Technics SU-G95 Service Manual

mi CONTENTS
Page
SAFETY
PRECAUTION
..........-:sccscesssnssssnesescsssennensensnrersesenssnensesnenses
WIRING
CONNECTION
DIAGRAM.............::.:ssessscsstsessststrsnensnennes
22
PROTECTION CIRCUITRY.........-:ssssssecssssescens PRINTED CIRCUIT BOARDG.......2...sccseesssstesnssessnsessenoresseraces 23~27
a4
BEFORE
REPAIR
AND
ADJUSTMENT
TERMINAL
GUIDE
OF
IC’S,
TRANSISTORS
AND
DIODES.....
28
ey
LINE-UP
COMPONENTS
......ccsscesesssssstsans
TERMINAL
FUNCTION
OF
IC..........ccsceccseceecsssotsnnsstsocsonsansnteaneaes
i FRONT PANEL CONTROLG......... REPLACEMENT PARTS LIST......
{= DISASSEMBLY INSTRUCTIONS ate CABINET PARTS LOCATION .....
A FAN MOTOR TROUBLE SHOOTING GUIDE..........--------s-ssseseeseen 9
REPLACEMENT PARTS LIST ...........00+s000
f BLOCK DIAGRAM..........s:scs:sssscsessesesersensnsenseetsnunennenneatassessess 10~12 RESISTORS AND CAPACITORS
PACKAGING .......sssccsrserscnssssesnsnsnsanesuesseserseensenseasnenensensnanesenenensees
4, SCHEMATIC DIAGRAM -sssscssssssssssstesnsssaneseneestensnsesnees 13~21
Note:
Refer
to
the
placement,
Equipment
connections
and
Remote
control
operation
of
Service
manual
for
Model
No.
ST-K55
(PP),
Order
No.
AD9401001C1.
=
:
Mi
SAFETY
PRECAUTION
(this
“safety
precaution”
is
applied
only
in
U.S.A.)
. Before servicing, unplug the power cord to prevent an electric shock.
. When replacing parts, use only manufacturer’s recommended components for safety.
. Check the condition of the power cord. Replace if wear or damage is evident.
. After servicing, be sure to restore the lead dress, insulation barriers, insulation papers, shields, etc.
.
Before
returning
the
serviced
equipment
to
the
customer,
be
sure
to
make
the
following
insulation
resistance
test
to
prevent
the
customer
from
being
exposed
to
a
shock
hazard.
¢ INSULATION RESISTANCE TEST
1. Unplug the power cord and short the two prongs of the plug with a jumper wire.
2. Turn on the power switch.
3. Measure the resistance value with ohmmeter between the jumpered AC plug and each exposed metal cabinet
part, such as screwheads, antenna control shafts, handle brackets, etc. Equipment with antenna terminals
should read between 3MQ and 5.2MQ to all exposed parts. (Fig. A) Equipment without antenna terminals
should read approximately infinity to all exposed parts. (Fig. B)
Note: Some exposed parts may be isolated from the chassis by design. These will read infinity.
aAhROD
Antenna
terminal
Exposed Exposed
metal metal
‘ part part
: Ohmmeter
(Fig. A) (Fig. B)
Resistance=3MQ—-5.2MQ Resistance=Approx. oo
4. If the measurement is outside the specified limits, there is a possibilty of a shock hazard. The equipment
should be repaired and rechecked before it is returned to the customer.
Mi PROTECTION CIRCUITRY
Ohmmeter
The protection circuitry may have operated if either of
the following 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 example, the positive and negative
speaker connection wires are “ shorted”, or if speaker
systems with an impedance less than the indicated
rated impedance of the amplifier are used.
Mi BEFORE REPAIR AND ADJUSTMENT
If this occurs, follow the procedure outlines below:
1. Turn off the power.
2. Determine the cause of the problem and correct it.
3. Turn on the power once again after one minute.
Note:
When the protection circuitry functions, the unit will
not operate unless the power is first turned off and
then on again.
Disconnect AC power, Discharge both Power Supply Capacitors C703 and C704 (80V 1200uUF), C705 and C706 (63V
2200u1F) through a 100, 5W resistor to ground. DO NOT SHORT-CIRCUIT DIRECTLY (with a screwdrive blade, for
instance), as this may destroy solid state devices. After repairs are completed, restore power gradually using a
variac, to avoid overcurrent.
Current consumption at 120V, 60Hz in NO SIGNAL mode should be 410~810mA.
—2—

Technics SU-G95 Specifications

General

Brand	Technics
Model	SU-G95
Category	Amplifier
Language	English