Yamaha MSP10 Service Manual page 8

MSP10
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8. Variation Response of TRIM
Use the output level when the TRIM (HIGH, LOW) is "0" as reference (0dB) for the speaker terminals LF and HF
respectively, check that the output level varies as shown in the table below when 50 Hz and 10 kHz, -20 dBu sine
wave signals are applied to LINE IN.
Applied signal EQ
50Hz LOW
10kHz HIGH
9. Low Cut Filter
Use the output voltage at output terminal LF when an 80 Hz, -20 dBu sine wave signal is applied to the input terminal
and the low cut filter switch is turned off as reference (0dB), and check that it is -3.0 +/-1.5 dB when the switch is
turned on.
10. Stability
When the power voltage varies by +/-10%, or a 100P to 0.002µ F capacitor is connected to the speaker terminal,
check that no abnormal condition such as oscillation occurs.
11. Protection Circuit
When the CN601 connector is disconnected from the connector, check that the relay turns off within one second;
when the CN601 connector is connected, check that the relay turns on within 5 seconds .
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12. Clip Indicator
L 13942296513
When 400 Hz or 7 kHz +10 dBu signal is input to the LINE input terminal respectively, check that the LED color
changes from green to red.
13. Phase of Speaker
Check that the output of both LF and HF terminals are in phase with respect to the input.
14. Others
Connect the speaker system and the amplifier unit.
When a 40 Hz to 20 kHz sine wave signal or a music signal are applied, check that no abnormality occurs, such as
voice coil contact, air leakage and vibration.
(The power amplifier output level is not clipped)
Also,when each knob is moved, check that the sound volume and quality vary smoothly.
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