Tektronix FG 5010 User Manual

П
C
C
n
П
П
n
1
n
n
·
П
П
П
7
П
C
C
( default frequency ) . In the Cal mode , the automatic switch
ing for the
voltage
controlled
oscillators
and
the low pass
filters
are
disabled .
Make
certain
the
CONT
pushbutton light
in the MODE group is illuminated . Connect an external
squarewave
generator to the TRIG
/ GATE IN
connector . Set
the output
amplitude
of the
generator within the
triggering
range of the FG 5010 and the frequency less than 500 Hz or
greater
than 2
kHz . Set the
generator
for a
squarewave out
put .
Remove the
shield
over Q1830 on the
Loop
2
board
,
place the board on an extender , and connect the oscillo
scope probe to the collector of Q1830 . This is the charge
pump output . The waveform visible on the oscilloscope
should be a
steady dc
voltage ,
either
approximately
+1.44 V or
−0.56 V (
+1 V
or
-1 V
centered
around
+0.44
V
) .
This dc
voltage
exists
for
large
frequency
differ
ences between the external generator and 1 kHz . As the
frequency
difference
decreases
the
signal
changes from a
dc level
to a
varying period
pulse
waveform . The
polarity
depends
on
whether
the
external generator is above or
be
low 1
kHz . As
the
external
generator
approaches the 1
kHz
frequency , the steady dc voltage changes to a +0.44 V
+1 V or
-1 V
pulse
waveform . The
duty
cycle
of
this
waveform
decreases
until the
frequencies are
equal
.
This
is
indicated on
the
oscilloscope
by
a
very low
duty
cycle
posi
tive and negative - going pulse waveform . As the external
generator is varied in the opposite direction ,
away
from
the
1 kHz frequency , the duty cycle of the waveform increases
until
a
steady dc
voltage is
again
present .
To
check
the low
pass
filter
,
move
the
oscilloscope
probe
to pin
8 of
U1820C .
The voltage at
this
point
should
vary
from
approximately
+1 V
to
+10 V
when the
input frequen
REV JAN
1982
Maintenance - FG 5010
cy moves from below to above 1 kHz . Operation of the over
and underrange detectors may be checked by connecting
the oscilloscope probe to U1820D pin 1 for the underrange
and pin 7 for the output of the overrange detector . The
overrange signal should be high when the external gener
ator frequency is above 2.5 kHz . Below about 2 kHz , it
should be low .
The
underrange signal should
be high with an
input frequency below about 180 Hz and low when the input
frequency is raised
above about
200 Hz .
Troubleshooting the frequency control circuits can also
be
done in the
Cal
mode
. In
the Cal
mode the
processor
can
take readings at the operating frequency , but will not correct
the frequency . This allows checking the operation of the fre
quency
control
logic
and
counters
without
frequency
adjust
ment by the processor . In the Cal mode , and with any mode
except
PH
LOCK
selected
, the
processor will
repeatedly ini
tiate measurements if the ± SLOPE button is not illuminat
ed .
When +
SLOPE is
selected , the
measurement
is
initiated only
when the
TRIGGER
MAN button is
depressed .
Each time
this
measurement is
completed
the
data from
the
loop cycle counter is displayed on the front panel . This data
is
useful to
determine if
the
counters
are
operating
properly .
Depress the ID
button
to
clear this
number
from the
display .
If
the
VCF
button is
pressed ,
the
actual
frequency
of
the
FG 5010 can
be varied
up to 1000
to 1 while
data to the
loop cycle counter is unchanged . If the TRIG or BURST
modes are
used for
these tests , the
processor
initiates
mea
surements first ,
and
triggers
Loop
1 or
Loop
2
frequency
generating
circuits
second .
7-15

Tektronix FG 5010 Specifications

General

Brand	Tektronix
Model	FG 5010
Category	Portable Generator
Language	English