SAMSUNG MM26LC Service Manual

Samsung Electronics Co., Ltd. Sep. 1996. Code No. AH68-20129A

MICRO COMPONENT SYSTEM

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

VOLUME

BAND

MUTE

PRESET

PUSH EJECT

SRS

ON/STANDBY

TUNING

COUNTER

REC/STOP

POWER

TUNER

TAPE

AUX

PHONES

SRS

SERVICE

Manual

MICRO COMPONENT SYSTEM

MM-26

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 230V 50Hz (Option) 90W 162(W)x280(H)x278(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 10dB 50dB 60dB

1.5% 25dB

522 ~ 1611KHz 50dB 40dB 33dB 2%

146 ~ 290KHz 60dB 33dB

125Hz ~ 8KHz

0.2% 50dB 40dB

2.5%

100Hz ~ 10KHz(¡ 1dB) 85dB(1kHz 0dB) 75dB(1kHz 0dB)

0.1%(1kHz 0dB)

12.5W/CH

0.5% 50Hz ~ 30KHz 70dB 40dB

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 Cabinet-Top, Cabinet-Rear

1. Remove 8 screws of ! and 6 screws of @ of its rear part.

2. Pull its top part upward vertically as shown in the figure 3-1.

Samsung Electronics 3-1

Figure 3-1

3-2 Main-PCB

1. Remove the Main-PCB backward.

3-2 Samsung Electronics

Main-PCB

Figure 3-2

Disassembly and Reassembly

3-4 CD-Pack

1. Undo 4 screws of ! and then remove the CD-Pack downward.

3-3 Cabinet-Bottom

1. Remove 3 screws of ! and pull it out backward.

Samsung Electronics 3-3

Figure 3-3

Figure 3-4

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-knob #.

4. Remove the Center-ring $ .

5. Remove the Spring-T/Table % .

6. Remove the Turn-Table (M) ^ .

7. Remove 2 screw & and then remove the Spindle-Motor * .

8. Remove the Cover-Gear ( by pushing the hook.

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

10. Lift the Gear(b) 1 .

11. Remove the Gear(a) 2 .

12. Remove 2 screws 3 and then remove the Feed-Motor 4 .

13. Remove the Chassis-Deck(M) 5.

3-4 Samsung Electronics

Figure 3-5

Disassembly and Reassembly

***

Remark

*** After adjusting the AM, be sure to adjust the FM.

4. Alignment and Adjustments 4-1 Tuner

FM T.H.D Adjustment

SSG FREQ. 98MHz Adjustment

point FM DETECTOR COIL

(IFT2))

Minumum output(Figure 4-1)

AM Search Level Adjustment

SSG FREQ. 999KHz Adjustment

point SEMI-VR(20KB)

(ISVR2)

"TUNED" is shown on LCD(Figure 4-3)

AM I.F Adjustment

SSG FREQ. 450KHz SET FREQ. 522KHz

Adjustment point AM IF COIL

(IFT1)

"TUNED" is shown on LCD(Figure 4-3)

FM Antenna Terminal

Speaker Terminal

Input

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

Figure 4-3 AM Auto Search Level Adjustment

Output

Distortion Meter

Oscilloscope

FM SSG

AM SSG

52dB

20K

Test Loop Antenna

GND

20dB

75Ω Dummy

FM IN

FM Antenna

SET

5 kB

SET

Output GND

FM Stereo Adjustment

SSG FREQ. 98MHz Adjustment

point SEMI-VR(5KB)

(ISVR1)

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

Figure 4-2 FM Stereo Separation Adjustment

4-1Samsung Electronics

AM Antenna

AM Loop antenna jack

Speaker Terminal

Oscilloscope

OUT

SET

GND

60 cm

Electronic Voltmeter

Alignment and Adjustments

4-2 Cassette Deck

Recording/Play head

4-2-1 To Adjust Tape Speed

NOTES

1. Measuring tape: i) MTT-111 (or equivalent) (Tapes recorded with 3KHz)

ii) MTT-5512 (or equivalent)

2. Connect the set to the frequency counter

as in Figure 4-4.

Step

Item

NOR SPEED Control counter

Pre-Setup Condition

Figure 4-4

Pre-Setup

1) Deck: MTT-111

2) Press PLAY SW

button

SET

To Adjust

Turn JVR51 to left and right.

4-2-2 To Adjust Azimuth and Record BIAS

Speaker Terminal

Frequency Counter

Output

Figure 4-4

Standard

Remark

3KHZ 1%

NOTES

1) Measuring tape : i) MTT-113CN (or equivalent 8 kHz AZIMUTH

control).

2) The SET is connections as shown in Figure 4-6.

1.Adjust 1-Deck Replay Level

Step

Item

AZIMUTH

Pre-Setup Condition

Figure 4-5

Pre-Setup

After putting MTT

-113CN into Deck .

1) Press FWD PLAY button.

2) Press REV PLAY button.

Forward Play

SET

JC25

(GND)

To Adjust

1) Figure 4-5

2) Adjust the right control screw to playback Rev.

Mode.

AZIMUTH control

Figure 4-5

DUMMY

Figure 4-6

Standard

Max output and same phase (both channels).

Reverse Play

Frequency Counter

Remark

After adjustment secure it with REGION LOCK.

2.Adjust Record Bias Level

Step

Item

BIAS

Pre-Setup Condition

Figure 4-6

Pre-Setup

Insert MTT-5512 into Deck,then press REC button.

To Adjust

Turn BIAS oscillator frequency coil (JT1) to the right and left

Standard

85KHz 5%

Samsung Electronics4-2

Remark

See the diagram for adjustment locations

4-3Samsung Electronics

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

6. Troubleshooting

6-1 Main

6-1-1 Power Malfunction

Samsung Electronics 6-1

Front PCB µ-com VDD(5V)

normal?

UIC1 pin no. 9,36,37

Replace RIC1

Main PCB RIC1(BA3950) IN: 20V

Input voltage normal?

Yes

Check the Power PCB; RF4 (T3.15 AL 250V)

Yes

Front PCB

Does UX1(4.5MHz)

oscillate ?

FRONT PCB POSNS

voltage normal ?

(pin no. 13 ;5.0V)

Check the Main PCB RZD2,RC4,RR3,RR4, RR2,RC1,RD1

Replace µ-com

Yes

Front PCB

When the power is

ON 'H' displays

at pin no. 49 ?(5V)

Yes

Connect Front PCB and Main PCB.

Check the connector Main PCB.

Wafer JWC3,JWC4

6-2 Samsung Electronics

Troubleshooting

6-1-2 No Output

Yes

AQ1L/1R Base B+ ?

Yes

Is Mute selected ?

Headphone Jack short ?

Remove it with Remocon

Replace Headphone jack soldering condition

Main PCB AIC1(LM1876TF)

pin no. 4,2,15

B+,B- circuits

Check the B+ power source part in RD2(PBL403), RC3 and RC14.

Yes

Confirm for TR short replace it.

Yes

Samsung Electronics 6-3

Troubleshooting

6-1-3 Tuner Malfunction (FM/AM)

IZD1 Voltage ok ?

Yes

Check TUNER IC(LA1836)

pin no.10 ; 7.6V pin no.14 ; 6.5V

AM ; 0V ?

HZD1 (5.6V) Voltage ok?

HIC1 (LC72131) FM/AM BAND

Switching ok?

Yes

LC72131

CONTROL ok?

Yes

FM VT

LC72131 pin no.20

1.7V 7.5V ?

Yes

AM VT

LC72131 pin 20

Check the LC72131

CONTROL ok ?

Yes

Check HIC1

pin 20 ?

LPF(IL1, IL2)

output ok?

Check LC75394E function ok?

Check FEP interior

pattern, and any line

disconnections.

1) Power settion

defective ?

2) LC72131 Oscillator (HX1 : 7.2MHz) ok ?

3) System line ok?

Yes

Check for µ-com IC

Replace LC72131

Yes

0.9V 7V

Check IZD1 (6.8V), IR6

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