Technics SU-VX720 Service Manual

SU-VX720
m@ CONTENTS
Page
@BEFORE REPAIR AND ADJUSTMENT.........0.0.0-.......-. 2
@PROTECTION CIRCUITRY ................00 00000000 2
@eACCESSORIES .............. i ichales ne ee suases a antes 2
*PUNCTION OF CONTROLS. 2.4.6 Qe ieees nih eyee esa eeks 3
eCONNECTIONS ...... 0. oo ees 4~-6
eDISASSEMBLY INSTRUCTIONS ...................45. 7~14
@SCHEMATIC DIAGRAM ............ 0.00.00 12~18
@PRINTED CIRCUIT BOARD DIAGRAM..............-- 19~24
WIRING CONNECTION DIAGRAM 9.00000.000 00sec D5
@eMEASUREMENTS AND ADJUSTMENTS —....... 0.02. 26
@eFUNCTIONS OF IC TERMINALS ........0.........0.005. 27
@BLOCK DIAGRAM....0.00 00 ee ee 28
@REPLACEMENT PARTSLIST .................. . 29~32. 35
eCABINET PARTS LOCATION......................005- 33, 34
SPACKAGING © oocecss ccc ere tod a a atewiaead haan oteia dae! 36
m BEFORE REPAIR AND ADJUSTMENT
(1) Turn off the power supply. Using a 10, 10 W resistor, shortcircuit both ends of power supply capacitors 2701-1 and 2701-2 in order to discharge
the voltage.
(2) Before turning on the power switch of the unit.
A. Connect the voltage controlier to the primary side.
B. Connect the AC ampere meter to the primary side or connect the DC voltage meter to the “+B” circuit of the secondary side.
C. Turn the VR of ICO (VR451 and VR452) to minimum (counterclockwise).
D. After setting the output to zero of the voltage controller, turn on the power switch of the unit.
And increase the output of voltage controlier gradually.
Then, check carefully whether the current value of primary side become more than following value or whether the DC voltage of secondary side is
increasing siowly.
E.
If
the
value
of
current
is
increasing
unusuaily
or
the
DC
voltage
is
not
increasing,
lower
the
output
level
of
voltage
controller
immediately.
®The
current
value
of
the
primary
side
at no
signal.
(Confirm
the
power
supply
voltage
of each
area
and
provided
voltage
of
the
unit.)
Power supply voltage
Consumedcurrent {| 50Hz
m@ PROTECTION CIRCUITRY
The protection circuitry of the amplitier may have operated if either of
the foliowing conditions is noticed:
@No sound is heard when the power is turned on.
Sound stops during a performance.
The function of this circuitry is to prevent circuitry damage if, for
exampie, the positive and negative speaker connection wires are
“shoried", or if speaker systems with an impedance less than the
indicated rated impedance of the amplifier are used.
320~520 mA
m ACCESSORIES
@AC power supply COP 6. ie eee eee eee bane j
<RJA0019-1K>: (EG). (EO)
<SJA193>: (EB)
<RJA0004 >: (GC)
<SJA173>: (GN)
Batteries
<RO3>
The configuration of the AC power supply cord differs according to area.
AC 110~127 V AC 220~240 V AC 230 V
110-~-310mA
AC 240V
100-~-300 mA
110~310 mA
If this occurs, follow the procedure outlined below:
1. Turn off the power.
2. Determine the cause of the problem and correct it.
3. Turn on the power once again.
Note:
When the protection circuitry functions, the unit will not operate
unless the power is first turned off and then on again.
e Power piug adaptor
<SJP9215>: (GC) area only
Cw
@ FUNCTION OF CONTROLS
1 2 [3 |
STEREC WTEGAATED snmmweO Sova ee
4) © (S| ful &
[1] Power switch (POWER)
[2] Operation indicators
(AMPLIFIER OPERATION MONITOR)
These indicators ituminate to indicate the operating condi
tion of this unit.
VOLTAGE CONTROL:
When the power is switched ON, this indicator illuminates
when the unit is in the operating condition.
CURRENT DRIVE:
When the power is switched ON, this indicator illuminates
after about 4 seconds when the unit is in the operating condi-
tion.
if an abnormal condition in the circuitry is detected, such as
DC voltage appearing in the output, or a short-circuit of the
positive (+) and negative (—)} wires from the speaker ter-
minals, the protection circuit functions and this indicator will
not illuminate.
[3] Source direct switch (SOURCE DIRECT)
This switch is used when enjoying high quality sound
playback such as that from a CD.
[4] Volume control (VOLUME)
[5] Recording selector (REC SELECTOR)
This selector is used to select the sound source to be record:
ed by the connected first tape deck and/or second tape deck
(or DAT).
Remote control input indicator
(REMOTE SELECTOR)
This indicator illuminates to indicate the input source
selected (TAPE 1, CD or TUNER).
While this indicator is illuminated, the input wil not change
even if the input source is changed using the main unit input
selector.
Remote control input erase button (OFF)
This button is used to erase the input selected on the remote
contro! transmitter in order to select the desired source us-
ing the input selector on the main unit.
Input selector (INPUT SELECTOR)
This selector is used to select the sound source to be heard,
such as a disc, radio broadcast, etc.
13, [14 15 16
[9i Headphones jack (PHONES)
Speaker selector (SPEAKERS)
This selector is used to select the speakers to be
used.
Tone controls (BASS/TREBLE)
The dass control is used to adjust the low-frequency sound
range, and the treble contro! is used to adjust the high-
frequency sound range.
12] Balance control (BALANCE)
This control is used to adjust the left/right volume balance.
13] Loudness switch (LOUDNESS)
This switch is used when listening to music at a low volume
level. Auditory perception of sound in the low frequency
range falls off at low volume, but when the switch is set to
the "ON" position, this deficiency is compensated for, so
that the full impact of the musical performance can be en-
joyed.
[14] Subsonic filter switch (SUBSONIC FILTER)
This switch is used to eliminate ultra-iow-frequency noise
such as motor “rumble" and unusual vibration of the woofer
cone caused by a warped disc. etc.
15: Mode selector (MODE)
This selector is used to select stereo or Monaural operation.
[16 Phono cartridge selector
(PHONO SELECTOR)
This selector shouid be set to the position which cor-
responds to the type of cartridge used on the turntable.
7; Remote control signal receptor
(REMOTE SENSOR)
Receives the signals from the remote control.
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Technics SU-VX720 Specifications

General

Brand	Technics
Model	SU-VX720
Category	Amplifier
Language	English