Marantz 2275 - FM Dolby Level and Audio Adjustments

Set the FM signal generator to provide 1KuzV at 98MHz and accurately tune the receiver to
the same frequency.
Turn the MUTING pushswitch on. Shift the FM signal generator frequency higher and lower
and note both higher and lower shifted frequencies at which undesirable audio side responses
are muted out. Adjust the R363 so that the same shifted frequencies mute the undesirable
side responses.
Adjust R362 for preferred frequency shift at which the muting circuit operates.
. FM DOLBY LEVEL ADJUSTMENT
Set the FM SG to provide a 400Hz, 50% modulated 98MHz mono signal, at 1KuV output.
Precisely tune the receiver to 98MHz.
Depress the FM DOLBY pushswitch, and adjust RCO1 and RCO2 until the outputs of both
channels are 580mV.
. AUDIO ADJUSTMENTS
35V B+ voltage adjustment (Power Supply)
Connect a DC voltmeter between the pins J804 and J805, and adjust the trimming resistor
R806 for 35V DC.
Main Amplifier DC offset adjustment.
Connect a DC voltmeter with 0.5 or 1V range across the speaker terminals and adjust the
trimming resistor R741 for ‘‘zero’’ DC output on the meter.
Repeat the same procedure for the other channel.
Note: During this alignment no load should be connected to the speaker terminals.
Idle-current adjustment
Connect a VTVM between pins J707 and J708 (or T.P.’s J711 and J712). Next, rotate the
trimming resistor R742 fully counterclockwise, then rotate it clockwise until the VTVM
reads 10mV DC (25mA).
Repeat the same procedure for the ohter channel.
Note: During this alignment no load should be connected to the speaker terminals.
Re-check the DC offset voltage per procedure 2 and if any DC output is observed on the DC
voltmeter, adjust R741 again for ‘’zero” output.
Phono-amplifier adjustment
Connect an oscilloscope to the TAPE MONITOR OUT jacks and an audio signal generator to
the PHONO jacks. Place the selector switch in the PHONO position. Increase the 1kHz audio
signal level gradually until a slight clipping on top of the sine-wave is observed on the
oscilloscope. Adjust the trimming resistor R408 for equal clipping level.
For the other channel, adjust R409.