Samsung MM-18 User manual

MICRO COMPONENT
SYSTEM
MM-18
SERVICE Manual
MICRO COMPONENT SYSTME CONTENTS
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
mm18(10) 3/23/98 2:32 PM Page 1

ELECTRONICS
© Samsung Electronics Co.,Ltd. March 1998
Printed in Korea
Code no. AH68-20183A
mm18(10) 3/23/98 2:32 PM Page 2

1. Precautions
Follow these safety, servicing and ESD precautions to prevent damage and protect against potential hazards
such as electrical shock and X-rays.
Samsung Electronics 1-1
1-1 Safety Precautions
1. Be sure that all of the built-in protective
devices are replaced.
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.
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 connec-
tors. Such alterations might create a safety
hazard. Also, any design changes or addi-
tions will void the manufacturer's warran-
ty.
5. Leakage Current Hot Check (Figure 1-1):
Warning: Do not use an isolation
transformer during this test. Use a leakage-
current 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 power-
plug 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
Device
Under
Test
(Reading should
not be above
0.5mA)
Leakage
Currant
Tester
Earth
Ground
Test all
exposed metal
surfaces
Also test with
plug reversed
(using AC adapter
plug as required)
2-Wire Cord
Antenna
Terminal
Exposed
Metal Part
ohm Ohmmeter
Fig. 1-1 AC Leakage Test
Fig. 1-2 Insulation Resistance Test
S/S 4Page(Eng Q) 3/23/98 2:37 PM Page 1

Samsung Electronics1-2
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.
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.
1-2 Servicing 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.
Precautions
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.
S/S 4Page(Eng Q) 3/23/98 2:37 PM Page 2

Samsung Electronics 1-3
1-3 Precautions for Electrostatically Sensitive Devices (ESDs)
1-4 Special Precautions and Warning Labels for Laser Products
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.
Precautions
UL : Manufactured for U.S.A. Market.
CSA : Manufactured for Canadian Market.
EU : Manufactured for European Market.
SCAN : Manufactured for Scandinavian
Market.
This Product Complies with
DHHS Rules 21CFR, Sub
chapter J.At date of Manu-
facture
(UL)
(SCAN)
(EU)
CERTIFIED ONLY TO CANADIAN
ELECTRICAL CODE.
CERTIFIE EN VERTU DU CODE
CANADIAN DE LELETRICITE
SEULEMENT
(CSA)
CLASS 1
LASER PRODUCT
(EU)
Fig. 1-3 Warning Labels (Location: Enclosure Block)
Fig. 1-4 Warning Labels (Location: Disc Clamper, Inner Side of Unit Door or Nearby Unit Chassis )
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!
S/S 4Page(Eng Q) 3/23/98 2:37 PM Page 3

Samsung Electronics1-4
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.
6. After replacing the Pickup, reopen the Short
Terminal. See diagrams below:
Precautions
THE UNIT
(1) WRIST-STRAP
FOR GROUNDING
1M
1M
CONDUCTIVE SHEET
short
terminal short terminal short
terminal short
terminal
SOH91VI(LDP) SOH91CI(CAR,walkman) SOH94T4N
(CMS-V10,CMS-V30)
SOH-A1
(CMS-V10,CMS-V30)
S/S 4Page(Eng Q) 3/23/98 2:37 PM Page 4

2. Product Specfications
Samsung Electronics 2-1
General
Amp
Cassette
Tuner
Compact Disc
FM
MW
(AM)
LW
(option)
Power source
Power consumption
Dimensions (mm)
Power output (Front)
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 distortion
Frequency range
WOW FLUTTER
Erasing effect
Signal to noise ratio
Total harmonic distortion
Frequency response
Signal to noise ratio
Channel separation
Total harmonic distortion
Audio Output
125Hz ~ 10KHz
0.35%
55 dB
40 dB
2.5%
20Hz ~ 20KHz(±1dB)
90 dB(1kHz)
75 dB(1kHz)
0.1% (1KHz)
1V (1kHz 0dB)
Frequency range
Usable sensitivity
Signal to noise ratio
146 ~ 290KHz
63 dB
31 dB
87.5 ~ 108MHz
6 dB
50 dB
60 dB
0.8%
25 dB
522 ~ 1611KHz (Option)
56 dB
38 dB
45 dB
2%
5W / Ch (4 ohm)
0.5% (1kHz)
50Hz ~ 17kHz
68 dB
38 dB
AC 115/230V 50/60Hz(Option)
30W
160(W) x 255(H) x 264(D)
Specifications are subject to change without notice.
mm18(10) 3/23/98 2:48 PM Page 1

Remote Control
mm18(10) 3/23/98 2:48 PM Page 2

3. Disassembly and Reassembly
3-1 Cabinet-Top, Cabinet-Rear
1. Remove 6 screws of !and 8 screws of @of its rear part
2. Pull its top part upward vertically as shown in the figure 3-1
Figure 3-1
Samsung Electronics 3-1
mm18(10) 3/23/98 2:54 PM Page 1

Figure 3-2
3-2 Samsung Electronics
3-2 Main PCB
Disassembly and Reassembly
1. Pull out the Main-PCB backward horizontally.
mm18(10) 3/23/98 2:54 PM Page 2

3-3 Cabinet-Bottom
1. Pull out the Cabinet-Bottom backward.
1. Undo 4 screws of !and then remove the CD-Pack downward.
Figure 3-3
Figure 3-4
3-4 CD-Pack
Samsung Electronics 3-3
Disassembly and Reassembly
mm18(10) 3/23/98 2:54 PM Page 3

Figure 3-8
3-4 Samsung Electronics
3-6 CD Deck
1. Remove the Shaft !.
2. Lift the P/U @.
Note : Take extreme care not to touch the surface of lens.
If there is an alien materials, clean it with swab smeared alcohol.
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 screws &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.
11. Remove 2 screws 3and the then remove the Feed-Motor 4.
12. Remove the Chassis-Deck (M) 5.
Disassembly and Reassembly
4
6
713
21
9
10
11
12
14
15
8
3
5
mm18(10) 3/23/98 2:54 PM Page 4

4. Alignment and Adjustments
4-1 Tuner
Samsung Electronics 4-1
FM THD Adjustment
Minimum Distortion (Figure 4-1)
SSG FREQ.
Adjustment
point
(IT1)
98 MHz
FM DETECTOR COIL
FM Stereo Adjustment
L-CH/R-CH : Maximum(Figure 4-3)
SSG FREQ.
Frequency
Adjustment
point
(ISVR1)
98MHz
98MHz
SEMI-VR(5KΩ)
FM Search Level Adjustment
Adjust ISVR2 so that “TUNED” of LCD
is lighted (Figure 4-2)
Figure4-2 FM Auto Search Level Adjustment
Figure4-3 FM Stereo Separation Adjustment
Figure4-1 IF CENTER and THD Adjustment
SSG FREQ.
Adjustment
point
(ISVR2)
98 MHz
BEACON
SENSITIVITY
SEMI-VR(50KΩ)FM SSG
FM
SSG
75Ω
Dummy
5KΩ
Stereo
Modulator
(Pilot 10%)
OUT
Oscilloscope
FM antenna
SET
Speaker
Terminal
EXT
GND
VTVM
GND
22 dB
FM SSG
Output
GND
Speaker
Terminal
FM
Antenna
Terminal
Distortion Meter
Input
SET
Input
output
Oscilloscope
FM IN
FM Antenna
SET
50 kΩ
ISVR1
IT1
FM DET
ISVR2
mm18(5) 3/23/98 3:03 PM Page 1

4-2 Samsung Electronics
4-1-1 Test Equipment
4-1-2 Pre-Adjustment
4-1-3 AM Adjustment
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
1. Check the source voltage
2. Press TUNER/BAND to select the AM(MW) function.
3. Set the volume control to mid position.
Intermediate
frequency (IF)
adjustment
AM frequency
coverage
adjustment
AM tracking
adjustment
Figure 4-4
Connect DC
voltmeter to AM VT
and GND(OKV1)
1
2
4
5
3
Figure 4-5
Figure 4-5
450 KHz
594 KHz
Figure 4-4
SET
60 cm
AM Signal
Generator Test Loop
Antenna
Speaker
Terminal
VTVM
IN OUT
GND
Oscilloscope
AM
Loop
Antenna Jack
Figure 4-5
SET
AM VT(OR1)
OKV1 GND
Input
DC Voltmeter
594 KHz OL 1
-
-- -
-
-
-
-
522 KHz
522 KHz
IT 2
OT 1 0.9V
Maximum output
Maximum output
Non Adjust
Non Adjust
Remark
FREQ. Setting Adjust. PointSSG.FREQ.Item
Step Connection
Alignment and Adjustments
mm18(5) 3/23/98 3:03 PM Page 2

Samsung Electronics 4-3
4-2-1 Additional Test Equipment : Testing Tape
1. MTT-111 (or equipment) : Test tape on which 3KHz signal is recorded (Tape speed adjustment)
2. MTT-113CN (or equivalent) : Test tape on which 8KHz signal is recorded (Azimuth adjustment)
Tape
speed
1
2
Figure 4-6
Figure 4-8
SVR Inside motor
Figure 4-7
3KHz
Maximum output and
identical phase of L,R
channel.
Set the screw
after adjustment
Remark
Adjustment Point
Location no.
Item
Step Tape
Insert MTT-111 to
Deck.
Press PLAY button
Insert MTT-113CN
to Deck.
Press PLAY button
AZIMUTH
(DECK)
adjustment
TP3
Cassette Deck
Speaker
Terminal
output
LINE OUT
Frequency Counter
Figure 4-6
Figure 4-7
Recording /Play head
REVERSE PLAY
AZIMUTH control knob
Figure 4-8
In Out
Speaker
Terminal
Oscilloscope
SET
(GND)
VTVM
V H
4-2 Cassette Deck
Alignment and Adjustments
mm18(10) 3/23/98 2:59 PM Page 1

Samsung Electronics 5-1
5. Special Circuit Descriptions
5-1 RF Amp Block
5-1-1 RF Amplifier
5-1-2 Focus Error Amp
PD1
PD2
VC
RF-
RFO
RF SUMMINGAMP
VC
VC
VB 10K
58K
IV AMP
VA 10K
58K
IV AMP
+
-
+
-
+
-
65
66 73
74
32K
160K
4K
32K
164K
3K
+
-
+
-
+
-
63
59 FE1
VB>
VA>
SW1
FEBIAS
FEBIAS
sev-stopb
VC fe-stopb
fcmpo
sev-stop
X1 X2 X4 X8 X16
<5 Bit Counter>
The two currents from input pins PD1 (A+C) and PD2 (B+D) are converted into voltages through I/V Amp,
and they are added to RF summing Amp. The photo diode (A+B+C+D) signal which is I-V changed is
outputted by RFO (pin74). At this pin, the eye pattern can be checked.
The output of the focus error amp is the difference between RF I-V AMP(1) output Va and RF I-V AMP(2)
output Vb,just is the Photo Diode ((A+C) - (B+D)) signal which is I-V changed.
The focus error bias voltage applied to the (+) of focus error amp can be changed by D/A converter as shown
in diagram, so that the offset of focus error amp can be adjust automatical.
Focus error bias can be adjusted from the range of +100mV ~ -100mV by connectiong the resistor with pin 63
(FEBIAS).
mm18(10) 3/23/98 3:14 PM Page 5-1

Special Circuit Descriptions
5-2 Samsung Electronics
5-1-3 Tracking Error Amp
5-1-4 Focus OK Circuit
The current signals from the side spot photo diode (E and F) are input to the E and F pin and converted into
voltage signals by E I-V and F I-V AMP. The output of tracking error amp is due to the difference between
E I-V AMP voltage output.
The E-F balance can be adjusted by modifying the gain of E I-V AMP, and the tracking gain(Pin TE1) can be
adjusted automatically by micom program.
Extracting the DC part of RFI and RFO and comparing with the basic DC level, if RF Level is more than basic
level, the FOK is output. The focus OK circuit generates a timing window of focus on to monitor the focus
search status of focus serve.
+
-
79
68
67
F
E
EI
TGFI
BAL< 4 0 >
GAIN< 3 : 0 >
from Digital
TGL
TGH
TE1 LPFT
BALL
To ISTAT,TRCNT
BALH
GAIN
-
UP/DOWN
75K
220K 110K
56K 27K 13K
13K
16K
7.5K 3.3K 1.5K
IV AMP
IV AMP
WIN COMP
WIN COMP
54 55
-
40K
40K
40K 90K
57K
FOK
VC+0.625V
+
-
74
75 40
+
-
mm18(10) 3/23/98 3:14 PM Page 5-2

Special Circuit Descriptions
Samsung Electronics 5-3
5-1-5 Mirror Circuit
5-1-6 EFM Comparator
After RFI signal is amplified by mirror amp, mirror signal is held in peak and bottom circuit. The following of
100KHZ traverse is possible in peak hold circuit and the loss of track count due to defect is counted in bottom
hold circuit. Mirror output beyond 2KHz is. ÒLÓ at track on disc, ÒHÓ at interval between track on disc, ÒHÓ
when the defect beyond 1.4ms is detected.
The time constant for the mirror hold must be sufficiently large than of the traverse signal
The EFM comparator converts a RF signal into a binary signal
As the asymmertry due to variations in disc manufacturing can not be eilminated by thr AC coupling alone,
the reference voltage of EFM comparator is controlled utilizing the fact that the generation probability of 1,0
50% each in the binary EFM signals.
+
-
+
-
+
-
+
-
75
1
39
38K
96K
17K
1.5K
2.5K
17K
19K
IRF
MIRROR
MCP
Peak and
Bottom
Hold
+
-
+
-
+
-
77 1
39
40K
100K
100K
20K
85K
19K
RFI EFM
ASY
mm18(10) 3/23/98 3:14 PM Page 5-3

Special Circuit Descriptions
5-4 Samsung Electronics
5-1-7 Defect Circuit
5-1-8 APC Circuit
The RFO signal bottom, after being inverted, is held with two time constant of long and short.
The short time-constant bottom hold is done for a disc mirror defect more than 0.1msec, the long
time-constant bottom hold is done with the mirror level prior to the defect. By differentiating this with a
capacitor coupling and shifting the level, both signals are compared to generate the mirror defect detection
signal.
As the laser diode has large negative temperature characteristic in its optical output when driven with a
constant current on laser diode. Therefore, the output on processing monitor photo diode, must be a
controlled current for getting regularly output power, thus the APC (Auto Power Control) circuit is composed.
75K
43K
28K
75K
VC
37.5K
75
2
5 4
41
RFO
DCB
SSTOP/DFCT
DFCT
DCC2DCC1
+
-
+
-
BOTTOM
HOLD
BOTTOM
HOLD
43.5K LD
5.15K
150K
150K
150K
300K
0.75K
69 70
PD
LDON
PN
From Micom
+
-
+
-
mm18(10) 3/23/98 3:14 PM Page 5-4

Special Circuit Descriptions
Samsung Electronics 5-5
5-1-9 AGC Stability Circuit
5-1-10 Post Filter
5-1-11 Center Voltage Generation Circuit
The gain is adjusted by AGC Block with the function of maintainning the definite RF peak to peak level,
after the operation of RF envelop detection and comparing with reference voltage.
RFO level is kept stable in 1Vp-p, and input to EFM Slice.
The adjustment of audio output gain and the integration of possible de-emphasis output are executed by
the low pass filter. If the control by MUTE signal from micom exist, and when input signal absent, two
channel of right and left is builted in.
The Center Voltage is generated by using resistor dividing voltage.
75 78
76
IRF CAGC
ARF
EQUALIZEVCA
25K
CH2O
GC2O
GC1O
CH1O
25K
CH2I
GC2I
GC1I
GC1I
MUTEI (From Micom)
+
-
+
-
+
-
+
-
+
-
12
10
15
13
19
30K VC
30K
+
-
mm18(10) 3/23/98 3:14 PM Page 5-5