Tektronix 323 Service manual

OPERATORS
HANDBOOK
TYPE 323
OSCILLOSCOPE
This handbook is a reference document on
basic characteristics, operation, performance
check, maintenance, and applications. Com
plete and detailed information is provided in
the standard manual supplied with the
instrument.
070-1155-00 1270

CONTENTS
Page
Specifications
Power Requirements 4
Power Pack Replacement 5
Battery Care 6
Fuse Location 9
Function of Controls and Connectors 2
Performance Check and Familiarization 8
Measurement Technique 26
Triggering 28
Single Sweep Operation 3
Internal External Sweep Operation 32
Selecting Sweep Rate 35
Signal Application to Vertical Input 35
How to Measure Voltages 37
Time Measurement 42
Frequency Measurement 43
Phase Measurement 44
How to Use External Blanking 46 “
Common Operational Errors 46
Copyri ht © 1970 by Tektronix, Inc.,
Beaverton, Ore on. Printed in the United
States of America. All ri hts reserved. Con
tents of this publication may not be repro
duced without permission of the copyri ht
owner.

ABRIDGED SPECIFICATIONS
(Electrical)
Complete updated specifications are provided in
the Instruction manual.
Characteristic Performance Requirement
Deflection Factor
Accuracy Within 3% of VOLTS/DIV
indication.
nput R & C ±2%, 45 pF ±4 pF.
Bandwidth/Rise-
time
XI Gain At least 4 MHz (90 ns)
X 0 Gain At least 2.75 MHz ( 30 ns)
Low Frequency
(—3 dB) Point,
AC Coupled
2 Hz or less
Maximum Input
Voltage 500 V (DC + peak AC) with or
without probe
Step Response
Aberrations Within 3% (total peak to peak)
Overload
Recovery Within /is after a signal
change, at the VERT INPUT,
of ±30 divisions of deflection.
© 323 1

Characteristic Performance Requirement
Trigger Sensi
tivity
nternal 0.3 div. to 400 kHz increasing
to 0.75 div. for 4 MHz
External 75 mV to 400 kHz increasing
to 90 mV for 4 MHz. (Signal
applied to EXT TRIGGER IN
PUT connector, ATTEN set to
IX position. Increase signal
level for 0X position of the
ATTEN switch.)
AC Coupled,
including AUTO Sensitivity decreases sharply below 30 Hz
ACLF REJ
Mode Sensitivity decreases sharply
below 30 kHz.
External Trigger
nput R & C M£2 ±2%, 62 pF ±4 pF
Maximum Input
Voltage 300 V (DC + peak AC)
Horizontal Sweep
Timing Accuracy
(with VARiable
control in CAL
position)
Unmagnified 5 jiis/div to 0.2 s/div, within
3%
0.5 s/div to s/div, within 4%
®
2323

Characteristic Performance Requirement
Magnified 2 jus/div to 20 ms/div., within
4%
0.5 jus/div, .0 jus/div. 50 ms/
div, and 0. s/div, within 5%
External Horizon
tal nput Deflec
tion Factor
200-300 mV/div.
Square Wave
Calibrator
Amplitude 0.5 V, ±2% (peak to peak).
Frequency Approximately 850 Hz
Risetime
(leading edge) 2 jus or less
External Blanking
Frequency
Range DC to 00 kHz
Voltage Level Blanks at approximately +5 V
to +20 V
Maximum Input
Level 50 V (DC + peak AC)
nput Resistance Approximately 00 k!TL
323 3

Characteristic Performance Requirement
Power Supply
Battery Pack Six NiCdC Cells
Operating Time 3 to 7 hours, depending on
display intensity, amplitude,
and input signal frequency.
Charge Time
(Full Charge) Approximately 6 hours
External DC
Supply 6 V to 6 V at 4.5 watts maxi
mum
Line Voltage
(to battery pack)
Range 90 V to 36 V AC
or
80 V to 272 VAC
Frequency 48 Hz to 400 Hz
POWER SOURCE REQUIREMENTS
The instrument requires an internal power pack,
with NiCd batteries, or an external (+6 V to + 6
V) DC source for power. A three position switch to
the power pack selects either power source, and
the battery charge rate when AC power is applied.
The instrument will not operate from an AC power
source if the battery is missing or defective.
4323

Either 5 V or 230 V nominal AC line source
can be used for AC powered operation. Connect
the AC source to the battery pack with the power
cord, then switch power source switch to AC/
BATT position. Refer to Figs. , 2, and 3 for
power pack removal, fuse location and 5 V or
230 V AC hook-up instructions.
The battery can be charged with the power pack
out of the instrument if desired. Extra power packs
can, therefore, be charged to serve as spares. See
Battery Care for instructions.
To operate the 323 from an external DC power
source; set the power pack source switch to EXT
DC position, connect a +6 to + 6 volt DC source
to the banana jacks above the line cord receptacle
(observe polarity markings) and switch the front
panel POWER switch to ON.
POWER PACK REPLACEMENT
WARNING
The power pack battery can deliver enough
energy, if short circuited by such items as
rings and watch bands, to produce severe
burns. Switch the power selector switch to
EXT DC position to reduce the number of
points that have battery voltage or remove
rings and other items before handling the
power pack.
323 5

The 323 will not operate from the internal
battery or an AC source if the selector switch is
left in EXT DC position. The battery will, how
ever, charge at full charge rate if AC Power is
applied. Fig. illustrates removal and replacement
procedure.
BATTERY CARE
The power pack uses six sealed NiCd cells con
nected in series for the battery. These cells require
little maintenance, have high discharge rate, accept
long term overcharging and operate over a rela
tively wide range of temperature. If properly cared
for, you can expect about 500 to 600 charge/
discharge cycles before their capacity drops to
about 80% of specified value. Some of the more
important battery characteristics and care are
described below so maximum operating time
between recharge cycles can be obtained.
SELF DISCHARGE is a continuous process as
long as the battery has any charge. The rate of self
discharge depends on ambient temperature, state
of charge, and impurities in the battery. Self
discharge at 45°C is approximately five times
greater than it is at 20°C. A fully charged NiCd cell
may lose 0% to 5% of full capacity during the
first 24 hour period. This discharge rate decreases
to about 0.68% per day or 0% to 5% per month
after the initial discharge. To obtain the maximum
6323

power / / Cover-securing
connection ' screw
A. Loosen securing screw and pull dust cover off.
B. Disconnect interconnecting power leads. Release securing
clamp.
AC Fuse location; pull
cover straight down to
expose fuse; align cover
d e te n ts and fuse
mounting base when re
placing cover.
C. Power pack.
Fig. . Removing the battery power pack.
323 7

A. 5 V AC connection. Fuse size 0,25 A.
B. 230 V AC connection. Fuse size 0, 25A,
Fig. 2. 5 V/230 V connections for Type 323.
®
8323

c.ouev'
Power Supply
board
L
A. DC Fuse
DC Fuse ( A)
.(operating j
J power) °
C. Spare fuses
Fig. 3. Fuse location.

operating time, the battery should be fully charged
and maintained at this level by using the TRICKLE
CHARGE feature to offset self-discharge until the
pack is ready to use.
On FULL CHARGE, the power pack delivers a
constant current that is approximately / 0 the
ampere hour rating of the cells in the battery. This
charge rate allows the battery to be overcharged
without cell damage. CHARGE TIME for the
battery is about 4 to 6 hours at the FULL
CHARGE rate.
OVERCHARGE is continued charging after the
cells have reached full charge. Short periods of
overcharging will cause no problems. During the
overcharge period, the charge energy is dissipated
as heat. If continued for an extended period (over
24 hours) it will dry the electrolyte.
TRICKLE CHARGE maintains the battery or
cell at full charge. It will not recharge the cells,
because most of the current is used to recover the
self-discharge current. Use TRICKLE CHG to
maintain the full charge state of the cells.
OPERATING TIME is a function of tempera
ture and charge state. You can expect about 4
hours of operation under average conditions. The
LOW BATT indicator, on the front panel, indicates
by blinking when the battery charge level has
decreased about 90%. The battery voltage starts to
10 323 ®

decrease rapidly at this point; therefore, operation
should be terminated within 0 to 5 minutes or as
soon as possible after the indicator starts to blink.
This reduces the possibility of the cells becoming
reverse charged. Reverse charging occurs when
some cells overcome the charge of the weaker cells.
CHARGE BALANCING consists of charging the
cells beyond the period required to bring them up
to full charge. This balances the charge of the cells
in the battery and reduces the possibility of any
cells reverse charging. Once a month, or every 5
charge/discharge cycles, change the charge time to
about 24 hours. After a cell has been replaced, the
battery should be overcharged to balance the cells.
Avoid partial charges, if possible; however, if
only a partial charge is practical, about 30 to 45
minutes of operation can be expected per hour
charge.
Additional data regarding maintenance and
repair of the power pack and the NiCd cells is
furnished in the standard manual.
323 11

FUNCTION OF CONTROLS
AND
CONNECTORS
Selects vertical deflection factor and a 5 div cali-
' brator si nal to calibrate X I and X10 GAIN. Note
effect on X I0 VERT GAIN (front panel) switch on
display.
Varies Volts/Div be
tween calibrated steps.
Ran e at least 2.5X.
Flashes to indicate
when battery char e
state is close to dis
char e (refer to Battery
Care).
Switches power to
oscilloscope circuits,
does not affect battery
char in operation.
Selects input couplin from the VERT INPUT con
nector to oscilloscope vertical amplifiers.
— AC—Low frequency cutoff is 2.0 Hz; 0.2 Hz with
10X probe.
GND—Oscilloscope amplifier input is rounded but
not the si nal conductor.
DC—DC si nal component is applied to oscillo
scope vertical amplifiers.
NOTE
Prechar e feature allows rapid char e or dis
char e of input couplin capacitor. Useful for
AC si nals that ride on lar e DC volta e levels.
Apply si nal with selector at GND position,
then switch to AC. Return to GND position
before chan in to a si nal with a new or differ
ent DC level.
12 323 ®

L. r~~
i. —iZE I l
i
--4--
f j - l ~ ±
I ;
si ;
Ln $M !
____ — - __________________ _________ /
Positions display horizontally. Pullin the control
out ma nifies (10X) the center portion of the dis
play, which effectively divides the indicated sweep
rate (TIM E /D IV) by 10. The portion of the display
that is expanded is selected by the POSITION
function of the control. An externally applied hori
zontal si nal is amplified 10X when the control is
pulled out.
323 13

FOCUS and INTENSITY adjusted for sharp bri ht display. Bri ht
ness affects battery operatin time.
Selects sweep (horizontal)
rate. In EXT HORIZ position,
horizontal deflection depends
on si nal applied to EXT
H O R IZ IN P U T connector
(side panel).
NOTE
For external horizontal
sweep, the Tri er se
lector must be in the
EXT TRIG OR HORIZ
position.
Varies TIM E /D IV be
tween calibrated steps.
Ran e at least 2.5X.
When TIM E /D IV selec
tor is in EXT HORIZ
mode, control attenu
ates horizontal si nal
from IX to at least
10X.
INT TRIG tri ers the display on
the applied vertical si nal.
ACLF REJ position; has low
frequency cutoff at about 30
kHz.
AC positions; low frequency
cutoff is about 30 Hz.
EXT TRIG tri ers the display
from si nal applied to EXT IN
PUT connector (side panel).
AC position: low frequency
cutoff is about 30 Hz.
DC position: has no low fre
quency cutoff.
Selects tri er mode. In fully CCW or CW position, tri erin is
automatic on the + or — slope of the tri erin si nal. Between the
two extreme positions, control selects tri erin level on the + or —
slope. Automatic tri erin provides base line in the absence of
tri erin si nal. Low frequency limit is approximately 30 Hz.
14 323 ®

In 10X position the
E X T TRIG OR
HORIZ INPUT si 
nal is attenuated by
a factor of 10.
Connects to oscilloscope chassis. Pro
vides a common round return to si nal
source. Common round must be pro
vided to insure measurement reliability
and to eliminate possibility of oscillo
scope case risin to the si nal source
potential.
Vertical si nal input
DC coupled input
for blankin si nal.
Input level between
+5 V and +20 V.
For external horizontal or tri erin
si nal. Source of 0.5 V cali
brated square-wave.
Deflection sensitivity:
20 to 30 mV/div; ATTEN in IX position
and X10 HO RIZ MAG pulled out.
200 to 300 mV/div; ATTEN IX position
and X10 HORIZ MAG pushed in, or
ATTEN, 10X position, and X10 HORIZ
MAG pulled out.
2 to 3 V/div; ATTEN, 10X position and
X10 HO RIZ MAG pushed in.
323 15

EXT DC POWER connectors (red +, and black —)
for applyin DC power source to the oscilloscope.
Ne ative (—) connector is connected to oscillo
scope case. DC volta e application does not char e
the internal battery. Reversin the volta e polarity
will blow the power pack fuse. Input volta e ran e
is +6 V to +16 V. Sur e current to 1 ampere.
Receptacle for applyin AC power to char e the
internal batteries and operate the oscilloscope. Line
volta e ran e of 90 to 136 V or 180 to 272 V
depends on the internal connection to the power
transformer (see instructions for 115 V /230 V
operation). Line frequency ran e 48 Hz to 440 Hz.
Selects battery char e rate or external DC power
source.
With AC power applied, FULL CHG position will
fully char e battery in 16 hours; TRICKLE CHG
position will maintain but not increase char e level.
In AC/BATT position, internal battery is power
source for 323. In EXT DC position, battery is
disconnected and an externally applied +6 V to
+ 16 V DC source becomes the power source.
®
16 323

Asti matism. Adjusts for optimum
sharpness of vertical and horizontal
lines at the same settin of the
FOCUS control.
Adjusts (after VERT X I GAIN
has been adjusted) to provide cali
brated ain factors with X10
VERT GAIN pulled out.
Adjusts for no trace shift accompany
in switchin between X I and X10
positions o f X10 VERT GAIN
control, under no-si nal conditions.
Adjusts the horizontal sweep path to
parallel horizontal raticule lines.
Adjusts to provide calibrated ain
factors with X10 VERT GAIN
pushed in.
Adjusts for no trace shift durin rota
tion of VARIABLE (VOLTS/DIV)
knob, under no-si nal conditions.
® I 323 17