Adjustment - Rotel RX-975 Technical Manual

Am/fm stereo receiver

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Adjustment

1. FM Alignments

Necessary measurement equipment:

Stereo Generator, FM/AM Signal Generator, Distortion meter, Oscilloscope,

Digital Volt Meter (DVM)

(A) Center Adjust

Stereo Generator Setting: MODE; MONO, Audio Frequency; 1 kHz

FM Signal Generator Setting: Deviation; 75 kHz, Frequency; 98.1 MHz, Output Level; 66 dB

RX-975 Setting: FM Frequency; 98.1 MHz, FM MODE; MONO

1) Turn FM Signal Generator Modulation On.

2) Connect DVM (+) (-) terminals to both ends of resistor R726 and measure the volt.

3) Make this measured volt '0' by adjusting T704 (FM-DET-A Coil). (The adjustment should be within ± 2mV)

4) After this adjustment, measure THD (Distortion) with Distortion Meter.

5) Adjust THD to minimum point with T-705 (FM-DET-B Coil). (THD should be within 0.5%)

(B) Channel Separation Adjust

Stereo Generator Setting: MODE; STEREO (Only L-channel or R-channel Signal Out),

Audio Frequency; 1 kHz

FM Signal Generator Setting: Deviation; 75 kHz, Frequency; 98.1 MHz, Output Level; 66 dB

RX-975 Setting: FM Frequency; 98.1 MHz, FM MODE; STEREO

1) Turn FM Signal Generator Modulation On after modulating only L-channel or R-channel at Stereo

Generator.

2) Confirm if 'STEREO' indicator is light On on the display.

3) Measure output level via Distortion Meter and make the level as standard.

4) Turn FM Signal Generator Modulation On after modulation only R-channel or L-channel at Stereo

Generator.

5) Measure output level via Distortion Meter (measure per a "dB").

6) Adjust output level to minimum position with VR702. (lower than –40 dB)

Stereo Generator Setting: MODE; STEREO, Audio Frequency; 1 kHz

FM Signal Generator Setting: Deviation; 75 kHz, Frequency; 98.1 MHz, Output Level; 26 dB

RX-975 Setting: FM Frequency; 98.1 MHz, FM MODE; STEREO

1) Turn FM Signal Generator Modulation On. (confirm if output level is 26 dB)

2) Adjust VR702 up ton the moment where 'STEREO' & 'TUNE' indicator turn OFF & ON again.

3) Confirm if 'STEREO' & 'TUNE' turn OFF when decreasing the output level slowly from 26 dB to 25 dB,

24dB ~ ~ ~. (Repeat the above 2)~3) if not OFF in lower than 24 dB)

4) Push RX-975's TUNE UP and DOWN button "long" at Signal Generator Output Level 26 dB and start Auto

Search. Confirm if search stops at FM Frequency 98.1 MHz. (confirm both of High Frequency to 98.1 MHz

search, Low Frequency to 98.1 MHz search)

2. AM

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