LG RAD125 User manual

MODEL: RAD125 (RAS125F)
SERVICE MANUAL
P/NO : AFN73250985 JANUARY, 2010 MODEL: RAD125 (RAS125F)
Website http://biz.lgservice.com
Internal Use Only
Mini Hi-Fi System
SERVICE MANUAL

1-1
[CONTENTS]
SECTION 1. GENERAL
• SERVICING PRECAUTIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
• ESD PRECAUTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
• SERVICE INFORMATION FOR EEPROM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5
•
PROGRAM DOWNLOAD GUIDE
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
• SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-8
SECTION 2. EXPLODED VIEWS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
• CABINET AND MAIN FRAME SECTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
• MECHANISM DECK SECTION (CDM-340). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3
• SPEAKER SECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5
• PACKING ACCESSORY SECTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6
SECTION 3. ELECTRICAL PART
• TROUBLESHOOTING GUIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
• DETAILS AND WAVEFORMS ON SYSTEM TEST AND DEBUGGING. . . . . . . . . . . . . . . 3-14
• WIRING DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-18
• BLOCK DIAGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-19
• CIRCUIT DIAGRAMS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-21
• CIRCUIT VOLTAGE CHART . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-31
• PRINTED CIRCUIT DIARGAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-33
SECTION 4. REPLACEMENT PARTS LIST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1

1-2
SERVICING PRECAUTIONS
NOTES REGARDING HANDLING OF THE PICK-UP
1. Notes for transport and storage
1) The pick-up should always be left in its conductive bag until immediately prior to use.
2) The pick-up should never be subjected to external pressure or impact.
2. Repair notes
1) The pick-up incorporates a strong magnet, and so should never be brought close to magnetic materials.
2) The pick-up should always be handled correctly and carefully, taking care to avoid external pressure and
impact. If it is subjected to strong pressure or impact, the result may be an operational malfunction and/or
damage to the printed-circuit board.
3) Each and every pick-up is already individually adjusted to a high degree of precision, and for that reason
the adjustment point and installation screws should absolutely never be touched.
4) Laser beams may damage the eyes!
Absolutely never permit laser beams to enter the eyes!
Also NEVER switch ON the power to the laser output part (lens, etc.) of the pick-up if it is damaged.
5) Cleaning the lens surface
If there is dust on the lens surface, the dust should be cleaned away by using an air bush (such as used
for camera lens). The lens is held by a delicate spring. When cleaning the lens surface, therefore, a cot-
ton swab should be used, taking care not to distort lens.
6) Never attempt to disassemble the pick-up.
Spring has excess pressure. If the lens is extremely dirty, apply isopropyl alcohol to the cotton swab.
(Do not use any other liquid cleaners, because they will damage the lens.) Take care not to use too much
of this alcohol on the swab, and do not allow the alcohol to get inside the pick-up.
Storage in conductive bag Drop impact
NEVER look directly at the laser beam, and don’t allow
contact with fingers or other exposed skin.
Magnet
How to hold the pick-up
Conductive Sheet
Cotton swab
Pressure
Pressure
SECTION 1. GENERAL

1-3
NOTES REGARDING COMPACT DISC PLAYER REPAIRS
1. Preparations
1) Compact disc players incorporate a great many ICs as well as the pick-up (laser diode). These components
are sensitive to, and easily affected by, static electricity. If such static electricity is high voltage, components
can be damaged, and for that reason components should be handled with care.
2) The pick-up is composed of many optical components and other high-precision components. Care must be
taken, therefore, to avoid repair or storage where the temperature or humidity is high, where strong magne-
tism is present, or where there is excessive dust.
2. Notes for repair
1) Before replacing a component part, first disconnect the power supply lead wire from the unit
2) All equipment, measuring instruments and tools must be grounded.
3) The workbench should be covered with a conductive sheet and grounded.
When removing the laser pick-up from its conductive bag, do not place the pick-up on the bag. (This is
because there is the possibility of damage by static electricity.)
4) To prevent AC leakage, the metal part of the soldering iron should be grounded.
5) Workers should be grounded by an armband (1 MΩ)
6) Care should be taken not to permit the laser pick-up to come in contact with clothing, in order to prevent
static electricity changes in the clothing to escape from the armband.
7) The laser beam from the pick-up should NEVER be directly facing the eyes or bare skin.
Resistor
(1 MΩ)Conductive
Sheet
Resistor
(1 MΩ)
Armband

1-4
ESD PRECAUTIONS
Electrostatically Sensitive Devices (ESD)
Some semiconductor (solid state) devices can be damaged easily by static electricity. Such components
commonly are called Electrostatically Sensitive Devices (ESD). Examples of typical ESD devices are integrated
circuits and some field-effect transistors and semiconductor chip components. The following techniques should
be used to help reduce the incidence of component damage caused by static electricity.
1. Immediately before handling any semiconductor component or semiconductor-equipped assembly, drain off
any electrostatic charge on your body by touching a known earth ground. Alternatively, obtain and wear a
commercially available discharging wrist strap device, which should be removed for potential shock reasons
prior to applying power to the unit under test.
2. After removing an electrical assembly equipped with ESD devices, place the assembly on a conductive surface
such as aluminum foil, to prevent electrostatic charge buildup or exposure of the assembly.
3. Use only a grounded-tip soldering iron to solder or unsolder ESD devices.
4. Use only an anti-static solder removal device. Some solder removal devices not classified as "anti-static" can
generate electrical charges sufficient to damage ESD devices.
5. Do not use freon-propelled chemicals. These can generate electrical charges sufficient to damage ESD
devices.
6. Do not remove a replacement ESD device from its protective package until immediately before you are
ready to install it. (Most replacement ESD devices are packaged with leads electrically shorted together by
conductive foam, aluminum foil or comparable conductive materials).
7. Immediately before removing the protective material from the leads of a replacement ESD device, touch the
protective material to the chassis or circuit assembly into which the device will by installed.
CAUTION : BE SURE NO POWER IS APPLIED TO THE CHASSIS OR CIRCUIT, AND OBSERVE ALL OTHER
SAFETY PRECAUTIONS.
8. Minimize bodily motions when handing unpackaged replacement ESD devices. (Otherwise harmless motion
such as the brushing together of your clothes fabric or the lifting of your foot from a carpeted floor can generate
static electricity sufficient to damage an ESD device).
CAUTION. GRAPHIC SYMBOLS
THE LIGHTNING FLASH WITH APROWHEAD SYMBOL. WITHIN AN EQUILATERAL TRIANGLE, IS
INTENDED TO ALERT THE SERVICE PERSONNEL TO THE PRESENCE OF UNINSULATED
“DANGEROUS VOLTAGE” THAT MAY BE OF SUFFICIENT MAGNITUDE TO CONSTITUTE A RISK OF
ELECTRIC SHOCK.
THE EXCLAMATION POINT WITHIN AN EQUILATERAL TRIANGLE IS INTENDED TO ALERT THE
SERVICE PERSONNEL TO THE PRESENCE OF IMPORTANT SAFETY INFORMATION IN SERVICE
LITERATURE.

1-5
SERVICE INFORMATION FOR EEPROM
POWER ON
FLD no disc status
Remote control ‘2’ + Front ‘STOP’
push same timing during 5s
FLD ‘OP-0….
Move to appropriate position
and make changes
with Rmc ‘skip, mode, play’ key.
Press STOP key
FLD ‘write ok’
Remote control ‘Fwd skip’ +
Front ‘STOP’ push same timing
FLD ‘E2P CLR’
Completed
NAME
OPT 0
OPT 1
OPT 2
OPT 3
OPT 4
OPT 5
OPT 6
OPT 7
OPT 8
OPT 9
DETECT NEW EEPROM
(OPTION EDIT SCREEN)
HEX
09
00
00
01
00
68
80
05
20
00

1-6
PROGRAM DOWNLOAD GUIDE
1. AUDIO PROGRAM
Download program file name must be RAD125.HEX
If security program (Water Wall) is activated on your PC, you must save the file to the usb storage
device and disable the security software, then download the file to your set.
Caution: When downloading the file, you should neither unplug the usb device, change to the other
function, nor power off the device. Usb device must be unplugged when the downloading
process is completed.
ON VFD DISPLAY SCREEN
NO USB
↓← Insert usb device at usb function
READ
↓
FIRMWARE
↓
WRITE 00 .. 100
↓
UPDATED
↓
POWER OFF AUTOMATICALLY ← When completed, remove usb device.

1-7
2. CD PROGRAM
Download program file name must be HB001_DATE_00.BIN
If security program (Water Wall) is activated on your PC, you must save the file to the usb storage
device and disable the security software, then download the file to your set.
Caution: When downloading the file, you should neither unplug the usb device, change to the other
function, nor power off the device. Usb device must be unplugged when the downloading
process is completed.
ON VFD DISPLAY SCREEN
NO USB
↓← Insert usb device at usb function
READ
↓
FIRMWARE
↓
FINISH
↓
UPDATED
↓
POWER OFF AUTOMATICALLY ← When completed, remove usb device.

1-8
SPECIFICATIONS
• GENERAL
Power supply Refer to main label
Power consumption Refer to main label
Net Weight 3.5 kg
External dimensions (W x H x D) 202 x 307 x 278 mm
Bus Power Supply (USB) DC 5 V 500 mA
Operating conditions Temperature 5 °C ~ 35 °C,
Operation status: Horizontal
Operating humidity 5 % ~ 85 %
Laser Semiconductor laser, wavelength 650 nm
• TUNER FM/AM [MW]
FM Tuning Range (87.5 ~ 108.0) MHz or (87.50 ~ 108.00) MHz
FM Intermediate Frequency 128 kHz
AM Tuning Range (522 ~ 1 620) kHz, (520 ~ 1 710) kHz or
(522 ~ 1 710) kHz
AM Intermediate Frequency 45 kHz
• AMPLIFIER
Output Power 60 W + 60 W (4 Ωat 1 kHz, THD 10 %)
• CD
Frequency Response (40 ~ 20 000) Hz
Signal-to-noise ratio 75 dB
Dynamic range 80 dB
• SPEAKERS
Front Speaker
Type 2 Way 2 Speaker
Impedance 4 Ω
Rated Input Power 60 W
Max. Input Power 120 W
Net Dimensions (W x H x D) 210 x 310 x 235 mm
Net Weight 2.6 kg
Designs and specifications are subject to change without prior notice

D
H
G
C
B
A
C
F
B
G
F
E
H
E
D
A
FRONT
SMPS
MAIN
USB
253
251
252
460
250
254
460
255L
256L
256R
255R
460
260L
460
264
451
A47
460
261 460
CABLE2
276
265
A26
460
460
A46
460
259
300
460
273 460
460
460
262
260R
A43
257
258A
258B
258C
274
A44
A42
SECTION 2. EXPLODED VIEWS
• CABINET AND MAIN FRAME SECTION (RAD125)
2-1 2-2
NOTES) THE EXCLAMATION POINT WITHIN AN
EQUILATERAL TRIANGLE IS INTENDED
TO ALERT THE SERVICE PERSONNEL
TO THE PRESENCE OF IMPORTANT
SAFETY INFORMATION IN SERVICE
LITERATURE.

2-3 2-4
• MECHANISM DECK SECTION (CDM-340)
018
439
014
013
017
019
026
015
431
020
A01
A02 001
002
003
016
036
010
012
012A
012A
012
432
432
037 A03
A26
SP : Non SVC Parts

2-5
• SPEAKER SECTION
1. FRONT SPEAKER (RAS125F)
A60

2-6
• PACKING ACCESSORY SECTION
825 FM Wire Antenna
900 Remote Control
803 Packing
803 Packing
808 Battery
802 Box
801 Instruction Ass'y
804 Bag
824 AM Loop Antenna
910 Battery Cover

3-1
SECTION 3. ELECTRICAL PART
AUDIO ELECTRICAL TROUBLESHOOTIHG GUIDE
1. POWER (SMPS)
No .3.7 VA
YES
Is the F901 normal? Replace the F901 (Use the same Fuse)
YES
NO
Is the BD901 normal? Replace the BD901
YES
NO
Is the TH901(TH902) normal? Replace the TH901
YES
NO
Is Vcc
(10 V ~ 18 V) supplied to
IC901 Pin7? Is the D904 normal?
YES
NO
Check or Replace D904
Is there
about 2.5 V at
IC903 Pin1? Replace the IC903
YES
NO
Is the D923 normal? Replace the D923
YES
NO
Is the D921 normal? Replace the D921
YES
NO
Is the D924 normal? Replace the D924
YES
NO
Is the D925 normal? Replace the D925
YES
NO
Is the D922 normal? Replace the D922
YES
NO
Power Line of I/O PCB is short
NO

3-2
No .PVDD
YES
Is the F901 normal? Replace the F901 (Use the same Fuse)
YES
NO
Is the BD901 normal? Replace the BD901
YES
NO
Is the TH901(TH902) normal? Replace the TH901
YES
YES
NO
Is Vcc
(10 V ~ 18 V) supplied to
IC902 Pin7? Is the D905 normal?
YES
NO
Check or Replace the D905
Check the power CTL "H" signal
from u-com or check PC902
Is the Q902 normal? Replace the Q902
Check or Replace the Q910
YES
NO
Is the D929 normal? Replace the D929
YES
NO
Is there about 2.5 V
at the IC904 Pin1? Replace the IC904
YES
NO
Is the Q910 Base "H"?
Power Line of Main PCB is short
NO
NO

3-3
No 12 V
Is Vcc
(15 V) supplied to Q953
Collector?
Check or Replace the D921
YES
YES
NO
Is the
13 V Supplied to Q953
Base?
Check the ‘P.CTL “H” signal
from μ-COM
YES
NO
Check or Replace the Q953
No 5 V
Is Vcc
(6 V) supplied to IC951
pin1?
Check or Replace the D923
YES
YES
NO
Is the
IC951 Pin4 “H”?
Check the ‘PWR CTL
“H”’ signal from μ-COM
YES
NO
Check or Replace the IC951

3-4
2. MICOM PART CHECK I
YES
MICOM PART
CHECK I
Check
P-SENS CN105
pin9,10
(3.7 VA)
Check
if input voltage of
IC101 is over
3.7 V
Check both
end voltage of IC105
(KIA7027)
Refer to SMPS
Troubleshooting
NO
NO
Check voltage of
IC102(LC87Fxxx) pin59,36
Check the periphery of
IC105 (KIA7027)
NO Replace
IC105
(KIA7027)
NO
Check if IC105 voltage is
over 3.5 V
OK OK
YES
YES
YES
YES
YES
No VFD
Is the D925 normal? Check or Replace the D925
YES
YES
NO
Is the ZD951 normal?
Is the Q951 normal?
Check or Replace the ZD951
Check or Replace the Q951
YES
YES
NO
NO
Check or Replace VFD

3-5
3. MIOM PART CHECK II
MICOM PART
CHECK II
Refer to SMPS Troubleshooting
NO
Check if
voltage of CN105 pin10
is 3.7 VA
Check if output of
D105(MBR0540) is 3.7 V
NO
Check
both end voltage of
D105, 102
Check if IC102_pin49 and
IC102_pin36,59 are 3.5 V
YES
Check D105, 102 Replace D105, 102
NONO
X101:32.768KHz
X102:9.8304MHz
Check the operation
OK
YES
YES
YES
YES
YES
OK
4. IC101(S24CS16A01)CHECK
CHECK
IC102 PIN47,48
Refer to Micom Troubleshooting
NO
pin47: DATA
pin48: CLK
Replace MICOM
NO
YES
Check MICOM
voltage 3.5 V
Check MICOM
YES
OK OK
YES
YES
NO

3-6
5. FLD DISPLAY CHECK
FLD DISPLAY CHECK
OK
YES
Check
CN104 pin1,2,3 voltage
input
YES
Check if both end voltage of
F1,F2 are over 3.4 V
VKK : over 26 V
NO
Refer to SMPS
YES
Check CN304
connection and power
pin14,15,16(VKK,FL-,FL+),
pin11(3.7 VA)
YES
OK
NO
Check CN304 connection
YES
Check each
pin voltage
YES
Check
IC501(ET6315) voltage
pin30 VKK:-26 V
pin13, 43:+5 V
YES
Check
IC102->IC501
data communication
pin pin
3pin->9pin STB
2pin->7pin DATA
4pin->8pin CLK
FLD light on?
OK
NO
If voltage is Not 3.7 VA,
check input and output of D501
YES
Check IC501
YES
NO
Replace IC501
NO IC102 : 2,3,4 pin
check data Input
YES
OK
Check IC102
YES
NO
Replace IC102
2pin data out
check data input
YES
YES
YES

3-7
6. PWM MODULATION CHECK
PWM MODULATION PART CHECK
Check
CN105 pin10 3.7 VA
CN106 pin3 3.3 VA
Check IC602(PS9850) VDD pin voltage
(16,24,29,32,35,40,48,61,64) 3.3 V
Check VDD Core pin voltage (1,21,43,57,59,60) 1.2 V
and X602(19.2 MHz)
NO
Refer to SMPS Troubleshooting
Check
X602(19.2 MHz)
operation
NO
Replace X602(19.2 MHz)
Check X602
(19.2 MHz)
OK
YES
NO
IC602(PS9850)
pin55 CLK input
check
Check
IC102(LC87Fxx)
pin41:PWM REST
pin45:PWM SDA
pin46:PWM SCL
output
NO
Replace R636,R637,R638
Check line
resistor output
RST: R636 / SCL: R637 /
SDA: R638
NO
YES
YES
YES
YES
YES
YES
OK
YES