Philips PM 6302 Instruction Manual page 37

37
3,5.2.
Adjusting procedures
3.S.2.
1.
Potentiometer
713
—
Check that the
scale
marking coincides with the left-hand stop
of
the potentiometer
—
Measure the resistance at scale
point
1
(R713/1) and
at scale
point 10 {R71 3/10)
Measuring
fault
<
1
%
(e.g.
with
PHILIPS
PM
2421 digital
multimeter)
-
With
the
measured values
713/1
and 713/10 found above,
read
out
the values for the adjusting resistors
from
table
I
(take
always
die
next higher value)
Procedure:
—
Solder a resistor
of the
found
value
for
659 into the
circuit.
Replace resistor
637 by
a resistance
decade
adjusted to the value
found.
—
From
table
I,
solder resistor
658 into the
circuit
and replace
resistor
635
by
a
resistance
decade
also
adjusted
to
the value found.
—
By
alternating
the adjustment
of scale
points
1
and 10
in
range xl
kfi,
the definitive
values for resistors
635
and
637
can be determined.
Scale point
1
must
be
adjusted
with
a
sample of
1
kfi
±1
%.
,
while
scale
point
10 must be adjusted with a
10 k£2
±
1
%»
sample.
3.5.22.
Reference capacitor
-
From
table
I
take the value
for
R|\|
relevant to the
measured
values of
R713/1 and
R713/10
—
From
table
II
take the values
for capacitors
516
and
517
relevant
to the value
found
for
Rn
—
Solder capacitor
516
with the value
found
into
the circuit
—
Replace capacitor
517 by a
capacitance decade
adjusted to the value
found
-
Set range switch to position
xIO nF
-
Set frequency
scale to
10
-
Connect
a
sample of
100 nF
±
1
%.
between
sockets
l-E
-
Reduce
the
detuning of the bridge to
a
minimum
by
varying capacitance
517
—
Solder the
selected capacitor value into the
circuit
35.2.3. 0.1
n-
resistor
-
Switch off the
instrument
-
Set range switch to position
100 mfl
-
Make
a
measuring
set-up
with
a
standard resistor
of
100 mft
as
shown
in
fig.
18
—
Check
that the voltage
drop
across resistor
71
1 is
the
same
as
that across the
standard resistor of
1
00 mft.
Tolerance:
<
0.3 %.
—
Adjustment
is
possible
by using solder
tin
between
the resistance
wire
and
the
normal wire
Fig. 18.
Measuring
set-up
with standard
resistor
of 100 mD.