A-9355
OPERATION CHECK-1
SPEAKER PROTECT-1 (CURRENT DETECTION)
GND
25Vp-p
50Hz
IN
GND
3.3k
10k
1SS133
x 6
3.3k
OUT
GND
0.01 F
0.1 F
<Fig-1>
Dummy
load
Oscillator
Differentiation
circuit
Oscilloscope
CD
A-9355
SPEAKERS A
[When]
Exchange parts on Power amplifier PC board (NACLD-9283) and PC board ass’y.
<Note>
1. Do not check two or more channels at the same time.
2. Do not connect dummy load to speaker terminal longer than 2 seconds.
[Procedure]
1. Connect the AC power cord to a wall outlet and turn on the unit.
2. Set the unit as follows.
VOLUME : MIN. , SPEAKERS : A, SELECTOR : CD, PURE DIRECT : ON
3. Connect the oscilloscope to SPEAKERS A Lch. Refer to
<Fig-1>
4. A square wave of
50Hz
is output from the oscillator, and this signal is input to the
CD
via the differentiation circuit.
5. Adjust for the output wave form of the SPEAKERS A Lch to become
25 Vp-p
by adjusting VOLUME.
6. Connect the
2
ohms dummy load to the SPEAKERS A Lch.
And check the speaker relay RL5001 is
not turned off
.
7. Connect the
1
ohm dummy load to the SPEAKERS A Lch terminal.
And check speaker relay RL5001 is immediately
turned off
and power indicator blinks.
Do not connect the load for 2 seconds or more when it doesn't turn off the relays.
8. Check Rch according to the same procedure.
9. Press POWER button to turn off the unit.
10. Disconnect the AC power cord and oscilloscope.
