Maintenance
—7D14
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
7D14
are color coded to facilitate tracing a wire from
one
point
to another in the unit.
substitute
a 7D14 known to be operating correctly into the
indicator
unit
and see
if the problem persists. Check
that
the
inputs are properly connected and that the intercon
necting
cables are not
defective.
3.
Visual Check.
Visually check
the portion of
the
instrument
in which the trouble is
suspected. Many troubles
can
be located by
visual indications,
such as unsoldered
connections,
broken
wires, damaged circuit boards, dam
aged
components, etc.
Semiconductor
Lead
Configuration.
Fig. 4-1 shows the
lead configuration of the semiconductor devices
used in this
instrument.
Troubleshooting
Equipment
The
following
equipment is
useful
for troubleshooting
the
7D14:
1.
Semiconductor
Tester—Some
means
of testing the
transistors, diodes,
and FET's used in this
instrument is
helpful.
A transistor-curve
tracer
such as
the Tektronix
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 are required.
3.
Test
Oscilloscope—A test oscilloscope
is required to
view
waveforms at different points in the circuit.
A Tektronix 7000-series Oscilloscope with 7D13 Digital
Multimeter unit, 7B-series Time-Base
unit,
and a 7A-series
Amplifier unit with a
10X probe will meet the needs for
items 2 and 3.
Troubleshooting
Procedure
This
troubleshooting procedure
is arranged in an
order
which
checks the simple trouble possibilities
before pro
ceeding
with extensive
troubleshooting.
1.
Check Control
Settings.
Incorrect
settings
of the
7D14 controls
can
indicate
a trouble that does not exist. If
there
is any question about the correct function or oper
ation
of a control or front-panel connector, see the Oper
ating
Instructions section.
2. Check
Associated Equipment.
Before proceeding with
troubleshooting
of the 7D14, check that
the equipment
used
with this instrument is operating correctly. If possible.
4. Check Instrument Performance.
Check the calibration
of
the unit,
or the affected circuit by performing Part I —
Performance
Check of
Section 5. The apparent trouble may
only be a
result of misadjustment and may be corrected by
calibration.
Complete calibration instructions
are given in
Part II
of
Section 5.
5.
Check
Voltages
and Waveforms.
Often
the defective
component
or stage can be located by checking for the
correct
voltage
or waveform in the circuit. Typical voltages
and
waveforms
are given on the diagrams; however,
these
are
not
absolute and may
vary slightly between instru
ments. To
obtain
operating
conditions similar to those used
to take these
readings, see the instructions
in the Diagrams
section.
6. Check
Individual Components.
The
following
methods are
provided
for checking the individual
compo
nents
in
the 7D14. Components which are soldered in place
are
best checked
by disconnecting one end
to isolate the
measurement
from the effects
of surrounding circuitry.
A. TRANSISTORS AND INTEGRATED CIRCUITS.
The
best
check of transistor and integrated
circuit opera
tion
is actual
performance under operating conditions. If a
transistor
or integrated
circuit is
suspected
of being defec
tive,
it can best be checked by substituting a component
known
to
be good; however, be sure that circuit conditions
are
not such that a replacement might
also
be damaged. If
substitute
transistors are not available, use a dynamic tester
(such
as
Tektronix Type 576). Static-type testers may be
used,
but since they do not
check operation under simu
lated
operating conditions, some defects may go unnoticed.
Fig.
4-1
shows base pin
and socket arrangements of semi
conductor devices. Be sure the power is off before attempt
ing
to remove
or replace any transistor or integrated circuit.
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
integrated circuits. Use care when
checking voltages and waveforms around the integrated cir-
4-3
Summary of Contents for 7D14
Page 4: ...7D14 ...
Page 11: ...Operating Instructions 7D14 Fig 2 1 7D14 front panel controls and connectors 2 2 ...
Page 33: ... 3 13 Fig 3 11 Logic diagram for Zero Cancel Logic stage Circuit Description 7D14 ...
Page 38: ...3 18 Fig 3 16 Time Base and Control circuit detailed block diagram Circuit Description 7D14 ...
Page 44: ...NOTES ...
Page 46: ...NJ Fig 4 1 Electrode configuration for semiconductors in this instrument I ...
Page 68: ...NOTES ...
Page 96: ... 7DI 4 DIGITAL COUNTER UNIT ...
Page 98: ...GRS 0371 BLOCK DIAGRAM ...
Page 99: ......
Page 103: ...0 0 I 200 mV 500 µs 0 001 200 mV 500 µs 0 001 MHz 00 mV E 00 µs 0 001 MHz ...
Page 106: ...1 ...
Page 110: ...A2 Logic Circuit Board Assembly jQ798i 798 jc743 CR744t uni R724 R742 JL744S FrR796 ...
Page 113: ......
Page 114: ...P 0 A2 LOGIC BOARD ...
Page 121: ... A B D t F H J NPR Tj ZWX V A AC M AEA HUM qAZ DEF HJ N P R S T J V V7X y ABM APAI AA 7DI4 ...
Page 129: ......
Page 130: ...4 7D14 DIGITAL COUNTER ...