HP 400D, Инструкция по эксплуатации и обслуживанию

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1) Connect a 400 cps sine wave signal to the INPUT
of the vtvm under test. Adjust signal level for a
reading of 0 . 9 0 on the 0 . 1 volt range : Adjust mon­
itor meter to establish a "reference level" on the
upper
end of a convenient range .
2) Change input signal to 4 mc and set amplitude to
"reference level". Adjust capacitor C21 in vtvm
under test for a reading of 0. 90.
3) Change input si.gna.l to 1 mc and set amplitude to
"reference level". Capacitor C26
in the
plate cirCuit
of V4 can be adjusted in value between limits of
15
f.ij.t f
and 82 l.q.Lf to control the I mc response.
If
you change C26, repeat steps
1
through 3.
4) Change input signal to 6. 4 mc and set amplitude
to "reference level".
5) The reading on the vtvm under test should not be
more than 5%
of
full scale above 0. 90. Any reading
below 0. 90 is acceptable . A high frequency peak is
undesirable at frequencies above 4 mc.
If
the reading is more than 5% high, add capacitor
C40 and resistor RS2
if
not already in the cathode
circuit of V2 in
your
vtvm. Repeat steps
I
through 5
if
these parts are added.
The values
of
R82 and C40
can
be adjusted to bring the
6. 4 mc response below the 5% maximum.
If
you
change either
R82 o r C40 in
value, repeat steps
1
through 5.
6) Change the input signal to 10 cps and set the ampli­
tude to the "reference level"
of
step 1. TIle reading on
the
vtvm
under test should be 0.90, :1:5%
of
full scale.
To increase the 10 cps indication, remove RSO
if
present in V2 grid circuit. Add RBl in V3 grid cir­
cuit
if
additional increase is needed after RaO re­
moval. Conversely, to decrease the indication, re­
move RBl and add RSO
if
necessary. Either but not
both resistors can be added. Both resistors can be
omitted. A value of 2. 2 megohms or higher should
be used for RSO or
RBI
when adjusting low frequency
response. Check tubes and coupling capacitors
if
you
find that a resistor value below 2. 2 megohms
is required.
7) Increase the input signal to about 20 cps and set
the amplitude to the "reference level"
of
step 1. The
reading on the
vtvm
under test should not be more
than :l:2% of full scale from O. 90.
If
necessary,
make
compromise resistor adjustments to satisfy steps
6 and 7.
B) Switch the vtvm unde r test to the O. Ol volt range.
Establish a new 400 cps "reference level" for this
range by setting to 0 . 9 0 on the 0 to 1 scale.
Sect.
IV
Page 9
9) Change the input signal to 4 mc and set the input
amplitude to the "reference level" established in
step 8. The reading on the vtvm under test should
be set to 0. 90 by adjusting capacitor C16.
10) Switch the vtvm under test to the 1. 0 volt range.
E stablish a new 400 cps "reference level" by setting
to 0.90 on the 1 volt range.
11) Change the input signal
to
20 kc and set the am­
plitude to
the
"reference level" established
i n
step 10.
Adjust capacitor C4 for a reading
of
O. 90.
12) Change the input signal to 4 mc and set the am­
plitude to the "reference level" established in step
10. The reading on the
vtvm
under test should not
be more than :1:2% of full scale from 0.90.
Adjust R6 in the input divider to bring the 4 mc
response within ±2%. This res istor consists
of
several parallel resistors. IncreaSing the resistance
of R6 will raise the frequency response at
4 mc.
Lowering the re sistance will decrease the 4 mc
response.
13) Switch the vtvm under test to the 3. 0 volt range .
E stablish a new 400 cps "reference level" by setting
to 0.90 on the 0 - 1 scale .
14) Change the input signal
to
4 mc and set the am­
plitude to the "reference level" established in step
13.
Adjust capaCitor
C14 to
obtain an indication
of
0.90 on the vtvm under test.
L.
FINAL CHECK & ADJUSTMENT
Repeat f'.e Basic Calibration procedures given in
paragraphs 4-7E and 4-7F.
4-8 TROUBLE SHOOTING
To assist in trouble shooting, a chart has been pre­
pared which lists various trouble symptoms, pos­
sible causes and/or remedies.
If the
cause
of
trouble
is of a more obscure nature than can be covered
by the chart, trouble can
be
located by test: first
by sectionalizing, and second by localization within
the
section by means of voltage and resistance mea­
surements. The circuit sections are indicated in
the block diagram (Figure 3-1).
1) The first step in sectionalizing is to check the
output of the regulated high-voltage supply: the dc
voltage between pin 1
of
V7 and ground shOuld mea­
sure 250 volts, ±5 volts.
H
the regulator output is not within these limits,
see paragraph 4-9.