Maintenance-Type
453/R453
Interior. Dust
in
the interior of the instrument should be
removed occasionally due to
its
electrical conductivity under
high-humidity conditions.
The
best way to clean the interior
it
to blow off the accumulated dust with dry, low-velocity
air.
Remove
any dirt which remains with a soft paint brush
or a cloth dampened with a
mild
detergent and water solu-
tion. A cotton-tipped applicator
is
useful
for cleaning
in
narrow spaces or for cleaning ceramic terminal strips and
circuit boards.
The
high-voltage circuits, particularly parts located
in
the high-voltage compartment and the area surrounding the
post - deflection
anode
connedor, should receive special
attention. Excessive dirt
in
these areas may cause high-
voltage arcing and result
in
improper instrument operation.
Lubrication
General.
The
reHability of potentiometers, rotary switches
and other moving parts can be maintained
if
they
are
kept
properly lubricated.
Use
a cleaning-type lubricant (e.g.,
Tektronix Part No. 006-0218-00) on switch contacts.
Lubri-
cate switch detents with a heavier grease (e.g., Tektronix
Part No. 006-0219-00). Potentiometers which are not per-
manently sealed should be lubricated
with
a lubricant which
does not affect electrical characteristics (e.g., Tektronix Part
No. 006-0220-00).
The
pot lubricant can also be used on
shaft bushings.
Do
not over-lubricate. A lubrication
kit
con-
taining the necessary lubricants and instructions
is
available
from
Tektronix,
Inc.
Order Tektronix Part No. 003-0342-00.
Fan.
The
fan-motor bearings
are
sealed and do not
re-
quire lubrication.
Visual Inspection
The
Type
453
should be inspected occasionally for such
defects as broken connections, broken or damaged ceramic
strips, improperly seated transistors, damaged circuit boards
and heat-damaged parts.
The
corrective procedure for most visible defects
is
obvi-
ous; however, particular care
must
be taken
if
he·at-damaged
components
are
found. Overheating usually indicates other
trouble
in
the instrument; therefore,
it
is
important that the
cause of over-heating be corrected to prevent recurrence of
the damage.
Transistor Checks
Periodic checks of the transistors
in
the Type
453
are
not
recommended.
The
best check of transistor performance
is
its
actual operation
in
the instrument. More details
on
check-
ing
transistor operation
is
given under Troubleshooting.
Recalibration
To
assure accurate measurements, check the calibration of
this
instrument after each 1000 hours of operation or every
six
months
if
used infrequently.
In
addition, replacement of
components may necessitate recalibration of the affected
circuits. Complete calibration instructions
are
given
in
the
Calibration section.
The
calibration procedure can also be helpful
in
localiz-
ing cerain troubles
in
the instrument.
In
some cases, minor
4-2
troubles may be revealed
and/
or corrected by recalibra-
tion.
TROUBLESHOOTING
Introduction
The
following information
is
provided to facilitate trouble-
shooting of the Type 453. Information contained
in
other
sections of
this
manual should be used along with the
fol-
lowing information to aid
in
locating the defective compon-
ent.
An
understanding of the circuit operation
is
very help-
ful
in
locating troubles. See the Circuit Description section
for complete information.
Troubleshooting Aids
Diagrams. Circuit diagrams
are
given on foldout pages
in
Section
9.
The
component number and e·lectrical value of
each component
in
this
instrument are shown on the dia-
grams.
Each
main circuit
is
assigned a series of component
numbers. Table
4-1
lists
the main circuits
in
the Type
453
and
the series of component numbers assigned to each. Import-
ant
voltages and waveforms
are
also shown on the diagrams.
The
portions of the circuit mounted
on
circuit boards
are
enclosed with a blue line.
TABLE
4-1
Component
Numbers
c
omponen
D.
1agram
Numbers on
Number Circuit
Diagrams
1-99
1
Channel 1
Vertical
Preamp
100-199
3
Channel 2 Vertical Preamp
200-299
5
Vertical Switching
300-399
6
Vertical Output Amplifier
400-429
7
Trigger Preamp
430-499
8
A Trigger Generator
500-599
9
A Sweep Generator
600-699
10
B Trigger Generator
700-799
11
B Sweep Generator
800-899
13
Horizontal Amplifier
900-999
16
CRT
Circuit
1000-1099
15
Z
Axis
Amplifier
1100-1199
17
Power Supply and Distribution
1250-1299
18
Calibrator
Switch Wafer Identification. Switch wafers shown
on
the diagrams are coded to indicate the position of the wafer
in
the complete switch assembly.
The
numbered portion of
the code refers to the wafer number counting
from
the front,
or mounting end of the switch, toward the rear.
The
letters
F and R indicate whether the front or rear of the wafer per-
forms
the particular switching function.
For
example, a wafer
designated
2R
indicates that the rear of the second wafer
from
the front
is
used for
this
particular switching function.
Circuit
Boards.
Fig.
4-6 through 4-14 show the circuit
boards used
in
the Type 453.
Fig.
4-5 shows the location
of each board within the instrument.
Each
electrical
com-
ponent
on
the boards
is
identified by
its
circuit number.
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