Teac A-550RX - Page 7

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A-SSORX
5
ELECTRICAL
ADJUSTMENTS
AND
CHECKS
NOTES
1.
Before
performing
adjustments
and
checks,
clean
and
demagne-
tize
the
entire
tape
path.
2.
Make
sure
the
deck
is
properly
set
for
the
voltage
in
your
locality.
3.
In
general,
adjustments
and
checks
are
done
in
the
order
of
L-ch
then
R-ch.
Double
REF.
Nos.
indicate
L-ch/R-ch.
(Example:
R11/R21)
4.
The
value
of
“dB”
refers
to
O
dB
(0.775
V).
If
an
AC
voltmeter
calibrated
to
0
dB
(1
V)
is
to
be
used,
appropriate
compensation
should
be
made.
5.
The
AC
voltmeter
used
in
the
procedures
must
have
an
input
impedance
of
1
M-ohms
or
more.
6.
Note
the
“Deck
settings”
at
the
top
of
each
chart.
The
settings
must
be
used
for
all
the
checks
or
the
chart
unless
explicitly
stated
otherwise.
5-1
POWER
SUPPLY
PCB
ADJUSTMENT
1.
Adjust
R844
for
+23
VDC
at
terminal
13
of
the
PCB
to
ground.
2.
Adjust
R845
for
+15
V
DC
at
terminal
23
to
ground.
3.
Check
that
there
is
—15V
DC
at
terminal
25
to
ground.
DC voltmeter
mo
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Fig. 5-2
,
—70 dB or more ... What does it mean?
Values
in
dB
are
often
given
like
this:
"—70
dB
or
more”.
-This
sometimes
leads
to
confusion.
ls
—76
dB
more
than
—70
dB
or
less?
To
put
the
record
straight,
the
“more”
refers
to
the
absolute
value.
The
absolute
value
of
—70
is
170|.
The
absolute
value
of
—76
is
1761
which
is
6
more
than
70.
So,
—76
dB
is
“more”
than
—70
dB
—55 dB is “less” than —60 dB