Sanyo 2050 Service Manual

Page 2

ADJUSTMENTS OF TUNER SECTION

INSTRUMENTS USED FOR ADJUSTMENTS

This set is specified by high grade of standard, especially in
distortion and carrier leak, as compared With the conven-
tional receivers. Therefore, the instruments used for various
adjustments of this set should be of high quality and high
grade, and always serviced and adjusted strictly.

DSG Output, more than 50 dB; high grade
(Digital leadout SG) of standard.

Stereo modulator Strictly calibrated in phase;high grade
of standard conforming to the level
of FM DSG.

20 Hz to 15 kHz, level within i0.1 dB,
low distortion (less than 0.01).

For automatic level; measurable up to
0.05%.

Distortion less than 0.02% (at 100 mV
to 1.5 V), S/N more than 80 dB.

'19 kHz band pass More than 40 dB/oct, 38 kHz attenua-
filter tion (more than .60 dB).

Frequency counter Input level in the vicinity of 76 kHz,

AF OSC
Distortion meter

lHF filter

(with AMP) possible at 0.5 mV; small input capa-
city (cable), less than 50pF; high input
impedance, more than 500K ohms (at
76 kHz);displayable up to 76,000 kHz.

DVM _ Resolution less than 1 mV (DC).

(Digital volt meter)

NOTE

0 Use high quality lHF filter, otherwise the center 0"
point may not coincide with the minimum distortion
point in the tuning meter center 0" adjustment.

0 If the phase of the stereo modulator is calibrated by
means of ordinary oscilloscope, an error may be caused.
Hence, the phase calibration should be performed
strictly. -

0 The output figures are given for open type DSG.

FM I F ADJUSTMENT

1. V-curve adjustment

(1) Connect TP-2 (mafia TP-3 or 102 (ground) to the
output terminals of sweep generator, and TP-202 (hot)
and TP-206 (ground) to the input terminals.

(2) Disconnect ceramic capacitor C217 (0.022uF).

(3) Reduce the input level of the set as small as possible so
that the output waveform may not be saturated.

(4) While watching the sweep waveform, adjust the T201
until the sweep waveform presents the pattern as in
Fig. 1

NOTE

Match the center of V-curve with the center line of the

ceramic filter being.

V curve

FM IF CURVE
Fig. 1

2. S-curve adjustment

(1) Connect TP-2 (hot) and TP-3 or 102 (ground) to the
output terminals of the sweep generator, and TP-201
(hot) and TP-206 (ground) to the input terminals.
NOTE
In order to cut the direct current at the hot side of the
sweep generator, connect a capacitor (1pF/16V)
between TP-207 and input terminal.

(2) Turn T202 until the waveform of the sweep generator
presents the pattern as in Fig. 2. Avoid turning T203
unless absolutely necessary.

5 curve

FM DETECTOR CURVE

Fig. 2

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Fig.3

FM TRACKING ADJUSTMENT

Make this adjustment after Pre-adjustment is done. Con-
nect the instruments as Fig. 4.
(1) Receive 'a 111.4 MHz image signal of 90 MHz (a 127.4
MHz image signal for 106MHz) by feeding an over
70 dB input. A
(2) Reduce the input so that the distortion factor gets
- worst or the audio output is minimized. Raise the
distortion factor nearly to 20 per cent as an aim.r
Adjust the 111.4'MHz image signal by rotating L102
and L104. Adjust the 127.4 MHz one by TC1 and TC2.
Make tracking by repeating the above adjustments;