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OPERATION CHECK-1
SPEAKER PROTECT-1 (CURRENT DETECTION)
[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.
<Fig-1>
Oscillator
50Hz
Differentiation
circuit
A-9355
CD
SPEAKERS A
GND
1SS133
3.3k
0.1 F
x 6
IN
10k
GND
Dummy
load
3.3k
OUT
0.01 F
GND
A-9355
25Vp-p
Oscilloscope
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