Sony XR-4803 service manual Tuner dB=1 µV, FM Auto Scan/Stop Level Adjustment

TUNER SECTION 0 dB=1 µV

Cautions during repair

When the tuner unit is defective, replace it by a new one be- cause its internal block is difficult to repair.

Note: Adjust the tuner section in the sequence shown below.

1.FM Auto Scan/Stop Level Adjustment.

2.FM Stereo Separation Adjustment.

3.AM (MW) Auto Scan/Stop Level Adjustment.

FM Auto Scan/Stop Level Adjustment

Setting:

[SOURCE] button: FM

FM RF signal

generator

			antenna jack (J1)
		0.01 ∝F
					set
Carrier frequency	: 98.0 MHz
				∝V)
Output level	: 22 dB (12.6
Mode	: mono
Modulation	: 1 kHz, 22.5 kHz deviation (30%)

Procedure:

1.Set to the test mode. (See page 14.)

2.Push the [SOURCE] button and set to FM.

FM Stereo Separation Adjustment
Setting:
[SOURCE] button: FM
FM RF signal	antenna jack (J1)	level meter
generator
	∝	4 Ω
	0.01 F
	set	+
		–

Carrier frequency	: 98.0 MHz	speaker out terminal
Output level	: 70 dB (3.2 mV)
Mode	: stereo
Modulation	: main: 1 kHz, 20 kHz deviation (26.7%)
	sub: 1 kHz, 20 kHz deviation (26.7%)
	19 kHz pilot: 7.5 kHz deviation (10%)

Procedure:

FM Stereo	Level meter	Level meter
signal generator
	connection	reading (dB)
output channel
L-CH	L-CH	A
		B
R-CH	L-CH	Adjust RV4 on TU1
		for minimum reading.
R-CH	R-CH	C
		D
L-CH	R-CH	Adjust RV4 on TU1
		for minimum reading.

SHUF1

Display

FM 98￿ .0 ￿

L-CH Stereo separation: A-B

R-CH Stereo separation: C-D

The separations of both channels should be equal.

Specification: Separation more than 28 dB

3.Adjust with the volume RV2 on TU1 so that the “FM” indica- tion turns to “FMI” indication on the display window.

But, in case of already indicated “FMI”, turn the RV2 so that put out light “I” indication and adjustment.

Adjustment Location: See page 16.

SHUF1

Display

FM 98￿ .0

Adjustment Location: See page 16.

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