Tektronix 5A14N Service manual
TBktronix
®
COMMfTTED TO EXCELLENCE
Tektronix, Inc.
P.O. Box 500
Beaverton,
Oregon 97077 Serial Number
PLEASE CHECK FOR CHANGE INFORMATION
AT THE REAR OF THIS MANUAL.
5A14N
FOUR CHANNEL
AMPLIFIER
INSTRUCTION MANUAL
070-1229-00 First Printing OCT 1972
Product Group
52
Revised OCT 1987
Copyright © 1971 Tektronix, Inc. All rights reserved. Contents of this
publication may not be reproduced in any form without the written
permission of Tektronix, Inc.
Products of Tektronix, Inc. and its subsidiaries are covered by U.S. and
foreign patents and/or pending patents.
TEKTRONIX, TEK, SCOPE-MOBILE, and ® are registered trade-
marks of Tektronix, Inc. TELEQUIPMENT is a registered trademark of
Tektronix U.K. Limited.
Printed in
U.S.A.
Specification and price change privileges are
reserved.
INSTRUMENT SERIAL NUMBERS
Each instrument has a serial number on a panel insert, tag, or stamped
on the chassis. The first number or letter designates the country of
manufacture. The last five digits of the serial number are assigned
sequentially and are unique to each instrument. Those manufactured in
the United States have six unique digits. The country of manufacture is
identified as follows:
BOOOOOO Tektronix, Inc., Beaverton, Oregon, USA
1000000 Tektrnoix Guemsey, Ltd., Channel Islands
2000000 Tektronix United Kingdom, Ltd., London
3000000 Sony/Tektronix, Japan
7000000 Tektronix Holland, NV, Heerenveen, The Netherlands
5A14N Instruction
TABLE OF CONTENTS
Operators Safety Summary ii
Servicing Safety Summary. Jii
Frontispiece iv
SECTION
1—OPERATING
Instrument Description 1-1
Controls and Connectors. 1-1
Basic Operation 1-1
General Information 1-2
Electrical Characteristics 1-4
Repackaging for Shipment 1-4
THE FOLLOWING SERVICING INSTRUCTIONS ARE FOR USE BY QUALIFIED PERSONNEL
ONLY. TO AVOID PERSONAL INJURY, DO NOT PERFORM ANY SERVICING OTHER THAN
THAT CONTAINED IN OPERATING INSTRUCTIONS UNLESS YOU ARE QUALIFIED TO DO SO,
INSTRUCTIONS
Preparation 1-1
C3aln Check (All Channels) 1-2
Applying Signals 1-2
Channel Sequence Logic 1-3
Input Coupling 1-3
Deflection Factor 1-3
Display Modes 1-3
Trigger Source 1-3
Oscllloscxjpe Applications 1-3
Performance Conditions 1-4
Display Modes 1-4
Bandwidth (-3 dB) 1-4
Deflection Factor 1-4
Maximum Safe Input Voltaga 1-4
Channel Isolation 1-4
Input RC 1-4
WARNING
SECTION
SECTION
SECTION 4—DIAGRAMS AND PARTS LISTS
2—THEORY
Introduction 2-1
Plug-In Logic 2-1
Input Coupling 2-1
Input Attenuator 2-1
Amplifier 2-1
Cfiannel Switching 2 2
Probe Sensing 2-2
3—CALIBRATION
Test Equipment Requried 3-1
Procedure 3-1
OF OPERATION
Inti-oduction. 3-1
Instrument Maintenance 3 1
Service Available 3-1
General 3 1
Calibration Equipment Alternatives 3 1
Special Calibration Fixtures. 3-1
Test Instruments 3-1
Accessories 3 1
Preparation 3-3
Initial Control Settings 3-3
1.
Step Attenuator Balance 3-3
2.
Input and Attenuator Compensation .3-3
3. Amplifier Gain and VOLTS/DIV Accuracy 3-3
4.
Amplifier Bandwidth 3-4
REV MAR 1987
5A14N Instruction
OPERATORS SAFETY SUMMARY
The general safety information in this part of the summary is for tx)th operating and servicing personnel. Specific warnings and
cautions will be found throughout the manual where they apply, but may not appear
in
this summary.
TERMS
In This Manual
CAUTION statements identify conditions or practices that
could result in damage to the equipment or other property.
WARNING statements identify conditions or practices that
<x)uld result
in
personal injury or
loss
of life.
As Marked On Equipment
CAUTION indicates a personal injury hazard not immediately
accessible as one reacJs the marking, or a hazard to property
including the equipment
DANGER indicates a personal injury hazard immediately
accessible as one reads the marking.
itself.
SYMBOLS
In This Manual
^p Static-Sensitive Devices.
|\ This symtxjl indicates where applic:able cautionary
A
or other information
is
to
be
fourid.
As Marked On Equipment
Use the Proper Power Cord
Use only the power cord and connector specified for your
product. Use only a power
Refer cord and connector changes to qualified personnel.
cord
that is in gcxjd condition.
Grounding the Product
This product is grounded through the grounding conductor
of the mainframe power
the power cord into a properly wired receptacle before
connecting to the product input or output terminals. A
protective-ground connection, by way of the grounding
conductor
in
the power
cord.
To avoid electric shock, plug
cord,
is essential for safe operation.
Danger Arising From Loss of Ground
Upon loss of the protective-ground connection, all
accessible conductive parts (including knobs and controls
that may appear to be insulating), can render an electric
shock.
Do Not Operate In Explosive
Atmospheres
To avoid explosion, do not operate this product in an
atmosphere of explosive gasses unless it has been
specifically certified for
such
operation.
^ DANGER—High voltage.
^Q Protective ground (earth) terminal.
/!\ ATTENTION—refer to manual.
WARNINGS
Power Source
This prcxjuct is intended to operate in a mainframe
connected to a power source that will not apply more than
250 volts rms between the supply conductors or between
either supply conductor and ground. A protective ground
connection, by way of the grounding conductor in the power
cord,
is essential for safe operation.
Do Not Remove Covers or Panels
To avoid personal injury, do not rennove the protective
covers or panels. Do not operate the product without
the
covers
and
panels properiy installed.
Do Not Operate Without Covers
(For TM 500 Plug-Ins Only)
To avoid personal injury, do not operate this product without
covers or panels installed. Do not apply power to the plug-in
via a plug-in extender.
REV MAR 1987
5A14N Instruction
SERVICING SAFETY SUMMARY
FOR QUALIFIED SERVICE PERSONNEL ONLY
Refer also to
the preceding
Operators Safety Summary
Use Care When Servicing Do Not Service Alone
With Power On
Do not perform internal servrce or adjustment of this prcxiuct
Dangerous voltages exist at several points in this product. To unless another
avoid personal injury, do not touch exposed connections resuscitation
and
components while power
Disconnect power before removing protective panels,
soldering,
or replacing components.
is
on.
person
is
present,
capable of rendering first aid and
REV MAR 1987
jjj
5A14N Instruction
VOLTS'DIV
«"'« OU!.K OlSPUY
IV
„«,.o.,..
FOURCHANIKEL^
8*^*" AMPLIFIER rr
5A14N Four Channel Amplifier.
REV MAR
1987
SECTION 1
OPERATING INSTRUCTIONS
5A14N
INSTRUMENT DESCRIPTION
The 5A14N Four Channel Amplifier is a general-purpose
plug-in unit (refer to current Tektronix Products Catalog for
compatible mainframe information). The unit contains
independent amplifier channels with identical characteristics,
and features solid-state circuitry and simplicity of
operation.
provide a direc^t readout of calibrated deflection factor either
with or without a probe. Any channel may be used to
produce a single-channel display. All channels may be displayed alternately, or channel 4 and 3 may be alternated
with 2 and 1 to produce four displayed channels. While
designed primarily for use as a vertical amplifier, the unit can
be operated in conjunction with the horizontal deflection
system of the oscilloscope for X-Y displays.
The VOLTS/DIV knob skirts are lighted to
CONTROLS AND CONNECTORS
This is a brief description of the function or operation of the
controls and connectors. Additional operating information
is given under General Information.
DISPLAY
POSITION
Applies kigic levels to the oscilloscope system to enable
plug-in operation. The switch
functions only when the
in is operated in one of the
vertical plug-in compartments.
Positions display.
plug-
Input Coupling
Pushbuttons
Single or Dual Beam
Selector (Internal)
Input Connectors
AC-DC: Button pushed in
selects capacitive coupling of
input signal; button out
ects direct coupling of input
signal.
GND:
Disconnects the input
signal and provides ground
reference to the ampliiier input stage.
PRECHG: Both AC and GND
buttons pushed in allows
precharging of the coupling
capacitor. Release GND for
measurement.
Slide switch at the rear of the
plug-in that selects the chan-
nel logic sequence. When
the switch is in the forward
position (toward the front
panel), the plug-in is in the
single-beam mode, which
provides a 4-3, 4-3, 2-1, 2-1
logic sequence. In the opposite position, the plug-in is
in the dual-beam mode,
which provides a 4-3-2-1 logic
sequence.
BNC connectors for application of external voltage
nals.
Includes a coded-probe
input ring for activation of 10X
readout.
sel-
sig-
VOLTS/DIV
Variable (CAL) Volts/Div
REV MAR 1987
Volts per major graticule
division.
deflection factors from 1
mV/div to 5 V/div; 12 steps in
a 1-2-5 sequence. Knob skirt
is illuminated to indicate
deflection factor. Readout is
automati-cally scaled when
readout-coded 10X probe is
installed.
Provides uncalibrated,
tinuously variable deflection
factor between calibrated
steps;
V/ div.
Selects calibrated
con-
extends range to 12.5
BASIC OPERATION
Preparation
The 5A14N is calibrated and ready for use when received.
It can be installed in any compartment of any 5000-series
oscilloscx}pe, but it is intended for use primarily in vertical
cxjmpartments (the center and left compartments). For X-Y
operation,
(right) compartment (refer to the 5000 Oscilloscope System Instruction Manual for information on X-Y operation).
the 5A14N may also be installed in the horizontal
1-1
Operating Instructions—5A14N
NOTE
// the oscilloscope system receives no DISPLAY ON logic levels from the vertical plug-ins,
ii is designed to display the unit in the left
compartment
To install, align the upper and lower rails ofthe 5A14N with
the plug-in compartment tracks and fully insert it (the
in panel must be flush with the oscilbscope panel). To remove,
pull the release latch to disengage the 5A14N from
the oscilloscope.
The first few steps of the following procedure are intended
to quickly obtain a trace on the screen and prepare the instrument for immediate use. The remainder of the steps
demonstrate some of the basic functions of the 5A14N.
Operation of the other instruments in the system is described in the instruction manuals for those units.
1.
Insert the unit all the way into the oscilloscope system
plug-in compartment.
2.
Turn the oscilloscope Intensity control fully counter-
clockwise and turn the oscilloscope power on. Preset the time-base and triggering controls for a 2-ms/
division sweep rate and automatic triggerng.
3. Set the 5A14N front-panel controls as follows:
CH 1 through CH 4
DISPLAY
POSITION
VOLTS/DIV
Input Coupling
Adjust the Intensity control for normal viewing of the
four traces.
Position the traces two divisions apart with the
TION controls.
Apply a 400-miHivolt peak-to-peak signal (available at
the oscilloscope Calibrator loop) through a test lead
or IX probe to the CH 1 input connector.
Release the CH 1 GND pushbutton. The display
should be square waves approximately two divisions
in amplitude, with the bottom of the display at the
reference established in step 5. Adjust trigger Level,
if necessary, to obtain a stable display. Rotate the
CAL control throughout its range, observing a
reduction of the display amplitude. Return the CAL
control to the detent (calibrated Volts/Div) position).
The preceding procedure applies for each
channel.
for the time-base plug-in is obtained from CH 1
only.
However, the internal trigger signal
ON (deflection factor
illuminated)
Midrange
0.2 V (Calibrated)
DC,
GND
NOTE
plug-
POSI-
To demonstrate AC-coupled operation, position
(with the POSITION control) the bottom of the display
to the graticule centeriine.
Push in the AC button and note that the display
shifts downward to its average level.
Gain Check (All Channels)
The vertical and horizontal deflec:tion system of the 5000series oscilloscopes are gain-standardized to permit a
in to be moved from one oscilloscope to another (or from
one compartment to another within the oscilloscope)
out the need to recheck the calibration each time.
This completes the basic operating procedure for the
5A14N.
that need further explanation are discussed under General
Instrument operations not explained here or those
Information.
plug-
with-
GENERAL INFORMATION
Applying Signals
When measuring DC voltage, use the largest deflection
factor (5 V/Div) when first connecting the 5A14N to an un-
known voHage source. H Ihe deflection is loo small to make
the measurement, switch to a smaller deflection factor.
In general probes offer the most convenient method of
connecting a signal lo the input of the 5A14N. Tektronix
probes are shielded to prevent pickup of electrostatic
interference. A 10X attenuator probe oilers a high input
impedance and allows the circuit under test to perform very
close to normal operating conditions. The 5A14N is de-
signed for compatibility with coded probes,. The input
connector has an outer ring to which the coding ring on the
probe connector makes contact. This type of probe allows
the vertical deflection factor indicated by the readout to
correspond with the actual deflection factor at the probe tip,
eliminating the need to consider the attenuation factor of
the probe when measuring the signal amplitude on the
graticule scale. See your Tektronix, Inc., catalog lor
characteristics and compatibility of probes for use with this
system.
Sometimes unshielded test leads can be used to connect
the 5A14N to a signal source, particularly when a high-level,
low-frequency signal is monitored at a low-impedance
point. However, when any of these factors is missing, it
becomes increasingly important to use shielded signal
cables. In all cases, the signal transporting leads should be
kept as short as practical. Be sure to establish a common
ground connec:tion between the device under test and the
5A14N.
signal probe provides an adequate common ground
nection.
The shield of a coaxial cable or ground strap of a
con-
1-2
REV MAR
1987
Operating Instructions—5A14N
Channel Sequence Logic
The 5A14N has two channel-sequence modes selected by
the internal Single Beam/Dual Beam selector. In the forward or Single Beam position (toward the front panel), the
channels are displayed in a 4-3, 4-3,
the rear or Dual Beam position, the channels are displayed
in a
4-3-2-1,
quence is necessary in order to display all channels when
operating with a single-beam oscilloscope where each vertical compartment is given two time slots in sequence
before the other compartment receives its two time slots.
Since a possible four channels per compartment may be
desired,
sary. The Dual Beam sequence is useful when only one
vertical compartment of a single-beam oscilloscope is being
used,
any YT mcxie.
4-3-2-1 sequence. The Single Beam se-
a double count of each 4-3 and 2-1 pair is neces-
or when a dual-beam oscilloscope is being used in
2-1,
2-1 sequence. In
Input Coupling
The AC-DC pushbutton switch allows a choice of input
coupling.
coupling used.
DC coupling (button out) can be used for most applica-
tions.
larger than the AC component, AC coupling (button in) will
probably provide a better display. DC coupling should be
used to display AC signals below atout 2 hertz as they will
be attenuated in the AC position.
In the AC position, the DC component is blocked by a capacitor in the input circuit. The low-frequency response in
the AC position is about 2 hertz (-3 dB point). Therefore,
some low-frequency attenuation can be expected near this
frequency limit. Distortion will also appear in square waves
which have low-frequency components.
The type of display desired will determine the
However, if the DC component of the signal is much
b. Wait about one second for the coupling capacitor to
charge.
c. Remove the ground from the coupling capacitor
(GND button out). The display will remain on-screen
and the AC component can be measured in the
usual manner.
Deflection Factor
The amount of trace deflectbn produced by a signal is determined by the signal amplitude, the attenuation factor (if
any) of the probe, the setting of the VOLTS/DIV switch,
and the setting of the Variable control. The deflection factors indicated by the VOLTS/DIV switch are calibrated only
when the CAL control is rotated fully clockwise to the detent position.
The range of the CAL control is at least
uncalibrated deflection factors covering the full range between the fixed settings of the VOLTS/DIV switch. The
control can be set to extend the deflection factor to at least
12.5 volts/division.
2.5:1.
It provides
Display Modes
SINGLE TRACE. To display a single channel, apply the
signal to the desired input and press the DISPLAY button
to display the corresponding channel.
FOUR TRACE. To display all four channels, press all the
DISPLAY buttons.
The GND pushbutton provides a ground reference at the
amplifier input. The signal applied to the input connector is
presented with a one-megohm
put is grounded. This eliminates the need to externally
ground the input to establish a DC ground reference.
Pre-charging. To minimize surge currents in the circuit under test when using deflection factors of 50 mV/div
through 1 mV/div and a test lead or IX probe, use the ACDC and GND pushbuttons to take advantage of the precharging circuit permits charging the coupling capacitor to
the DC source voltage when the AC and GND buttons are
pressed in, and also limits surge current to the coupling capacitor from the signal source. The procedure for using
this circuit is as follows:
a. Before connecting the 5A14N to a signal containing
a DC component, push in the AC and GND buttons.
Then connect the input to the circuit under test.
REV MAR 1987
load,
while the amplifier in-
Trigger Source
The internal trigger signal lor the time-base plug-in unit is
obtained from the Channel 1 display only. Select the
ger source by pushing the CH 1 DISPLAY button.
trig-
Oscilloscope Applications
Refer to the Operating Instructions of a 5000-series
Oscilloscope System manual for basic oscilloscope
applications, including peak-to-peak AC voltage meas-
urements, instantaneous DC voltage measurements,
comparison measurements, time-duration measurements,
determining frequency, rise time measurements, X-Y
measurements, etc.
1-3
Operating Instructions—5A14N
ELECTRICAL CHARACTERISTICS
In this manual the word Volts/Div or division refers to major
graticule division.
Performance Conditions
The following charac^teristics apply when the 5A14N is operating within the environment described in the 5000series Oscilloscope System manual. In addition, the
5A14N must have been calibrated at an ambient temperature between -i-220° C and •i-30° C.
Display Modes
Selectable by switch on rear panel. All four channels displayed alternately, i.e.,
alternated with 2 and 1, i.e.,
vides a lull display of left ancl right vertical channels when
the 5A14N is usecd in a 3 plug-in single-beam system.
4-3-2-1
-4-3-2-1,
4-3-4-3-2-1-2-1,
or channel 4 and 3
which pro-
Bandwidth (-3 dB)
REPACKAGING FOR SHIPMENT
If the Tektronix instrument is to be shipped to a Tektronix
Servk^ Center for service or repair, attach a tag showing:
owner (wKh address) and the name of an individual at your
firm that can be contacted. Include complete instrument
serial number and a description of the service required.
Save and re-use the package in whk:h your instrument was
shipped.
available, repackage the instrument as foltows:
Surround the instrument with polyethylene sheeting to
protect the finish of the instrument. Obtain a carton of
corrugated cardboard of the corre<:t carton strength and
having inside dimensions of no less than six inches more
than the instrument dimensions. Cushton the instrument
by tightly packing three inches of dunnage of urethane
foam t>etween carton and instrument, on all sides. Seal
carton with shipping tape or industrial stapler.
The carton test strength for your instrument is 200 pounds.
If the original packaging is unfit for use or not
DC (DIRECT) COUPLED: DC to at least 1 MHz.
AC (CAPACITIVE) COUPLED: 2 Hz or less to at least
1 MHz.
Deflection Factor
1 mV/Divto 5 V/div within 2% in a 12 step, 1-2-5 sequence.
Uncalibrated, continuously variable between steps and to
12.5 V/div.
Maximum Safe Input Voltage
DC (DIRECT) COUPLED: 350 V (DC + peak AC).
AC (CAPACITIVE) COUPLED: 350 VDC.
Channel Isolation
At least 50 dB with any displayed combination.
input RC
1 Mn paralleled by =47 pF.
1-4
REV MAR
1987
WARNING
THE FOLLOWING SERVICING INSTRUCTIONS
ARE FOR USE BY QUALIFIED PERSONNEL
ONLY. TO AVOID PERSONAL INJURY, DO NOT
PERFORM ANY SERVICING OTHER THAN THAT
CONTAINED IN OPERATING INSTRUCTIONS
UNLESS YOU ARE QUALIFIED TO DO SO.
REFER TO OPERATORS SAFETY SUMMARY
AND SERVICE SAFETY SUMMARY PRIOR TO
PERFORMING ANY SERVICE.
SECTION 2
THEORY OF OPERATION
5A14N
INTRODUCTION
This section contains an electrical description of the circuits
in the 5A14N Four Channel Amplifier unit. A complete
block and schematic diagram is given on a pullout page at
the back of the manual.
The four channels are nearly identical except for Trigger
Pickoff, which occurs in Channel 1 only. Thus, this discussion concerns only Channel 1 except for the Channel
Switching portion, which necessarily involves all the chan-
nels.
PLUG-IN LOGIC
When the DISPLAY button, S510, is pressed, a logic level
is applied to the electronic switching circuit in the oscilloscope to enable plug-in operation (this button has no effect
when the plug-in is inserted in a horizontal plug-in
compartment). Power is applied to illuminate the frontpanel knob-skirt readout lamps, indicating the ON mcxJe.
INPUT COUPLING
Signals applied to the front-panel input connectors may be
capacitive coupled (AC), direct coupled (DC), or internally
disconnected (GND). Provision is made to precharge (or
discharge) the input capacitor to protect delicate circuitry
under test. When both the AC and GND buttons are
pressed,
input capacitor is pre-charged through a one-megohm
resistor to the level of the applied input signal.
the input to the amplifier is grounded and the
AMPLIFIER
The Input amplifier consists of two identical feedback
amplifiers, connected in a paraphrase configuration.
Quiescently, the two sides of the amplifier are balanced by
the internal Step Atten Bal adjustment Rl 15 so there is no
current through the gain-setting resistor (R123 through
R128). See Figure 2-1. An input signal is developed
across the gain-setting resistor, shifting the current
through
-sov
130
Q120A,
INPUT R123thru R128 OUTPUT
Q120B
O130
1 mA
1 mA
(134
Q134
INPUT ATTENUATOR
The deflection factor of the plug-in is set by a combination
of gain switching in the amplifier and input attenuatbn.
The input attenuator is a frequency-compensated voltage
divider that provides 100X attenuation in the 0.1 V to 5 V
positions of the VOLTS/DIV switch. At DC and for tow-frequency signals, the divider is essentially resistive
(attenuation ratio determined by the resistance ratio of
R107 and R108). At higher frequencies, the capacitive
reactance becomes effective and the attenuation ratio is
determined by the impedance ratio.
In addition to providing constant 10OX attenuation, the input attenuator maintains a constant input RC characteristic
(one megohm paralleled by about 47 pF) for 0.1 V to 5 V
settings of the VOLTS/DIV switch.
REV MAR 1987
+5V
VT\
j > R129 ^^
+30V 1136
Figure 2-1. Input amplifier partial diagram show-ing
quiescent current paths.
0136
0138
-30V
2-1
Theory of Operation—5A14N
Q134 and Q138 by the amount established through R123R128,
and developing a push-pull output signal across
R134 and R138. The gain of this amplifier ranges from
about one to fifty, and is primarily determined by the ratio of
the gain-setting resistor to the sum of R134 and R138.
The push-pull signal voltage from 0134 and 0138 collectors then passes through emitter followers 0142 and Q146
and is transformed to a signal current by 0160 and 0162.
The Variable VOLTS/DIV (CAL) potentiometer R168, and
the Gain-setting potentiometer R166, reduce the gain in
the Q160-Q162 stage by developing an adjustable amount
of signal voltage between their emitters.
Q150,
0156 and 0158 in Channel 1 only receive the pushpull signal and provide a single-ended trigger signal out.
0177 and Q178 provide positioning current.
CHANNEL SWITCHING
When only the CH 1 DISPLAY button S510 is pressed,
0510 is biased off, turning on Channel 1 switches 0180
and 0182 and albwing a signal to pass.
When only the CH 2 DISPLAY button S520 is pressed,
Q510 is biased on, switching Q516 off. This action turns
Channel 2 switches Q280 and 0282 on.
When both CH 1 and CH 2 buttons are pressed (dual-trace
mode), the state of O510 and 0516 is determined by the
channel-switching signal generated in the oscilloscope
mainframe. The form of this signal is selected on the sweep
plug-in by the Alternate-Chop Mode button.
Channels 3 and 4 operate as a switched pair just as Channels 1 and 2. Thus, the Channel 3 switches Q380 and
0382 are controlled by Q520, and the Channel 4 switches
Q480 and 0482 are controlled by Q526. When both
Channels 3 and 4 are ON, they are either alternated or
chopped as a pair through Q520 and 0526 by the channelswitching signal.
Channels 1 and 2 are displayed as a composite pair when
their composite switches Q530 and 0534 are turned on.
This occurs when Q550 is biased off. Channels 3 and 4
composite switches Q540 and 0544 are similariy turned on
when 0556 is biased off. When one or two channels from
each composite pair are ON, U550 switches between the
two pairs at either 1/2 or 1/4 the Alternate or Chop rate of
the channel-switching signal. U550 divides the channel-
switching signal by 2 in the Dual Beam position or by 4 in
the Single Beam position of S550. The divided channel-
switching signal from S550 determines the state of Q550
and Q556 when 1 or 2 channels from each composite pair
are
ON.
PROBE SENSING
Either of two lamps located behind the VOLTS/ DIV knob
skirt illuminates the selected deflection factor to provide a
direct readout. Normally, DS190 is lit; connection of a
readout-coded 10X probe extinguishes DS190 and lights
DS196. This changes the knob skirt readout by a factor of
10 to reflect the probe attenuation, eliminating possible
operator error.
2-2
REV MAR
1987
SECTION 3
CALIBRATION
5A14N
Introduction
This section of the manual contains a procedure to return
the circuits of the 5A14N within their designed operating
capabilities. Calibration is generally required alter a repair
has been made, or after long time intervals in which normal
aging of components may affect instrument accuracy. For
initial inspection, verify instrument operation by performing
the procedures described under Basic Operation in Section 1.
Instrument Maintenance
Before complete calibration, thoroughly clean and inspect
this instrument as outlined in the Maintenance section of
the Oscilloscope System manual. Also, the System manual
contains information for general maintenance of this instrument, including preventive maintenance, component
identification and replacement, etc.
Service Available
Tektronix, Inc. provides complete instrument repair and
calibration at local Field Service Centers and at the Factory
Sen/ice Center. Contact your local Tektronix Field Office or
representative for further information.
test equipment are not given in this procedure. Refer to
the instruction manual for the test equipment if more infor-
mation is needed.
Special Calibration Fixtures
Special Tektronix calibration fixtures are used in this procedure only where they facilitate instrument calibration.
These special fixtures are available from Tektronix, Inc. Order by part number through your local Tektronix Field
Office or representative.
Test Instruments
1.
5000-series oscilloscope system. For this proce-
dure,
a 5110 Oscilloscope with a 5B10N Time-Base
plug-in is used.
2.
Constant amplitude sine-wave generator. Fre-
quency, 2 Hz to 1 MHz; output amplitude, about 0.5
V to at least 4 V P-P. Tektronix FG 501 Function
Generator recommended (requires a TM 500-series
power module).
3. Standard amplitude calibrator. Output signal, 1 kHz
square wave; output amplitude, 5 mV to at least 20 V;
accuracy, within 0.25%. Tektronix PG 506 Calibration
Generator recommended (requires a TM 500-series
power module).
TEST EQUIPMENT REQUIRED
General
The following test equipment and accessories, or the
equivalent are required for complete calibration of the
5A14N.
the minimum necessary for accurate calibration. Therefore,
some of the specifications listed may be less rigorous than
the actual performance capabilities of the test equipment.
All test equipment is assumed to be correctly calibrated and
operating within the listed specifications.
Specifications given for the test equipment are
Calibration Equipment Alternatives
If other test equipment is substituted, control settings or
set-up may need altering to meet the requirements of the
equipment used. Detailed operating instructions for the
REV MAR 1987
Accessories
1.
Coaxial cable, Impedance,
connectors, BNC. Tektronix Part No.
2.
Input RC normalizer. RC time constant, 47 ms
x 47 pF); connectors, BNC. Tektronix Calibration
Fixture 0067-0541-00 recommended.
3. In-line termination. Impedance, 50 il, accuracy,
within 2%; connectors, BNC. Tektrnoix Part No.
0049-01 recommended.
4.
Plug-in extension for the 5000-series oscilloscope
system.
(not mandatory for this procedure).
Tektrnoix Calibration Fixture 0067-0645-03
50fi;
length, 42 inches;
012-0057-01.
(1
Mi2
011
3-1
-
Calibration—5A14N
3-2
^OUOOOO
:C3-
.an
'•CID
Q'^O'OOQQO
is.^
^
>^-l.y>
OO
OOOOQ
-T^_T
c—n
e a
^i^^
Figure 3-1. Internal adjustment locations.
CH 2 GAIN
R266
CH 3 GAIN
R366
.CH 4 GAIN
R466
REV MAR 1987
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