Marantz 2245 Service Manual page 14

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14. Muting Circuit Alignment
15. Audio Adjustment
1. Voltage adjustment
Connect
a DC voltmeter
between
pin Tenia
J802
and J803, and adjust the trimming
resistor R809 for 35V DC.
2. Main Amplifier DC off-set alignment
Connect a DC voltmeter with 0.5 or 1V range between the speaker terminals and adjust the
trimming resistor R762 for ''zero'' DC output on the meter.
3. Idle-current adjustment
Connect a VTVM
between pin terminals J753 and J754. Next, rotate the trimming resistor
R763 fully counterclockwise, then rotate it clockwise again until the VTVM
reads S5mV DC.
Repeat the same procedure for the other channel.
5. Phono-amplifier adjustment
Connect-a oscilloscope to the TAPE
OUT jacks and an audio signal generator to the PHONO
jacks. Place the selector switch in the PHONO
position. Increase 1KHz audio signal gradual ly
until a slight clipping on top of the sine-wave
is observed
on the oscilloscope.
Adjust the
trimming resistor R708 for equal clipping level.
For the other channel adjust R709.
6. Main Amplifier ASO adjustment
For this alignment two DC oscilloscopes are necessary.
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