Tektronix TM 503 User manual

INSTRUCTION
MI ANIUOAL
Serial Number
Tektronix, Inc. -@ P.O. Box 500 -@ Beaverton, Oregon 97005 -@ Phone: [phone] -@ Cables: Tektronix
070-1305-00 572

e Warranted against
rkmanship for one year. Any =
and price change privileges reserved.
Copyright © 1972 by Tektronix, Inc:, Beaverton; Oregon.
Printed: in the United States of America: Alt-rights reserved.
Contents of this publication may. not be reproduced in any
form without permission of Tektronix, Inc.

TM 503
TABLE OF CONTENTS
Page
INSTALLATION PROCEDURE 1
OPERATING INSTRUCTIONS 4,
POWERING UP 4
BUILDING A SYSTEM 6
SPECIFICATIONS 7
SYSTEM MAINTENANCE 8
GENERAL 8
TROUBLESHOOTING AIDS 9
TROUBLESHOOTING TECHNIQUES 9
PARTS
ORDERING
AND
REPLACEMENT
1
OPTION INFORMATION 15
SERVICE INFORMATION 18
INTERFACE PIN ASSIGNMENTS 19
DETAILED BLOCK DIAGRAM 19
PARTS LOCATION GRID 20
ELECTRICAL PARTS LIST 21
POWER SUPPLY >
MECHANICAL PARTS LIST 24
EXPLODED VIEW DRAWING
REV. C, MAY, 1976 i

TM 503
INSTALLATION PROCEDURE
Before you start...
1. Check the rear panel markings. If the factory settings are compatible with the available line voltage and frequency, insert
the desired plug-ins. Use the bail to raise the front of the instrument.
-.-g0 to Operating Instructions...
2. if a change is needed, follow these steps:
a. Line Selector Block(s)
Remove the five hold-down screws on the top of the dust cover cabinet and lift the cabinet off. This gives easy access
to the Line Selector blocks located on the main circuit board.
In-service
@ athe instrument can be
ig damaged by using the
4120 V Line Sefector block
with a 220 V nominal tine
oltage.
1 REV. JULY 1974 ®

b. Line Range Taps
TM 503
Universal Transformer (SN BO50000 - up)
Line
Selector
Block
Position
120-Volts Nominat
Regulating Ranges
220-V olts Nominal
90 VAC to 110 VAC
180 VAC to 220 VAC
99 VAC to 121 VAC
198 VAC to 242 VAC
108 VAC to 132 VAC 216 VAC to 264 VAC
Line Fuse
Data
1.6 A slow-biow
0.8 A slow-blow
Standard Transformer (SN BO50000 - below)
CAUTION. BRRELROUS URE PUTERTIALS,
ARE PRESENT GH SHS ROARS.
Line Selector
Block Position
Regulating Ranges
L Do not use
Internally Disconnected
M(i10V
H (120 V Nominal)
c. Rear Panel
220 Volts
& & slow-blow
ae
ete
\/
Line Fuses
420 Volts
1.6 A slow-blow
3. Replace the cabinet,
Nominal)
99 VAC to 121 VAC
408 VAC to 132 VAC
4.
{f
necessary,
change
the
line
cord
power
plug
to
match
the
power
source
receptacle
or
use
an
adapter.
5. Plug the cord into the power source.
6. Insert the desired plug-ins.
7. Use the bail to raise the front of the instrument.
REV. 0, SEPT. 1974
..go
to
Operating
Instructions...

£1306-01
TM 503 Power Module with plug-ins.
3
REV
8,
JUN
1978

TM 503
OPERATING
INSTRUCTIONS
INTRODUCTION
Description
The TEKTRONIX TM 503 Power Module is a three-
compartment-wide mainframe for the TM 500 Series of
Modular instrumentation, It accepts up to three independ-
ently functional plug-in modules to form a compact,
versatile and low cost instrumentation system. The TM 503
is a basic power source and provides an interconnecting
scheme for the other members of the TM 500 Series family.
Factory options allow customer modification using signal
access at the plug-in module/power module interface to
provide rear panel inputs and outputs, and interconnections
between compartments.
Power Source
This
instrument
is
designed
to
operate
from
a
power
source
with
its
neutral
at
or
near
earth
(ground)
potential
with
a
separate
safety-earth
conductor.
It
is
not
intended
for
operation
from
two
phases
of
a
multi-phase
system,
or
across
the
legs
of
a
single-phase,
three-wire
system.
Power Usage
With three plug-in modules installed, the TM 503 can
require up to 120 W of power at the upper limits of the
high fine voltage ranges. Actual power consumption
depends on the particular module combination and
operating mode selected at any one time.
Operating Temperatures
The TM 503 can be operated in an ambient air
temperature of O°C to +60°C. Thermal cutout devices
protect the system by disconnecting the power to the TM
503 Power Module when internal temperatures rise above a
safe operating level. These devices automatically return
power to the unit when the internal temperatures return to
a safe level.
Since the TM 503 can be stored in temperatures between
—40°C and +75°C, allow the instrument's chassis to return
to within the operating limits before applying power.
POWERING UP
Plug-in Modules
it is not necessary that all the plug-in compartments be
utilized in order to operate the Power Module. The only
modules needed are those necessary to accomplish the task.
CAUTION
re PPPS
LARA)
Turn the Power Module off before inserting the plug-
in; otherwise, damage may occur to the plug-in
circuitry.
Module Installation
1. Check the location of the white plastic barriers on the
interconnecting jack to insure that their locations match
the slots in the edge of the plug-in module’s circuit board.
REV. B, JAN. 1975
2. Align the plug-in module chassis with the upper and
lower guides of the selected compartment. Push the module
in and press firmly to seat the circuit board in the
interconnecting jack. (Remove the plug-in module by
pulling on the white release latch located in the lower left
corner of each module.)
3, Pull the PWR button on the left side of the TM 503.
Some plug-in modules have independent power switches,
usually labeled OUTPUT, controlling application of main-
frame power to the module itself. Push this button to
activate the plug-in module.
Loading Considerations
With three plug-in modules installed, the TM 503 can
require
up
to
120
W
of
power
from
the
fine
at
high-line

Operating Instructions—TM 503
voltage range settings. Actual power consumed, of course,
depends on the particular module combination selected at
any one time.
This power capability can best be utilized by carefully
planning the functional combinations of plug-ins, their
external joads, and the resulting power distributions.
Optimum conditions would be (1} equal loads in all three
compartments, {2} as much power as possible dissipated in
external loads, and (3) operating in an ambient temperature
around +25°C.
The TM 503 provides each plug-in module with access to
a pair of heat-sinked, chassis-mounted transistors, one NPN
and one PNP. These Series-Pass transistors allow the plug-in
modules to operate in power ranges not possible if the
power had to be dissipated in the modules themselves.

Operating Instructions—TM 503
BUILDING A SYSTEM
Family Compatibility
Mechanically, the plug-in modules are very similar to
other TEKTRONIX product families. However, they are
not electrically compatible. Therefore, the TM 503 inter-
face has barriers on the mating connectors between pins 6
and 7 to insure that incompatible plug-ins cannot be
inserted. See Figure 1. A compatible module will have a
matching slot between pins 6 and 7 of its main circuit
board edge connector. This slot and barrier combination is
the primary keying assignment.
Another
modules
identifier for TM 500-compatible plug-in
is the white color of the release latch.
Customizing the Interface
The modularity of this instrumentation system provides
for a host of functions to be performed by the plug-in
modules. Specific functions are grouped into families or
classes, of which there may be several plug-in module
SIGNAL SOURCE
FAMILY KEY
MEASUREMENT
FAMILY KEY
members, For instance, some classes are Power Supplies,
Signal Sources, Measurement and so forth. Each modular
member of a functional family will have a second slot
peculiar to its family assignment located in its edge
connector. The TM 503 user can “program” one or more
compartments to accept only members of that family by
installing a second barrier in the interface connector to
match the module's stot location. Entire TM 503’s could be
“programmed” in this manner to set up instrumentation
systems for specific work functions. For extra barriers
order TEKTRONIX Part Number 214-1593-02.
a
Jumper wires can be used to further specialize the
interface. Compartments can be made to ‘talk’ to each
other by connecting jumpers on the back side of the
interface board, using pins 14 through 28, A-side and B-side
both, of the interconnecting jacks. See the following
description of catalog Option 2. Refer to each plug-in
module’s Manual for the 1/O assignments of each pin at the
rear interface. Once having made interconnections of a
specialized nature, it is recommended that barriers be
installed on the interconnecting jacks to insure module
compatibility with the customized wiring.
POWER SUPPLY
FAMILY KEY
TM 500
FAMILY KEYING
1B
Figure 1. Keying assignments for family functions, One of many possible sequence combinations,

Operating Instructions-TM 503
Rear Panei
The rear sub-panel is punched for BNC and multi-pin
connector mountings, Customer- or factory-installed
connectors and wiring {see following description of catalog
Option 2} could provide external access to the interface for
external I/O control. This feature makes the TM 500 Series
Modular Instrumentation System very flexible in bench-top
or rackmounted systems.
Option 2. This factory-installed option adds 25-mil
squarepin connectors to the rear of the interconnecting
jacks at all pin locations from pins 14A and B through pins
28A.and B. This will keep the interface flexible by making
it easy and fast to change customized wiring using prepared
wires with squarepin receptacles and long-nose pliers or
tweezers. {t also protects the circuit board from damage by
repeated soldering and unsoldering of jumper wires, This
option also adds three BNC connectors and one 50-pin
connector to the rear panel. These connectors are not
pre-wired in order to give a system designer as much
flexibility as possible. Instead, prepared jumpers, coax
cables, and interconnection jack barriers are included in a
kit.
Stacking and Rackmounting
TM 503‘s with their cabinets and feet in place may be
stacked on top of each other. The feet provide clearance for
the lower unit’s handle and at the same time give adequate
spacing for the necessary ventilation,
The TM 503 is designed to be half-rack width. Field
conversion kits with slide-out tracks are available to mount
one or two TM 503’s in a standard 19-inch rack, Vertical
space
needed
is
5
1/4
inches.
i
For the necessary hardware and instructions to mount
two TM 503’s side-by-side with slide-out assemblies, order
TEKTRONIX Part Number 040-0616-01.
To mount a single TM 503 with a half-rack assembly and
slide-out tracks, order TEKTRONIX Part Number
040-6617-01.
To convert from a rackmount to a bench configuration
for a single TM 503, order TEKTRONIX Part Number
040-0618-01.
SPECIFICATIONS
Power Requirements
Line Voltage Ranges. Universal Transformer: 100, 110,
120, 200, 220, 240 VAC, all within 10%. Range changing
for
transformer
accomplished
with
quick-change
line-
selector block.
Line Frequency Ranges. Universal Transformer: 48 Hz
to 440 Hz.
Power Consumption. Maximum primary power approxi-
mately 120 W at high line. Actual power consumption
depends on plug-in selection and operating modes.
Power Cord Conductor Identification
Conductor Color Alternate Color
Ungrounded {Line} Brown Black
Grounded (Neutral) Blue White
Grounding (Earthing) | Green-Yellow Green-Yellow
Supplies (Unregulated)
Two 25 VAC windings, 500 mA each, supplied to each
compartment, independently. 719 Jo, f5 ip SB/L
+33.5 V and —33.5 V, 1 A maximum each supply, shared | |
by all compartments. 2374900 34.7
47.5 VAC and +11.5 V, 3.6 A maximum, shared in any
combination between these two supplies and shared among
all compartments.
se dé Bleu 2 3el*
jesse 4 Fox FO Io NOTE gst
Current and voltage ratings are for main frame
maintenance only. in practice, not all available power
may be used at once, More detailed information is
supplied with kit 040-0652-02 (TM 500-plug-in}.
Temperature Range
Operating: O°C to +50°C. Nonoperating: ~—40°C to
+75°C,
Altitude Range
Operating: To 15,000 feet. Nonoperating: To 50,000
feet.
Other
Dimensions with Feet and Bail:
16.3 in.
H 6.0 in., W 8.7 in, L
Weight without Plug-ins: Approximately 9.5 Ib.
7
REV. F. JAN. 1977

TM 503
SYSTEM
MAINTENANCE
GENERAL
Introduction
This section of the manual is meant to support the entire
TM 500 Series family of modules with a general coverage of
the most commonly-needed service information pertinent
to preventive maintenance, troubleshooting, ordering parts,
and replacing components and sub-assemblies.
Cabinet Removai
WARKING
Dangerous potentials exist at several points through-
out the system. When the system must be operated
with the cabinet removed, do not touch exposed
connections or components. Some transistors have
voltages present on their cases. Disconnect power
before cleaning the system or replacing parts.
Two screws on the top secure the cabinet to the TM
503 frame. Remove them and lift the cabinet straight up.
Do not operate the system with the cabinet removed any
longer than necessary for troubleshooting and calibration.
Re-install the cabinet to protect the interior from dust and
to remove personnel shock hazards,
Cleaning
pee
> CAUTION i
thal
Avoid using chemical cleaning agents which might
damage plastic parts. Avoid chemicals containing
benzene, toluene, zylene, acetone, or similar solvents.
Exterior. Loose dust may be removed with a soft cloth
or a dry brush. Water and a mild detergent may be used;
however, abrasive cleaners should not be used.
Interior. Cleaning the interior of a unit should precede
calibration since the cleaning processes could alter the
settings of calibration adjustments. Use jow-velocity
compressed air to blow off accumulated dust. Hardened
dirt can be removed with a soft, dry brush, cotton-tipped
swab, or a cloth dampened in a solution of water and mild
detergent.
Preventive Maintenance
Preventive maintenance steps performed on a regular
basis will enhance the reliability of the instrumentation
system. However, periodic checks of the semiconductors in
the absence of a malfunction are not recommended as
preventive maintenance measures. See the semiconductor
checking information under Troubleshooting Techniques
which follow. A convenient time to perform preventive
maintenance is just before instrument calibration.
Calibration
To insure accurate signal generation and measurement,
the performance of individual units comprising the system
should be checked periodically. Refer to the Instruction
Manual for each unit for complete calibration and verifica-
tion procedures,

System Maintenance--TM 503
TROUBLESHOOTING AIDS
Introduction
The following is provided to augment information
contained elsewhere in this and other TM 500 Series family
manuals when troubleshooting becomes necessary.
Circuit Descriptions
Each manual has a section devoted to explaining circuit
operating theory. Used conjointly with the schematics, this
can be a powerful analytic tool.
Diagrams
Block diagrams and detailed circuit schematics are
located on foldout pages in the service section of most of
the TM 500 Series family manuals, The schematic diagrams
show the component values and assigned circuit reference
numbers of each part necessary to the circuit design.
Usually the first page of the service sections defines the
circuit symbols and reference designators used in that
particular instrument, Major circuits are usually identifi-
able by a series of component numbers. Important wave-
forms
and voltages may be shown within the diagrams or on
adjoining aprons. Those portions of the circuits located on
circuit boards are enclosed with a blue tint outline.
Cam Switch Charts
Cam switches shown on the diagrams are coded on
comprehensive charts to locate the cam number of the
switch contact in the complete switch assembly, counting
from the front, or knob end, toward the rear of the switch,
The charts also indicate with a solid dot when each contact
is closed.
Circuit Board Hlustrations
Line Hlustrations showing component locations keyed
with a grid scheme for each circuit board are usually placed
on the back of a foldout page and sequenced as close as
possible to an associated schematic. The GRID LOC
column in the Electrical Parts Lists keys each component to
the Location illustrations.
Component and Wiring Color Codes
Colored stripes or dets on electrical components signify
electrical values, tolerances, etc., according to EIA
standards. Components not color-coded usually have
information printed on the body. The wiring coding follows
the same EIA standards.
Testing Equipment
Generally, a wide-band oscilloscope, a probe, and a
multimeter are all that is needed to perform basic waveform
and voltage checks for diagnostic purposes. The calibration
procedures in the manual for each plug-in module list
specific test equipment and the features necessary to
adequately check out that particular module.
TROUBLESHOOTING TECHNIQUES
Introduction
This troubleshooting procedure is arranged in an order
which checks the simple trouble possibilities before pro-
ceeding to extensive troubleshooting.
Control Settings
Incorrect control settings can indicate a trouble that does
not exist. {f there is any question about the correct
function or operation of any control, see the Operating
Instructions section of the manual for the instrument
involved,
System and Associated Equipment
Before proceeding with troubleshooting the TM 500
Series system, check that the instruments in the system are
operating correctly. Check for proper interconnection
between the power module and the plug-in modules. Check
the line voltage at the power source. Check that the signal is
properly connected and that the interconnecting cables and
the signal source are not defective.
The associated plug-in modules can be checked for
proper operation quickly by substituting other like units
REV.B, AUG, 1976

known to be operating properly. !f the trouble persists after
substitution, then the power module is probably at fault.
Moving a properly operating plug-in from compartment to
compartment will help determine if one or more compart-
ments has a problem,
Visual Check
Inspect the portion of the system in which the trouble is
suspected. Many troubles can be located by visual clues
such as unsoldered connections, broken wires, damaged
circuit boards, damaged components, etc.
Instrument Calibration
Check the calibration of the suspected plug-in module or
the affected circuit if the trouble is obviously in a certain
circuit. The trouble may only be a result of misadjustment
or may be corrected by re-calibration. Complete calibration
instructions are given in the manual for each instrument in
the system.
Circuit Isolation
Note the symptom. it often identifies the circuit in
which the trouble is located. When trouble symptoms
appear in more than one circuit, check the affected circuits
by making waveform and voltage measurements.
Incorrect operation of alf circuits often means trouble in
the power supplies. Using a multimeter, check first for
correct voltages of the individual regulated supplies
according to the plug-in module schematics and calibration
procedures, Then check the unregulated supplies of the
power modules. Defective components elsewhere in the
instruments can appear as power supply problems. In these
instances, suspected circuits should be disconnected from
apparently bad power supplies one at a time to narrow the
search.
Voltages and Waveforms
Often defective components can be located by using
waveform and voltage indications when they appear on the
schematic or in the calibration procedures. Such waveforms
and voltage labels are typical indications and will vary
between instruments. To obtain operating conditions
similar to those used to take these readings, refer to the
first diagram in the service sections.
Component Checking
'f
a
component
cannot
be
disconnected
from
its
circuit,
then
the
effects
of
the
associated
circuitry
must
be
considered
when
evaluating
the
measurement.
Except
for
soldered
in
transistors
and
integrated
circuits,
most
compo-
nents
can
be
lifted
at
one
end
from
the
circuit
board.
®
System Maintenance—TM 503
Transistors and [C’s. Turn the power switch off before
removing or replacing any semiconductor.
A good check of transistor operation is actual perform-
ance under operating conditions. A transistor can most
effectively be checked by substituting a new component for
it (or one which has been checked previously). However, be
sure that circuit conditions are not such that a replacement
transistor might also be damaged. {f substitute transistors
are not available, use a dynamic tester. Static-type testers
are not recommended, since they do not check operation
under simulated operating conditions. A suction-type
desoldering tool must be used to remove soldered-in
transistors; see component replacement procedure for
details.
Integrated circuits can be checked with a voltmeter, test
oscilloscope, or by direct substitution. A good under-
standing of the circuit description is essential to trouble-
shooting circuits using IC’s, Operating waveforms, logic
levels, and other operating information for the IC’s are
given in the circuit description information of the appro-
priate manual. Use care when checking voltages and
waveforms around the IC’s so that adjacent leads are not
shorted together. A convenient means of clipping a test
probe to the 14- and 16-pin in-line [C’s is with an
integrated-circuit test clip. This device also doubles as an
extraction tool.
Diodes. Do not use an ohmmeter that has a high internal
current, High currents may damage the diode.
A diode may be checked for an open or shorted
condition by measuring the resistance between terminals.
With an ohmmeter scale having an internal source of
between 800 mV and 3V, the resistance should be very
high in one direction and very low when the leads are
reversed.
Resistors. Check the resistors with an ohmmeter, Resis-
tor tolerances are given in the Electrical Parts List in every
manual. Resistors do not normally need to be replaced
unless the measured value varies widely from the specified
value,
Capacitors. A leaky or shorted capacitor can be detected
by checking resistance with an ohmmeter on the highest
scale. Use an ohmmeter which will not exceed the voltage
rating of the capacitor. The resistance reading should be
high after initial charge of the capacitor. An open capacitor
can best be detected with a capacity meter, or by checking
whether it passes AC signals.
10

System Maintenance—TM 503
PARTS
ORDERING
AND
REPLACING
Ordering
Standard Parts. All electrical and mechanical replacement
parts
can
be
obtained
through
the
local
TEKTRONIX
Field
Office or representative. However, many of the standard
electronic components can be obtained locally in less time
than is required to order them from Tektronix, Inc. Before
purchasing or ordering replacement parts, check the Parts
Lists for value, tolerance, rating, and description. When
selecting
replacement
parts,
it is
important
to
remember
that the physical size and shape of the component may
affect its performance in an instrument. All replacement
parts should be direct replacements unless it Is known that
a different component will not adversely affect the instru-
ment performance.
Special
Parts.
Some
parts
are
manufactured
or
selected
by
Tektronix,
Inc.,
to
satisfy
particular
requirements,
or
are
manufactured
for
Tektronix,
Inc.,
to
our
specifications.
Most
of
the
mechanical
parts
used
in
this
system
have
been
manufactured
by
Tektronix,
Inc.
Order
all
special
parts
directly
from
the
local
TEKTRONIX
Field
Office
or
representative.
Ordering Procedure. When ordering replacement parts
from Tektronix, Inc., please include the following mini-
mum information:
1. Instrument Type (PS 501, SG 502, DC 501, etc.)
2. Instrument Serial Number (For example, BO10250)
3. A description of the part (if electrical, include the
circuit number)
4. TEKTRONIX part number
Please do not return any instruments or parts before
receiving directions from Tektronix, Inc.
A listing of TEKTRONIX Field Offices, Service Centers,
and Representatives can be found in the TEKTRONIX
Product Catalog and Supplements.
V1
Replacing
The
exploded
view
drawings
associated
with
the
Mechanical
Parts
Lists,
located
to
the
rear
of
most
manuals,
may
be
especially
helpful
when
disassembling
or
re-
assembling
individual
components
or sub-assembles.
Circuit
Boards.
if
a
circuit
board
is
damaged
beyond
repair,
the
entire
assembly
including
all
soldered-on
com-
ponents,
can
be
replaced,
Part
numbers
are
given
in
the
mechanical
parts
lists
for
the
completely
wired
(670
prefix)
board.
To remove or replace a board, proceed as follows:
1.
Disconnect
all
leads
connected
to
the
board
(both
saidered
lead
connections
and
solderless
pin
connections},
2. Remove all screws holding the board to the chassis or
other mounting surface. Some boards may be held fast by
plastic
mounting
clips
around
the
board
edges.
For
these,
push
the
mounting
clips
away
from
the
circuit
board
edges
to free the board. Also, remove any knobs, etc., that would
prevent the board from being lifted out of the instrument.
3.
Lift
the
circuit
board
out
of
the
unit.
Do
not
force
or
bend
the
board.
4. To replace the board, reverse the order of removal.
Use care when replacing pin connectors; if forced into place
incorrectly positioned, the pin connectors may be damaged.
Transistors and iC’s. Transistors and IC’s should not be
replaced unless they are actually defective. If removed from
their sockets during routine maintenance return them to
their original sockets. Unnecessary replacement or
switching of semiconductor devices may affect the calibra-
tion of the instruments. When a transistor is replaced, check
the operation of the part of the instrument that may be
affected.
REV.C, JAN. 1975

System Maintenance—TM 503
c.f os
acre
S38
SSS
i I
ML 5 SU
Plastic-Cased Transistors
See manufacturer's “A Pint
specifications sheet (toput) Pin 2
{Gutput)
Ir = &
hs ¥ / Pin
— (Ground)
Power
Transistors
FET’s
Regulator
(C's
Heat dissipator
{may be applied
to some metal-
cased transistors)
Metal-Cased Transistors
Integrated Circuits
Figure 2. Semiconductor device lead configurations found in the TM 500 family.
Replacement semiconductors should be of the original
type or a direct replacement. Figure 2 shows the lead
configuration of the semiconductors used in this instrument
system. When removing soldered-in transistors, use a
suction-type de-soldering tool to remove the solder from
the holes in the circuit board.
An extracting too! should be used to remove the 14- and
16-pin integrated circuits to prevent damage to the pins.
This tool is available from Tektronix, Inc. Order TEK-
TRONIX Part No. 003-0619-00. If an extracting tool is not
REV.C, MAY, 1975
available, use care to avoid damaging the pins. Pull slowly
and evenly on both ends of the IC. Try to avoid having one
end of the IC disengage from the socket before the other
end.
To replace one of the power transistors mounted on the
Power Module chassis adjacent to the interface circuit
board, first unsolder the leads, Then, loosen the nuts which
clamp the transistor to the chassis. Remove the defective
transistor. When replacing the transistor, use a mica washer
on the metal tab to increase heat transfer from the
transistor to the chassis.
12

System Maintenance—TM 503
interconnecting Pins. To replace a pin which is mounted
on a circuit board, first disconnect any pin connectors.
Then,
unsolder the damaged pin and pull it out of the
board with a pair of pliers. Be careful not to damage the
wiring on the board with too much heat. Ream out the hole
in the circuit board with a 0.031-inch drill. Remove the
ferrule from the new interconnecting pin and press the new
pin into the hole in the circuit board. Position the pin in
the same manner as the old pin. If the old pin was bent at
an angle to mate with a connector, bend the new pin to
match the associated pins.
NOTE
A pin replacement kit including necessary tools,
instructions, and replacement pins is available from
Tektronix, inc. Order TEKTRONIX Part No.
040-0542-00.
Cam Switches. Repair of cam-type switches should be
undertaken only by experienced maintenance personnel.
Switch alignment and spring tension of the contacts must
be carefully maintained for proper operation of the switch.
For assistance, contact your local TEKTRONIX Field
Office or representative.
NOTE
A cam-type switch repair kit including necessary
tools, instructions, and replacement contacts is avail-
able from Tektronix, Inc. Order TEKTRONIX Part
No, 040-054 1-00.
The cam-type switches consist of rotating cam drums
which are turned by front-panel knobs, and sets of
spring-leaf contacts mounted on adjacent circuit boards.
The contacts are actuated by lobes on the cams. These
switches can be disassembled for inspection, cleaning,
repair, or replacement as follows:
1. Remove the screws which hold the metal cover on the
switch, and lift the cover off the switch. The switch is now
open for inspection or cleaning.
2. To completely remove a switch from the circuit
board, first remove any knobs or shaft extensions. Loosen
the coupling at the potentiometer at the rear of the switch,
and pull the long shaft out of the switch assembly.
3. Remove the screws (from the opposite side of the
circuit board} which hold the cam drum to the board,
4. To remove the cam drum from the front support
block, remove the retaining ring from the shaft on the front
of the switch and slide the cam drum out of the support
block. Be careful not to lose the small detent roller.
5. To replace defective switch contacts, follow the
instructions given in the switch repair kit.
6. To re-install the switch assembly, reverse the above
procedure.
Pushbutton Switches. The pushbutton switches are not
repairable and should be replaced as a unit if defective. Use
a suction-type de-soldering tool to remove solder from the
circuit board when removing these switches.
incandescent Bulbs. Most of these light bulbs are
mounted on the sub-panel using plastic sleeve stand-offs.
Unsolder the lead wires and pull the bulb out of the sleeve
from the rear of the sub-panel.
Light-Emitting Diodes. LED’s used as indicators are
mounted on the sub-panels with plastic sleeve sockets
similar to the incandescent bulb mountings or they are
soldered directly to a sub-assembly and so mounted that
they protrude through holes in the panel. fn these cases, the
sub-assembly must be exposed and the anode and cathode
lead orientations carefully noted before unsoldering the
defective LED. See Figure 3 for LED lead identifying
information.
Red-dot, cathode
Anode
Short bulb
Long bulb
Top of character
Decimal point
Bent leads
Cathode
Seven-segment character chip
Figure 3. Light-emitting diode (LED) lead orientation illustration.
13

Power Transformer, Replace the transformer only with a
TEKTRONIX direct replacement transformer, Refer to the
exploded view drawing at the rear of the Power Module
manuals for disassembly of the rear panel to expose the
power transformer. Refer to the schematic diagram color
coding information for correct wiring. After replacement,
check out the power supply voltages before installing a
plug-in module.
REPACKAGING FOR SHIPMENT
Hf the Tektronix instrument is to be shipped to a Tektronix
Service Center for service or repair, attach a tag showing:
owner (with address) and the name of an individual at your
firm that can be contacted, complete instrument serial
number and a description of the service required.
Save and re-use the package in which your instrument was
shipped. lf the original packaging is unfit for use or not
available, repackage the instrument as follows:
REV. B, AUG. 1976
System Maintenance—-TM 503
. Obtain a carton of corrugated cardboard having inside
dimensions of no less than six inches more than the
instrument dimensions; this will aflow for cushioning.
Refer to the following table for carton test strength
requirements,
protect the finish of the instrument.
. Surround the instrument with polyethylene sheeting to
Cushion the instrument on ail sides by tightly packing
dunnage or urethane foam between carton and instru-
ment, allowing three inches on all sides.
. Seal carton with shipping tape or industrial stapler.
SHIPPING CARTON TEST STRENGTH
Gross Weight (Ib)
0-10
10-30
30-120
120-140
140-160
Carton Test Strength (Ib)
200
275
375
500
600
14

Option
Information
--
TM
503
OPTION
INFORMATION
Your
instrument
may
be
equipped
with
one
or
more
options.
This
section
describes
those
options,
or
directs
the
reader
to
where
the
option
is
documented.
Pages
Option
2
Optional
Interface
Described
in
this
section
2
15