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mi CONTENTS
Page
SAFETY PRECAUTION ..........-:sccscesssnssssnesescsssennensensnrersesenssnensesnenses
WIRING CONNECTION
DIAGRAM.............::.:ssessscsstsessststrsnensnennes 22
PROTECTION CIRCUITRY.........-:ssssssecssssescens
PRINTED CIRCUIT BOARDG.......2...sccseesssstesnssessnsessenoresseraces 23~27
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FRONT PANEL CONTROLG.........
REPLACEMENT PARTS LIST......
{=
DISASSEMBLY INSTRUCTIONS
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CABINET PARTS LOCATION .....
A
FAN MOTOR TROUBLE SHOOTING GUIDE..........--------s-ssseseeseen 9
REPLACEMENT PARTS LIST ...........00+s000
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BLOCK DIAGRAM..........s:scs:sssscsessesesersensnsenseetsnunennenneatassessess 10~12
RESISTORS AND CAPACITORS
PACKAGING .......sssccsrserscnssssesnsnsnsanesuesseserseensenseasnenensensnanesenenensees
4,
SCHEMATIC DIAGRAM -sssscssssssssssstesnsssaneseneestensnsesnees 13~21
. 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.
¢ 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—
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