Tektronix 7A19 User manual

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Scans by ArtekMedia © 2008

TABLE OF CONTENTS
SECTION 1 SPECIFICATION
Introduction
Option
4
SECTION 2 OPERATING INSTRUCTIONS
Front Panel Controls and Connectors
Operating Instructions and Checkout
Applications
SECTION
3 CIRCUIT DESCRIPTION
Block Diagram
Detailed Circuit Description
SECTION
4 MAINTENANCE
Preventive Maintenance
Troubleshooting
Corrective Maintenance
SECTION
5 CALIBRATION
Performance Check
Test Equipment Required
Calibration Procedure
Index to Calibration Procedure
SECTION
6 ELECTRICAL PARTS LlST
SECTION 7 DIAGRAMS
Circuit Board Illustrations
Semiconductor Electrode Configurations
SECTION
8 MECHANICAL PARTS LlST
Exploded View Drawing
Page
1-1
1-1
CHANGE INFORMATION
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Fig. 1-1. 7A19 Amplifier plug-in (Left) and 7A19with Variable delay option (Right).
-
REV. A, AUG. 1976
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ARTEK MEDIA
Digitally signed by ARTEK MEDIA
DN: cn=ARTEK MEDIA, c=US, o=DC
Henderson
Date: 2008.01.31 18:36:47 -06'00'

Section 1-7A19
SPECIFICATION
Introduction
The following electrical characteristics are valid over the
stated environmental range for instrumentscalibrated at an
ambient temperature of +20°c to +30°c, and after a five
The 7A19 Amplifier plug-in unit
is a wide band amplifier
minute warmup unlessotherwise noted,
designed for use with TEKTRONIX 7000-Series oscillo-
scopes. Readout encoding circuitry is provided in tile 7A19
to allow probe coding, deflection factor readout, and
option 4
IDENTIFY functions. The 7A19 can be operated in any
compartment of the 7000-Series oscilloscopes, but is pri- An optional VARIABLE DELAY may be ordered with
marily intended for use in the vertical plug-in compartments. the 7A19 to provide a signal delay of up to f500 ps.
TABLE 1-1
ELECTRICAL
,-.. "" .-*.
7-----
Characteristic
- -- -
- - - -- - -
--
Deflection Factor
Calibrated Range
Gain Ratio Accuracv
- -- - ---- "
Frequency Response (8 divi-
sion reference, mainframe
dependent)
Upper BandwidthAC or
DC coupled 10 rnV/div
to 1Vldiv
Lower Bandwidth
AC Coupled
Maximum Input Power
DC or AC coupled
Voltage (ACcoupled)
lnput Impedance
Resistance(DC or
DC GND)
Reflection Coefficient
(TimeDomain)
Maximum lnputCurrent
Performance Requirement
-- " ----
-- .- - - - -- - - - - - - -- - --
*
10 mVIdiv to 1 Vldiv, 7 steps in a 1, 2, 5
sequence
Within 3% with GAlN adjusted at 10
mVIdivwhen driven from 50 ohm source.
- -----
With 7400, 65 MHz; With 7500, 100
MHz; With 7700, 115 MHz; With 7900,
500 MHz
1 kHz or less
2 watts average or 50 divisions peak
deflection.
100volts (DC
+ peak AC) not to.exceed
2 watts average or 50 divisions peak.
Supplemental Information
"" , .", .". .. . - ." .-. ."" - -.-"--.-.-.'---""-.a-
..-"~w"*-~.--"---"-.-"-
Pre-Charge circuit may be used as a
calibrated 100X attenuator
Front panel GAlN control allows calibra-
tion to mainframe.
CAUTION
Pre-charge circuit must be used for both
charging and discharging AC coupling
capacitor to potentials greater than
50
divisionsequivalent voltage.
p-m--*-----p" -. .-- ".-*"..---.."--
50ohms +I ohm VSWR is typically less than 1.25 @ 500
1
MHz
Less than 0.1 peak to peak
Less than 0.2 mA
REV. B, SEPT. 1977 1-1
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Specifications--7A I9
TABLE 1-1 (cont)
Characteristic
-- - --
- -
IDENTIFY
Trace Positioning
"--"--
Display Noise
(Tangentially Measured)
DC Drift
Driftwith ambient
temperature (line
voltage constant)
Variable Delay (Option
4)
Range
Accuracy
Input Polarity
Performance Requirement
-*-
---
I00 PV/C" or less
Variable from
-0.5 ns to +0.5 ns
To 1 ns within k0.05 ns of dial setting
Supplemental Information
-----
Deflects trace approximately 0.3 division
At least
+8 divisions
----
Less than 0.1 division
Front panel switch selects +UP or
INVERT
TABLE
1-2 TABLE 1-3 -
ENVIRONMENTAL CHARACTERISTICS PHYSICAL
--
Refer to the specifications for the associated
oscilloscope.
- .-.. -. - -- .... ""
7A19 (option I): 1.3 kilograms or 2.9 Ibs.
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Section 2-7A19
OPERATING INSTRUCTIONS
General
To effectively use the 7A19, the operation and
capabilities of the instrument must be known. This section
describes front-panel control functions, general information
on signal input connections, and other subjects that pertain
tovarious measurement applications.
Installation
I-he 7A19 is calibrated and ready for use as received. It
can be installed in any compartment of TEKTRONIX
7000-Series Oscilloscopes, but is intended for principal use
in vertical plug-in compartments. To install, align the upper
and lower rails of the 7A19 with the oscilloscope tracks and
insert it. 'The front panel will be flush with the front of the
oscilloscope and the latch
at the bottomleft corner will be
in place against the front panel when the 7A19 is fully
inserted.
,...
i o remove the 7A19, pull on the latch (inscribed with
the unit identification "7A19") and the 7A19 will unlatch.
Continue pulling to slide the 7A19 out of the oscilloscope.
FRONT PANEL
CONTROLS AND CONNECTORS
VOL 1 SIDIV Selects calibrated deflection factors
from 10 mV/Div to 1VIDiv;
7
steps in a 1-2-5sequence.
INVERT: A positive-going signal at
the INPUT connector deflects the
CR9 display downward.
InputCoupling Selects signal input coupling mode.
Switch AC: The AC component of the
signal is coupled to the amplifier
input while the DC component is
blocked.
AC GND: Grounds the amplifier
input while maintaining the same
AC load for the input signal.
PRE-CHG: Provides
a charge path
for the AC coupling capacitor to
pre-charge the input circuit before
switching the Input coupling switch
to AC.
DC: Both AC and DC components
of the signal are coupled to the
amplifier input.
DC GND: Grounds the amplifier
input while maintaining the same
DC load for the input signal.
INPU-I Connector Provides a means for connecting a
signal.
POSITION Controls the position of the trace.
lDENTIFY Deflects the trace about
0.3 division for trace identification.
In instruments with readout, also
replaces readout with the word
"IDENTIFY".
GAIN Adjustment Screwdriver adjustment permits
calibration of deflection factor.
POLARITY Provides
a means of inverting the
display.
+UP: A positive-going signal at the
INPU'I connector deflects the CRT
display upward.
VARIABLE DELAY Delays the signal up to k500
(Option 4) picoseconds by using a calibrated
10 turn dial.
OPERATING INSTRUCTIONSand CHECKOUT
Probes
Probes recommended for use w~ththe 7A19 are the
P6056 (10X)or P6057 (100X).BotCl probesare compatible
to 50 ohm systelrls, and will allow optimum frequency
response. These probes also conta~ntrace IDEN
I IFY and
readout encoding funct~ons.
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Operating Instructions--7A19
If the P6201 Probe is used, a one megohm input
impedance may be achieved. Consult your local
TEK-
7 RONIX Field Engineer or Representative for further
information.
Vertical Gain Check and Adjustment
To check the gain of the 7A19, set the VOLTSIDIV
switch to 10 mV and connect 20 mV, 1kHz signal from the
oscilloscope Calibrator to the INPUT connector. The
vertical deflection should be exactly two divisions. If not,
adjust the front panel GAIN control for exactly two
vertical divisions.
lnput Coupling
The input coupling switch allows a choice of input
coupling methods. The type of display desired and the
applied signalwill determine the coupling to use.
The DC coupling position can be used for most
applications. For AC signals with frequencies below about
1kHz, and square waves whose low-frequency components
are important to the display, it is necessary to use DC
coupling to obtain asatisfactory presentation.
DC GND position disconnects the signal source from the
amplifier and connects itto a resistive 50 ohm termination,
thus providing the same type of load to the signal source.
The input to the amplifier is also provided with a ground
reference.
In the AC coupling position, the DC component of the
signal is blocked by a capacitor in the input circuit. The AC
coupling position provides the best display of signalswith a
DC component much larger than the AC component.
"Phe PRE-CHG feature should be used when there is a
possibility of having a residual charge on the input
capacitor of the opposite polarity to the intended input,
and when the algebraic sum of the charges may be greater
than the maximum input linlitations of the amplifier. To
use this feature, first set the coupling switch to PRE-CHG,
then connect the signal source to the INPUT and wait
about two seconds for the coupling capacitor to charge, set
the coupling switch to AC.
Another useful feature of the PRE-CHG position is that
it can be used as a calibrated 100X attenuator having an
input impedance of five kilohms in series with two
microfarads. "Phis extends the Low Frequency response to
less than 20 Hz. lnput power should be limited to
118 watt
inthis mode.
The AC GND positiondisconnects the signal source from
the amplifier and connects it to a capacitive coupled 50
ohm termination, thus providing the same type of load to
the signal source. The input to the amplifier is also pro-
vided with a ground reference.
VOLTSIDIV Switch
The amount of deflection produced by a signal is
determined by the signal amplitude, the attenuation factor
of the probe, the setting of the VOLTSIDIV switch, and
the setting of the lnput Coupling switch. Calibrated
deflection factors represented by the VOL 1-SIDIV switch
apply only when the probe attenuation
is XI and when the
Input Coupling switch is not inthe PRE-CHGposition (the
PRE-CHG position has an attenuation of 100X).
POLARITY Switch
1 he POLAR1I'Y switch provides a means of inverting the
displayed signal. With the POLARITY switch set to+UP, a
positive-going signal at the INPUT produces an upward
deflection of the CRT display. With the POLARITY switch
set to INVERT, a positive-going signal will produce a
downward deflection of the CRT display.
Trace Identification and Readout Functions
When the IDENTIFY button is pressed, the trace is
deflected upward about 0.3 division to identify the 7A19
trace. Phis feature is particularly useful when multiple
traces are displayed on the CRT. In mainframes with
readout, it also replaces the deflection factor readout with
the word "IDENTIFY".
The 7A19 is equipped with probe encoding circuitry
that, when used with acoded probe, corrects the deflection
factor readout.
VARIABLE DELAY (Option 4)
The optional VARIABLE DELAY line provides ameans
for delaying the signal applied to the INPUT for up to+500
DS.
APPLICATIONS
General
The following ~nformationdescribes the proceduresand
techniques for making measurements with
a 7A19 and the
associated rE
K 1"HONIX oscilloscope and time-base. These
applications are not described in detail, since each
application must be adapted to the requirements of the
individual measurements. rhis instrument can also be used
for many applications which are not described in this
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Operating Instructions---7A19
manual. Contact your local TEKTRONIX Field Office or
representative for assistance in making specific measure-
ments.
Peak-to-PeakVoltage Measurements (AC)
1'0 make peak-to-peak voltage measurements, use the
following procedure:
1. Apply the signal to the INPUT connector.
2. Set the Coupling switch to AC.
NOTE
For low-frequency signalsbelow about I kHz, use the
DC position toprevent attenuation of the signal.
Position to
center vertical
line
Fig.
2-1. Measuring the peak to peak voltage of a waveform.
3. Set the VOLTSIDIV switch to display about five
vertical divisionsof the waveform.
vertical probe
Volts
= deflection X
4. Set the time-base Triggering controls for a stable VOLTS'DIVsetting
x attenuator
(divisions) factor
display. Set the time base to a sweep rate which displays
several cycles of the waveform
Substituting the given values:
5. Turn the 7A19 POSITION control so the lower
portion of the waveform coincideswith one of the graticule Volts Peak to Peak
- 4.5 X 1 X 10
lines below the center horizontal line, and the top of the
waveform is within the viewing area. With the time base The peak-to-peakvoltage is
45 volts.
Position control, move the display so one of the upper
peaks liesnear the center vertical line (see Fig.
2-1).
When using a coded probe and an oscilloscope equipped
with readout, simply multiply the distance measured in step
6. Measure the divisions of vertical deflection peak to
6 by thedeflection factor displayed on the CRT.
peak.
NOTE
InstantaneousVoltage Measurements (DC)
This technique can also be used to make To measure the DC level at agiven point on awaveform,
measurements between two points on the waveform, proceed as follows:
rather than peak topeak.
1. Connect the signal to the INPUT connector.
7. Multiply the distance measured in step
6 by the
VOLTSIDIV switch setting. Include the attenuation factor
of the probe, if used.
2. Set the VOLTSIDIV switch to display about five
d~visions.
EXAMPLE: Assurne that the peak to peak vertical 3. Set the Coupling switch to GND, and position the
deflection is
4.5 divisions using a 10X attenuator probe, trace to the botlot-n graticule line or other referenceline. If
and the VOL"PS1DIV switch is set to 1V. the voltage is negative with respect to ground, position the
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Operating I nstructions-7A19
trace to the top graticule line. Do not move the POSITION
control after this reference line has been established.
4. Set the Coupling switch to DC. The ground reference
line can be checked at any time by switching to the GND
position.
NOTE
To measure a voltage level with respect to another
voltage rather than ground, make the following
changes to Step
4. Set the Coupling switch to DC and
apply the reference voltage to the INPUT connector.
Then position the trace to the reference line and
disconnect the reference voltage.
5. Set the time-base Triggering controls for a stable
display. Set the Time Base sweep rate for an optimum
display of the waveform.
6. Measure the distance in divisions between the
reference line and the point on the waveform at which the
DC level is to be measured. For example, in Fig.
2-2 the
measurement is between the referenceline and point A.
7. Establish the polarity of the waveform. With the
POLARITY switch in the NORM position, any point above
the referenceline is positive.
8. Multiply the distance measured in step 6 by the
VOLVSIDIV switch setting. Include the attenuation factor
of the probe, if used.
EXAMPLE: Assume the vertical distance measured is
3.6 divisions (see Fig. 2-2) and the waveform is above the
reference line, using a 10X probe with a VOLPSIDIV
switch setting of 0.5 V.
Using the formula:
Instan- vertical VOLTS/ probe
taneous
= distance X polarity X DIV X attenuation
voltage (divisions) setting factor
Substituting the given values:
lnslantaneous Voltage - 3.6 X 1 X 0.5 V X 10
The instantaneousvoltage is 18 volts.
Matching transit times using two 7A19's. one
having VARIABLE DELAY (Option
4)
In some applications it is necessary to view the tirne
relationship of two signals, one with respect to the other.
Z
Reference line
Fig.
2-2. Measuring instantaneol~s voltage with respect to same
reference.
With high speed signals, the transit times of the probes and
amplifiers can distort the true time relationship of the two
signals. By using the VARIABLE DELAY (Option
41, the
transit times between two units can be matched to within
-,
50 ps, thus giving a true time relationship of the signals
being viewed.
For matching transit times of two 7A19 with probes,
proceed as follows:
-
1. Install the 7A19 without the VARIABLE DELAY
option in the left vertical plug-incompartment,
2. Install the 7A19 with VARIABLE DELAY option in
the rightvertical plug-incompartment.
3. Connect the probes to a common signal source of
greater than 100
kHz and adjust the time-base unit for the
fastest sweep available.
4. Set the Trigger Source switch to left Vert, and
Vertical Mode to Alternate.
5. Set both 7A19's to the same deflection factor
settings.
6. Center both displays vertically.
-
7. Adjust VARIABLE DELAY so that the two displays
are superimposed. I^hetransit times of both units are now
matched.
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Section 3-7A19
CIRCUIT DESCRIPTION
Iniroduction
This section of the manual contains adescription of the
circuitry used in the 7A19 amplifier. The description begins
with a discussionof the instrument using the block diagram
shown in the Diagrams section. Then, each circuit is
described in detail using block diagrams to show the
interconnections between stages in each major circuit and
the relationship of the front panel controls to the individual
stages.
A complete schematic of the circuits are given in the
Diagrams section. Refer to this schematic throughout the
following circuit description for electrical values and
relationship.
BLOCK DIAGRAM
The following discussion is provided to aid in under-
standing the overall concept of the 7A19 before the
individual circuits are discussed in detail. Only the basic
interconnections between the blocks are shown on the
block diagram (see Diagrams section). Each block repre-
sents a major circuit in the instrument.
Signals to be displayed on the CRI are applied to the
INPUT connector. The signal passes through the lnput
Coupling Switch, where the appropriate coupling is
selected, to the Attenuators. i"he VOLTSIDIV switch
selects the correct amount of attenuation.
Transit time for the 7A19 is standardized by the Fixed
Delay Line. An optional Variable Delay Line can be
ordered that allows the transit time of the plug-in to be
varied up to 1 ns.
Signals from the Delay Line are connected to the Signal
Line. The Signal Line represents a 50
!2 line that is
connected to Signal Amplifier, Trigger Amplifier, Limiter,
and is terminated in the Signal Line Terminater. lnput
impedance is effectively adjusted, therefore, by the lnput
Current control.
Overvoltage protection is provided by the Limiter
circuitry and the fuse located in the InputCoupler.
7 he S~gnalAmpl~f~erand Tr~ggerAmplifier circu~tsare
identical. They provide positioning and galn switch~ngfor
the 10 mV and 20 mV ranges. GAIN calibration and
temperature compensation is provided by the Gain Current
Ampl~fier.
The Signal Amplifier and Trigger Amplifier is connected
to the Polarity circuit where the oscilloscope is provided
with +UP or inverted signal and trigger outputs. Outputs are
connected to the oscilloscope via the interface connectors.
DETAILED CIRCUI"F DESCW IPTION
lnput Coupling
Input signals connected to the INPUT connector can be
AC-coupled, DC-coupled, or internally disconnected. S5 is a
cam-type switch; a contact-closure chart showing the
operation is given on the schematic in the Diagramssection.
When the lnput Coupling Switch is in the DC position, the
input signal is coupled direc.tly to the Attenuator. The DC
GND position disconnects the input signal from the
ALtenuators and connects it to ground through two 100 R
resistors in parallel. Paralleling the 100 i2 resistors reduces
the inductance associated with the resistors so that the
combination will remain 50 R for all frequencieswithin the
limits of this plug-in.Connected in a similar manner and for
the same reasons are the input fuses F6 and F7. Inthe AC
position, the input signal passes through capacitor C5. The
capacitor prevents the DC component of the signal from
passing to the Attenuator. AC GND position disconnec-cs
the input signal from the Attenuators and connects it to
ground through C5 and the two 100R resistors. This
represents the same load to the signal source. The PRE-
CHG position limits the instantaneous current caused by
connecting a large signal to the INPUT connector by
inserting a resistor in series with C5. Since this resistor is
4.95 kR and the input to the Attenuator is 50 a,the
PRE-CHGposition will act as
a XI00attenuator.
Attenuator
The effective overall deflection factor of the 7A19 is
determined by the setting of the VOLTSIDIV switch, S135
and the Step Attenuator, A10. Gain switching for the
10 mV and 20 mV positionsoccur in the Signal and Trigger
Amplifiers.
r he signal in the 10 mV and 20 mV position is
passed through the Step Attenuator, unattenuated. Pre-
cision microwave aitenuators, located in the Step Attenu-
ator, are switched in at all other VOLsiS/DIV positions.
Delay Lines
Unless Variable Delay Option 4 is requested, all 7A19's
are equipped with a Fixed Delay Line consisting of a
precision length of 50
a cable. ['he Fixed Delay Line is
inserted in series with the Signal Line so that the transit
times of all 7A19 plug-in's can be closely regulated. The
optional Variable Delay Line, when requested, replaces the
Fixed Delay Line.
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Circuit Description.-7A19
Signal Line Terminator Gain Current Source
The Signal Line Terminator consists of acurrent sensing
operational amplifier connected to the Signal Line. This
operational amplifier senses changes in currents at the
Signal Line and compensates by adding or subtracting
currents. The Input Current control sets the quiescent
current at the Signal Line. This is the major controlling
factor for input impedance. Changes of input current due
to positioning or polarity switching are also compensated
by this circuit. R121 and C121 compensate for the addition
of this circuit to the Signal Line.
Limiter
CR124, CR125 provide overload protection. An over-
load condition at the signal INPUT connector will cause
one or both diodes to forward bias. If this condition
continues, the current flowing through the diodes will soon
cause the fuses F6, F7 to burn out. DiodesCR124, CR 125
are connected to the Signal Line through an impedance
matching
"T" network, L124, L125, and C123.
Signal Ainplifier and Trigger Amplifier
The Signal Amplifier and Trigger Amplifier circuitry are
identical. 'rhe description for the Signal Amplifier applies
equally to the 'Trigger Amplifier.
'The Signal Amplifier consists mainly of
a TEK1-HONIX-
made hybrid integrated circuit (U40) and its related
circuitry. A representation of U40 is shown in the
schematic diagramssection. The Signal Line is connected to
the S~gnalAmplifier input through a "T" network con-
sisting of C20, L21, and 1-22. The
"T" coils, L21and L22
are adjusted for minimum aberrations
at high frequencies.
I he paraphase input of U40converts the single ended input
to a differential signal. Frequency compensation, signal
balancing, gain, and temperature compensation are all
accomplished in the emitters of the paraphase amplifier.
Frequency compensation is achieved through the use of the
series of resistors, capacitors, and an inductor connected to
pins 5 and 11. R38 signal balance control balances our the
resultant currents in the amplifier.
Temp Comp control, R76, sets the voltage at the emitter
of 076. The current through R74 is set by the current
generator 073 and Gain control R73. As the d~ermal
resistor R74 changeswith temperature so will the voltage at
the collector of Q73; therefore, compensating for temper-
ature changeswithin the plug-in.
Positioning is achieved by varying the DC level at the
input of the paraphase amplifier (pin
4, U40). Q56A and
Q56B is a DC amplifier having an inverting input and
non-inverting input. Gain of this amplifier is selected by the
VOLTSIDIV switch. With the VOLTSIDIV switch in the
10 mV position, the gain of 056 is set by R66. In the
20 mV position the gain of 056 is doubled. The POSITION
control (R68) applies a DC signal to either the inverting or
non-inverting input. This is selected so that a clockwise
rotation of the POSl rlON control will always produce an
upward deflection of the displayed trace. The output of the
position amplifier is applied to the Signal and Trigger
Amplifier through an inverting buffer Q50. This signal is
also applied to the Signal Line Terminator which com-
pensates for the current changes that occur as a result of
the positioning circuitry.
Polarity Circuit
The output from the Signal and Trigger Amplifiers is -
connected through the Polarity switch to the interface
connector. The Polarity switch, in the INVEH
l position,
not only inverts the Signal and Trigger outputs but it
inverts the polarity signal so that a clockwise rotation of
the POLARI
1 Y control always producesan upward deflec-
tion. See the description for the PositionCircuit for details.
Connectors
All connections made to the mainframe by the 7A19 are
shown on the schematic located in the Diagrams section of
this manual. Also shown are the power supply decoupling
components.
Readout
The 7A19 incorporates standard vertical readout en-
coding circuitry. Refer to any 7000-Series Oscilloscope
with readout for more information.
Scans by ArtekMedia © 2008

Section 4--7A19
MAINTENANCE
Introduction
This section of the manual contains maintenance infor-
mation for use in preventive maintenance, corrective
maintenance,and troubleshooting of the 7A19.
Further maintenance information relating to general
maintenance can be found in the instruction manuals for
the 7000-Seriesoscilloscopes.
PREVENTIVE MAINTENANCE
General
Preventive maintenance, consisting of cleaning, visual
inspection, etc., performed on a regular basis, will improve
the reliability of this instrument. Periodic checks of the
semiconductor devices used in the unit are not recom-
mended as a preventive maintenance measure. See
semiconductor-checking information given under Trouble-
shooting.
Cleaning
Front Panel. Loose dust may be removed with a soft
cloth or a dry brush. Water and mild detergent may be
used; however, abrasive cleaners should not be used.
Interior. Cleaning the interior of the unit should precede
calibration, since the cleaning process could alter the
settings of the calibration adjustments. Use low-velocity
compressed air to blow off the accumulated dust. Hardened
dirt can be removed with a soft, dry brush, cotton-tipped
swab, or cloth dampened with a mild detergent and water
solution.
Lubrication
Use a cleaning-type lubricant on shaft bushings in
connecting plug contacts, and switch contacts. Lubricate
switch detents with a heavier grease.
A lubrication kit
containing the necessary lubricating materials and instruc-
tions is available through any TEKTRONIX Field Office.
Order by TEKTRONIX Part No. 003-0342-01. Local
purchase is recommended whenever possible.
-
General
The following is provided to augment information
contained in other sections of this manual when trouble-
shooting the 7A19. The schematic diagrams, circuit descrip-
tion, and calibration sections should be used to full
advantage. The circuit description section gives detailed
information on circuit behavior and output requirements.
Troubleshooting Aids
Diagrams. Circuit diagrams are given on foldout pages in
Section 7. The circuit number and electrical value of each
component in this instrument are shown on the diagrams.
Important voltages and semiconductor lead configurations
are also shown.
Circuit Board. The circuit board used in the 7A19 is
outlined on the schematic diagrams, and
a photograph of
the board
is shown on the back of the schematic diagrams.
Each board-mounted electrical component is identified on
the photograph by its circuit number.
Component and Wiring Color Code. Colored stripes or
dots on resistors and capacitors signify electrical values,
tolerances, etc., according to the EIA standard color code.
Components not color coded usually have the value printed
on the body.
The insulated wires used for interconnection in the
7A19 are color coded to facilitate tracing a wire from one
point to another in the unit.
Troubleshooting Equipment
The following equipment is useful for troubleshooting
the 7A19.
1. Semiconductor Tester-Some means of testing the
transistors and diodes, used in this instrument is helpful.
A
transistor-curve tracer such as the T"EK7RONIX Type 576
will give the most complete information.
2. DC Voltmeter and Ohmmeter--A voltmeter for
checking voltages within the circuit and an ohmmeter for
checking resistors and diodes
is required.
3. Test Oscilloscope-A test oscilloscope is required to
view waveforms at different points in the circuit.
A
TEKT RONlX 7000-Series Oscilloscope equipped with a
readout system, 7D13 Digital Multimeter unit, 7B-Series
I'ime-Base unit, and a 7A-Series Amplifier unit with a 10X
probe will meet the needs of both items 2 arid 3.
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CORREC1-IVE MAINTENANCE
General
Corrective maintenance consisfs of component replace-
ment and instrument repair. Special techniques required to
replace components in this instrument are given here.
Obtaining Replacement Parts
Standard Parts. All electrical and mechanical part re-
placements for the 7A19 can be obtained through your
local
I tK1 HONIX Field Office or representative.However,
many of the electronic components can be obtained locally
in less time than is required to order them from Tektronix,
Inc. Before purchasingor ordering replacement pat
ts, check
tile parts I~stfor value, tolerance, rating and description.
NOTE
When selecting replacement parts, it is important to
remember that the physical size and shape of a
component may affect the performance of the
instrument, particularly at high frequencies. All re-
placement parts should be direct replacements unless
it is known that a different component will not
adversely affect instrument performance.
Special Parts. In addition to the standard electronic
components, some special parts are used in the 7A19. These
parts are manufactured or selected by Tektronix, Inc., in
accordance with our specifications.
"'f hese special parts are
indicated in the parts list by an asterisk preceding the part
number. Most of the mechanical parts used in this
instrument have been manufactured by Tektronix, Inc.
Order all special parts directly from your local
'I'f KTRONIX Field Office or representative.
Ordering Parts. When ordering replacement parts from
Tektronix, Inc., include the following information:
1. InstrumentType.
2. Instrument Serial Number
3. A description of the part (ifelectrical, include circuit
number).
4.
1 EKTRONIX Part Number.
Soldering Techniques
WARNING
Disconnect the instrument from tire power source
before soldering.
Circuit Boards. The components mounted on the circuit
boards in the 7A19 can be replaced using normal circuit
board soldering techniques. Keep the following points in
mind when soldering on the circuit board:
1. Use a pencil-type soldering ironwith awattage rating
from 15 to 50watts.
2. Apply heat from the soldering iron to the junction
between the component and the circuit board.
3. Heat-shunt the lead to the component by means of a
pair of long-nosepliers.
4. Avoid excessive heating of the junction with the
circuit board, as this could separate the circuit board wiring
from the base material.
5. Use electronic grade 60-40tin lead solder.
6. Clip off any excess lead length extending beyond the
circuit board. Clean off any residual flux with a flux-
removing solvent.
Metal I'erminals. When soldering metal terminals
(potentiometers, etc.) use 60-40 tin lead solder and a 15 to
50 watt soldering iron. Observe the following precautions
when soldering metal terminals:
1. Apply only enough heat to make the solder flow
freely.
2. Apply only enough solder toform asolid connection.
Excess solder may impair the function of the parl.
3. If a wire extends beyond the solder joint, clip off the
excess.
4. Clean the flux from the solder joint with a flux-
removing solvent.
Component Replacement
Disconnect the equipment from the power source
before replacing components,
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Semiconductor Replacement. Transistors and integrated 1. Remove the inductors and associated capacitor by
circuits (IC's) should not be replaced unless actually usi~ga low wattage soldering iron and a vacuum type
defective if removed from their sockets during routine desoldering device.
maintenance, return them to their original sockets. Unnec-
essary replacement of semiconductors may aifect the
calibration of this instrument. When semiconductors are 2, Insert the replacement capacitor on the circuit board
replaced, check the performance of the part of the and bend the leads to form a loop approximately
318 inch
instrumentwhich may be affected. high.
Replacement semiconductors .should be of the original
3. Solder the capacitor and inductors to the circuit
type or a direct replacement. Lead configuration of the board.
semiconductors used in this instrument are shown on the
schematic diagrams. If the replacement semiconductor is
not of the original type, check the manufacturer's basing Replacement of any of the inductorswill affect the high
diagram for proper basing. frequency characteristics of the 7A19 and re-calibration
will be necessary.
TEKTRONIX Integrated Circuits. If it should become
necessary to replace the TEKTRONIX integrated circuils
U40and U100 use the following procedures:
1. Remove the common heat sink (No. 64 in Fig. 1
EXPLODED of the Mechanical Parts List section).
2. Unsolder the two ground straps from either side of
the integrated circuit case and unplug the integrated circuit.
3. To install, align the tab of the integrated circuit with
the dot, marked on the circuit board. Then, making sure
pins are aligned with their sockets, gently push into the
socket.
NOTE
rhe leads of the integrated circuit are cut at the
factory to prevent the integrated circuit from resting
directly on the circuit board. Defeating this purpose
may allow the pin sockets to short against the
integrated circuit case. Solder the ground leads to the
case and replace theheat sink.
Inductor Replacement (L21, L22, L81, 1.82, L124,
L125). Inductors are replaced as a pair along with their
associated capacitor (e.g., L21, L22, and C20). The
inductors are formed by the leads of the capacitor, see Fig.
4-1.To replace a pair of inductors, proceed as follows:
REPACKAGING FOR SHIPMENT
If the Tektronix instrumerlt is to be shipped to a Tektronix
Service Center for service or repair, attach a tag showing:
owner (withaddress) andthe name of an individualatyour
firm that can be contacted, complete instrument serial
number and a description of the service required.
-
Save and re-usethe package inwhichyour instrumentwas
shipped. If the original packaging is unfit for use or not
available, repackage the instrument as follows:
1. Obtain a carton of corrugated cardboard having inside
dimensions of no less than six inches more than the
instrument dimensions; this will allow for cushioning.
Refer to the following table for carton test strength
requirements.
2. Surround the instrument with polyethylene sheeting to
protect the finish of the instrument.
3. Cushion the instrument on all sides by tightly packing
dunnage or urethane foam between carton and instru-
ment, allowing three inches on all sides.
4. Seal carton with shipping tape or industrial stapler
SHIPPING CARTON TEST STRENGTH
Gross Weight (Ib) Carton Test Strength (Ib)
0-10 200
10-30 275
30-120 375
Fig. 4-1. Inductor ("T" coil) replacement.
4-4 REV. A, AUG. 1976
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Section 5-7/1\19
CALIBRATION
Introduction
TEST EQUIPMENT REQUIRED
'To assure instrument accuracy, check the calibration of
the 7A19 every
1000 hours of operation or every six
months if used infrequently. Before complete calibration,
thoroughly clean and inspect this instrument as outlined in
the Maintenance section.
TE KTRON IX Field Service
Tektronix, Inc., provides complete instrument repair and
recalibration service at local Field Service Centers and the
Factory Service Center. Contact your local field office or
representativefor further information.
Performance Check
General
The following test equipment and accessories, or its
equivalent, is required for complete calibration of the
7A19. Specifications given for the test equipment are the
minimum necessary for accurate calibration. "l'herefore, the
specifications of any test equipment used must meet or
exceed the listed specifications. All test equipment is
assumed to be correctly calibrated and operating within the
listed specifications. Detailed operating instructions for the
test equipment are notgiven inthis procedure. Refer to the
instruction manual for the test equipment if more infor-
mation is needed.
Special Calibration Fixtures
The performance of this instrument can be checked by Special TEKTRONIX calibration fixtures are used in this
performing only the
d CHECK steps. Performing the steps procedure only where they facilitate instrument calibration.
marked with a
4 indicates that the instrument is checked These special calibration fixtures are available from
against the tolerances listed as a Performance Requirement Tektronix, Inc. Order by part number through your local
(see Specification section). TEKTRONIX Field Officeor representative.
Limits and tolerances given in other check steps are
calibration guides and should not be interpreted as instru-
ment specifications. Operator front-panel adjustments are
Calibration Equipment Alternatives
adjusted as part of the Performance Check procedure.
Calibration
To verify proper calibration of the 7A19 and to prevent
unnecessary re-calibration of the entire instrument, perform
the Adjust- portion of a step only if the tolerance given in
the Check-part of the slep
is not met.
For best overall instrument performance when per-
forming a complete calibration procedure, make each
adjustment to the exact setting even if the Check-
is within
allowable tolerance.
All of the listed test equipment
is required to completely
check and adjust this instrument. The Calibration pro-
cedure
is based on the first item of equipment given as an
example of applicable equipment. When other equipment is
substituted, control settings or calibration setup may need
to be altered slightly to meet the requirements of the
substitute equipment. If the exact item of test equipment
given as an example in the lest Equipment list is not
available, first check the Specifications column carefully to
see if any other equipment is available which might suffice.
-
I hen check the Usage column to see what this item of test
equipment is used for. If used for a check or adjustment
which is of little or no importance to your measurement
requirements, the item and corresponding step(s) can be
deleted.
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Test Equipment
1. Calibration
Oscilloscope TEKIRONIX
7000-Series 500 MHz
1 bandwidth required for
1 complete procedure. I
Used throughout the a. TEK I HONIX 7904 oscilloscope.
procedures to provide
,
display.
I
1
sweep rate required for / sweep.
1
2. Time Base Plug-
In Unit
3. Vertical Plug-In
Unit
complete procedure.
-
2TEKTRONIX 7A-Series
vertical plug-in unit.
Dual trace with 500,uV
per division sensitivity
~TEKTRONIX 75-Series
time base unit. 0.5 ns
1 required.
I
4. Standard Amplitude j~m~litudeaccuracy
Calibrator
' within 0.25%; range,
60 mV to 2 V into
50
a; frequency,
1kHz.
-- --
5. Constant frequency,
Signal Generator less than 10MHz;
Used throughout
procedure to provide
22 Dual Trace
(step 3) and Input
ResistanceAdjust.
1
a. TEKTHONIX 7B92A Time Base unit.
amplitude accuracy, 9).
within 1% of reference
frequency; frequency
range, to 500 MHz;
amp litude range,
80 mV to
8 V into
b. Wavetek 1002 SweepISignal Gener-
ator.
U
s e d f o r G A l N
CheckIAdjust only
c. General Radio 1362 UHF oscillator
with 1263-C Amplitude Regulating
supply.
--
- -- -
for Reflection a. TEKTRONIX 7S12 I UHISAMPLER
a. iektronix PG 506 Calibration Gen-
erator,'
Reflectometer
1 350 ps +35 ps; pulse Coefficient Check only plug-in unit with S-I sampling head and
(step6).
'1 amplitude, 200 mV. 1 (step 10). 1 S-52 Pulse Generator head. (This system
Sensitivity, to 100 mp.
is to be used with the Calibration
I Oscilloscope.)
--- ---
7. Differental Sampling System rise time, at
' Used for Rise Time and 1 a. Use the Time Domain Reflectometer
System
1 least 350 ps; pulse Aberration Check1 system with the addition of a 7Sll
! amplitude, 200 mV; 1 Adjust only (Step 8). vertical sampling plug-in and a S-l
I Input, differential;
1 sensitivity, 50 mV1div. sampling head.
ACCESSORIES
8. Cable Impedance, 50 ohms;
length, 42 inches; Used throughout
a. If KIHONlX Part No. 012-0057-01
procedures for signal
1
connectors, BNC. connections.
9. GR Cable
15%; length, 10 inches; connections during 1
connectors, GR. refleciion coeff~cient
and HF aberrations.
--- - - - 1
' Requires TM 500 - Series Power Module
5-2
REV. A, MAR. 1978
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Calibration-7A19
'Test Equipment (cont)
Description Minimum Specifications Usage Examplesof Applicable
Test Equipment
---- * - - -
--- - - - -
- -- - - - -
a. TEKTRONIX Part No. 017-0515-00.
- -- - --
- *
Impedance, 50 ohms
*5%; length, 20 inches;
connectors,
G R.
Used during reflection
coefficient check for
signal connection.
10. GR Cable
11. Adapter
12. Adapter
BNC male to GR. Used throughout pro- a. TEKTHONIX Part No. 017-0064-00.
cedures.
13. Adapter
BNC female to
GR.
--
BNC female to B
Used throughout pro-
cedures.
P
BNC "'T".
I female. I mode checkladjust. I
a. TEKTRONlX Part No. 017-0063-00.
15. Adapter
Used for common
mode checkladjust.
I SMA (3-mm) male to I Used for reflection co- 1 a. TEKTRONIX Part No. 015-1007-00.
a. TEKTRONIX Part No. 103-0030-00.
I GR. 1 efficient and risetime 1
Divider
................... ....
17,. 1OX Attenuator ance, 50 ohms;
and aberrations.
- - ----
Used for reflection co-
efflcient check.
"- -
Used for frequency re-
-- - - - - - -.
a. TEKTHONIX Part No. 017-0082-00.
- - - - -- -
a. TEKTRONIX Part No. 017-0078-00.
18. Plug-in Extender
I
Rigid plug-in extender
for 7000-Serles plug-
ins.
. -
Flexible plug-in ex-
tender for 7000-Ser~es
plug-ins.
accuracy,
+2%; con-
nectors, G R.
Used throughout pro-
cedures.
sponse check.
a. TEKT
RON lX Part No. 067-0589-00.
19. Plug-in Extender Used for risetime and
aberrations check/
adjust.
......
a. TEKTHONIX Part No. 067-0616-00.
20. Signal Pick-off
with GR adapters Signal pick-off connects
to the rear connector of
7000-Series vertical
amplifiers for gaining
access to signal and
trigger lines.
Used for common
mode check/adjust,
HF
aberration check and
adjust.
a. TEKTRONIX Part No. 067-0655-00.
CALIBRATION PROCEDURE
POSITION). Internal adjustments and associated
equipment conlrols are initially capitalized only (e.g.,
oscilloscope Vertical Mode).
General
The following procedure IS arranged so that the 7A19
can be cal~bratedwitti the least interaction of adjustments
and re-connection of equipment. The control settings and
test equipment setup throughout this procedure contlnue
from the preceding step(s) unless otherwise noted. Refer to
Fig. 5-1for locatlon of adjustments.
NOTE
Control titles which are printed on the
front panel of
the
7A 19 are capitalized in this procedure (e.g.,
Preliminary Procedurefor Calibration
1. Removethe side panels of the plug-in.
2. Insert 7A19 with plug-in extender in the calibration
oscilloscope left vertical compartment.
3. Insert the time-base unit in the calibration oscillo-
scope B Horizontal compartment.
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