Integra DTA-9.4 Service Manual page 30

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OPERATION CHECK-2
DC VOLTAGE DETECTION OF POWER AMPLIFIER CIRCUIT
Notes
No load and No signal input.
How to check?
1. Connect the power supply card to a wall outlet.
2. Power On the unit.
3. Set the INPUT SELECT switch of a rear panel to the RCA side.
4. Apply DC+3V to a RCA terminal.
5. Check that the speaker relay RL701 is turned off.
6. Apply DC+3V to a RCA terminal.
7. Check that the speaker relay RL701 is turned off.
Rear panel
OVER CURRENT DETECTION OF POWER AMPLIFIER CIRCUIT
Notes
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1. Check only one channel at a time.
L 13942296513
2. Interrupt a input signal, immediately after a speaker relay goes out.
3. Don't change into the state where load was connected to amplifier, more than for 3 seconds.
How to check?
1. Set the output of the oscillator into the minimum level.
2. Connect the oscilloscope to the OUTPUT terminal.
3. Output a 200Hz rectangular wave from an oscillator, and input into a RCA terminal through the appointed differentiation circuit.
4. Turn on the unit.
5. Adjust the output level of oscillator so that the level of the waveform of the OUTPUT terminal become 35 Vp-p.
6. Connect 2-ohms load to the OUTPUT terminal.
7. Check that the speaker relay RL701 is not turned off .
8. Connect 0.3-ohm load to the OUTPUT terminal.
9. Check that the speaker relay RL701 is turned off immediately.
200Hz
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3.3k
0.1 F
Input
10k
.
GND
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Differentiation
circuit.
1SS133 3.3k
Output
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y
0.01 F
i
GND
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8
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3 6 7 1 3
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2 9 9 4 2 8
DC+3V or -3V
1 5 0 5 8 2 9 9 4
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co
DTA-9.4
9 9
2 8 9 9
35Vp-p