Philips PM 3266 - 3.4. CHECKING AND ADJUSTING

148
3.4.
CHECKING
AND
ADJUSTING
3.4.1.
General
infornnation
The following
information
provides the
complete
checking
and
adjusting
procedure
for
the PM
3266
oscilloscope.
As
various
control
functions
are
interdependent,
a
certain
order of
adjustment
is often
necessary.
The
procedure
is,
therefore,
presented
in a
sequence which
is
best
suited
to this
order,
cross-reference
being
made to
any
circuit
which
may
affect
a particular
adjustment.
Before
any check
or adjustment,
the
instrument
must
attain
its normal
operating
temperature.
Under
average
conditions
this
will
be
approximately
30 minutes
after
switching
on.
All
controls
which
are
mentioned
without
item
numbers are
located
on
the front
plate
of the
oscilloscope.
3.4.2.
Recommended
test
equipment
Digital
r.m.s.
meter
e.g.
PHILIPS
PM
2527.
Oscilloscope
calibrator,
e.g. TEKTRONIX
TM503-tSG503-tTG501+PG506.
2:1
dummy
probe (Fig.
3.27.),
e.g. TEKTRONIX type
067.0537.00
Oscilloscope
with
differential
input
facility,
e.g. PHILIPS PM
3240
Low
capacitance
trimming
tools.
3.4.3
Preliminary
control
settings
All
preset
potentiometers
and
trimming
capacitors
are
indicated on
the
drawings
of the
printed-wiring
board,
see the figures
3.31.
and
3.32.
—
Push
the Y
POSITION
control to
the NORM
position.
—
Depress
push-buttons
DC of the
signal-coupling
controls.
—
Set the DELAY
TIME
control
(R1
)
to
0
(fully anti-clockwise)
—
Depress
push-button
MAIN
TB
of the X deflection
controls
(S2)
—
Push the TB MAGN
control
to position x1.
—
Depress
push-button
AUTO of
the trigger
mode
controls.
—
Set
the
MAIN
TIM E/D IV switch
to 1 ms
-
Set the DEL'D TIME/DIV
switch
to OFF
—
Set the
TIME/DIV
vernier controls
to
CAL.
—
Depress push-buttons
DC of
the trigger-coupling
controls
—
Depress
push-buttons
A of the trigger-source controls
(S21, S22).
—
Except
for the adjustment
of
the
storage function
(3.4.16.) the adjustments
are carried out
in the
MEMORY
OFF mode.
3.4.4. Power
supply
3.
4.4.1.
Power consumption
—
Check
that the voltage
has been set to the local mains
voltage and connect
the instrument
to such
a
voltage.
—
Switch the
oscilloscope on and
check that
the pilot lamp on the front panel lights up.
—
Check that the power consumption
does
not
exceed
50 W (measured with a moving-iron
meter).
3.4.4.
Z
+12,7 V supply voltage (Unit
5)
—
Check
at a mains voltage of 220
V that
the voltage on the positive pole of Cl 831
is +12,7
V
±
100 mV;
if
necessary, readjust
potentiometer R1826
on the power supply board.
—
Check
that this voltage
does
not
vary more
than
±
50 mV when the mains voltage is varied
between
200 and 265
V.
Pre-set
potentiometer
R1827
This
potentiometer is a factory adjustment
control.
THE
SETTING
OF
THIS POTENTIOMETER
MUST
NOT
BE
DISTURBED
UNLESS IT IS
ABSOLUTELY IMPOSSIBLE
TO
SET
THE 12.7 V WITH THE AID
OF POTENTIOMETER
R1826.
Adjusting
procedure:
—
Set the
main input voltage
to 220 V.
—
Turn potentiometer R1827
fully
anti-clockwise.
—
Check
that the voltage
on the positive
pole
of Cl 831 is
12,7 V
±
100 mV; if
necessary; readjust
potentiometer R1826
on the
power supply board.