
The
4096 - bit
memory can
be
formatted
into 4
channels
of
1024
data bits , 8
channels
of 512
data bits
, or 16
channels
of
256 data
bits , for
a wide
range of bit serial
, byte
serial , or word
serial
data .
The
flexible
external
( synchronous
) or
internal (
asynchronous )
sample rate
clock
capability will
accomodate
nearly
all
of the logic family speeds in use .
Three
trigger
delay modes ( PRE
, CENTER
, and
POST )
allows selection
of the best
mode for the
application .
Negative
trigger
delay ( PRE
)
allows analysis
of the
sequence
of events
that
precede a
fault trigger
.
Digital data
outputs
provide a
serial or
parallel
format to " loop
back "
stored
data
to a
computer for
quick
error
checks .
This
feature
allows analysis or
logging of data while
viewing it , or it can
be used
without a
display
device .
Horizontal and
vertical
magnification ,
with
positioning , provide
high
resolution . A
unique vertical
positioning
system .
allows the
selection and
positioning
of any one
trace for
timing
comparisons with
other traces
in the raster
.
The
LA 501
can be
powered by any
TM - 500 -
series
power module
which has three
- unit , or
greater ,
capability .
1967-1

OPERATING INSTRUCTIONS
TM 500 - SERIES INSTRUMENTS
The LA 501 Logic Analyzer is a member of Tektronix '
growing TM 500 line of Test and Measurement Instruments .
This product line consists of both general- and special - purpose
instruments such as digital
multimeters
,
counter
-
timers ,
variable dc
power
supplies ,
pulse
generators ,
function
gener
ators ,
calibration
sources
,
oscilloscopes ,
signal
processors ,
and others . Each instrument is a plug - in module . Power
module
mainframes with 1 , 3 ,
4 , 5 , and 6
compartments
are
available . The power module provides power and an overall
housing for the plug - in modules , and permits internal signal
interconnections
between
plug - in
instruments
to
reduce
clutter or to allow two or more instruments to perform a
function
which
neither could
perform alone .
Each user can
thus select from
a broad choice
of
instrumentation to
assemble a multi - function test set to fit his needs . This test
set is
compact and
portable
; yet
it can be quickly
recon
figured by exchanging plug - in instruments when test needs
change . TM 500 systems can be configured for benchtop ,
rackmount , roll - about , and portable applications . For more
information on the
TM 500
line ,
please
contact your Tek
tronix
Field Office or
representative
.
SAFETY INFORMATION
The following warnings must be observed during maintenance
and adjustment of the LA 501 .
Component Replacement
To avoid
electrical shock ,
disconnect
the LA 501
from the
power
source before
replacing
components
.
Soldering
To avoid electrical shock , disconnect the LA 501 from the
power source before soldering .
Semiconductor
Replacement
Semiconductors that have
heat
radiators
use
silicone
grease
to increase heat
transfer . When
one of these
semiconductors
is replaced , the silicone grease must also be replaced . Handle
silicone
grease
with care .
Avoid getting
silicone grease in
eyes . Wash hands thoroughly after use .
FRONT -
PANEL
CONTROLS
,
CONNECTORS , AND INDICATORS
The major
controls
and
connectors for
operation of the
LA 501 are located on the front panel . Figure 1-1 shows
and
briefly
describes the front -
panel
controls
,
connectors ,
Section 1 - LA 501
and indicators . More information is given under Detailed
Operating Information in this section .
Several connectors and switches are located inside the
LA 501. These are described under Internal Connectors
and Switches in this section .
INTERNAL CONNECTORS AND SWITCHES
Figure 1-2 shows the location of the internal connectors and
switches . A brief description of these internal functions is
given here . More information is given under Detailed Oper
ating Information in this section .
A Data Input Connector
Multi - pin connector for use with the Data Acquisition Probe
to
provide
the
following
functions :
DATA INPUTS . Provides input for each of the 16 channels
( selected when the front - panel INPUTS switch is in the
PROBE
position
) .
CLOCK OUT . Provides signal output from the internal
clock .
INVALID MODE . Provides an input to indicate an external
source sample
interval
that
is too fast for
the
selected
memory
format ( selected by jumper - connector P300 ) .
B Data Output Connector
Multi - pin connector with the following functions :
PARALLEL
DATA
OUTPUT
.
Provides
outputs for each of
the 16 memory channels .
SERIAL DATA OUTPUT . Provides an output for serial
data
from
the
memory .
FLAG
OUTPUT .
Provides an
output that
indicates the start
of each channel of data .
FORMAT
OUTPUT
.
Provides
an
output
that
indicates
memory format ( selected by jumper - connector P300 ) .
1-1

Operating Instructions - LA 501
1-2
1
2
16
15
14
13
12
INPUT
SAMPLE
INTERVAL
MS 20pF
10X
PROBE ONLY
EXT
CLOCK
2000
2001
MONITOR
CH
1
TEKTRONIX®
≈100K
230pf
10
EXT TRIG
THRESHOLD + 1.4V
2
THRESHOLD
M3 200F 10X PROBE ONLY
CH 1
CH 2
VAR
TTL
ECL
INPUT TRIGGER
MONITOR
FORMAT
CH 0-3
*
1024
CH0-7
*
512
20m
MAX
CH
0-15
*
258
500
MAX
CH 3
3
DATA
OUTPUT
TRIG'D
POST
CENTER
PRE
SLOPE
L
+
SOURCE
INPUTS
CH
EXT
L PROBE
L.
BNC
4
LA
501
LOGIC
ANALYZER
RECORD
DISPLAY TIME - C -
MANUAL
10s
BLANK OUT
CHANNEL /
POSITION
SELECT
C
POSITION
MAG -
POS
X1
( NORM )
X5
Y
VERT OUT
MAG - C - POS
XI
(
NORM )
Fig . 1-1 . Front -
panel controls ,
connectors
, and
indicators
.
DATA
INPUT
X10
X
HORIZ OUT
5
6
7
8
9
SAMPLE INTERVAL Switch - Selects data input sample interval . The EXT position selects input from the EXT CLOCK
connector . The knob skirt lamp blinks when the sample interval is too fast when in 8 or 16 channel record format .
10
11
THRESHOLD Control : Provides a variable threshold voltage level for data input channels ( selected by VAR switch ) .
MONITOR Pin Jack : Provides an output to monitor the dc threshold voltage level of the data input channels .
VAR Switch : Selects the variable THRESHOLD control .
TTL Switch : Selects a preset data input threshold voltage level for TTL logic .
ECL Switch : Selects a preset data input threshold voltage level for negative voltage ECL logic .
(
8
)

6
3
TRIGGER
4
5
6
7
8
TRIG'D Indicator : Lights when record circuit has received a trigger signal .
POST Switch : Selects data to be stored after the trigger .
CENTER Switch : Selects data to be stored before and after the trigger .
PRE
Switch :
Selects data to be
stored
before
the
trigger
.
SLOPE Switch : Selects the positive or negative - going edge of the record trigger signal .
SOURCE Switch : Selects Channel or EXT TRIG connector for record trigger source .
RECORD
DISPLAY TIME Control : A variable control sets the time which memory stored data will be held for display before a
new record cycle
begins .
MANUAL Switch : A push button switch which resets the trigger circuit to start a new record cycle .
CHANNEL / POSITION
16
SELECT Switch : Selects any
channel
for
positioning
within
the raster .
POSITION Control : Vertically positions channel selected by SELECT switch .
Operating
Instructions
-
LA 501
INPUTS Switch - Selects data
input signals
from CH
through
CH 3
front - panel BNC
high
impedance
connectors or the
internal low impedance DATA INPUT connector .
9
Z
BLANK OUT
Connector -
BNC
connector for
output
of crt
retrace
blanking
pulses
.
10 X HORIZ OUT Connector - BNC connector for output of horizontal ( X - axis ) display signal .
11
Y VERT OUT
Connector
-
BNC
connector for output
of Y - axis
display
signal .
MAG / POS
Controls
-
Provides
variable
vertical
magnification
(
X1 to X5 ) and
vertical
positioning
of the
displayed
raster .
MAG / POS
Controls
-
Provides variable
horizontal
magnification ( X1 to X10 )
and
horizontal
positioning of the
displayed
raster .
12 ) CH
Through CH 3
Connectors - BNC
connectors for data inputs
with 10X probes
( selected by
INPUTS switch in the
BNC
position
) .
13
MONITOR
Probe -
Tip
Connector
-
Provides output to
monitor the EXT
CLOCK
connector
when
compensating
high
impe
dance
10X
probes
.
( 14 ) EXT
CLOCK Connector - BNC
connector
for
input of
external
sampling clock signal (
selected
by
SAMPLE INTERVAL
switch
in
the EXT
position
) .
15 ) EXT TRIG
Connector
- BNC
connector
for external
input to record
trigger circuit (
selected by SOURCE
switch in the EXT
position
) .
FORMAT
CH 0-3 X 1024 Switch : Selects channel through channel 3 for data recording with 1024 bits of memory per channel .
CH 0-7 X 512
Switch : Selects
channel
through channel 7
for data
recording with 512 bits
of
memory
per
channel .
Maximum
sample
interval
is 50
nanoseconds
.
CH 0-15 X 256
Switch : Selects
channel through
channel 15 for data
recording with 256 bits
of memory per
channel .
Maximum
sample interval is 20
nanoseconds .
Fig . 1-1 . Front - panel controls , connectors , and indicators . ( Continued )
1967-6
1-3

Operating
Instructions - LA 501
BLANKING
POLARITY
SWITCH
S720
D
EXT CLOCK
THRESHOLD
SWITCH S848
C
DISPLAY - STORE MODE OUTPUT . Provides an output to
indicate whether the memory is in a Display or Store Mode
( selected by jumper - connector P300 ) .
1-4
FRAME
OUTPUT
.
Provides
an
output
to
show a
complete
memory scan
when
reading the
memory
serially
(
selected
by
jumper -
connector
P300 ) .
DISPLAY - CLOCK OUTPUT . Provides an ECL - level clock
output during the Display Mode ( selected by jumper - connec
tor P300 ) .
Z - AXIS INPUT . Provides an input to intensify a crt display
via the front - panel Z BLANK OUT connector .
E
DISPLAY CLOCK
SWITCH
S835
Fig . 1-2 . Location of internal connectors and switches .
200
Co
Co
B
DATA
OUTPUT CONNECTOR
A
DATA INPUT CONNECTOR
BOTTOM
OF
UNIT
1967-12
RECORD ENABLE . Provides an input to set the memory
into a Store Mode .
EXT
DISPLAY
CLOCK INPUT
.
Provides
an input
to read
the
memory
with an
external
clock
signal ( ECL
level ) .
C External Clock Threshold Switch ( S848 )
ernal
Selects the external clock threshold level source . In the up
position ,
threshold
levels
are
selected by
front
-
panel
INPUT
switches VAR , TTL , or ECL . In the down position , a fixed
ECL
threshold
level is
selected .
@

DBlanking
Polarity
Switch
(
S720
)
Selects the
polarity of
the blanking
pulses
at
the Z
BLANK
OUT
connector
. In the up
position , the
blanking pulses
are
+5
volts (
positive blanking
signal ) . In
the down
position ,
the blanking pulses are -5 volts ( negative blanking signal ) .
Display Clock Switch ( S835 )
A three position switch that selects the source of the display
clock signal applied to the clock gate . In the up position ,
an ECL input clock signal from the DATA OUTPUT connec
tor is selected . In the center position , the front - panel EXT
CLOCK connector is selected . In the down position , the
500 kHz internal display clock signal is selected .
INSTALLATION
The LA 501 is calibrated and ready for use when received .
It is designed to operate in a TM 500 - series power module
only . Before proceeding with installation , check that the
internal
switches
and
jumpers
are
set as
necessary to
operate
the LA 501
with the
associated
equipment
.
For more
information , refer to Internal Connectors and Switches in
this section .
POWER
MODULE
BARRIER
Turn the power module off before inserting or
removing the LA 501 ; otherwise , damage may
occur to the LA 501 circuitry .
CAUTION
To install (
refer to Figure 1-3 )
, align the
upper and lower
rails of the LA 501 with the power module tracks and fully
insert it .
The front will
be flush
with the front
of the
power
module when the LA 501 is fully inserted .
BOTTOM
GROOVE
Operating
Instructions -
LA
501
To remove the LA 501 , pull on the release latch at the
bottom of the front panel and the LA 501 will unlatch . Con
tinue pulling on the release latch to slide the LA 501 out of
the
power
module .
Fig . 1-3 . LA 501 installation and removal .
PLUG - IN
TOP
GROOVE
RELEASE
LATCH
BARRIER
SLOT
1967-4
1-5

Operating Instructions - LA 501
FUNCTIONAL
CHECK
The following procedure provides a method to check the
basic
operation of this
instrument . The
procedure
can be
used for
incoming
inspection
to
verify proper
operation .
The
procedure can also
be used by
the
operator for
instru
ment
familiarization or
system
troubleshooting .
Functions only are checked in this procedure . Measurement
quantities and tolerances are not checked . Therefore , a
minimum
amount of
test
equipment is
required .
Test
Equipment
Required
The following test equipment was used as a basis to write
the Functional Check procedure . Other test equipment ,
which meets the requirements , may be substituted . When
other equipment is substituted , the control settings or set up
might need to be altered .
1.
Test
Oscilloscope
Description :
Frequency
response , dc
to 500
kilohertz
minimum ; deflection factor , 50 millivolts to 2 volts /
division . Test oscilloscope must have an external Z - axis
input . Time base should have an external horizontal
amplifier input
with
deflection factor of
50 millivolts
/
division .
Type Used : Tektronix 5403 / D40 Oscilloscope system
with 5A45 Amplifier , and 5B40 Time Base .
2.
Power
Module
Description : Tektronix TM 500 - series power module
with
3
or
more
plug
-
in
compartments .
Type Used : Tektronix TM 503 Power Module ( used
with
the
LA
501 and
pulse
generator
)
.
3. Pulse
Generator
Description : Frequency range , 10 kilohertz to 10 mega
hertz minimum ; output amplitude , minus 2 volts to plus
2 volts with
50 - ohm
output impedance .
Type Used : Tektronix PG 502 Pulse Generator ( used
with TM
503
Power
Module
)
.
1-6
4.
Cables ( 5
Required )
Description : Impedance , 50 ohms ; length , 18 inches .
( 2
needed ) , 42
inches
( 3
needed
) ;
connectors ,
BNC .
Type Used : Type RG - 58 / U , 50 ohm coaxial , Tektronix
Part 012-0076-00 ( 18 inch ) , Tektronix Part 012-0057-01
( 42 inch ) .
5.
Termination
Description : Impedance , 50 ohms ; connectors , BNC .
Type Used : 50 - ohm termination with BNC connectors ,
Tektronix Part 011-0049-01 .
6. T Connector
Description
: Connectors
, BNC - to
- BNC .
Type
Used : BNC
- to - BNC T
connector , Tektronix
Part
103-0030-00 .
Preliminary
Set
Up
1. Within the LA 501 , set the slide switches as follows ( see
Figure 1-2 for switch locations ) :
a
.
Display
Clock
switch ( S835
) , set to down
position for
internal Display Clock .
b . External Clock Threshold switch ( S848 ) , set to up
position for
front - panel
selection of
threshold
level .
c
. Blanking
Polarity
switch ( S720
) , set
to
down position
for negative Z - axis blanking .
NOTE
If the Tektronix 5403 / D40 test oscilloscope is
not
used , check
the oscilloscope
or
monitor
instruction manual for the required Z - axis
blanking polarity .
2. Install the LA 501 in the 2 right side compartments and
the
pulse
generator in the left
compartment of power
module
( see Figure 1-4 ) .
3. Turn on power module and test oscilloscope system .
(
68
)

10
4. Set pulse generator for 10 kilohertz square wave . Using
a O - volt base - line reference , set output amplitude to +0.25
volts
.
5. Connect cables from LA 501 to test oscilloscope as shown
in
Figure
1-5 .
6. Set LA
501
controls as
follows
:
SAMPLE
INTERVAL
INPUT
FORMAT
TRIGGER
SLOPE
SOURCE
INPUTS
DISPLAY
TIME
CHANNEL
SELECT
Vertical MAG
Vertical POS
Horizontal MAG
Horizontal POS
PG 502
7. With
test
oscilloscope
inputs grounded , set the
display
to
graticule
center ,
and adjust
oscilloscope
for well -
defined
display
. If
necessary
,
refer to
oscilloscope
instruction
manual
for operating instructions .
50 Ω
TERMINATION
OUTPUT
1
μs
TTL
CH 0-3 X1024
POST
( + )
CH
18
INCH
CABLE
BNC
1 s
OFF
X1 (
NORM )
Midrange
X1
(
NORM
)
Midrange
TM
503
LA
501
-ON
42
INCH
CABLES
>
O
Y
хо
8.
Set test
oscilloscope for
vertical
deflection factor
of 100
millivolts
/
division with dc
input coupling .
9. Set test oscilloscope for external horizontal amplifier
operation ( horizontal deflection factor of 50 millivolts /
division
with
dc input
coupling
) .
Raster
Display
If necessary , perform the Preliminary Set Up procedure . To
obtain a raster display , proceed as follows :
Operating
Instructions
- LA
501
1.
Connect
the
+0.25
volt
,
10
kilohertz
square
-
wave
signal
from pulse generator ( as set in Preliminary Set Up procedure )
to LA
501
CH
input
connector .
2. Check that TRIG'D indicator is lit.
EXTERNAL
INTENSITY
INPUT
( Z - AXIS ) (
IN
REAR
)
3. Set the
LA 501
vertical
and
horizontal POS
controls
for
centered
display
.
4. Set test
oscilloscope
intensity control at desired
viewing
level .
5. Check display for one square wave ( top trace , channel )
and 3
trace
lines .
5A45
INPUT
Fig . 1-4 . Equipment set up for Functional Check .
5403 /
D40
5B40
EXT
HORIZ
AMPL
1967-11
1-7

Operating Instructions - LA 501
LA
501
NO
>
O
хо
Display
Functions
If necessary , perform the Preliminary Set Up procedure . Use
the
following
procedure to
check the
Display Functions
:
2. Check test oscilloscope for a square - wave display on
channels and 1 .
1.
Connect the +0.25 volt ,
10
kilohertz square - wave
signal
from pulse generator ( as set in Preliminary Set Up procedure )
to CH and CH 1 input connectors with BNC T connector .
Fig . 1-5 . LA 501 and monitor X , Y , and Z signal connections for Functional Check .
4.
Check for square
- wave display
on
channels and 2 .
1-8
X ( HORIZ INPUT )
3. Disconnect pulse generator signal from CH 1 , and connect
to CH 2 ( retain connection to CH ) .
5. Disconnect pulse generator signal from CH 2 , and
connect
to
CH 3
.
6. Check for square - wave display on channels and 3 .
Y ( VERT INPUT
)
7. Check that display expands vertically as vertical MAG
control is rotated to X5 .
8.
Return
vertical
MAG
control
to
X1
position .
Z - AXIS
(
EXTERNAL
INTENSITY
INPUT
)
MONITOR
9. Check that display expands horizontally as horizontal
MAG control is rotated to X10 .
10. Return MAG control to X1 position .
11. Press in CH 0-7 X512 FORMAT switch .
12.
Set the LA 501
Vertical and
Horizontal POS controls
for
centered
display .
13. Check display for 8 traces .
14. Press in CH 0-15 X256 FORMAT switch .
1967-14
15. Set the LA 501 Vertical and Horizontal POS controls
for
centered
display .
16. Check display for 16 traces .
17. Set CHANNEL : SELECT switch to .
18. Check that channel O trace can be positioned anywhere
within raster as POSITION control ( CHANNEL / POSITION )
is rotated .

19. If desired , repeat step 18 for remainder of channel
selections .
20. Return CHANNEL : SELECT switch to OFF .
21. Set RECORD DISPLAY TIME control to ∞ detent
position .
22.
Disconnect pulse
generator from CH 3
connector
.
23. Press in
RECORD MANUAL switch and
release it .
24.
Check
display for
square wave on
channel only .
25.
Return
RECORD
DISPLAY TIME
control
to
1 s .
26.
Check that
SAMPLE
INTERVAL knob skirt
lamp
blinks
as
SAMPLE
INTERVAL
switch is set to 20
ns and 10
ns .
27. Set
SAMPLE INTERVAL switch
to EXT .
28.
Disconnect the
pulse
generator
from
CH
connector
.
29.
Press
in
INPUT
:
ECL
switch
.
30. Press
in CH 0-3
X1024
FORMAT
switch
.
31. Set pulse generator for O - volt base - line reference , and
set output amplitude to −0.2 volts .
32.
Connect
-0.2
volt
,
10
kilohertz
square -
wave
signal
from
pulse generator ( as set in step 31 ) to EXT CLOCK and
CH
connectors .
33.
Check
display for 4
traces .
34. Disconnect pulse generator from EXT CLOCK and CH
connectors .
Trigger
Functions
If necessary , perform the Preliminary Set Up procedure . Use
the following procedure to check the Trigger Functions :
1. Set SAMPLE INTERVAL switch to 50 ns .
Operating
Instructions -
LA 501
2.
Connect a
+0.25 volt , 10
kilohertz square - wave
signal
from pulse generator ( as set in Preliminary Set Up procedure )
to CH connector .
3. Check that
channel
( top
trace ) has
positive
- going tran
sition at left side of trace .
4. Press in TRIGGER : CENTER switch .
5. Check that positive - going transition is now near center of
trace
.
6. Press in TRIGGER : PRE switch .
7. Check that positive - going transition is at right side of
trace .
8. Set
SLOPE
switch to -
.
9.
Check for
negative - going
transition
at
right side of
trace
.
10.
Disconnect pulse
generator signal from
CH
connector
.
11. Press in
TRIGGER
:
POST switch
.
12. Set
SLOPE
switch
to
+ .
13. Set
SOURCE
switch
to
EXT .
14.
Using
a
-
volt
base
-
line reference ,
set
pulse generator
output
amplitude to
+2 volts .
15.
Connect the
+2 volt ,
10
kilohertz
signal ( as set
in pre
vious step )
to LA 501
EXT TRIG
connector
.
16. Check that
TRIG'D
indicator is lit.
17.
Check
display for 4
traces
.
1-9

Operating
Instructions
-
LA 501
18. Disconnect signal from EXT TRIG connector .
This
completes
the
Functional Check
procedure .
DETAILED
OPERATING
INFORMATION
Signal
Connection
Probes offer the most convenient means of connecting sig
nals to the LA 501 inputs . Tektronix probes are shielded to
prevent
pickup of
electrostatic
interference ,
and are
designed
to
monitor the
signal source
with minimum
circuit loading
.
10X PROBES . The P6108 ( optional accessory ) , a 10X atten
uation
probe ,
offers a high
input
impedance
and
allows the
circuit
under test to
perform very
close to
the normal
operating
conditions .
When
using
10X
probes ,
select a
probe
with a rise
time
of
less
than 2.25
nanoseconds
, and
which is
capable of com
pensating 20
picofarads
of
input
capacitance .
10X PROBE COMPENSATION . When using 10X probes
on
the EXT
CLOCK and CH
to CH 3
front - panel BNC
in
put
connectors , the
probe
capacitance
must be
compensated
to
match
instrument input
capacitance to
obtain
the
best
rise
-
time response
. See
Figure
1-6 for
probe
compensation
set
up
and
procedure
.
DATA
ACQUISITION
PROBE . The
P6450 (
standard
accessory ) is
a
passive , 5X
attenuation
probe ,
which
is de
signed for
use
with the
LA
501. When
plugged
into
the
DATA
INPUT connector
, it offers input
connections
to all
16 channels .
DATA
OUTPUT
CABLE .
In
order to use
DATA
OUTPUT
connector
,
J120 , it is
necessary
to
assemble
a
special
cable .
One
end of the
cable must
be
terminated with a
connector
to
meet the test
requirements .
The other
end of
the
cable
is
terminated
with a
connector to mate
with the
DATA
OUTPUT
connector . Use
a type DB
- 25P , 25 - pin
, male con
nector
; order
Tektronix
part
131-0570-00 .
For
further
information ,
contact
your
Tektronix
Field
Office or
representative
.
COAXIAL CABLE . The front - panel output signals , Z
BLANK
OUT , Y
VERT OUT , and
X HORIZ OUT
, should
be
connected
to
other equipment
with
50 - ohm
coaxial
cables . Use
high -
quality , low
- loss
cables .
1-10
Display
Monitor
The display monitor may be any oscilloscope or display
monitor with X , Y , and Z - axis capabilities with the following
characteristics :
Frequency
response
Deflection factor
Horizontal
Vertical
External
Z
- Axis
sensitivity
( external intensity input )
dc
to
500
kilohertz
50
millivolts / division
100 millivolts / division
plus
or
minus 5
volts
Connections from the LA 501 X , Y , and Z outputs to the
oscilloscope
or
monitor
inputs
should
be
made
with
coaxial
cables .
Figure 1-5 shows
the
proper set up for
operation .
Check the
oscilloscope
or
monitor
instruction
manual
for
the
required Z
-
axis blanking
polarity
. Set
the
Blanking
Polarity
switch ( S720 )
down for
negative
blanking , or up
for
positive
blanking .
See
Figure
1-2
for
the
location of
S720
.
For
more information
on
blanking
polarity
selection , see
Internal
Switches
in
this section
.
Sample
Interval
The
SAMPLE
INTERVAL
Switch
selects
calibrated
sample
interval
times
from the
internal
clock
. The
number of
times
that the
input
channels
are
sampled
is
determined by
the
format
selected
. A 4
- channel
format is
sampled
1024
times
;
8
- channel
format ,
512
times ; and a
16 -
channel
format ,
256
times
.
To
capture
and
store the
state of a
pulse
, one
or
more
sample
intervals
must
occur
during
the pulse
.
Resolution is
deter
mined by
the
number of
samples
taken during
the
pulse .
The
lamp
that
illuminates
the
SAMPLE
INTERVAL
knob
skirt
blinks
when the
sample
interval is
too
fast for 8
channel
(
10
nanosecond )
or 16
channel ( 10
or 20
nanosecond
)
storage
.
When
using an
external
clock
signal ,
the
EXT posi
tion
of the
SAMPLE
INTERVAL
switch
selects the
front
panel EXT CLOCK connector .
External
Clock
Input
The EXT CLOCK input provides a means of using a clock
signal
from the
equipment
under test ,
or any
other
clock
signal that
the
operator may
desire .
EXT
CLOCK
. This
connector
allows the
connection of ex
ternal
clock
signals . The
external
clock
threshold
level
is
selected by
an internal
switch
( S848
) that
selects a
preset
OI

1
( 2
3
LA 501
EXT
CLOCK
CONNECTOR
MONITOR
PROBE TIP
CONNECTOR
TEST
OSCILLOSCOPE
SYSTEM
4
2
VERTICAL
INPUT
1
Operating
Instructions
-
LA 501
PROBE TO BE
COMPENSATED
TEST OSCILLOSCOPE
10X PROBE ( COMPEN
SATED TO THE TEST
OSCILLOSCOPE SYSTEM )
GROUND
CLIP
IF
NEEDED
Connect the 10X probe to be compensated to the LA 501 EXT CLOCK connector .
TO SQUARE - WAVE
SIGNAL SOURCE
Insert the test oscilloscope 10X probe tip into the EXT CLOCK MONITOR probe - tip jack .
Fig . 1-6 . 10X probe compensation set up and procedure .
Connect the 10X probe to be compensated to a 600 mV , fast - rise , 1 KHz square - wave signal
source ( e.g. , oscilloscope calibrator ) for low - frequency compensation . For high - frequency
compensation ( if applicable ) , use a 600 mV square wave with a rise time of 3 ns or less . The
test oscilloscope bandwidth should be at least 100 MHz .
4
Adjust the probe compensation adjustment ( s ) ( see probe instruction manual for adjustment
locations ) for an optimum square front corner and flat top on the test oscilloscope display .
3
1967-13
1-11

Operating Instructions - LA 501
ECL threshold voltage level or the front - panel INPUT
THRESHOLD controls . When in the EXT CLOCK mode ,
either the positive or negative slope may be used for the
clock edge . When the negative edge is selected , data sample
intervals are stored into memory on the negative edge of the
external
clock
signal .
When the
positive edge is
selected
,
data sample
intervals
are
stored into
memory on the
positive
edge of the external clock signal . An internal jumper - connec
tor , P831 , provides polarity selection . Figure 1-7 shows the
location of P831 and the selection positions .
MONITOR . This probe - tip jack allows the operator to view
the external clock signal , and is also used for compensating
10X probes . Refer to 10X Probe Compensation in this
section for more
information
.
Input
Threshold
Controls
The INPUT THRESHOLD controls allow the selection of
two fixed threshold levels , or the variable THRESHOLD
level control . Fixed threshold levels are for TTL and ECL
logic .
1-12
P831
POLARITY
SELECTOR
NEGATIVE
;
EDGE
POSITIVE
EDGE
Iniz
RELEASE
LATCH
TTL . This switch selects a preset TTL input threshold level
for each of the data input channels , and for the EXT CLOCK
input . When the recommended probes are used , the input
threshold level is +1.4 volts .
ECL . This switch selects a preset ECL input threshold level
for each of the data input channels and for the EXT CLOCK
input . When the recommended probes are used , the input
threshold level is -1.25 volts .
VAR . This switch selects the variable THRESHOLD level
control
.
THRESHOLD . The variable THRESHOLD control allows
the selection of a wide range of threshold levels for the data
input channels and for the EXT CLOCK input . When the
recommended probes are used , the threshold level is adjust
able from 10 volts to +10 volts .
MONITOR . The MONITOR pin jack provides an output to
monitor the dc threshold voltage level .
BOTTOM
LEFT
RAIL
FRONT
RIGHT
CORNER
OF
INSTRUMENT
.
Fig . 1-7 . Location of EXT CLOCK polarity selector .
1967-15
(
6
)

Trigger
Controls
The
TRIGGER
controls provide
a means to select
the signal
source ,
select the
slope on
the
waveform
to stop the
storage
cycle , and
select the
point
in
the
storage
cycle at which
the
trigger will occur .
TRIG'D INDICATOR . This light provides a convenient in
dication of the
Trigger circuit
condition . If the
INPUT
THRESHOLD controls are correctly set for the input logic
level
used and the
Trigger circuit
has
received a trigger , the
TRIG'D light is on . If the TRIG'D light is off , the LA 501
is in the storage cycle , but has not yet received a trigger .
POST . This switch selects data for memory storage after the
trigger has occurred . The stored data consists of 6 per cent
before - trigger data and 94 per cent after - trigger data .
CENTER
. This
switch selects
data for
memory
storage be
fore and after the trigger has occurred . Half of the stored
data is before the trigger , and the other half is data after the
trigger
.
PRE . This switch selects data for memory storage before the
trigger has occurred . The stored data consists of 94 per cent
before - trigger data and 6 per cent after - trigger data .
SLOPE . This switch determines whether the Trigger circuit
responds to a positive- or a negative - going transition of the
trigger signal . When the SLOPE switch is set to - , the
Trigger circuit responds to negative - going transitions . When
the SLOPE switch is set to + , the Trigger circuit responds
to
positive
- going
transitions .
SOURCE . This switch selects the source of the signal for
the Trigger circuit . When the switch is set to CH , the input
signal connected to the channel input is used for the trigger
source . When the switch is set to EXT , an external signal
connected to the EXT TRIG connector is selected for the
trigger
source
.
EXTERNAL TRIGGER . Trigger signals from the equipment
under test , or other equipment the operator may prefer to
use , can be connected to the EXT TRIG connector .
Ext Trig . This connector allows the connection of an exter
nal TTL logic level trigger signal . The input threshold level
is fixed at +1.4 volts . This connector is selected when the
SOURCE switch is in the EXT position .
Operating
Instructions -
LA 501
Format
Switches
The
FORMAT
switches select
the
number of data
channels
to be used . Three switches allow the operator to select 4 ,
8
, or
16
data
channels .
CH 0-3 ( X1024 ) . This switch selects the first 4 data channels .
In this mode , each channel has a memory storage capacity
of 1024 bits . The 4 - channel mode has a maximum sample
rate
of 10
nanoseconds
.
CH 0-7 ( X512 ) . This switch selects the first 8 data channels .
In this mode , each channel has a memory storage capacity
of 512 bits . The 8 - channel mode has a maximum sample
rate of 20 nanoseconds .
CH 0-15 ( X256 ) . This switch selects all 16 data channels .
In this mode , each channel has a memory storage capacity
of 256 bits . The 16 - channel mode has a maximum sample
rate of 50 nanoseconds .
Record Controls
The RECORD controls allow the operator to select the dis
play time to view stored information , and also allows manual
or automatic resetting of the Trigger circuit .
DISPLAY TIME . This variable control sets the time during
which stored
data will be
held for display
before a new
storage cycle begins . The display time is variable from 1 to
10 seconds , or is held indefinitely when turned to the fully
clockwise detent position ( ~ ) .
MANUAL
.
This switch resets
the Trigger
circuit to start a
new storage cycle .
Monitor
Output
Signals and Controls
Vertical , horizontal , and Z - axis output signals are provided
to produce a raster display on the display monitor . The
vertical and horizontal outputs each have magnification and
positioning
controls .
Z BLANK OUT . When connected to a display monitor ex
ternal Z - axis input , the Z - axis blanking signal performs two
functions
.
The first function is to blank the crt retrace lines . The se
cond function is , if the new storage cycle fails to go through
1-13

Operating Instructions - LA 501
a full memory storage cycle before a trigger is received , old
data ( bad
data ) is
blanked out on the
crt
display .
Positive
or
negative
blanking
pulses
are
selected
by
Blanking
Polarity
switch
,
S720 .
Y VERT OUT
. When
connected
to a
display
monitor
Y
- axis
(
vertical
)
input
, this
output
signal provides an on -
screen
display of
serial data
from the
memory .
Channel
separation
is accomplished by stepping each channel down with a dc
offset
voltage .
Channel O is at the
top of the
display
.
Mag ( Y - Axis ) . This control provides a variable X1 to X5
amplification of the Y
VERT OUT
signal to
permit greater
display
resolution
.
Pos ( Y -
Axis ) . This
control
vertically
positions the
raster
within the display area of the monitor . To obtain maximum
use of the Vertical POS control , the display monitor must
first be adjusted for a centered spot with the X- and Y - axis
inputs grounded . All vertical position adjustments are then
made with the LA 501 Vertical POS control .
X HORIZ OUT
. When
connected
to a
display
monitor
X - axis ( horizontal ) input , this output signal provides the
display with an X - axis sweep . The sweep rate is determined
by the FORMAT switch setting . If desired , an external
clock source may be used to scan the memory ; however , any
clock rate other than that of the internal clock will affect
the sweep length . The external clock signal may be from
the front - panel EXT CLOCK connector , or from the Ext
Display Clock input at the DATA OUTPUT connector . The
display clock source is selected by the internal Display
Clock
switch (
S835
)
.
Mag ( X - Axis ) . This control provides a variable X1 to X10
amplification of the X
HORIZ
OUT
signal to
permit greater
display
resolution
.
Pos ( X -
Axis ) . This
control
horizontally
positions
the
data
channels within the display area of the monitor . To obtain
maximum use of the horizontal control , the display monitor
must first be adjusted for a centered spot with the X- and
Y - axis inputs grounded . All horizontal position adjustments
are then made with the LA 501 Horizontal POS control .
CHANNEL / POSITION . The SELECT and POSITION
controls
under this title are
used
for
comparison of
any one
channel
with
any other
channel
.
Select . This
switch
selects
any
channel
(
through 15 ) for
positioning within the display raster .
1-14
Position
.
This
control
vertically
positions the
selected com
parison channel
within the
display .
Data
Input
Signals
Both low
impedance
and
high
impedance inputs are
provided
for the data
channels
.
Front - panel
BNC
connectors , CH
through CH 3 , provide high impedance inputs , and multi - pin
DATA INPUT connector , J100 , provides low impedance
inputs to all 16 channels . The INPUTS switch selects the
desired input connector ( s ) . 10X probes are used for connec
ting signals to the front - panel data input connectors .
INPUTS . This switch selects the desired data input probe
connector ( s ) . When in the BNC position , the four front
panel CH through CH 3 connectors are selected . When in
the PROBE position , the multi - pin DATA INPUT connector
is
selected
.
CH THROUGH CH 3. The four front - panel BNC connect
ors provide a means of connecting data signals through 10X
probes to the channel , 1 , 2 , and 3 input preamplifiers .
The 10X probes must be compensated for use with ECL
logic , due to the low signal levels .
DATA
INPUT
. The
internal
,
multi - pin
connector , J100
,
provides a means of connecting data signals through the Data
Acquisition Probe to the inputs of all 16 channels . Figure
1-8 identifies the pin assignments for the DATA INPUT
connector . The Clock Out at pin 22 is an unterminated
ECL - level output of the internal clock signal . Pin 23 of
J100 ( probe line A ) is connected to Signal Selector jumper ,
P300 . At the factory , P300 is wired to connect pin 23 of
J100 to the Invalid Mode Input line . However , this connec
tion can be changed to a different signal line if desired . For
further information , see P300 Signal Selector in this section .
Data
Output
Connector
Internal multi - pin connector , J120 , provides several functions .
Figure 1-9 identifies the DATA OUTPUT connector pin
assignments . As shown in Figure 1-9 , three of the pins of
J120 are connected to Signal Selector jumper , P300 . At the
factory , P300 is wired to make signal - line connections to
these pins as shown in Figure 1-10 . The connections can be
changed to
different signal lines
if desired
. For
further
information , see P300 Signal Selector in this section . The
functions provided by the Data Output connector are
described as follows :
PARALLEL
DATA
OUTPUT
.
Output connections are
pro
vided from each of the 16 memory channels to read the
memory in parallel data form . The parallel data outputs are
ECL - logic
level signals .