SAMSUNG SCM6700LC Service Manual

Samsung Electronics Co., Ltd. Aug. 1996. Code No. AH68-20126A

MUSIC CENTER

1. Precautions

2. Specifications

3. Disassembly and Reassembly

4. Alignment and Adjustments

5. Special Circuit Descriptions

6. Troubleshooting

7. Exploded Views and Parts List

8. Electrical Parts List

9. Block Diagrams

10. PCB Diagrams

11. Wiring Diagram

12. Schematic Diagrams

MONO/ST

CLOCK TIMER

TUNING

TUNER

TAPE

PHONO

VOLUME

BAND

PRESET/MANUAL

MEMORY

CLASSIC POPS ROCK

EQ PRESET

PLAY/PAUSE

STOP/CLEAR

HI-SPEED DUBBING

OPEN/CLOSE

DISPLAY INTRO

SKIP

REPEAT RANDOM

ON/STANORY

POWER

DECK 1

REC/PLAY

PLAYBACK

DECK 2

HIGH SPEED DUBBING CONTINUOUS PLAY

PHONES

REC PLAY REW STOP/EJ PAUSEF.FWD PLAY REW F.FWD STOP/EJ PAUSE

SERVICE

Manual

MUSIC CENTER

SCM-6700

CONTENTS

1. Precautions

Follow these safety, servicing and ESD precautions to prevent damage and protect against potential hazards such as electrical shock and X-rays.

1-1 Safety Precautions

1. Be sure that all of the built-in protective devices are replaced.

(Reading should

2. When reinstalling the chassis and its assemblies, be sure to restore all protective devices, including control knobs and compartment covers.

3. Make sure that there are no cabinet openings through which people-particularly children--might insert fingers and contact dangerous voltages. Such openings include the spacing between the picture tube and the cabinet mask, excessively wide cabinet ventilation slots, and improperly fitted back covers.

Device Under

Test

Test all

exposed metal

surfaces

2-Wire Cord

Also test with plug reversed (using AC adapter plug as required)

Fig. 1-1 AC Leakage Test

not be above

0.5mA)

Leakage Currant Tester

Earth Ground

4. Design Alteration Warning: Never alter or add to the mechanical or electrical design of the unit. Example: Do not add auxiliary audio or video connectors. Such alterations might create a safety hazard. Also, any design changes or additions will void the manufacturer's warranty.

5. Leakage Current Hot Check (Figure 1-1): Warning: Do not use an isolation transformer during this test. Use a leakagecurrent tester or a metering system that complies with American National Standards Institute (ANSI C101.1, Leakage Current for Appliances), and Underwriters Laboratories (UL Publication UL1410, 59.7).

With the unit completely reassembled, plug the AC line cord directly into a 120V AC outlet. With the unit's AC switch first in the ON position and then OFF, measure the current between a known earth ground (metal water pipe, etc.) and all exposed metal parts. Examples: Handle brackets, metal cabinets, screwheads and control shafts. The current measured should not exceed 0.5 milliamp. Reverse the powerplug prongs in the AC outlet and repeat.

6. Insulation Resistance Cold Check: (1) With the unit's AC plug disconnected from the AC source, connect an electrical jumper across the two AC prongs. (2) Set the power switch to ON. (3) Measure the resistance between the shorted AC plug and any exposed metallic parts. Example: Screwheads, antenna, control shafts or handle brackets.

If any of the exposed metallic parts has a return path to the chassis, the measured resistance should be between 1 and 5.2 megohms. If there is no return path, the measured resistance should be "infinite." If the resistance is outside these limits, a shock hazard might exist. See Figure 1-2

Antenna Terminal

Exposed Metal Part

ohm

Ohmmeter

Fig. 1-2 Insulation Resistance Test

Samsung Electronics 1-1

Precautions

1-1 Safety Precautions (Continued)

7. Components, parts and wiring that appear to have overheated or that are otherwise

damaged should be replaced with parts that meet the original specifications. Always determine the cause of damage or overheating, and correct any potential hazards

8. Observe the original lead dress, especially

near the following areas: Antenna wiring, sharp edges, and especially the AC and high voltage power supplies. Always inspect for pinched, out-of-place, or frayed wiring. Do not change the spacing between components and the printed circuit board. Check the AC power cord for damage. Make sure that no wires or components touch thermally hot parts.

1-2 Servicing Precautions

9. Product Safety Notice: Some electrical and mechanical parts

have special safety-related characteristics which might not be obvious from visual inspection. These safety features and the protection they give might be lost if the replacement component differs from the original--even if the replacement is rated for higher voltage, wattage, etc.

10 Components that are critical for safety are

indicated in the circuit diagram by

shading, or . Use replacement

components that have the same ratings,

especially for flame resistance and

dielectric strength specifications. A

replacement part that does not have the

same safety characteristics as the original

might create shock, fire or other hazards.

Warning1: First read the "Safety Precautions" section of this manual. If some unforeseen circumstance creates a conflict

between the servicing and safety precautions, always follow the safety precautions.

1. Servicing precautions are printed on the cabinet. Follow them.

2. Always unplug the unit's AC power cord from the AC power source before attempting to: (a) Remove or reinstall any component or assembly, (b) Disconnect an electrical plug or connector, (c) Connect a test component in parallel with an electrolytic capacitor.

3. Some components are raised above the printed circuit board for safety. An insulation tube or tape is sometimes used. The internal wiring may be clamped to prevent contact with thermally hot components. Reinstall all such elements to their original position.

4. After servicing, always check that the screws, components and wiring have been correctly reinstalled. Make sure that the portion around the serviced part has not been damaged.

5. Check the insulation between the blades of the AC plug and accessible conductive parts (examples: metal panels, input terminals and earphone jacks).

6. Insulation Checking Procedure: Disconnect the power cord from the AC source and turn the power switch ON. Connect an insulation resistance meter (500V) to the blades of the AC plug.

The insulation resistance between each blade of the AC plug and accessible conductive parts (see above) should be greater than 1 megohm.

7. Never defeat any of the B+ voltage interlocks. Do not apply AC power to the unit (or any of its assemblies) unless all solid-state heat sinks are correctly installed.

8. Always connect a test instrument's ground lead to the instrument chassis ground before connecting the positive lead; always remove the instrument's ground lead last.

Samsung Electronics1-2

1-3 Precautions for Electrostatically Sensitive Devices (ESDs)

Precautions

1. Some semiconductor ("solid state") devices are easily damaged by static electricity. Such components are called Electrostatically Sensitive Devices (ESDs). Examples include integrated circuits and some field-effect transistors. The following techniques will reduce the occurrence of component damage caused by static electricity.

2. Immediately before handling any semiconductor components or assemblies, drain the electrostatic charge from your body by touching a known earth ground. Alternatively, wear a discharging wrist-strap device. (Be sure to remove it prior to applying power--this is an electric shock precaution.)

3. After removing an ESD-equipped assembly, place it on a conductive surface such as aluminum foil to prevent accumulation of electrostatic charge.

4. Do not use freon-propelled chemicals. These can generate electrical charges that damage ESDs.

5. Use only a grounded-tip soldering iron when soldering or unsoldering ESDs.

6. Use only an anti-static solder removal device. Many solder removal devices are not rated as "anti-static" (these can accumulate sufficient electrical charge to damage ESDs).

7. Do not remove a replacement ESD from its protective package until you are ready to install it. Most replacement ESDs are packaged with leads that are electrically shorted together by conductive foam, aluminum foil or other conductive materials.

8. Immediately before removing the protective material from the leads of a replacement ESD, touch the protective material to the chassis or circuit assembly into which the device will be installed.

9. Minimize body motions when handing unpackaged replacement ESDs. Motions such as brushing clothes together, or lifting a foot from a carpeted floor can generate enough static electricity to damage an ESD.

1-4 Special Precautions and Warning Labels for Laser Products

(UL)

This Product Complies with DHHS Rules 21CFR, Sub chapter J.At date of Manufacture

(SCAN)

CAUTION : INVISIBLE LASER RADIATION WHEN OPEN

AND INTERLOCKS DEFEATEO AVOIDEXPOSURE TO BEAM

ADVARSEL:USYNLIG LASERSTRÅLING VED ABNING

NÅR SIKKERHEDSAFBRYDERE ER UDE AF FUNKTION

UNDGA UDSAETTELSE FOR STRALING

VARO:AVATTAESSA JA SUOJALUKITUS OHITETTAESSA

OLET ALTTINA NAKYMATTÖMALLE LASERSATEILYLLE ALA KATSO SATEESEEN!

VARNING:OSYNLIG LASERSTRÅLNING NAR DENNA DEL

AR OPPNAD OCH SPARREN AR URKOPPLAD BETRAKTA EJSTRÅLEN!

CERTIFIED ONLY TO CANADIAN ELECTRICAL CODE.

CERTIFIE EN VERTU DU CODE CANADIAN DE LELETRICITE SEULEMENT

Fig. 1-3 Warning Labels (Location: Enclosure Block)

(EU)

(CSA)

UL : Manufactured for U.S.A. Market. CSA : Manufactured for Canadian Market. EU : Manufactured for European Market. SCAN : Manufactured for Scandinavian

Market.

(EU)

CLASS 1 LASER PRODUCT

Fig. 1-4 Warning Labels (Location: Disc Clamper, Inner Side of Unit Door or Nearby Unit Chassis )

Samsung Electronics 1-3

Precautions

1-4 Special Precautions and Warning Labels for Laser Products (Continued)

1-4-1 Warnings

1. When servicing, do not approach the LASER exit with the eye too closely. In case it is necessary to confirm LASER beam emission, be sure to observe from a distance of more than 30 cm from the surface of the objective lens on the optical pick-up block.

2. Do not attempt to handle the objective lens when the DISC is not on the tray.

1-4-2 Laser Diode Specifications

Material: GaAs+ GaAlAs Wavelength: 760-800 nm Emission Duration: Continuous

Laser Output: 0.2 mw (measured at a

1.6 mm distance from the objective lens surface on the optical pick-up block.)

1-4-3 Handling the Optical Pick-up

1. Static electricity from clothing or the body may cause electrostatic breakdown of the laser diode in the Optical Pickup. Follow this procedure:

2. Place a conductive sheet on the work bench (i.e., the black sheet used for wrapping

repair parts.) Note: The surface of the work

bench should be covered by a copper

ground plane, which is grounded.

3. The repair technician must wear a wrist strap which is grounded to the copper sheet.

4. To remove the Optical Pickup block: Place the set on the conductive sheet, and momentarily touch the conductive sheet

with both hands. (While working, do not

allow any electrostatic sources--such as clothes--to touch the unit.)

5. Ground the "Short Terminal" (located on the PCB, inside the Pickup Assembly) before replacing the Pickup. This terminal should be shorted whenever the Pickup Assembly

is lifted or moved.

short terminal

SOH91VI(LDP)

short terminal

SOH91CI(CAR,walkman)

6. After replacing the Pickup, reopen the Short Terminal. See diagrams below:

THE UNIT

(1) WRIST-STRAP FOR GROUNDING

short terminal

SOH-A1

(CMS-V10,CMS-V30)

SOH94T4N

(CMS-V10,CMS-V30)

CONDUCTIVE SHEET

short terminal

Samsung Electronics1-4

Power source

Power consumption Dimensions (mm)

AC 115/230V 50/60Hz (Option) 30W 350(W)x328(H)x316(D)

Power output Total harmonic distortion Frequency range Signal to noise ratio Channel separation

Frequency range Usable sensitivity Signal to noise ratio IF rejection ratio Total harmonic distoration Separation (Stereo)

Frequency range Usable sensitivity Signal to noise ratio IF rejection ratio Total harmonic distoration

Frequency range Usable sensivity Signal to noise ratio

Frequecny range WOW FLUTTER Erasing effect Signal to noise ratio Total harmonic distortion

Frequency response Signal to noise ratio Channel separation Total harmonic distortion

87.5 ~ 108MHz 6µV 55dB 60dB

0.5% 25dB

522 ~ 1611KHz 600µV 40dB 30dB 1%

146 ~ 290KHz 1200µV 35dB

125Hz ~ 12.5KHz

0.15% 50dB 40dB

2.5%

20Hz ~ 20KHz(¡ 1dB) 85dB(1kHz 0dB) 75dB(1kHz 0dB)

0.1%(1kHz 0dB)

5W/CH

0.5% 50Hz ~ 17kHz 60dB 45dB

General

Amp

Tuner

Cassette

Compact Disc

Samsung Electronics 2-1

* Specifications are subject to change without notice.

2. Specifications

3. Disassembly and Reassembly

3-1 Turn-Table, Cabinet-Front, Cabinet-Bottom

1. Remove Door-CD (Direction A).

2. Release 6 screws !.

3. Remove Turn-Table (Direction B).

4. Release 2 screws @.

5. Release 2 screws #.

6. Remove Front-Cabinet.

Samsung Electronics 3-1

Figure 3-1

3-2 Deck-CD, Front-PCB, Cassette-Deck, Door-Cassette

1. Release 2 screws !.

2. Remove Deck-CD ASSÕY.

3. Release 4 screws @.

4. Remove Deck-CD.

5. Release 17 screws #.

6. Remove Front-PCB, SUB-PCB.

7. Release 7 screws $.

8. Remove Cassette-Deck.

3-2 Samsung Electronics

Figure 3-2

Disassembly and Reassembly

3-3 Cabinet-Bottom and Main-PCB

1. Release 3 screws !.

2. Remove Main-PCB.

Samsung Electronics 3-3

Figure 3-3

Disassembly and Reassembly

3-4 CD Pack

1. Undo 2 screws (A), and remove the Chuck-Bracket @, the Ferrite-Magnet 5, Chuck Union-Table $ and Chuck-Holder &.

2. Undo 2 screws (B), pull the Tray-M1 1 forward to remove.

3. Undo 1 screw (C), and remove the Cam-Spring 8 and the Cam #.

4. Undo 1 screw (D), and remove the Gear-Pulley (, the Belt-Pulley @, the Gear-A % and the Gear-B ^.

5. Undo 2 screws (E), and remove the Motor-Pulley ) and the Dc-Motor 0 .

6. Undo 2 screws (F), and remove the Leaf-Switch 9 and the Detector-Switch “. Disconnect the Lead- Connector assÕy 4 with soldering iron.

7. Remove the AssÕy PCB 3 with soldering iron and remove the PCB-Holder + .

8. Undo 4 screws from the CD-Shaft 7, and remove the CD-Rubber 6 and the CD-Deck ‘

3-4 Samsung Electronics

Figure 3-4

1 1

3 3 5 5 6 6

8 8

9 9

1010

1717

1818

1919

2020

1414

2121

1111

1212

1313

1414

1717 1616

1717

1616

2222

2323

2 2

4 4

7 7

1515

Disassembly and Reassembly

3-5 CD Deck

1. Remove the Shaft ! .

2. Lift the P/U @ . Note : Take extreme care not to touch the surface of lens.

3. Lift the Center-ring # .

4. Remove the Spring-T/Table $ .

5. Remove the Turn-Table (M) % .

6. Remove 2 screw ^ and then remove the Motor-Spindle & .

7. Remove the Gear-Cover * by pushing the hook.

8. Remove the Gear(c) ( by pushing the hook.

9. Lift the Gear(b) ) .

10. Remove the Gear(a) 1 .

11. Remove 2 screws 2 and then remove the Feed-Motor 3 .

12. Remove the Deck(M)-Chassis 4.

Samsung Electronics 3-5

Figure 3-5

Disassembly and Reassembly

4. Alignment and Adjustments 4-1 Tuner

CSVR801

CCON801

ISVR2

ISVR1

IT2

OT1

OT2

OCT2

OCT4

OCT3

OL2

OL1

TCON1

OCT1

IT1

KT431

FM T.H.D Adjustment

SSG FREQ. 98MHz Adjustment

point FM DETECTOR COIL

(IT1)

Minumum output(Figure 4-1)

FM Search Level Adjustment

SSG FREQ. 98MHz Adjustment

point SEMI-VR(50KB)

(ISVR1)

"TUNED" is shown on LCD(Figure 4-2)

FM Antenna Terminal

Speaker Terminal

Input

Figure 4-1 IF CENTER and T.H.D Adjustment

Figure 4-2 FM Auto Search Level Adjustment

Output

Distortion Meter

Oscilloscope

FM antenna

FM SSG

GND

30dB

75Ω Dummy

50Ω Dummy

FM IN

FM Antenna

SET

50 kB

SET

Output GND

FM Stereo Adjustment

SSG FREQ. 98MHz Adjustment

point SEMI-VR(5KB)

(ISVR2)

L-CH/R-CH : Maximum(Figure 4-3)

Figure 4-3 FM Stereo Separation Adjustment

EXT

FM SSG

Stereo Modulator (Pilot 10%)

Speaker terminal

SET

GND

OUT

VTVM

5KB

4-1Samsung Electronics

Step

Item

Connection SSG.FREQ.

FREQ. Setting

Adjust. Point

Remark

Maximum output

Intermediate frequency (IF) adjustment

AM frequency coverage adjustment

Figure 4-5

Figure 4-4 Connect DC

voltmeter to TCON1 and GND(TP1)

522 KHZ

522 KHZ IT 2

OT 1

OCT 2

OL 1

OCT 1

0.9V

522 KHZ

594 KHZ

1404 KHZ

1611 KHZ

594 KHZ

1404 KHZ

Figure 4-5

Repeat step 2 and 3 serveral times

Repeat step 5 and 6 several times

AM tracking adjustment

Figure 4-4 AM Frequecny Coverage Adjustment

Figure 4-5 AM Tracking Adjustment

SET

TP2

DC Voltmeter

Input

TP1

AM Signal Generator

Test Loop Antenna

AM Loop Antenna Jack

Speaker terminal

GND

Oscilloscope

VTVM

OUT

SET

60 cm

Samsung Electronics4-2

Alignment and Adjustments

4-1-1 Test Equipment

1. AM Standard Signal Generator (S.S.G) : 400Hz, 30% MOD

2. Oscilloscope

3. VTVM

4. Frequency counter

5. Loop antenna

6. Dummy load (4½)

7. DC voltmeter

4-1-2 Pre-Adjustment

1. Check the source voltage.

2. Set function and band switches to the band to be aligned.

3. Set the equalizer, volume and balance controls to mid position.

4-1-3 AM Adjustment

Alignment and Adjustments

Figure 4-6

Figure 4-7

Figure 4-8

4-2 Cassette Deck

4-2-1 Additional Test Equipment : Testing Tape

1. MTT-111 (or equivalent) : Test tape on which 3 KHz signal is recorded (Tape speed adjustment).

2. MTT-114 (or equivalent) : Test tape on which 10 KHz signal is recorded (Azimuth adjustment).

4-2-2 Recording Bias Adjustment

1. Connect frequency counter KC434 and press the REC button.

2. Adjust KT431(BIAS OSC COIL) until frequency counter reads 85¡ 0.2KHz.

Item

Connection

Preparation

Tape speed (normal speed) adjustment

Figure 4-6

Figure 4-8

3 KHz

CSVR801

AZIMUTH (DECK A,B) adjustment

Maximum output and identical phase of L,R channel. Set the screw after adjustment.

Insert MTT-111 to Deck A or B. Press PLAY button.

Insert MTT-114 to Deck A and Deck B. Press PLAY button.

CSVR801

CCON801

ISVR2

ISVR1

IT2

OT1

OT2

OCT2

OCT4

OCT3

OL2

OL1

TCON1

OCT1

IT1

KT431

Figure 4-7

AZIMUTH Adjustment screw

REC PB Head

Oscilloscope

OUT

INSET

Frequency Counter

Speaker Terminal

Remark

Adjustment point

SET

(GND)

VTVM

V H

4-3Samsung Electronics

Samsung Electronics4-4

4-3 CD

TP2

TP1

Vref

NVR1704

NVR1703 NVR1702

NVR1701

TE CENTER

FE CENTER

E.F BAL

F.BIAS

A=B

---100mV

---0V

---250mV

---0 V

---100mV

---0 V

4-3-1 To Adjust FOCUS BIAS(STOP mode)

4-3-3 To Adjust Focus Gain (PLAY mode)

4-3-2 To Adjust Tracking Gain (PLAY mode)

4-3-4 To Adjust E/F Balance (PLAY mode)

1. Set Volt/Div of the oscilloscope to DC 100mV.

2. Ground the scope input and set the waveform to 0V, DC range.

3. Connect the GND terminal of the oscilloscope to Vref, and (+) terminal to center of TP1.

4. Set NVR1701 to 0mV.

1. Connect the GND terminal of the oscilloscope to Vref and (+) terminal to TP2.

2. Load and play the disc

3. While the disc is running adjust the gain with NVR1704 as shown below.

1. Connect the GND terminal of the oscilloscope to Vref and (+) terminal to TP1.

2. Load and play the disc

3. While the disc is running adjust the gain with NVR1703 as shown in the following figure.

VOLT/DIV : 0.2V TIME/DIV : 2mS

Normal frequency

Low frequency

High frequency

Low frequency

High frequency

VOLT/DIV : 0.1V TIME/DIV : 2mS

VOLT/DIV : 0.2V TIME/DIV : 2mS

1. Set TIME/DIV of the oscilloscope to 2mS.

2. Set Volt/DIV of the oscilloscope to 0.5V.

3. Ground the scope input and set to DC and then set the DC range.

4. Connect the GND terminal of the oscilloscope to Vref and (+) terminal to center to TP2.

5. Load and play the disc.

6. Turn NVR1704 counterclockwise to the minimum value.

7. Raise NVR1702 and adjust the waveform so that its middle comes to GND of the oscilloscope (or until the upper half of waveform becomes symmetrical to the bottom half, A=B)

8. Adjust NVR1704 (arrow) for normal sound.

Alignment and Adjustments

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