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Condition
Troubleshooting Chart
Probable Cause
Remedy
No power.
1.
Power switch is off.
2.
Fuse is blown.
1.
Make sure rear panel Power
Switch is on.
2.
Replace primary fuse with fast
acting 5 A fuse (3 A for 220/240 V
use).
No output.
1.
Poor input connections.
2.
Poor loudspeaker connections.
1.
Check all connections from
preamplifier.
2.
Check all speaker wire termina-
tions.
Channels reversed or one channel dead.
1.
Improper input connections.
2.
Improper loudspeaker wiring.
1.
Correct input wiring.
2.
Correct loudspeaker wiring.
No peak power indications.
Inappropriate threshold settings.
Reset Threshold Selector Switches.
Note:
The
620
is equipped
with
a thermal
protection circuit which protects the unit
from damage caused by excessively high
operating
temperatures.
The
circuit will
'disconnect
the
power
to the
amplifier
when
the
output
transistors
reach
an
operating temperature of 80°C (176°F).
"This rarely occurs under normal use with
loudspeakers rated at 4 ohms or higher, but
an accidental short circuit, for example,
may cause the protection circuit to shut
down the amplifier. In the event that the
protection circuit is activated, turn down
the
volume
control,
and
turn
off the
power switch. Check all wiring to make
sure
there
are
no
short
circuits.
The
protection circuit will automatically reset
once
the amplifier has cooled to a safe
temperature.
SERVICE
INFORMATION
Please read all Notices and/or Warranty
Cards included with this unit.
Although it is unlikely that your 620 will
require repair, should
servicing ever be-
come necessary, please refer all such work
to qualified
personnel.
As there are no
user
serviceable
parts
inside
the
unit,
please do not attempt your own repairs.
Thank you for your confidence in Naka-
michi products.
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