Teac BX-550 - Idling Current Adjustment; Power Output Meter Adjustment (BX-550); LED Meter Adjustment (BX-330)

BX-550/BX-330
4-3
IDLING
CURRENT
ADJUSTMENT
.
Connect
the
DC
voltmeter
between
T.P-1
and
T.P-2
(L-ch).
.
Adjust
R139
(BX-550)
or
R130
(BX-330)
so
that
the
DC
volt-
meter indicates approx. 100 mV.
.
After
adjusting
R139
(BX-550)
or
R130
(BX-330),
allow
30
seconds for the amp to warm up.
. Readjust R139 (BX-550) or R130 (BX-330) so that the DC
voltmeter indicates 20~30 mV. (Idling current 30~45 mA).
.
Connect
the
DC
voltmeter
between
T.P-4
and
T.P-3
(R-ch)
.
Repeat
procedures
1 to
4
above
and
adjust
R239
(BX-550)
or
R230 (BX-330).
NOTE: When using an oscilloscope, instead of the DC voltmeter,
carefully connect the oscilloscope so that the oscilloscope
GND terminal is not connected to the GND of the ampli-
fier, thereby causing a short. Use the oscilloscope in an
ungrounded state.
Oem me meme ene =
PEAS.
DC VOLTMETER
20~ l0Omv
30mvV
Fig. 3
4-4-1
POWER
OUTPUT
METER
ADJUSTMENT
(BX-550)
Refer
to
Fig.
4.
1.
2.
Pw
oan n uo
Connect
the
AC
voltmeter
to
SPEAKERS
terminal
A.
Set
the
SPEAKERS
selector
to
A
and
the
SOURCE
selector
to
AUX.
. Set the VOLUME control to MAX.
.
Apply
a
1-kHz
input
signal
to
provide
an
output
power
of
1
W
(approx. 2.83 Vrms) to the AUX terminals.
.
Adjust
R726
so
that
the
Power
Output
Meters
indicate
1W.
.
Connect
the
DC
voltmeter
between
pin
8
and
pin
2
of
U701.
.
Adjust
R826
so
that
the
DC
voltmeter
indicates
OV.
.
Set
the
VOLUME
control
to
MIN.
.
Connect
the
DC
voltmeter
between
the
collector
of
0702
and
GND.
.
Adjust
R728
so
that
the
DC
voltmeter
indicates
OV.
ie
Faaion)
of ns
e
4-4-2 LED METER ADJUSTMENT (BX-330)
Refer to Fig. 5.
1.
2.
3.
4.
Connect the AC voltmeter to SPEAKERS terminal A.
Set the SPEAKERS selector to A and the SOURCE efector to
AUX.
Set the VOLUME control to MAX.
Apply a 1-kHz input signal to provide an output pover of 1W
(approx. 2.83 Vrms) to the AUX terminal.
. Adjust R903 (L-ch)/R904 (R-ch) so that the POWER LEVEL
meter just begins to indicate 3W.