Technics SLCH 7 Service Manual

Page 1

ORDER NO. AD9104084C8

Service Manual

Compact Disc Player Compact Disc Player
SL CH7
DIGITAL AUDIO
Color
(K) ......... Black Type
Areas
C833? Area Color
(E) Continental Europe.
(K)
((30) Third Region

System: SC-CH7

NEW MECHANISM SERIES (30001102)

Because of unique interconnecting cables,
when a component requires service, send or
bring in the entire system.

(DIN 45 500)
I AUDIO Notes:
Frequency response 2 Hz~20 kHz 1. Total harmonic distortion is measured by the digital spectrum
(:1 dB) analyzer.
Wow and flutter Below measurable limit 2. Specifications are subject to change without notice.
3. Weight and dimensions shown are approximate.
I PICKUP
Wavelength 780 nm
I GENERAL
Power consumption 17 W
Dimensions (WXHXD) 215x55><295 mm
(815/32 X 25/32 x 1 1 5/3)

Weight 2.0 kg (4.4 lb.)

System Tuner Amplifier CD player Cassette Deck Speakers

SC-CH7 ST-CH7L SU-CH7 SL-CH7 FIS-CH7 SB-CH7
Technics / Panasonic

(E) (60)

Page 2

SL-CH7

I CONTENTS

PRECAUTION OF LASER DIODE
LOCATION OF CONTROLS .......
HANDLING PRECAUTIONS FOR TRAVERSE DECK .
DISASSEMBLY INSTRUCTIONS . ..
SCHEMATIC DIAGRAM .......
PRINTED CIRCUIT BOARDS . ..
WIRING CONNECTION DIAGRAM .

BLOCK DIAGRAM

DIGITAL SERVO SYSTEM .......

I PRECAUTION OF LASER DIODE

CAUTION: This product utilizes a laser diode with the unit turned on, invisible laser radiation is emitted from the pick up lens.

Wave length: 780nm

Page

CHECKING THE OPERATION PROBLEMS ON THE
TRAVERSE DECK (OPTICAL PICKUP) ................ 24, 25
MEASUREMENTS AND ADJUSTMENTS ................ 25, 26
TROUBLESHOOTING GUIDE .......... t. 27. 28
DESCRIPTION OF FL PANEL .. ,t.. 29
FUNCTIONS OF IC TERMINALS .......... 30~34
REPLACEMENT PARTS LIST ............ ,. 35~38, 41
CABINET PARTS LOCATION ................ . .. . 39, 40
CABINET PARTS LOCATION (Loading unit parts) ............ 41

Maximum output radiation power from pick up: 100 uW/VDE

Laser radiation from the pick up lens is safety level, but be sure the followings:

ANN-4

. Do not disassemble the optical pick up unit, since radiation from exposed laserd diode is dangerous.
. Do, not adjust the variable resistor on the pickup unit. It was already adjusted.

. Do not look at the focus lens using optical instruments.

. Recommend not to look at pick up lens for a long time.

ACHTUNG: Dieses produkt enthélt eine Iaserdiode. Im eingeschalteten zustand wird unsichtbare laserstrahlung von der

lasereinhelt abgestrahlt.

Wellenlange: 780nm
Maximale strahlungsleistung der lasereinhelt: 100 uW/VDE

Die strahlung an der lasereinheit ist ungefahrlich, wenn folgende punkte beachtet werden:

1 Die lasereinhelt nicht zerlegen, da die strahlung an der freigelegten laserdiode gefahrlich ist.
2. Den werksseitig justierten einstellregler der lasereinreit nicht versteilen.

3. Nicht mit optischen instrumenten in die fokussierlinse blicken.

4. Nicht Uber langere zeit in die fokussierlinse blicken.

ADVARSEL: i dette a apparat anvendes laser.

Amuse: usvuuc LASERSTRALING
vm Aaums, Milli SIKKEIIHEUSAF-

mum: in UUE AF rummou.
uunaA unsmtsz run srnALmG.

VDRSICHT-Unslehtbaia DANGER-Invisible

Lasaistuhlunu, wenn laser million Mun

Ahdeckuno goiiiimt. wan.

Nicht III! Sushi AVOID DIRECT EX-

aussntnnt minim PUSURE T0 BEAM.
Note:

VARO' Avanaessa ja
suojelukitus
ohiIeItaessa olet
alniina nékymfittémélle
lasersateilylie.

Ala katso sateeseen.

VARNING! Osynlig

lasersirélning nér

denna del ar oppnad

och sparren air

urkopplad,

Betrakta ej stralen.
ROI-$0051

CLASS 1
LASER PRODUCT

Refer to the service manual for Model No. SU-CH7, Order No. ADQ104082C8 for intormation on
ACCESSORIES. INSTALLATION OF THE SYSTEM, CONNECTIONS and PACKAGING.

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Page 17

SL-CH7

I DIGITAL SERVO SYSTEM

The newly-developed digital servo system is adopted in the servo circuit of the units CD player instead of the
ordinary analog servo system.

i. The diagrams shown below represent differences between the analog servo and digital servo systems, The HEAD AMP. output signals (i.e., focus
error and tracksing error output signals) are analog. These analog signals are convened to the 8-bit digital signals through the MN6650. The

MN6650 performs the following adjustments automatically; locus offset, tracking oilset, locus gain, tracking gain, and tracking balance adjustments.

The outputs from the MN6650 such as the focus coil driving signal. tracking coil driving signal, and traverse motor driving signal are converted to
analog signals again and sent to the cells and motor to perform proper servo control for a disc.

ANALOG SERVO SYSTEM
® ® ® ® ® 8

6 VHS require adjustment

_ To EMF demodulation Digital audio I
RF Signa circuit ' '- playback J
AN8374 (Analog processing)
[ 1 AN8373 t : Focus coil h
|
|-> I FOCUS SERVO : Lens
. I $0
I |
A B Focus error ' I Tracking coil
output Signal : i
HEAD . TRACKING I
AMP. : SERVO :
C D | I
|
| l
Tracking error : TRAVERSE : .
PD output signal : SERVO I Traverse coH
J i
I i
l_ _ _ _ _ _ _ E , ad
Microcomputer
DIGITAL SERVO SYSTEM
O
Only 1 VR requires adjustment (best eye adjustment) i.
. To EMF demodulation Digital audio
RF mgnal- circuit - playback J!
I I AN8800 MN6650 (Digital servo processor) r
[*5 i
:
Focus error :
A B ' output signal l
HEAD l
AMP. 1 Soft
C D s microprogram
_->l processing
Tracking error j | Traverse coil
PD output signal : j
l |
L ___________ .-J
T
Microcomputer
_..22_

L SL-CH7

2. The servo processor lC MN6650 of the newly-developed digital servo circuit automatically performs the following adjustments which were

originally adjusted in the conventional analog sen/o circuit:

(1) Focus offset, (2) Tracking offset, (3) Focus gain. (4) Tracking gain, and (5) Tracking balance. Therefore. you do not have to perform
not the above-mentioned electrical adjustments manuallyt Only the best eye (PD balance) needs to be adjusted adjustment. You can obtain
an optimum servo control tor a disc to be played.

[You must perform the best eye (PD balance) adjustment manually]

The following flow chart shows the sequence of automatlc adjustments.

0Flow chart on automatic adjustment sequence

START
Focus search operation: ON

Focus offset adjustment

Because the microcomputer precisely performs
automatic adjustments as shown in the flow chart.
it will take approx. 5 seconds to finish reading TOC
data if a used disc is eccentric one or its surface is

Temporary adjustment of focus gain Warped»

Spindle motor starts rotation

Tracking offset adjustment

No

Does focus pull in? Approx. 2.5 sec.

Focus servo operation: ON
Tracking servo operation: ON

Temporary adjustment of tracking'gain

Tracking balance adjustment

NO Does tracking pull in?

\
Yes

Fine adjustment of focus gain

Fine adjustment tracking gain

END

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