Jvc RS 7 Service Manual

Page 1

MODEL
R-S7

STEREO RECEIVER

No. 2471
January 1979

Page 2

Contents

Page
1. Specifications ............................................................... 1
2. Removal Procedures
2-)1) Top Cover and Bottom Plate ................................................. 2
2-(2) Front Panel and Window Screen ............................................... Z
2-(3) TXX-180 Main Amp. P.C. Board Ass'y .......................................... 3
3. Main Parts Location and Part Numbers .............................................. 3
4. Exploded View and Part Numbers
4-(1) Front Panel ............................................................ 4
4-(2) Rear Panel ............................................................. 5
5. Dial Stringing Procedures ....................................................... 5
6. FM/AM Tuner Alignment Procedures
6-(1) FM Section ............................................................ 6
6-(2) AM Section ............................................................ 7
7. Power Amplifier Idling Current Adjustment Procedure .................................... 7
8. Printed Circuit Board Ass'y and Parts List
8-(1) TFC-27 FM/AM Tuner and Equalizer Amp. P.C. Board Ass'y ............................ 8
8-(2) TXX»180 Main Amp. and Power Supply P.C. Board Ass'y ............................. 12
9. Packing Materials and Part Numbers ............................................... 15
10. Accessories List ............................................................. 15
11. R-S7 Schematic Diagram .................................................... 16~17
12. Parts List with Specified Numbers for Designated Areas .................................. 18

Warning:
When replacing the parts marked with A, be sure to use the designated parts to ensure safety.

1. Specifications

FM Tuner Section
Tuning Range

:87.6 MHZ - 108 MHZ

AM Tuner Section
Tuning Range

: 525 kHz -1605 kHz

Usable Sensitivity (IHF) : 10.3 dBf Usable Sensitivity : 300/1V/m, 30 MV (External Antenna)
0.9 #V/75 {2 Signal to Noise Ratio : 50 dB
50 dB quieting sensitivity Distortion : 0.5 %
Mono : 14.8 (131 Selectivity :35 dB
Stereo : 38.3 dBf Amplifier Section
Distortion RMS power : 50 watts per channel
Mono : 0.15 % (1 kHz) (Both channels driven, at 8 ohms
Stereo : 0.30 % (1 kHz) from 20 Hz to 20 kHz)

Signal to Noise Ratio

RMS power

: 55 watts per channel

Mono :82 dB (74 dB, DIN) (Both channels driven at 8 ohms
Stereo : 70 dB (65 dB, DIN) at 1 kHz) 70 watts per channel
Selectivity :65 dB, 1400 kHz at 4 ohms

Capture Ratio

(45 dB :300 kHz, DIN)

:l.0dB

Total harmonic distortion

: 0.03 % at rated power (0.008 %

at half rated power, 1 kHz)

IF Pejection :90 dB at 98 MHZ Hum & Noise :PHONO 82 dB
Image Rejection : 60 dB at 98 MHZ (IHF short circuit TAPE PLAY 100 dB
Stereo Separation : 50 Hz - 35 dB A network)

1 kHz - 45 dB DIMENSIONS : H: 149mm (5-7/8)

10 kHz-35dB W:450mm(17-11/16")

No. 2471

WEIGHT (net)

_1_

D: 351mm (13-13/16")

: 8.5 kg (18.7 lbs)

Page 8

R ~57

Muting Level
Note: No adjustment is necessary. However, if the check-

1.

2.

3.

up is required, take the following steps.
Set the source select knob to FM MUTING during this
adjustment procedures.
Connect a VTVM and an oscilloscope to the Rec. Out
jacks on the rear panel.
Set the RF generator to 108MHz, a modulation of 1kHz
and a deviation of 75kHz, to provide an input of 511V.

. Turn R138 counterclockwise and remember the point

(or position) at which the muting ceases operating.

. Turn R138 clockwise slightly so that the output level

drops by 1dB.

. Attenuate the output of the RF generator to 2dB from

SuV of step 2 and check that the muting is still operat-
ing.

6-(2) AM Section

Tracking and Sensitivity
Low Frequency

1.
2.

01-13

Set the source select knob to AM.

Connect the RF generator to the antenna terminals on
the rear panel, set this to 600kHz with 30% modulation
at 400Hz.

. Connect an AC VTVM and an Oscilloscope to the Rec.

Out jacks on the rear panel.

. Set the dial pointer to 600kHZ.
. Adjust OSC coil L201 and the ferrite bar antenna adjust»

ing the coil to maximized the output signal.

High Frequency

6.

7.
8.

Set the RF generator to 1400kHz with 30% modulation
at 400Hz,

Set the dial pointer to 1400kHz.

Adjust the trimmers TC5 and T04 in the tuning gang so
that the output signal is maximized.

.Repeat these high and low frequencies adjustment

procedures alternately until maximum sensitivity is
obtained.

7. Power Amplifier Idling Current Adjustment Procedure

T P
~ T.P T.P 826
BZ5LE . 823 R E. oT'P
L'CH 824R-CH
T.P
. 322
GND

RY90I

®

R722

©

Adjustment Location on TXX-180 Main Amp. P.C. Board Ass'y

Precaution:
(1) Allow the set to warm up at least 5 minutes before connecting a DC VTVM.

(2) Must keep the heatsinks cooling to prevent overheating and consequent destruction of the semiconductor junction and
set the volume control to minimum during these adjustment procedures.

(

)2 for Right channel Adjustment

Procedures:
1. Turn R721 and R722 fully counterclockwise before the power switch on.
2. Connect a DC VTVM to the Test Point L-CH and L-E (R-CH and R-El.

3.
No. 2471

Adjust R721 (R722l for DC VTVM reading of 5mV.

Fig. 12