6.1
FACTORY REPAIR
Wavetek maintains a factory repair
department
for those
customers
not
possessing the necessary
personnel
or
test
equipment
to
maintain
the
instrument. If
an instrument
is
returned
to
the
factory for calibration
or
repair, a
detailed
description
of
the
specific problem
should
be
attached
to
minimize
turnaround
time.
6.2
TROUBLESHOOTING
CHART
·Troubleshooting charts are given
in
figures
6-1
thru
6-4.
The charts
do
not
cover every possible
trouble,
but
will
be
an aid
in
systematically
isolating
faulty components.
Figure 6-1.
Initial Checks
Figure 6-2. Generator Mode
Checks
Sheet
1 Generator
Check
Sheet
2 Generator Loop Check
Sbeet
3
VCG
Check
GCV
Check
TTL
Check
Figure 6-3. Power Supply Checks
Figure
6-4.
Synthesizer Mode Checks
Sheet
1 F
N Check
Sheet
2 Synthesizer Loop
Checks
Sheet
3 Synthesizer Loop Checks
_Sheet
4
Frequency
Ranging
Check
Sheet
5 Generator Phase Lock Loop
Check
Sheet
6 Reference Selector Check
6.3
TROUBLESHOOTING
INDIVIDUAL
COMPONENTS
6.3.1
1.
Transistor
A transistor
is
defective
if
more than one
volt
is
mea-
sured across its base
emitter
junction
in
the forward
direction.
2.
3.
4.
5.
SECTION
6
TROUBLESHOOTING
A transistor when used
as
a switch may have a few
volts
reverse bias voltage.
If the
collector and
emitter
voltages
are
the
same,
but
the base
emitter
voltage
is
less than
500
inV forward
voltage (or reversed bias),
the
transistor
is
defective.
A transistor
is
defective if its base
current
is
larger than
10%
of
its
emitter
current
(calculate
currents from
voltage across
the
base and
emitter
series resistors).
In
a transistor differential pair (common
emitter
stages),
either
their base voltages are the same
in
normal operating condition,
or
the
one with less
forward voltage across its base
emitter
junction should
be
off
(no collector current); otherwise, one
of
the
transistors
is
defective.
6.3.2
Diode
1. A diode
is
defective if there
is
greater than one volt
(typically
0.7 volt) forward voltage across it.
6.3.3 Operational
Amplifier
(e.g.,
UA741C,
LM318)
1.
The
"+"
and
"-"
inputs
of
an operational amplifier
will
have less than 15 mV voltage difference when
operating under normal conditions.
2.
If
the
output
voltage stays
at
maximum positive, its
"+"
input
voltage should
be
more positive than its
"-"
input
voltage,
or
vice versa; otherwise, the
operational amplifier
is
defective.
6.3.4 Capacitor
1.
Shorted capacitors have zero volts across their
termi-
nals.
2.
Opened capacitor can
be
located
(but
not
always) by
using a good capacitor connected
in
parallel
with the
capacitor
undertestand
observing the resulting effect.
6-1
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