Philips pm2521 - Checking and Adjusting

61
62
3. CHECKING
AND
ADJUSTING
WARNING:
Before
switching-on,
ensure
that the
instrument
has
been installed
in
accordance with
the
instructions
outlined
in
Section
5 of the
Operating
Manual.
The opening
of
covers or
removal
of parts,
except
those to
which
access
can be gained
by
hand
is likely
to expose
live
parts, and
accessible
terminals
may also
be liw.
The instrument
shall be
disconnected
from
all voltage
sources
before
any replacement
or
maintenance
and repair
during
which
the
instrument
will be
opened.
If
afterwards,
any adjustment,
maintenance
or repair
of the
opened
instrument
under
voltage
conditions
is inevitable,
it
shall be
carried
out
only by a
skilled
person who
is aware
of the
hazard
involved.
Bear
in mind
that
capacitors
inside
the instrument
may still be
charged
even
if the
instrument
is
separated
from all
voltage
sources.
The
tolerances
in this
chapter
correspond
to
the
factory
data,
which only
apply
to a completely
re-adjusted
instrument.
These
tolerances
may deviate
from
those
mentioned
in the
Technical
Data.
(Chapter
2. of the
Operating
Manual).
For
a
complete
re-adjustment
of
the
instrument
the
sequence
in
this chapter
should
be adhered
too. When
in-
dividual
components,
especially
semi-conductors
are replaced,
the
relevant
section
should
be completely
re-
adjusted.
To
calibrate
this
measuring
instrument
only
reference
voltages
and measuring
equipment
with the
required
accuracy
should
be applied.
If such
equipment
is
not
available,
comparative
measurements
can be
made with
another
calibrated
PM2521.
However,
theoretically
in
extreme
cases,
the
tolerances
may leave
some
room
for
doubt.
The
measuring
arrangement
should
be
such that
the
measurement
cannot
be affected
by external
influences.
Protect
the
circuit
against
temperature
variations
(fans,
sun).
With
all
the
measurement
the
cables should
be
kept
as short
as possible;
at higher
frequencies
co-axial
leads
should
be
used.
Non
screened
measuring
cables may
act as serials
so that the
measuring
instrument
will
measure
LF voltage
values
or hum. voltage.
Before
checking
and adjusting,
remove
the
top-cover.
Make
sure that
the cable
from
the
power
supply is
connected
with
X802.
In
the
software
there
are two
subroutines
which
are
used for
adjusting
the
PM2521.
To call these
subroutines
short
circuit
TP10 and
TP1
1
for
one second
(first
subroutine)
and
repeat it for
the
next
subroutine.
After
using
these
subroutines the
PM2521
should
be reset.
(Switch the
PM2521
off
and on).
Fig.
46. Adjusting elements