Panasonic SU-373 Service Manual page 2

SAFETY PRECAUTION
I. Before servicing, unplug
2. When replacing parts, use only manufacturer's
3. Check the condition of the power cord. Replace if wear or damage is evident.
4. After servicing, be sure to restore the lead dress, insulation barriers, insulation papers, shields, etc.
5. Before returning the serviced equipment
prevent the customer
• INSULATION RESISTANCE
i. Unplug the power cord and short the two prongs of the plug with
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
and 5.2MO to all exposed parts.
all exposed parts. (Fig. B)
Note: Some exposed parts may be isolated from the chassis by design. These will read infinity.
Antenna
term inal
Exposed
metal
part
4. If the measurement is outside the specified limits, there is a possibility of a shock hazard. The equipment should be
repaired and rechecked
PROTECTION
The protection circuitry
foilowing conditions is noticed
• No sound is heard when the power is turned
• Sound stops during a performance.
The function of this circuitry
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 this unit are used.
BEFORE REPAIR
Disconnect AC power, Dischargeboth PowerSupply CapacitorsC703 and C704 through a IOQ, 5Wresistorto ground.
DO NOT SHORT-CIRCUIT DIRECTLY (with a screwdriver blade, for instance), as this may distroy solid state devices.
After repairs are completed, restore power gradually using a variac, to avoid overcurrent.
Current consumption at 120V, 60Hz in NO SIGNAL
• Accessories
• AC power supply cord
(SJA172—1)
(This "safety precaution"
the power cord to prevent an electric
recommended components for safety.
to the customer, be sure to make the following
from being exposed to a shock hazard.
TEST
shafts, handle brackets, etc.
(Fig. A) Equipment without
Ohmmeter
(Fig. A)
Resistance 3MQ—5.2
before it is returned to the customer.
CIRCUITRY
may have operated if either of the
on.
is to prevent circuitry
• Flat cable for remote-control
operation
(SWKUV96KM)
is applied in U.S.A.)
shock.
a jumper wire.
Equipment with antenna terminals should read between 3MQ
antenna terminals should read approximately
Exposed
metal
part
MQ
If this occurs, follow
1. Turn off the power.
2. Determine the cause of the problem
3. Turn on the power once again after one minute.
damage
Note
When the protection
operate unless the power is first turned off and then on
again.
mode should be 250 & 500mA.
• Remote-control
transmitter
-2-
insulation resistance test to
Ohmmeter
(Fig. B)
Resistance = Approx 00
the procedure outlines
and correct
circuitry functions, the unit will not
• Batteries
(UM—3NEP)
.
(EUR64196)
infinity to
below.
it.
2