HPS 500 (120 & 230 V) TEST PROCEDURE
Idle current check, and output stage bias adjustment :
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Remove and expose amplifier assembly by following instructions on the preceding page. All connectors
must remain intact.
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Locate and disconnect the CD+ connector on the main board; insert a DC Ammeter set to a low
range between the two connectors.
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Locate and adjust R13 and R28 potentiometers on the main board near the connector to maximum CCW.
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Adjust R13 and R28 on the Feature-Linear board fully counter clockwise.
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Apply the appropriate AC power to unit, switch AC power on.
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Adjust R28 until current meter reads 5 mA + idle.
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Adjust R13 until current meter reads 10 mA + idle.
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Switch AC power off.
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Remove current meter and connect CD+ harness to CD+ connector on the Feature-Linear board.
Audio Test :
Check noise:
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Connect a true RMS voltmeter across the power amplifier output,
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(SPKR+ and SPKR- on the Feature-Linear board).
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Vary the Gain and Frequency controls from minimum to maximum, verifying the noise reading
on the voltmeter remains less than 8 mV AC.
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Adjust the Gain control to minimum.
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Apply an 800 mV, 60 Hz signal to the Left RCA low level input.
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Vary all controls while looking at the oscilloscope, watch and listen for any irregularities, or distortion.
Check power:
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Place a 20
W
resistive load across the power amplifier output.
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Connect a true RMS voltmeter across the power amplifier output.
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Set Frequency control to maximum.
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Adjust gain control to verify the amplifier will deliver:
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At least 90 Volts AC, “clean” - no visible distortion
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At least 100 Volts AC, with visible “rounding of the peaks” distortion.
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DO NOT RUN AMPLIFIER AT FULL POWER CONTINUOUSLY, FOR MORE
THAN 5 SECONDS.
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Amplifier/Subwoofer
HPS500