Marantz 1090 - Total Hum and Noise Test; Maximum Power Output Test; Harmonic Distortion Test Procedure

TOTAL HUM AND NOISE TEST
With shorting plugs connected to the Phono input
jacks and an 8 ohm resistive load connected across
HARMONIC DISTORTION TEST
. Set the frequency of the audio oscillator and the
distortion analyzer to 20 kHz.
the speaker system output terminals, connect a dis- 2
; . Set the controls of the analyzer for voltage measure-
tortion analyzer across the load.
ment on the 30 volt scale.
NOTE: 3. Adjust the audio oscillator output level until the
analyzer meter indicates 16.8 VAC.
If the distortion analyzer does not contain a built-in volt- 4
meter, an AC VTVM may be substituted.
. Switch the distortion analyzer to Set Level and
adjust SENSITIVITY for full scale readingon O~ 1%
scale.
Set the distortion analyzer controls for voltage 5
measurements and apply power to the amplifier.
Set the volume contro! fully CCW. Set the
SELECTOR switch to PHONO.
. Measure the total harmonic distortion with the
analyzer and verify it is less than 0.1%.
3. If the distortion analyzer indicates more than 2.0 mV, NOTE:
refer to the trouble analysis section of this manual.
Any parasitic oscillation in the amplifier will be displayed
on the oscilloscope when capacitance is switched into
the load.
4. Set the volume control fully CW. If the distortion
analyzer indicates more than 20 mV, refer to the
trouble analysis section of this manual.
MAXIMUM POWER OUTPUT
Connect the audio oscillator to the AUX input. Set
. Switch the distortion analyzer back to SET LEVEL.
(Do not readjust sensitivity of analyzer.)
audio oscillator frequency to 1 kHz. Set SELECTOR 7. Change the frequency of the audio oscillator and dis-
switch to AUX. tortion analyzer to 1 kHz. Adjust audio oscillator
j ~ Q
With the distortion analyzer connected across the GURUS fOr ¢. ull <seale Neading onthe O ~cle-scale:
output load (8-ohm), set the analyzer on the 30 VAC 8. Measure the distortion, verifying it'is no greater than
scale. 0.1%.
Turn the analyzer on and increase the audio oscillator 9. Repeat steps 7 and 8, changing frequency to 20 Hz.
output to 180 mV. The AC VTVM should read 16.8 Distortion should be no more than 0.1%,
VAC : an :
i 10. Check for parasitic oscillation; there should 9e none.